MULTIVALENT AGONISTS, PARTIAL AGONISTS, INVERSE AGONISTS AND ANTAGONISTS OF THE D1 RECEPTORS

Abstract: Disclosed are multibinding compounds which are agonists, partial agonists, inverse agonists or antagonists of the D1 receptors, preferably, agonists of the D1 receptors, which are involved in neurological disorders. The multibinding compounds of this invention containing from 2 to 10 ligands covalently attached to one or more linkers. Each ligand is an agonist, partial agonist, inverse agonist or antagonist of the D1 receptors. The multibinding compounds of this invention are useful for the prophylaxis and treatment of various disorders such as hypertension, angina, congestive heart failure, renal failure (including chronic and acute renal failure), impotence, psychosexual disorders, Parkinson's disease and the like.

Description: MULTIVALENT AGONISTS, PARTIAL AGONISTS, INVERSE AGONISTS AND ANTAGONISTS OF THE Dj RECEPTORS BACKGROUND OF THE INVENTION Field ofthe Invention This invention relates to novel multibinding compounds (agents) that are agonists, partial agonists, inverse agonists and antagonists for the dopamine D, receptors, and to pharmaceutical compositions comprising such compounds. The compounds are useful medications for the prophylaxis and treatment of various disorders, such as hypertension, angina, congestive heart failure, renal failure (including chronic and acute renal failure), impotence, psychosexual disorders, Parkinson's disease and the like. Priority Information This application claims priority to U.S.S.N. 60/092,938, filed July 15, 1998 by Mathai Mammen and Daniel Marquess entitled "Novel agents that modulate receptors," and U.S.S.N. 60/088,466, filed June 8, 1998 by Mathai Mammen entitled "Novel therapeutic agents for cellular receptors." State ofthe Art. Dopamine is a neurotransmitter which participates in a variety of different functions mediated by the nervous system, including vision, movement, and behavior. See generally Cooper, J. et al., The Biochemical Basis of Neirropharmacolofiy, 161-195 (Oxford University Press, NY 3d Ed. 1978). The diverse physiological actions of dopamine are in turn mediated by its interaction with two basic types of G protein-coupled receptors: D, and D 2 , which respectively stimulate and inhibit the enzyme adenylyl cyclase. (Kebabian, J. and Calne, D., Nature 277, 93-96 (1979)). Alterations in the number or activity of these receptors may be a contributory factor m disease states such as Parkinson's disease (a movement disorder) and schizophrenia (a behavioral disorder) A great deal of information has accumulated on the biochemistry of the D, - and D 2 - dopamine receptors, and methods have been developed to solubihze and purify these receptor proteins See Senogles, S et al , Affinity Chromatography of the Anterior Pituitary D 2 Dopamine Receptor, Biochemistry 25, 749-753 (1986), Senogles, S et al , Puπfication and Characteπzation of the D 2 Dopamine Receptor from Bovme Anteπor Pituitary, J. Biol. Chem. 263, 18996-19002 (1988), and Gingrich, J et al , Affinity Chromatography of the D, Dopamine Receptor from Rat Corpus Stπatum, Biochemistry 27. 3907-3912 (1988) The D, dopamine receptor in several tissues appears to be a glycosylated membrane protein of about 72 kDa Amlaiky, N et al , Mol. Pharmacol. 31. 129-134 (1987), N ik, H et al , Biochemistry 27, 7594-7599 (1988) Dopamine occurs at high concentrations withm the nerve terminals in the basal ganglia of the mammalian brain In the early 1960's, the loss of stπatal dopamine was established as a chemical sign of Parkinson's Disease This deficiency is still thought to be pπmary to the etiology of the disease state L-DOPA (dihydroxyphenylalanme), when used in conjunction with a peπpheral aromatic ammo acid decarboxylase inhibitor, and often supplemented with antichohnergic agents, has been shown to be useful m the treatment of Parkinson's Disease It is theoπzed that the therapeutic response to L-DOPA is a result of the conversion of L-DOPA into dopamine within the stnatum, and thus the response is linked to stimulation of both the D, and D, receptors The success of L-DOPA therapy has led to the testing of other compounds capable of mimicking the post synaptic receptor actions of dopamine Such direct acting agents might offer the therapeutic advantages of greater potency, increased duration of action, or fewer side effects over L-DOPA For example, bromocπptine, the direct acting dopamine agonist most widely used in the treatment of Parkinson's Disease, lowers the amount of L-DOPA required to achieve the maximal therapeutic response and allows for a delay in the onset of L DOPA therapy However, the response to bromocπptine alone is not as great as that of L-DOPA Intellectual impairment m Alzheimeis disease (AD) is associated with a loss of cholmergic presynaptic markers in cortex and hippocampus (Arendt et al , Neuroscience 14 1-14, 1985, Mountjoy et al , Brain 107 507-518, 1984, Whitehouse et al , Ann. Neurol. 10 122-126, 1981) and pathological changes in the basal forebrain (Whitehouse et al , Sci≤nc≤ 215 1237-1239, 1982, Wilcock et al , J Neurol. Sci. 57 407-417, 1982) Accordingly, the use of dopamine receptor agonists has been proposed for use m treating vaπous neurodegenerative disorders Stimulation ofthe peπpheral D, receptors causes vasodilation, particulaily in the renal and mesenteπc vascular beds where large numbers of these receptors are found This accounts for the utility of D, agonists such as dopamine in treating renal disorders Dopamine has been used the treatment of shock, congestive heart failure renal failure, and vaπous neurological disorders, for example, dementia and neurodegenerative diseases (Olton and Wenk, In Psychopharmacology The Third Generation of Progress, ed by H Y Meltzer, pp 941 -953, Raven Press, New York, 1987) Dopamme's utility has been limited by its ability to cause vasoconstπction at higher concentrations, presumably due to its secondary effects on adrenergic receptors, and by its emetic effects due to D 2 stimulation Dopammergic agents that show selectivity for different receptor subtypes have been proposed for use m obtaining the anticipated physiological response separate from other possibly less desirable effects Agents selective for the peπpheral D, receptors have been proposed for use for many disorders treated with dopamine. For example, Fenoldopam has been used to increase renal perfusion and to treat diuresis, natriuresis, hypotension, congestive heart failure and tachycardia. Fenoldopam and other D, agonists are associated with various side effects, including headaches, flushing, nausea, and dizziness, in a significant minority of patients. Cuπent agents available as dopamine D, receptor agonists include dopamine, apomorphine, SKF 75670, CY 208-243, fenoldopam, abeorphine, A C6H12, dihydrexidinem and analogues and prodrugs thereof. Many of them have poor bioavailabihty and a high incidence of side effects. It would be advantageous to provide agents useful as agonists, partial agonists, inverse agonists and antagonists ofthe D, receptors which have higher bioavailabihty and which can be modified to control their side effect profiles. It would also be advantageous to provide compounds with increased potency, increased selectivity for the D, receptors, and controlled efficacy (i.e., degree of agonism at the D, receptors). The present invention provides such agents. SUMMARY OF THE INVENTION This invention is directed to novel multibinding compounds (agents) that are agonists, partial agonists, inverse agonists, and antagonists of the D, receptors. The multibinding compounds of this invention are useful in the treatment and prevention of disorders mediated by the D, receptors. In particular, D, agonists can be used to treat hypertension, angina, congestive heart failure, renal failure (including chronic and acute renal failure), impotence, psychosexual disorders, Parkinson's disease and the like. Additional disorders which can be treated include Alzheimer's disease, HIV disease, head trauma, Huntington's disease, Pick's disease, Creutzfeldt-Jakob disease and stroke. In treating various neurological disorders, in particular, neurodegenerative disorders, the D, agonists may function by increasing extracellular brain acetylcholine levels. The compounds are preferably D j agonists, which may also have affinity for the D 2 receptors Where the compounds have affinity for D 2 receptors, it is preferred that the ratio of affinity for the D, receptors versus the D 2 receptors is at least 1 1, more preferably, at least 10 1, and most preferably, at least 50 1 In some embodiments, for example, treatment of renal disorders, it can be preferable for the compounds to have affinity for the D 5 receptors as well, which are prevalent in the renal arteπes In one of its composition aspects, this invention provides a multibinding compound compπsing from 2 to 10 ligands covalently attached to one or more linkers wherein each of said ligands independently compnses an agonist, partial agonist or antagonist or the D, receptors, and pharmaceutically-acceptable salts thereof In another of its composition aspects, this invention provides a multibinding compound of formula I (L) p (X) q wherein each L is independently a ligand compπsing an agonist, partial agonist, inverse agonist or antagonist of the D, receptors, each X is independently a linker, p is an integer of from 2 to 10, and q is an integer of from 1 to 20, and pharmaceutically-acceptable salts thereof Preferably, q is less than ? in the multibinding compounds of this invention Preferably, when the ligand is an agonist of the D, receptors, each ligand, L, m the multibinding compound of formula I is independently selected from a compound of formulas IA-F, which are modeled after the structural formulae for dopamine, fenoldopam, SKF 75670, apomorphine, CY 208-243, and dihydrexidine, also shown below: D 'hydrexidin< wherein A is H, alkyl, substituted alkyl or a direct link to the linker, M, 20 are, independently, H or a direct link to the linker, wherein only one of A or M, 20 is a link to the linker, and analogs thereof Suitable analogs include alkylated, acylated, ammated, thiolated, hydroxylated, amidated, carboxylated, phosphorylated, sulfonated, and halogenated analogs thereof In still another of its composition aspects, this invention provides a multibinding compound of formula II L'— X'— L' II wherein each L' is independently a ligand comprising an agonist, partial agonist, inverse agonist or antagonist of the D, receptors and X' is a linker, and pharmaceutically-acceptable salts thereof Preferably, in the multibinding compound of formula II, each ligand, L\ is independently selected from the group consisting of ligands of the formulae 1A-F above and X' is a linker, and pharmaceutically-acceptable salts thereof Preferably, in the above embodiments, each linker (1 e , X, X' or X") independently has the formula -X a -Z-(Y a -Z) m -Y b -Z-X a - wherein m is an integer of from 0 to 20, X a at each separate occurrence is selected from the group-consisting of -0-, -S-, -NR-, -C(O , -C(O)O-, -C(O)NR-, -C(S), -C(S)0- -C(S)NR- or a covalent bond where R is as defined below, Z is at each separate occurrence is selected from the group consisting of alkylene, substituted alkylene, cycloalkylene, substituted cylcoalkylene, alkenylene, substituted alkenylene, alkynylene, substituted alkynylene, cycloalkenylene, substituted cycloalkenylene, arylene, heteroarylene, heterocyclene, or a covalent bond, Y a and Y b at each separate occurrence are selected from the group consistmg of -C(O)NR'-, -NR'C(O)-, -NR'C(O)NR'-, -C(=NR')-NR'-, -NR'-C(=NR')-, -NR'-C(O)-O-, -N=C(X a )-NR'-, -P(O)(OR')-O-, -S(O) n CR'R"-, -S(O) n -NR'-, -S-S- and a covalent bond, where n is 0, 1 or 2, and R, R' and R" at each separate occurrence are selected from the group consisting of hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, substituted alkenyl, cycloalkenyl, substituted cycloalkenyl, alkynyl, substituted alkynyl, aryl, heteroaryl and heterocyclic In yet another of its composition aspects, this invention provides a pharmaceutical composition compπsing a pharmaceutically acceptable carrier and an effective amount of a multibinding compound compπsing from 2 to 10 ligands covalently attached to one or more linkers wherein each of said ligands independently compπses an agonist, partial agonist, inverse agonist or antagonist of the D, receptors, and pharmaceutically-acceptable salts thereof This invention is also directed to pharmaceutical compositions comprising a pharmaceutically acceptable carrier and an effective amount of a multibinding compound of formula I or II The multibinding compounds of this invention are effective agonists, partial agonists, inverse agonists or antagonists of the D, receptors, which are involved in a number of disorders Accordingly, m one of its method aspects, this invention provides a method for treating vaπous disorders mediated by the D, receptors Such disorders include vaπous diseases such as hypertension, angma, congestive heart failure, renal failure (including chronic and acute renal failure), impotence, psychosexual disorders, Parkinson's disease and the like When used to treat neurological or renal disorders, for example, the method involves admimsteπng to a patient having a neurological or renal disorders a pharmaceutical composition compπsing a pharmaceutically-acceptable earner and a therapeutically-effective amount of a multibinding compound comprising from 2 to 10 ligands covalently attached to one or more linkers wherein each of said ligands independently comprises an agonist, partial agonist, inverse agonist or antagonist ofthe D, receptors, and pharmaceutically-acceptable salts thereof This invention is also directed to general synthetic methods for generating large hbraπes of diverse multimeπc compounds which multimeπc compounds aie candidates for possessing multibinding properties with respect to the D, receptors The diverse multimeπc compound hbraπes provided by this invention are synthesized by combining a linker or linkers with a ligand or ligands to provide for a library of multimeπc compounds wherein the linker and ligand each have complementary 7 functional groups permitting co\ alent linkage The library ot linkers is preferably selected to have diverse properties such as valency, lmkei length, linker geometry and πgidity, hydrophihcity or hydrophobicity, amphiphilicity, acidity, basicity and polaπzabihty and'Oi polaπzation The hbrarv of ligands is preferably selected to have diverse attachment points on the same ligand, different functional groups at the same site of otherwise the same ligand This invention is also directed to hbraπes of diverse multimeπc compounds which multimeπc compounds are candidates for possessing multibinding properties with respect to the D, receptors These libraries are prepared via the methods descπbed above and permit the rapid and efficient evaluation of what molecular constraints impart multibinding properties to a hgandor a class oi ligands targeting the D [ receptors Accordingly, m one of its method aspects, this invention is directed to a method for identifying multimeπc hgand compounds possessing multibinding properties with respect to the D, receptors which method compnses (a) identifying a ligand or a mixture of ligands which bind to the D, receptors wherein each ligand contains at least one reactive functionality, (b) identifying a library of linkers wherein each linker in said library compπses at least two functional groups having complementary reactivity to at least one of the reactive functional groups of the ligand, (c) prepaπng a multimeπc ligand compound library by combining at least two stoichiometric equivalents ofthe hgand or mixture of ligands identified in (a) with the library of linkers identified in (b) under conditions wherein the complementary functional groups react to form a covalent linkage between said linker and at least two of said ligands, and (d) assaying the multimeπc ligand compounds produced m (c) above to identify multimeric hgand compounds possessing multibinding properties In another of its method aspects, this invention is directed to a method for identifying multimeric ligand compounds possessing multibinding properties which method compπses (a) identifying a library of ligands which bind to D, receptors wherein each ligand contains at least one reactive functionality, (b) identifying a linker or mixture of linkers wherein each linker compπses at least two functional groups having complementary reactivity to at least one ofthe reactive functional groups ofthe ligand, (c) prepanng a multimeπc ligand compound library by combining at least two stoichiometπc equivalents of the librarv of ligands identified in (a) w ith the linker or mixture of linkers identified m (b) under conditions-wherein the complementary functional groups react to form a covalent linkage between said linker and at least two of said ligands, and (d) assaying the multimeπc hgand compounds produced m (c) abov e to identify multimenc ligand compounds possessing multibinding properties The preparation of the multimeπc ligand compound library is achieved by either the sequential or concurrent combination of the two or more stoichiometric equivalents ofthe ligands identified in (a) with the linkers identified in (b) Sequential addition is preferred when a mixture of different ligands is employed to ensure heteromeπc or multimeπc compounds are prepared Concurrent addition of the ligands occurs when at least a portion of the multimer comounds prepared are homomultimeπc compounds The assay protocols recited in (d) can be conducted on the multimeπc ligand compound library produced in (c) above, or preferably, each member of the library is isolated by preparative liquid chromatography mass spectrometry (LCMS) In one of its composition aspects, this invention is directed to a library of multimeπc hgand compounds which may possess multivalent properties which library is prepared by the method compπsing (a) identifying a ligand or a mixture of ligands which bind to the D receptors wherein each ligand contains at least one reactive functionality, (b) identifying a library of linkers wherein each linker in said library comprises at least two functional groups having complementary reactivity to at least one of the reactive functional groups of the ligand, and (c) prepanng a multimeπc ligand compound library by combining at least two stoichiometπc equivalents of the ligand or mixture of ligands identified m (a) with the library of linkers identified in (b) under conditions wherein the complementary functional groups react to form a covalent linkage between said linker and at least two of said ligands In another of its composition aspects, this invention is directed to a library of multimeric ligand compounds which bind to the D, receptors which may possess multivalent properties which library is prepared by the method compπsing (a) identifying a library of ligands which bind to the D, receptors wherein each hgand contains at least one reactive functionality, (b) identifying a linker or mixture of linkers wherein each linker compnses at least two functional groups having complementary reactivity to at least one ofthe reactive functional groups ofthe ligand, and (c) prepaπng a multimeπc ligand compound library by combining at least two stoichiometπc equivalents ofthe library of ligands identified in (a) with the linker or mixture of linkers identified in (b) under conditions wherein the complementary functional groups react to form a covalent linkage between said linker and at least two of said ligands In a prefeπed embodiment, the library of linkers employed in either the methods or the library aspects of this invention is selected from the group compπsing flexible linkers, πgid linkers, hydrophobic linkers, hydrophihc linkers, linkers of different geometry, acidic linkers, basic linkers, linkers of different polaπzabihty and/or polanzation and amphiphihc linkers For example, in one embodiment, each ofthe linkers m the linker library may compnse linkers of different chain length and/or having different complementary reactive groups Such linker lengths can preferably range from about 2 to 100A In anothei preferred embodiment, the ligand or mixture of ligands is selected to have reactive functionality at different sites on the ligands in order to provide for a range of onentations of said ligand on said multimeπc hgand compounds Such reactive functionality includes, by way of example, carboxylic acids, carboxylic acid halides, carboxyl esters, amines, halides, pseudohahdes isocyanates, vinyl unsaturation, ketones, aldehydes, thiols, alcohols, anhydndes, boronates and precursors thereof It is understood, of course, that the reactive functionality on the ligand is selected to be complementary to at least one of the reactive groups on the linker so that a covalent linkage can be formed between the linker and the hgand In other embodiments, the multimeπc ligand compound is homomeπc (1 e , each of the ligands is the same, although it may be attached at different points) or heteromeπc (1 e , at least one of the ligands is different from the other ligands) In addition to the combinatorial methods described herein, this invention provides for an iterative process for rationally evaluating what molecular constraints impart multibinding properties to a class of multimeπc compounds or ligands targeting the D, receptors Specifically, this method aspect is directed to a method for identifying multimenc ligand compounds possessing multibinding properties with respect to the D, receptors which method compπses (a) prepaπng a first collection or iteration of multimeric compounds which is prepared by contacting at least two stoichiometπc equivalents of the ligand or mixture of ligands which target the D receptors with a linker or mixture of linkers wherein said ligand or mixture of ligands compπses at least one reactive functionality and said linker or mixture of linkers compπses at least two functional groups having complementary reactivity to at least one of the reacti e functional groups of the hgand wherein said contacting is conducted under conditions wherein the complementary functional groups react to form a covalent linkage between said linker and at least two of said ligands, (b) assaying said first collection or iteration of multimeπc compounds to assess which if any of said multimeπc compounds possess multibinding properties, (c) repeating the process of (a) and (b) above until at least one multimeric compound is found to possess multibinding properties, (d) evaluating what molecular constraints imparted multibinding properties to the multimeπc compound or compounds found in the first iteration recited in (a)- (c) above, (e) creating a second collection or iteration of multimeric compounds which elaborates upon the particular molecular constraints imparting multibinding properties to the multimeπc compound or compounds found in said first iteiation (f) evaluating what molecular constraints imparted enhanced multibmdmg properties to the multimeπc compound or compounds found in the second collection or iteration recited in (e) above, (g) optionally repeating steps (e) and (f) to further elaborate upon said molecular constraints Preferably, steps (e) and (f) are repeated at least two times, more preferably at from 2-50 times, even more preferably from 3 to 50 times, and still more preferably at least 5-50 times BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates examples of D, receptor agonists Figure 2 illustrates examples of multibinding compounds compπsing 2 ligands attached in different forms to a linker Figure 3 illustrates examples of multibinding compounds comprising 3 ligands attached in different forms to a linker Figure 4 illustrates examples of multibinding compounds comprising 4 ligands attached in different forms to a linker Figure 5 illustrates examples of multibinding compounds compπsing 5-10 ligands attached in different forms to a linker Figures 6-8 are geneπc illustrations of the chemistry described in Examples 1-5, where the linker is a geneπc linker DETAILED DESCRIPTION OF THE INVENTION This invention is directed to multibinding compounds which are agonists partial agonists, inverse agonists or antagonists of the D, receptors, pharmaceutical compositions containing such compounds and methods for disorders mediated bv D, receptors When discussing such compounds, compositions or methods, the following terms have the following meanings unless otherwise indicated Any undefined terms have their art recognized meanings The term "alkyl" refers to a monoradical branched or unbranched saturated hydrocarbon chain preferably having from 1 to 40 carbon atoms, more preferably 1 to 10 carbon atoms, and even more preferably 1 to 6 carbon atoms This term is exemplified by groups such as methyl, ethyl, w-propyl, zso-propyl, n-butyl, iso- butyl, «-hexyl, n-decyl, tetradecyl, and the like The term "substituted alkyl" refers to an alkyl group as defined above, having from 1 to 5 substituents, and preferably 1 to 3 substituents, selected from the group consistmg of alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, acyl, acylamino, acyloxy, ammo, substituted ammo, ammoacyl, aminoacyloxy, oxyammoacvl, azido, cyano, halogen, hydroxyl, keto, thioketo, carboxyl, carboxylalkyl, thioaryloxy, thioheteroaryloxy, thioheterocyclooxy, thiol, thioalkoxy, substituted thioalkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy. heterocyclic, heterocyclooxy, hydroxyammo, alkoxyamino, nitro, -SO-alkyl, -SO-substituted alkyl, -SO-aryl, -SO-heteroaryl, -S0 2 -alkyl, -SO 2 -substιtuted alkyl, -SO : -aryl and -SO 2 -heteroaryl The term "alkylene" refers to a diradical of a branched or unbranched saturated hydrocarbon chain, preferably having from 1 to 40 carbon atoms, more preferably 1 to 10 carbon atoms and even more preferably 1 to 6 carbon atoms This term is exemplified by groups such as methylene (-CH 2 -), ethylene (-CH 2 CH 2 -), the propylene isomers (e g , -CH 2 CH 2 CH 2 - and -CH(CH 3 )CH 2 -) and The term "substituted alkylene" refers to an alkylene group, as defined above, having from 1 to 5 substituents, and preferably 1 to 3 substituents, selected from the group consisting of alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, acyl, acylamino, acyloxy, amino, substituted amino, aminoacyl, aminoacyloxy, oxyaminoacyl, azido, cyano, halogen, hydroxyl, keto, thioketo, carboxyl, carboxylalkyl, thioaryloxy, thioheteroaryloxy, thioheterocyclooxy, thiol, thioalkoxy, substituted thioalkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocyclic, heterocyclooxy, hydroxyamino, alkoxyamino, nitro, -SO-alkyl, -SO-substituted alkyl, -SO-aryl, - SO-heteroaryl, -SO 2 -alkyl, -SO 2 -substituted alkyl, -SO 2 -aryl and -SO 2 -heteroaryl. Additionally, such substituted alkylene groups include those where 2 substituents on the alkylene group are fused to form one or more cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, aryl, heterocyclic or heteroaryl groups fused to the alkylene group. Preferably such fused groups contain from 1 to 3 fused ring structures. The term "alkaryl" refers to the groups -alkylene-aryl and -substituted alkylene-aryl where alkylene, substituted alkylene and aryl are defined herein. Such alkaryl groups are exemplified by benzyl, phenethyl and the like. The term "alkoxy" refers to the groups alkyl-O-, alkenyl-O-, cycloalkyl-0-, cycloalkenyl-O-, and alkynyl-O-, where alkyl, alkenyl, cycloalkyl, cycloalkenyl, and alkynyl are as defined herein. Prefeπed alkoxy groups are alkyl-O- and include, by way of example, methoxy, ethoxy, n-propoxy, ύopropoxy, w-butoxy, tert-butoxy, .sec-butoxy, «-pentoxy, «-hexoxy, 1 ,2-dimethylbutoxy, and the like. The term "substituted alkoxy" refers to the groups substituted alkyl-O-, substituted alkenyl-O-, substituted cycloalkyl-0-, substituted cycloalkenyl-O-, and substituted alkynyl-O- where substituted alkyl, substituted alkenyl, substituted cycloalkyl, substituted cycloalkenyl and substituted alkynyl are as defined herein. The term "alkylalkoxy" refers to the groups -alkylene-O-alkyl, alkylene-O-substituted alkyl, substituted alkylene-O-alkyl and substituted alkylene-O-substituted alkyl wherein alkyl, substituted alkyl, alkylene and substituted alkylene are as defined herein Prefeπed alkylalkoxy groups are alkylene-O-alkyl and include, by way of example, methylenemethoxy (-CH 2 OCH 3 ), ethylenemethoxy (-CH 2 CH 2 OCH,), «-propylene-«o-propoxy (-CH 2 CH 2 CH 2 OCH(CH 3 ) 2 ), methylene-t-butoxy (-CH 2 -0-C(CH 3 ) 3 ) and the like The term "alkylthioalkoxy" refers to the group -alkylene-S-alkyl, alkylene-S-substituted alkyl, substituted alkylene-S-alkyl and substituted alkylene- S-substituted alkyl wherein alkyl, substituted alkyl, alkylene and substituted alkylene are as defined herein Preferred alkylthioalkoxy groups are alkvlene-S- alkyl and include, by way of example, methylenethiomethoxy (-CH 2 SCH 3 ), ethylenethiomethoxy (-CH 2 CH 2 SCH 3 ), (-CH 2 CH 2 CH 2 SCH(CH 3 ) 2 ), methylene-t-thiobutoxy (-CH 2 SC(CH 3 ) 3 ) and the like The term "alkenyl" refers to a monoradical of a branched or unbranched unsaturated hydrocarbon group preferably having from 2 to 40 carbon atoms, more preferably 2 to 10 carbon atoms and even more preferablv 2 to 6 carbon atoms and having at least 1 and preferably from 1-6 sites of vinyl unsaturation Preferred alkenyl groups include ethenyl (-CH=CH 2 ), «-propenyl (-CH 2 CH=CH 2 ), /5o-propenyl (-C(CH 3 )=CH 2 ), and the like The term "substituted alkenyl" refers to an alkenyl group as defined abov e having from 1 to 5 substituents, and preferably 1 to 3 substituents, selected from the group consistmg of alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, acyl, acylamino, acyloxy, ammo, substituted ammo, ammoacyl, aminoacyloxy, oxyaminoacyl, azido, cyano halogen, hydroxyl, keto, thioketo, carboxyl, carboxylalkyl, thioaryloxy, thioheteroaryloxy, thioheterocyclooxy, thiol, thioalkoxy, substituted thioalkox , aryl, aryloxy, heteroaryl, heteroaryloxy, heterocyclic, heterocyclooxy, hydroxyammo, alkoxyammo, nitro, -SO-alkyl, -SO-substituted alkyl, -SO-aryl, -SO-heteroaryl, -SO 2 -alkyl, -SO 2 -substιtuted alkyl, -S0 2 -aryl and -SO 2 -heteroaryl The term "alkenylene" refers to a diradical of a branched or unbranched unsaturated hydrocarbon group preferably having from 2 to 40 carbon atoms, more preferably 2 to 10 carbon atoms and even more preferably 2 to 6 carbon atoms and having at least 1 and preferably from 1-6 sites of vinyl unsaturation This term is exemplified by groups such as ethenylene (-CH=CH-), the propenylene isomers (e g , -CH 2 CH=CH- and -C(CH 3 )=CH-) and the like The term "substituted alkenylene" refers to an alkenylene group as defined above having from 1 to 5 substituents, and preferably from 1 to 3 substituents, selected from the group consistmg of alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, acyl, acylammo, acyloxy, ammo, substituted ammo, ammoacyl, aminoacyloxy, oxyammoacyl, azido, cyano, halogen, hydroxyl, keto, thioketo, carboxyl, carboxylalkyl, thioaryloxy, thioheteroaryloxy, thioheterocyclooxy, thiol, thioalkoxy, substituted thioalkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocyclic, , hydroxyammo, alkoxyammo, nitro, -SO-alkyl, -SO-substituted alkyl, -SO-ary l - SO-heteroaryl, -S0 2 -alkyl, -S0 2 -substιtuted alkyl, -SO,-aryl and -S0 2 -heteroar l Additionally, such substituted alkenylene groups include those where 2 substituents on the alkenylene group are fused to form one or more cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, aryl, heterocyclic oi heteroaryl groups fused to the alkenylene group The term "alkynyl" refers to a monoradical of an unsaturated hydrocarbon preferably having from 2 to 40 carbon atoms, more preferably 2 to 20 carbon atoms and even more preferably 2 to 6 carbon atoms and having at least 1 and preferably from 1-6 sites of acetylene (triple bond) unsaturation Prefeπed alkynyl groups include ethynyl (-C≡CH), propargyl (-CH 2 C≡CH) and the like W wOυ 9 y 9 y /6o3 j 9y9y3. j PCT/US99/12778 -21- The term "substituted alkynyl" refers to an alkynyl group as defined above having from 1 to 5 substituents, and preferably 1 to 3 substituents, selected from the group consisting of alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, acyl, acylammo, acyloxy, 5 ammo, substituted ammo, ammoacyl, aminoacyloxy, oxyammoacyl, azido, cyano, halogen, hydroxyl, keto, thioketo, carboxyl, carboxylalkyl, thioaryloxy, thiohetero aryloxy, thioheterocyclooxy, thiol, thioalkoxy, substituted thioalkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocyclic, heterocyclooxy, hydroxyammo, alkoxyammo, nitro, -SO-alkyl, -SO-substituted alkyl, -SO-aryl, 10 -SO-heteroaryl, -SO 2 -alkyl, -SO 2 -substιtuted alkyl, -S0 2 -aryl and -S0 2 -heteroaryl The term "alkynylene" refers to a diradical of an unsaturated hydrocarbon preferably having from 2 to 40 carbon atoms, more preferably 2 to 10 carbon atoms and even more preferably 2 to 6 carbon atoms and having at least 1 and 15 preferably from 1-6 sites of acetylene (tπple bond) unsaturation Prefeπed alkynylene groups include ethynylene (-C≡C-), propargylene (-CH 2 C≡C-) and the like The term "substituted alkynylene" refers to an alkynylene group as defined 20 above having from 1 to 5 substituents, and preferably 1 to 3 substituents, selected from the group consisting of alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, acyl, acylammo, acyloxy, ammo, substituted ammo, ammoacyl, aminoacyloxy, oxyammoacyl, azido, cyano, halogen, hydroxyl, keto, thioketo, carboxyl, carboxylalkyl, thioaryloxy, 25 thioheteroaryloxy, thioheterocyclooxy, thiol, thioalkoxy, substituted thioalkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocyclic, heterocyclooxy, hydroxyammo, alkoxyammo, nitro, -SO-alkyl, -SO-substitute Lalkyl, -SO-aryl, - SO-heteroaryl, -SO 2 -alkyl, -SO 2 -substιtuted alkyl, -S0 2 -aryl and -SO 2 -heteroaryl 30 The term "acyl" refers to the groups HC(O)-, alkyl-C(O)-, substituted alkyl- C(O)-, cycloalkyl-C(O)-, substituted cycloalkyl-C(O)-, cycloalkenyl-C(O)-, W wOυ 9 v9v/ / 6o3 j 9 y 9«3 PCT/US99/12778 -22- substituted cycloalkenyl-C(O)-, aryl-C(O)-, heteroaryl-C(O)- and heterocychc- C(0)- where alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, aryl, heteroaryl and heterocyclic are as defined herein. The term "acylamino" or "aminocarbonyl" refers to the group -C(0)NRR where each R is independently hydrogen, alkyl, substituted alkyl, aryl, heteroaryl, heterocyclic or where both R groups are joined to form a heterocyclic group (e.g., morpholino) wherein alkyl, substituted alkyl, aryl, heteroaryl and heterocyclic are 10 as defined herein. The term "aminoacyl" refers to the group -NRC(0)R where each R is independently hydrogen, alkyl, substituted alkyl, aryl, heteroaryl, or heterocyclic wherein alkyl, substituted alkyl, aryl, heteroaryl and heterocyclic are as defined 15 herein. The term "aminoacyloxy" or "alkoxycarbonylamino" refers to the group -NRC(O)OR where each R is independently hydrogen, alkyl, substituted alkyl, aryl, heteroaryl, or heterocyclic wherein alkyl, substituted alkyl, aryl, heteroaryl 20 and heterocyclic are as defined herein. The term "acyloxy" refers to the groups alkyl-C(0)0-, substituted alkyl- C(O)O-, cycloalkyl-C(O)0-, substituted cycloalkyl-C(0)0-, aryl-C(0)0-, heteroaryl-C(O)O-, and heterocyclic-C(0)O- wherein alkyl, substituted alkyl, 25 cycloalkyl, substituted cycloalkyl, aryl, heteroaryl, and heterocyclic are as defined herein. The term "aryl" refers to an unsaturated aromatic carbocyclic group of from 6 to 20 carbon atoms having a single ring (e.g., phenyl) or multiple condensed 30 (fused) rings (e.g., naphthyl or anthryl). Prefeπed aryls include phenyl, naphthyl and the like. Unless otherwise constrained by the definition for the aryl substituent, such aryl groups can optionally be substituted with from 1 to 5 substituents, preferably 1 to 3 substituents, selected from the group consisting of acyloxy, hydroxy, thiol acyl, alkyl, alkoxy, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, substituted alkyl, substituted alkoxy, substituted alkenyl, substituted alkynyl, substituted cycloalkyl, substituted cycloalkenyl, ammo, substituted ammo, ammoacyl, acylammo, alkaryl, aryl, aryloxy, azido, carboxyl, carboxylalkyl, cyano, halo, nitro, heteroaryl, heteroaryloxy, heterocyclic, heterocyclooxy, aminoacyloxy, oxyacylammo, thioalkoxy, substituted thioalkoxy, thioaryloxy, thioheteroaryloxy, -SO-alkyl, -SO- substituted alkyl, -SO-aryl, -SO-heteroaryl, -S0 2 -alkyl, -S0 2 -substituted alkyl, - S0 2 -aryl, -SO 2 -heteroaryl and tnhalomethyl Prefeπed aryl substituents include alkyl, alkoxy, halo, cyano, nitro, tnhalomethyl, and thioalkoxy The term "aryloxy" refers to the group aryl O- wherein the aryl group is as defined above including optionally substituted aryl groups as also defined above The term "arylene" refers to the diradical derived from aryl (including substituted aryl) as defined above and is exemplified by 1,2-phenylene, 1,3- phenylene, 1 ,4-phenylene, 1 ,2-naphthylene and the like The term "ammo" refers to the group -NH-, The term "substituted ammo refers to the group -NRR where each R is independently selected from the group consisting of hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, substituted alkenyl. cycloalken l substituted cycloalkenyl, alkynyl, substituted alkynyl, aryl, heteroaryl and heterocyclic provided that both R's are not hydrogen The term "carboxyalkyl" or "alkoxycarbonyl" refers to the groups "-C(O)O-alkyl", "-C(O)O-substιtuted alkyl", "-C(O)0-cycloalkyl", "-C(0)0- substituted cycloalkyl", "-C(0)0-alkenyl", "-C(0)0-substituted alkenyl". * 5 " My *> PCT US99/12778 -24- "-C(O)O-alkynyl" and "-C(O)O-substιtuted alkynyl" where alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, substituted alkenyl, alkynyl and substituted alkynyl alkynyl are as defined herein The term "cycloalkyl" refers to cyclic alkyl groups of from 3 to 20 carbon atoms having a single cyclic πng or multiple condensed πngs Such cycloalkyl groups include, by way of example, single πng structures such as cyclopropyl, cyclobutyl, cyclopentyl, cyclooctyl, and the like, or multiple ring structures such as adamantanyl, and the like 0 The term "substituted cycloalkyl" refers to cycloalkyl groups having from 1 to 5 substituents, and preferably 1 to 3 substituents, selected from the group consisting of alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, acyl, acylammo, acyloxy, amino, 5 substituted ammo, ammoacyl, aminoacyloxy, oxyammoacyl, azido, cyano, halogen, hydroxyl, keto, thioketo, carboxyl, carboxylalkyl, thioaryloxy, thioheteroaryloxy, thioheterocyclooxy, thiol, thioalkoxy, substituted thioalkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocyclic, heterocyclooxy, hydroxyammo, alkoxyammo, nitro, -SO-alkyl, -SO-substituted alkyl, -SO-aryl 0 -SO-heteroaryl, -S0 2 -alkyl, -SO 2 -substιtuted alkyl, -S0 2 -aryl and -SO-,-heteroarvl The term "cycloalkenyl" refers to cyclic alkenyl groups of from 4 to 20 carbon atoms having a single cyclic ring and at least one point of internal unsaturation Examples of suitable cycloalkenyl groups include, for instance, 5 cyclobut-2-enyl, cyclopent-3-enyl, cyclooct-3-enyl and the like The term "substituted cycloalkenyl" refers to cycloalkenyl groups having from 1 to 5 substituents, and preferably 1 to 3 substituents, selected from the gioup consisting of alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, 0 cycloalkenyl, substituted cycloalkenyl, acyl, acylammo, acyloxy, ammo, substituted ammo, ammoacyl, aminoacyloxy, oxyammoacyl, azido, cyano, halogen, hydroxyl, keto, thioketo, carboxyl, carboxylalkyl, thioaryloxy, thioheteroaryloxy, thioheterocyclooxy, thiol, thioalkoxy, substituted thioalkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocyclic, heterocyclooxy, hydroxyammo, alkoxyammo, nitro, -SO-alkyl, -SO-substituted alkyl, -SO-aryl, -SO-heteroaryl, -S0 2 -alkyl, -SO 2 -substιtuted alkyl, -S0 2 -aryl and -S0 2 -heteroaryl The term "halo" or "halogen" refers to fluoro, chloro, bromo and lodo The term "heteroaryl" refers to an aromatic group of from 1 to 15 carbon atoms and 1 to 4 heteroatoms selected from oxygen, nitrogen and sulfur withm at least one ring (if there is more than one ring) Unless otherwise constrained by the definition for the heteroaryl substituent, such heteroaryl groups can be optionally substituted with 1 to 5 substituents, preferably 1 to 3 substituents, selected from the group consisting of acyloxy, hydroxy, thiol, acyl, alkyl, alkoxy, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, substituted alkyl, substituted alkoxy, substituted alkenyl, substituted alkynyl, substituted cycloalkyl, substituted cycloalkenyl, ammo, substituted ammo ammoacyl, acylammo, alkaryl, aryl, aryloxy, azido, carboxyl, carboxylalkyl, cyano. halo, nitro, heteroaryl, heteroaryloxy, heterocyclic, heterocyclooxv , aminoacyloxy, oxyacylamino, thioalkoxy, substituted thioalkoxy, thioaryloxy, thioheteroaryloxy, -SO-alkyl, -SO-substituted alkyl, -SO-aryl, -SO-heteroaryl, - SO 2 -alkyl, -SO 2 -substιtuted alkyl, -SO 2 -aryl, -SO 2 -heteroaryl and tnhalomethyl Prefeπed aryl substituents include alkyl, alkoxy, halo, cyano, nitro, tnhalomethyl and thioalkoxy Such heteroaryl groups can have a single ring (e g , pyπdyl or furyl) or multiple condensed rings (e g , mdohzmyl or benzothienyl) Prefeπed heteroaryls include pyπdyl, pyrrolyl and furyl The term "heteroaryloxy" refers to the group heteroaryl-O- The term "heteroarylene" refers to the diradical group deπved from heteroaryl (including substituted heteroaryl), as defined above, and is exemplified by the groups 2,6-pyπdylene, 2,4-pyπdιylene, 1,2-quιnohnylene, 1 ,8- qumolmylene, 1,4-benzofuranylene, 2,5-pyπdnylene, 2,5-ιndolenyl and the like The term "heterocycle" or "heterocyclic" refers to a monoradical saturated or unsaturated group having a single πng or multiple condensed nngs, from 1 to 40 carbon atoms and from 1 to 10 hetero atoms, preferably 1 to 4 heteroatoms, selected from nitrogen, sulfur, phosphorus, and/or oxygen within the ring Unless otherwise constrained by the definition for the heterocyclic substituent, such heterocyclic groups can be optionally substituted with 1 to 5, and preferably 1 to 3 substituents, selected from the group consisting of alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, acyl, acylammo, acyloxy, ammo, substituted ammo, ammoacyl, aminoacyloxy, oxyammoacyl, azido, cyano, halogen, hydroxyl, keto, thioketo, carboxyl, carboxylalkyl, thioaryloxy, thioheteroaryloxy, thioheterocyclooxy, thiol, thioalkoxy, substituted thioalkoxy, aryl, aryloxy, heteroaryl. heteroaryloxy, heterocyclic, heterocyclooxy, hydroxyammo, alkoxyammo, nitro, -SO-alkyl, -SO- substituted alkyl, -SO-aryl, -SO-heteroaryl, -S0 2 -alkyl, -SO 2 -substιtuted alkyl, - SO 2 -aryl and -S0 2 -heteroaryl Such heterocyclic groups can have a single ring or multiple condensed nngs Prefeπed heterocyclics include morpholino, pipendmyl Examples of nitrogen heterocycles and heteroaryls include, but are not limited to, pyrrole, imidazole, pyrazole, pyridine, pyrazine, pynmidme, pyridazine, mdohzine, isoindole, indole, mdazole, punne, quinohzme, lsoqumolme, quinoline, phthalazine, naphthylpyπdme, quinoxaline, qumazohne, cmnolme, pteπdme, carbazole, carbohne, phenanthndme, acndme, phenanthrohne, isothiazole, phenazme, isoxazole, phenoxazme, phenothiazme, lmidazohdme, lmidazolme, piperidine, piperazine, mdolme, morpholino, pipendmyl, tetrahydrofuranyl, and the like as well as N-alkoxy-mtrogen containing heterocycles The term "heterocyclooxy" refers to the group heterocychc-O- The term "thioheterocyclooxy" refers to the group heterocychc-S- The term "heterocyclene" refers to the diradical group formed from a heterocycle, as defined herein, and is exemplified by the groups 2,6-morphohno, 2,5-morpholmo and the like The term "oxyacylammo" or "ammocarbonyloxy" refers to the group -OC(O)NRR where each R is independently hydrogen, alkyl, substituted alkyl, aryl, heteroaryl, or heterocyclic wherein alky l substituted alkyl, arvl, heteroaryl and heterocyclic are as defined herein The term "spiro-attached cycloalkyl group" refers to a cvcloalkyl group attached to another πng via one carbon atom common to both rings The term "thiol" refers to the group -SH The term "thioalkoxy" refers to the group -S-alkyl The term "substituted thioalkoxy" refers to the group -S-substituted alk l The term "thioaryloxy" refers to the group ar\ l-S- herein the an, 1 group is as defined above including optionally substituted aryl groups also defined abov The term "thioheteroaryloxy" refers to the group heteroaryl-S- wherein the heteroaryl group is as defined above including optionally substituted aryl groups as also defined above As to any of the above groups which contain one or more substituents, it is understood, of course, that such groups do not contain any substitution or substitution patterns which are steπcally impractical and/or synthetically non- feasible In addition, the compounds of this invention include all stereochemical isomers aπsing from the substitution of these compounds, whether the isomers are those ansmg in the ligands, the linkers, or the multivalent constructs including the ligands and linkers The term "pharmaceutically-acceptable salt" refers to salts which retain the biological effectiveness and properties of the multibinding compounds of this invention and which are not biologically or otherwise undesirable In many cases the multibinding compounds of this invention are capable of forming acid and/or base salts by virtue of the presence of ammo and/or carboxyl groups or groups similar thereto Pharmaceutically-acceptable base addition salts can be prepared from inorganic and organic bases Salts denved from inorganic bases, include by way of example only, sodium, potassium, lithium, ammonium, calcium and magnesium salts Salts denved from organic bases include, but are not limited to, salts of pnmary, secondary and tertiary ammes, such as alkyl ammes, dialkyl ammes, tπalkyl ammes, substituted alkyl ammes, dι(substιtuted alkyl) ammes, tπ(substιtuted alkyl) ammes, alkenyl amines, dialkenyl ammes, tnalkenyl ammes, substituted alkenyl ammes, dι(substιtuted alkenyl) ammes, tn(substιtuted alkenyl) amines, cycloalkyl ammes, dι(cycloalkyl) ammes, tπ(cycloalkyl) ammes, substituted cycloalkyl ammes, disubstituted cycloalkyl amme, tπsubstituted cycloalkyl ammes, cycloalkenyl ammes, dι(cycloalkenyl) am es, tπ(cycloalkenyl) ammes, substituted cycloalkenyl ammes, disubstituted cycloalkenyl amme, tπsubstituted cycloalkenyl ammes, aryl ammes, diaryl ammes, tnaryl amines, heteroaryl amines, diheteroaryl ammes, tnheteroaryl ammes, heterocyclic ammes, diheterocychc ammes, tnheterocychc ammes, mixed di- and tn-ammes where at least two ofthe substituents on the amine are different and are selected from the group consisting of alkyl, substituted alkyl, alkenyl, substituted alkenyl, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, aryl, heteroaryl, heterocyclic, and the like Also included are ammes where the two or three substituents, together with the ammo nitrogen, form a heterocyclic or heteroaryl group Examples of suitable ammes include, by way of example only, isopropylamine, tπmethyl amme, diethyl amme, tn(z.sσ-propyl) amme, tn(n- propyl) amme, ethanolarmne, 2-dιmethylammoethanol, tromethamine, lysine, argimne, histidine, caffeine, procaine, hydrabamme, choline, betame, ethylenediamine, glucosam e, N-alkylglucammes, theobromme, puπnes, piperazine, pipeπdme, morphohne, N-ethylpipeπdme, and the like It should also be understood that other carboxylic acid derivatives would be useful in the practice of this invention, for example, carboxylic acid amides, including carboxamides, lower alkyl carboxamides. dialkyl carboxamides, and the like Pharmaceutically acceptable acid addition salts may be prepared from inorganic and organic acids Salts derived from inorganic acids include hydrochloric acid, hydrobromic acid, sulfunc acid, mtπc acid, phosphonc acid, and the like Salts derived from organic acids include acetic acid, propiomc acid, glycohc acid, pyruvic acid, oxalic acid, malic acid, malomc acid, succmic acid maleic acid, fumaπc acid, tartaπc acid, citπc acid, benzoic acid, cinnamic acid, mandehc acid, methanesulfomc acid, ethanesulfomc acidj /j-toluene-sulfomc acid salicylic acid, and the like The term "pharmaceutically-acceptable cation" refers to the cation of a pharmaceutically-acceptable salt The term "protecting group" or "blocking group" refers to any group which when bound to one or more hydroxyl, thiol, ammo or carboxyl groups ofthe compounds (including intermediates thereof) prevents reactions from occuπing at these groups and which protecting group can be removed by conventional chemical or enzymatic steps to reestablish the hydroxyl, thiol, ammo or carboxyl group The particular removable blocking group employed is not cntical and prefeπed removable hydroxyl blocking groups include conventional substituents such as allyl, benzyl, acetyl, chloroacetyl, thiobenzyl, benzyhdme, phenacyl, t-butyl- diphenylsilyl and any other group that can be introduced chemically onto a hydroxyl functionality and later selectively removed either by chemical or enzymatic methods m mild conditions compatible with the nature ofthe product Prefeπed removable thiol blocking groups include disulfide groups, acyl groups, benzyl groups, and the like Prefeπed removable ammo blocking groups include conventional substituents such as t-butyoxycarbonyl (t-BOC), benzyloxycarbonyl (CBZ), fluorenylmethoxycarbonyl (FMOC), allyloxycarbonyl (ALOC), and the like which can be removed by conventional conditions compatible with the nature of the product Prefeπed carboxyl protecting groups include esters such as methyl, ethyl, propyl, t-butyl etc which can be removed by mild conditions compatible with the nature of the product The term "optional" or "optionally" means that the subsequently descπbed event, circumstance or substituent may or may not occur, and-that the description includes instances where said event or circumstance occurs and instances where it does not The term "ligand" as used herein denotes a compound that is an agonist, partial agonist, inverse agonist or antagonist of the D, receptors The specific region or regions of the ligand that is (are) recognized by the receptoi is designated as the "ligand domain" A ligand may be either capable of binding to a receptor by itself, or may require the presence of one or more non-hgand components for binding (e g , Ca +2 , Mg +2 or a water molecule is required for the binding of a ligand to various hgand binding sites) Examples of ligands useful in this invention are described herein Those skilled in the art will appreciate that portions of the ligand structure that are not essential for specific molecular recognition and binding activity may be varied substantially, replaced or substituted with unrelated structures (for example, with ancillary groups as defined below) and, m some cases, omitted entirely without affecting the binding interaction The pπmaiy requirement for a ligand is that it has a ligand domain as defined above It is undei stood that the term ligand is not intended to be limited to compounds known to be useful in binding to D, receptors (e.g , known drugs) Those skilled in the art will understand that the term ligand can equally apply to a molecule that is not normally associated with receptor binding properties In addition, it should be noted that ligands that exhibit marginal activity or lack useful activity as monomers can be highly active as multivalent compounds because of the benefits confeπed by multivalency The term "multibinding compound or agent" refers to a compound that is capable of multivalency, as defined below, and which has 2-10 ligands covalently bound to one or more linkers which may be the same or different Multibinding compounds provide a biological and/or therapeutic effect greater than the aggregate of unlinked ligands equivalent thereto which are made available for binding That is to say that the biological and/or therapeutic effect of the ligands attached to the multibinding compound is greater than that achieved by the same amount of unlinked ligands made available for binding to the hgand binding sites (receptors) The phrase "increased biological or therapeutic effect" includes for example increased affinity, increased selectivity for target, increased specificity for target, increased potency, increased efficacy, decreased toxicity, improved duration of activity or action, decreased side effects, increased therapeutic index, improved bioavaihbity, improved pharmacokmetics, improved activity spect m, and the like The multibinding compounds of this invention will exhibit at least one and preferably more than one ofthe above-mentioned effects The term "potency" refers to the minimum concentration at which a ligand is able to achieve a desirable biological or therapeutic effect The potency of a ligand is typically proportional to its affinity for its ligand binding site In some cases, the potency may be non-lmearly correlated with its affinity In comparing the potency of two drugs, e g , a multibinding agent and the aggregate of its unlinked ligand, the dose-response curve of each is determined under identical test conditions (e g , in an in vitro or in vivo assay, in an appropriate animal model) The finding that the multibinding agent produces an equivalent biological or therapeutic effect at a lower concentration than the aggregate unlinked ligand is indicative of enhanced potency The term "umvalency" as used herein refers to a single binding interaction between one ligand as defined herein with one ligand binding site as defined herein It should be noted that a compound having multiple copies of a hgand (oi ligands) exhibit umvalency when only one ligand is interacting with a ligand binding site Examples of umvalent interactions are depicted below The term "multivalency" as used herein refers to the concuπent binding of from 2 to 10 linked ligands (which may be the same or different) and two or more corresponding receptors (ligand binding sites) on one or more receptors which may be the same or different For example, two ligands connected through a hnkei that bind concuπently to two ligand binding sites would be considered as bivalency, three ligands thus connected would be an example of tnvalency An example of tπvalent binding, illustrating a multibinding compound beaπng three ligands versus a monovalent binding interaction, is shown below Umvalent Interaction Tπvalent Interaction It should be understood that all compounds that contain multiple copies of a ligand attached to a linker or to linkers do not necessarily exhibit the phenomena of multivalency, 1 e , that the biological and or therapeutic effect of the multibinding agent is greater than the sum of the aggregate of unlinked ligands made available for binding to the ligand binding site (receptor) For multivalency to occur, the ligands that are connected by a linker or linkers have to be presented to their ligand binding sites by the hnker(s) in a specific manner in order to bring about the desired hgand-onentmg result, and thus produce a multibinding event The term "selectivity" or "specificity" is a measure of the binding preferences of a ligand for different ligand binding sites (receptors) The selectivity of a ligand with respect to its target ligand binding site relative to another ligand binding site is given by the ratio of the respective values of K d (I e , the dissociation constants for each hgand-receptor complex) or, in cases where a biological effect is observed below the K d , the ratio of the respective EC 30 's (I e , the concentrations that produce 50% ofthe maximum response for the ligand interacting with the two distinct ligand binding sites (receptors)) The term "ligand binding site" denotes the site on the D, receptors that recognizes a ligand domain and provides a binding partner for the ligand The ligand binding site may be defined by monomeπc or multimeric structures This interaction may be capable of producing a unique biological effect, for example, agonism, antagonism, modulatory effects, may maintain an ongoing biological event, and the like The terms "agonism" and "antagonism" are well known m the art Ligands which are full agonists are ligands which when bound tngger the maximum activity seen by the natural ligands Ligands which are partial agonists are ligands which when bound tngger sub-maximum activity Ligands which are antagonists are ligands that when bound, inhibit or prevent the activity aπsmg from a natural ligand binding to the receptor Antagonists may be of the surmountable class (results in the parallel displacement ofthe dose-response curve of the agonist to the nght in a dose dependent fashion without reducing the maximal response for the agonist) or insurmountable class (results m depression ofthe maximal response for a given agonist with or without the parallel shift) Ligands which are inverse agonists are ligands that, when bound, decrease the basal activity ofthe unbound receptor or which provide an activity opposite of the natural agonist Ligands have measurable properties that relate to the interaction ofthe ligand and the receptor These include the affinity of the hgand for the receptor, which relates to the energetics ofthe binding, the efficacy ofthe ligand for the receptor, which relates to the functional downstream activity ofthe ligand, the kinetics ofthe hgand for the receptor, which defines the onset of action and the duration of action, and the desensitization of the receptor for the ligand Selectivity defines the ratio ofthe affinity and/or efficacy of a ligand across two receptors The term "modulatory effect" refers to the ability ofthe ligand to change the activity of an agonist or antagonist through binding to a ligand binding site It is a combination of these properties which provides the foundation tor defining the nature of the functional response It should be recognized that the ligand binding sites of the receptor that participate in biological multivalent binding interactions are constrained to v arying degrees by their mtra- and mter-molecular associations (e g , such macromoleculai structures may be covalently joined to a single structure, noncovalentlv associated in a multimenc structure, embedded in a membrane oi polymeric matrix, and so on) and therefore have less translational and rotational freedom than if the same structures were present as monomers in solution The term "inert organic solvent" means a solvent which is inert under the conditions ofthe reaction being descnbed in coni unction therewith including, b\ way of example only, benzene, toluene, acetomtπle, tetrahydro furan, dimethylformamide, chloroform, methylene chloπde, diethyl ether, ethyl acetate acetone, methylethyl ketone, methanol, ethanol, piopanol, isopropanol r-butanol dioxane, pyridine, and the like Unless specified to the contrary, the sol ents used in the reactions described herein are inert solvents The term "treatment" refers to any treatment of a pathologic condition in a mammal, particularly a human, and includes (1) preventing the pathologic condition from occurring m a subject which may be predisposed to the condition but has not yet been diagnosed with the condition and, accordingly, the treatment constitutes prophylactic treatment for the disease condition, (n) inhibiting the pathologic condition, I e , arresting its development (in) relieving the pathologic condition, l e , causing regression of the pathologic condition, or (iv) relieving the conditions mediated by the pathologic condition The term "pathologic condition which is modulated by treatment with a ligand" covers all disease states (l e , pathologic conditions) which are generally acknowledged in the art to be usefully treated with a hgand for the D, receptors in general, and those disease states which have been found to be usefully treated by a specific multibinding compound of our invention Such disease states include bv way of example only, hypertension, angina, congestive heart failure, renal failuie (including chronic and acute renal failure), impotence, psychosexual disorders, Parkinson's disease and the like The term "therapeutically effective amount" refers to that amount ol multibinding compound which is sufficient to effect treatment, as defined above when administered to a mammal in need of such treatment The therapeutically effective amount will vary depending upon the subject and disease condition being treated, the weight and age of the subject, the seventy of the disease condition, the manner of administration and the like, which can readily be determined by one of ordinary skill in the art The term "linker", identified where appropriate by the symbol X, X or X' , refers to a group or groups that covalently links from 2 to 10 ligands (as identified above) in a manner that provides for a compound capable of multivalencv Among other features, the linker is a hgand-oπentmg entity that permits attachment of multiple copies of a ligand (which may be the same or different) thereto In some cases, the linker may itself be biologically active The term "linker" does not, however, extend to cover solid inert supports such as beads, glass particles, fibers, and the like But it is understood that the multibinding compounds of this invention can be attached to a solid support if desired For example, such attachment to solid supports can be made for use m separation and purification processes and similar applications The term "library" refers to at least 3, preferably from 10 2 to 10 9 and more preferably from 10 2 to 10 4 multimeπc compounds Preferably, these compounds aie prepared as a multiplicity of compounds in a single solution or reaction mixture which permits facile synthesis thereof In one embodiment, the library of multimenc compounds can be directly assayed for multibinding properties In another embodiment, each member ofthe library of multimeric compounds is first isolated and, optionally, charactenzed This member is then assayed for multibinding properties The term "collection" refers to a set of multimeπc compounds which are prepared either sequentially or concuπently (e g , combmatonally) The collection compnses at least 2 members, preferably from 2 to 10 9 members and still more preferably from 10 to 10 4 members The term "multimenc compound" refers to compounds comprising from 2 to 10 ligands covalently connected through at least one linker which compounds may or may not possess multibinding properties (as defined herein) The term "pseudohahde" refers to functional groups which react in displacement reactions in a manner similar to a halogen Such functional groups include, by way of example, mesyl, tosyl, azido and cyano groups The extent to which multivalent binding is realized depends upon the efficiency with which the linker or linkers that joins the ligands presents these ligands to the aπay of available hgand binding sites Beyond presenting these ligands for multivalent interactions with ligand binding sites, the linker or linkers spatially constrains these interactions to occur within dimensions defined by the linker or linkers Thus, the structural features of the linker (valency, geometry, oπentation, size, flexibility, chemical composition, etc ) are features of multibinding agents that play an important role in determining their activities The linkers used m this invention are selected to allow multivalent binding of ligands to the ligand binding sites of D, receptors, wherever such sites are located on the receptor structure The ligands are covalently attached to the linker or linkers using conventional chemical techniques providing for covalent linkage of the hgand to the linker or linkers Reaction chemistnes resulting in such linkages are well known m the art and involve the use of complementary functional groups on the linker and hgand Preferably, the complementary functional groups on the linker are selected relative to the functional groups available on the ligand for bonding oi which can be introduced onto the ligand for bonding Again, such complementary functional groups are well known in the art For example, reaction between a carboxylic acid of either the linker or the ligand and a primary or secondary amme ofthe ligand or the linker m the presence of suitable, well-known activating agents results in formation of an amide bond covalently linking the ligand to the linker, reaction between an amme group of either the linker or the ligand and a sulfonv 1 halide of the hgand or the linker results formation of a sulfonarmde bond covalently linking the ligand to the linker, and reaction between an alcohol or phenol group of either the linker or the ligand and an alkyl or aryl halide of the hgand or the linker results in formation of an ether bond covalently linking the ligand to the linker Table I below illustrates numerous complementary reactive groups and the resulting bonds formed by reaction there between Table I First Reactive Group Second Reactive. Group Linkage hydroxyl isocyanate urethane amine epoxide β-hydroxyamme sulfonyl halide amme sulfonamide carboxyl amme amide hydroxyl alkyl/ aryl halide ether aldehyde amme NaCNBH 4 amme ketone amιne/NaCNBH 4 amme amine isocyanate urea The linker is attached to the ligand at a position that ietams ligand domain- hgand binding site interaction and specifically which permits the hgand domain of the ligand to onent itself to bind to the hgand binding site Such positions and synthetic protocols for linkage are well known in the art The term linker embraces everything that is not considered to be part of the ligand The relative onentation in which the ligand domains are displayed derives from the particular point or points of attachment of the ligands to the linker, and on the framework geometry The determination of where acceptable substitutions can be made on a ligand is typically based on prior knowledge of structure-activity relationships (SAR) of the ligand and/or congeners and/oi structural information about hgand-receptor complexes (e g , X-ray crystallography, NMR, and the like) Such positions and the synthetic methods for covalent attachment are well known m the art Following attachment to the selected linker (or attachment to a significant portion of the linker, for example 2-10 atoms of the linker), the univalent hnker-ligand conjugate may be tested for retention of activity in the relevant assay Suitable linkers and ligands are discussed more fully below At present, it is prefeπed that the multibinding agent is a bivalent compound, e g , two ligands which are covalently linked to linker X Methodology The linker, when covalently attached to multiple copies ofthe ligands, provides a biocompatible, substantially non-immunogenic multibinding compound The biological activity ofthe multibinding compound is highlv sensitive to the valency, geometry, composition, size, flexibility or rigidity, etc ot the linker and, in turn, on the overall structure of the multibinding compound, as well as the presence or absence of aniomc or cationic charge, the relative hydrophobicity/hydrophihcity ofthe linker, and the like on the linker Accordingly, the linker is preferably chosen to maximize the biological acti ity of the multibinding compound The linker may be chosen to enhance the biological activity ofthe molecule In general, the linker may be chosen from any organic molecule construct that orients two or more ligands to their ligand binding sites to permit multivalency In this regard, the linker can be considered as a "framework on which the ligands are arranged m order to bring about the desired hgand- onenting result, and thus produce a multibinding compound For example, different onentations can be achieved by including m the framework groups containing mono- or polycychc groups, including aryl and/or heteroaryl groups, or structures incorporating one oi more carbon-carbon multiple bonds (alkenyl, alkenylene, alkynyl or alkynylene groups) Other groups can also include oligomers and polymers which aie branched- or straight-chain species In prefeπed embodiments, ngidity is imparted by the presence of cyclic groups (e g , aryl, heteroaryl, cycloalkyl, heterocyclic, etc ) In other prefeπed embodiments the ring is a six or ten member ring. In still further prefeπed embodiments, the ring is an aromatic ring such as, for example, phenyl or naphthyl. Different hydrophobic/hydrophilic characteristics of he linker as well as the presence or absence of charged moieties can readily be controlled by the skilled artisan. For example, the hydrophobic nature of a linker derived from hexamethylene diamine (H 2 N(CH 2 ) 6 NH 2 ) or related polyamines can be modified to be substantially more hydrophihc by replacing the alkylene group with a poly(oxyalkylene) group such as found in the commercially available "Jeffamines". By controlling the hydrophihcity /hydrophobicity, the ability of the compounds to cross the blood/brain barrier can be controlled. This can be important when one wishes to maximize or minimize CNS effects. Examples of molecular structures in which the above bonding patterns could be employed as components ofthe linker are shown below. The identification of an appropriate framework geometry and size for ligand domain presentation are important steps m the construction of a multibinding compound with enhanced activity Systematic spatial searching strategies can be used to aid m the identification of prefeπed frameworks through an iterative process Numerous strategies are known to those skilled m the art of molecular design and can be used for prepanng compounds of this invention It is to be noted that core structures other than those shown here can be used for determining the optimal framework display orientation of the ligands The process may require the use of multiple copies of the same central core structure or combinations of different types of display cores The above-described process can be extended to tπmers and compounds of higher valency. Assays of each of the individual compounds of a collection generated as described above will lead to a subset of compounds with the desired enhanced activities (e.g., potency, selectivity, etc.). The analysis of this subset using a technique such as Ensemble Molecular Dynamics will provide a framework orientation that favors the properties desired. A wide diversity of linkers is commercially available (see, e.g., Available Chemical Directory (ACD)). Many of the linkers that are suitable for use in this invention fall into this category. Other can be readily synthesized by methods well known in the art and/or are described below. Having selected a prefeπed framework geometry, the physical properties of the linker can be optimized by varying the chemical composition thereof. The composition of the linker can be varied in numerous ways to achieve the desired physical properties for the multibinding compound. It can therefore be seen that there is a plethora of possibilities for the composition of a linker. Examples of linkers include aliphatic moieties, aromatic moieties, steroidal moieties, peptides, and the like. Specific examples are peptides or polyamides, hydrocarbons, aromatic groups, ethers, lipids, cationic or anionic groups, or a combination thereof. Examples are given below, but it should be understood that various changes may be made and equivalents may be substituted without departing from the true spirit and scope ofthe invention. For example, properties of the linker can be modified by the addition or insertion of ancillary groups into or onto the linker, for example, to change the solubility of the multibinding compound (in water, fats, lipids, biological fluids, etc.), hydrophobicity, hydrophihcity, linker flexibility, antigenicity, stability, and the like. For example, the introduction of one or more poly(ethylene glycol) (PEG) groups onto or into the linker enhances the hydrophihcity and water solubility of the multibinding compound, increases both molecular weight and molecular size and, depending on the nature of the unPEGylated linker, may increase the in vivo retention time Further PEG may decrease antigemcity and potentially enhances the overall rigidity of the linker Ancillary groups which enhance the water solubihty/hydrophihcity of the linker and, accordingly, the resulting multibinding compounds are useful in practicing this invention Thus, it is withm the scope of the present invention to use ancillary groups such as, for example, small repeating units of ethylene glycols, alcohols, polyols (e g , glyceπn, glycerol propoxylate, sacchandes, including mono-, ohgosacchaπdes, etc ), carboxylates (e g , small repeating units of glutamic acid, acrylic acid, etc ), ammes (e g , tetraethylenepentamme), and the like) to enhance the water solubility and/or hydrophihcity of the multibinding compounds of this invention In prefeπed embodiments, the ancillary group used to improve water solubility /hydrophihcity will be a polyether The incorporation of hpophihc ancillary groups within the structure of the linker to enhance the lipophihcity and/or hydrophobicity of the multibinding compounds descπbed herein is also within the scope of this invention Lipophihc groups useful with the linkers of this invention include, by way of example onl> aryl and heteroaryl groups which, as above, may be either unsubstituted or substituted with other groups, but are at least substituted with a group which allows their covalent attachment to the linker Other hpophihc groups useful with the linkers of this invention include fatty acid derivatives which do not form bilayers in aqueous medium until higher concentrations are reached Also within the scope of this invention is the use of ancillary groups which result in the multibinding compound being incorporated or anchored into a vesicle or other membranous structure such as a liposome or a micelle The term "lipid" refers to any fatty acid denvative that is capable of forming a bilayer or a micelle such that a hydrophobic portion of the lipid mateπal onents toward the bilayer while a hydrophihc portion onents toward the aqueous phase Hydrophihc characteristics denve from the presence of phosphato, carboxylic, sulfato, ammo, sulfhydryl, nitro and other like groups well known in the art Hydrophobicity could be confeπed by the inclusion of groups that include, but are not limited to, long chain saturated and unsaturated aliphatic hydrocarbon groups of up to 20 carbon atoms and such groups substituted by one or more aryl, heteroaryl, cycloalkyl, and/or heterocyclic group(s) Prefeπed lipids are phosphglycendes and sphingo lipids, representative examples of which include phosphatidylcholme, phosphatidylethanolamme, phosphatidylsenne, phosphatidylmositol, phosphatidic acid, palmitoyleoyl phosphatidylcholme, lysophosphatidylcholme, lysophosphatidyl-ethanolamme, dipalmitoylphosphatidylcholme, dioleoylphosphatidylcholme, distearoyl-phosphatidylcholme or dihnoleoylphosphatidylcholme could be used Other compounds lacking phosphorus, such as sphmgohpid and glycosphmgohpid families are also withm the group designated as lipid Additionally, the amphipathic hpids descπbed above may be mixed with other lipids including tnglycendes and sterols The flexibility ofthe linker can be manipulated by the inclusion of ancillary groups which are bulky and/or rigid The presence of bulky or rigid groups can hinder free rotation about bonds in the linker or bonds between the linker and the ancillary group(s) or bonds between the linker and the functional groups Rigid groups can include, for example, those groups whose conformational lability is restrained by the presence of nngs and/or multiple bonds withm the group, for example, aryl, heteroaryl, cycloalkyl, cycloalkenyl, and heterocyclic groups Other groups which can impart rigidity include polypeptide groups such as ohgo- or polyprolme chains Rigidity may also be imparted by internal hydrogen bonding or by hydrophobic collapse Bulky groups can include, for example, large atoms, ions (e g , iodine, sulfur, metal ions, etc ) or groups containing large atoms, polycychc groups, including aromatic groups, non-aromatic groups and structures incorporating one or more carbon-carbon multiple bonds (1 e , alkenes and alkynes) Bulky groups can also include oligomers and polymers which are branched- or straight-chain species Species that are branched are expected to increase the rigidity of the structure more per unit molecular weight gam than are straight-chain species In preferred embodiments, ngidity is imparted by the presence of cyclic groups (e g , aryl, heteroaryl, cycloalkyl, heterocyclic, etc ) In other prefeπed embodiments, the linker compπses one or more six-membered rings In still further prefeπed embodiments, the πng is an aryl group such as, for example, phenyl or naphthyl Rigidity can also be imparted electrostatically Thus, if the ancillary groups are either positively or negatively charged, the similarly charged ancillary groups will force the presenter linker into a configuration affording the maximum distance between each of the like charges The energetic cost of bringing the like-charged groups closer to each other will tend to hold the linker in a configuration that maintains the separation between the like-charged ancillary gioups Further ancillary groups beanng opposite charges will tend to be attracted to their oppositely charged counterparts and potentially may enter into both inter- and intramolecular ionic bonds This non-covalent mechanism will tend to hold the linker into a conformation which allows bonding between the oppositely charged groups The addition of ancillary groups which are charged, or alternatively, bear a latent charge when deprotected, following addition to the linker, include deprotectation of a carboxyl, hydroxyl, thiol or ammo group by a change m pH, oxidation, reduction or other mechanisms known to those skilled in the art which result in removal of the protecting group, is withm the scope of this invention In view ofthe above, it is apparent that the appropnate selection of a linker group providing suitable oπentation, restπcted/unrestπcted rotation, the desired degree of hydrophobicity/hydrophihcity, etc is well withm the skill of the art Eliminating or reducing antigemcity of the multibinding compounds descπbed herein is also withm the scope of this invention In certain cases, the antigemcity of a multibinding compound may be eliminated or reduced by use of groups such as, for example, poly(ethylene glycol) As explained above, the multibinding compounds descnbed herein compnse 2-10 ligands attached to a linker that links the ligands in such a manner that they are presented to the receptor for multivalent interactions with ligand binding sites thereon/therein The linker spatially constrains these interactions to occur within dimensions defined by the linker This and other factors increases the biological activity of the multibinding compound as compared to the same number of ligands made available in monobinding form The compounds of this invention are preferably represented by the empirical formula (L) p (X) q where L, X, p and q are as defined above This is intended to include the several ways m which the ligands can be linked together in order to achieve the objective of multivalency, and a more detailed explanation is described below As noted previously, the linker may be considered as a framework to which ligands are attached Thus, it should be recognized that the ligands can be attached at any suitable position on this framework, for example, at the termini of a linear chain or at any intermediate position The simplest and most prefeπed multibinding compound is a bivalent compound which can be represented as L-X-L, where each L is independently a ligand which may be the same or different and each X is independently the linker Examples of such bivalent compounds are provided in Figure 2, where each shaded circle represents a ligand. A trivalent compound could also be represented in a linear fashion, i.e., as a sequence of repeated units L-X-L-X-L, in which L is a ligand and is the same or different at each occuπence, as can X. However, a trimer can also be a radial multibinding compound comprising three ligands attached to a central core, and thus represented as (L) 3 X, where the linker X could include, for example, an aryl or cycloalkyl group. Illustrations of trivalent and tetravalent compounds of this invention are found in Figures 3 and 4 respectively where, again, the shaded circles represent ligands. Tetravalent compounds can be represented in a linear array, e.g., L-X-L-X-L-X-L in a branched aπay, e.g., L-X-L-X-L L (a branched construct analogous to the isomers of butane — /z-butyl, /so-butyl, sec- butyl, and t-butyl) or in a tetrahedral aπay, e.g., where X and L are as defined herein. Alternatively, it could be represented as an alkyl, aryl or cycloalkyl derivative as above with four (4) ligands-attached to the core linker. The same considerations apply to higher multibinding compounds of this invention containing 5-10 ligands as illustrated in Figure 5 where, as before, the shaded circles represent ligands However, for multibinding agents attached to a central linker such as aryl or cycloalkyl, there is a self-evident constraint that there must be sufficient attachment sites on the linker to accommodate the number of ligands present, for example, a benzene ring could not directly accommodate more than 6 ligands, whereas a multi-nng linker (e g , biphenyl) could accommodate a larger number of ligands Certain of the above descnbed compounds may alternatively be represented as cyclic chains of the form X X and vaπants thereof All ofthe above vaπations are intended to be withm the scope ofthe invention defined by the formula (L) p (X) q With the foregoing in mind, a prefeπed linker may be represented by the following formula -X a -Z-(Y a -Z) m -Y b -Z-X a - rn which m is an integer of from 0 to 20, X a at each separate occurrence is selected from the group consisting of -0-, -S-, -NR-, -C(O)-, -C(O)0-, -C(O)NR-, -C(S), -C(S)0-, -C(S)NR- or a covalent bond where R is as defined below, Z is at each separate occuπence is selected from the group consisting of alkylene, substituted alkylene, cycloalkylene, substituted cylcoalkylene, alkenylene, substituted alkenylene, alkynylene, substituted alkynylene, cycloalkenylene, substituted cycloalkenylene, arylene, heteroarylene, heterocyclene, or a covalent bond; Y and Y b at each separate occuπence are selected from the group consisting of: -S-S- or a covalent bond; in which: n is 0, 1 or 2; and R, R' and R" at each separate occurrence are selected from the group consisting of hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, substituted alkenyl, cycloalkenyl, substituted cycloalkenyl, alkynyl, substituted alkynyl, aryl, heteroaryl and heterocyclic. Additionally, the linker moiety can be optionally substituted at any atom therein by one or more alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, substituted alkenyl, cycloalkenyl, substituted cycloalkenyl, alkynyl, substituted alkynyl, aryl, heteroaryl and heterocyclic group. In one embodiment of this invention, the linker (i.e., X, X' or X") is selected those shown in Table II: Table II Representative Linkers Linker -HN-(CH : ,-NH-C(O)-(CH 2 )-C(O)-NH-(CH 2 ) 2 -NH- -HN-(CH : 2 -NH-C(O)-(CH 2 ) 2 -C(O)-NH-(CH 2 ) 2 -NH- -HN-(CH : -NH-C(O)-(CH 2 ) 3 -C(O)-NH-(CH 2 ) 2 -NH- -HN-(CH ; -NH-C(O)-(CH 2 ) 4 -C(O)-NH-(CH 2 ) : -NH- -HN-(CH : NH-C(O)-(CH 2 ) 5 -C(O)-NH-(CH 2 ) ,-NH- -HN-(CH 2 -NH-C(O)-(CH 2 ) 6 -C(O)-NH-(CH 2 ) 2 -NH- -HN-(CH ; -NH-C(O)-(CH 2 ) 7 -C(O)-NH-(CH,) 2 -NH- -HN-(CH 2 2 -NH-C(0)-(CH 2 ) 8 -C(0)-NH-(CH 2 ) ,-NH- -HN-(CH : 2 -NH-C(0)-(CH 2 ) 9 -C(0)-NH-(CH 2 ) 2 -NH- -HN-(CH 2 2 -NH-C(O)-(CH 2 ) 10 -C(O)-NH-(CH 2 ) 2 -NH- -HN-(CH ; -NH-C(O)-(CH 2 ), ,-C(O)-NH-(CH 2 ) 2 -NH- -HN-(CH : -NH-C(O)-(CH 2 ) 12 -C(O)-NH-(CH 2 ) 2 -NH- -HN-(CH- -NH-C(O)-Z-C(O)-NH-(CH 2 ) 2 -NH- where Z is 1 ,2-phenyl -HN-(CH : -NH-C(O)-Z-C(O)-NH-(CH 2 ) 2 -NH- where Z is 1 ,3-phenyl -HN-(CH. -NH-C(O)-Z-C(O)-NH-(CH 2 ) 2 -NH- where Z is 1,4-phenyl -HN-(CH. -NH-C(O)-Z-O-Z-C(O)-NH-(CH 2 ) 2 -NH- where Z is 1 ,4-phenyl -HN-(CH 2 -NH-C(O)-(CH 2 ) 2 -CH(NH-C(0)-(CH 2 ) s -CH 3 )-C(0)-NH-(CH 2 ) : - NH- -HN-(CH. 2 -NH-C(0)-(CH 2 )-0-(CH 2 )-C(0)-NH-(CH 2 ) 2 -NH- -HN-(CH 2 ) 2 -NH-C(0)-Z-C(O)-NH-(CH 2 ) 2 -NH- where Z is 5-(/-z-octadecyloxy)- 1 ,3-phenyl -HN-(CH 2 ) 2 -NH-C(O)-(CH 2 ) 2 -CH(NH-C(0)-Z)-C(0)-NH-(CH 2 ) 2 -NH- where Z is 4-biphenyl Linker -HN-(CH 2 ) 2 -NH-C(O)-Z-C(O)-NH-(CH 2 ) 2 -NH- where Z is 5-(n-butyloxy)- 1 ,3-phenyl -HN-(CH 2 ) 2 -NH-C(O)-(CH 2 ) g -tra«^-(CH=CH)-C(O)-NH-(CH 2 ) 2 -NH- -HN-(CH 2 ) 2 -NH-C(O)-(CH 2 ) ,-CH(NH-C(O)-(CH 2 ) 12 -CH 3 )-C(O)-NH-(CH 2 ) 2 - NH- -HN-(CH 2 ) 2 -NH-C(O)-(CH 2 ) 2 -CH(NH-C(O)-Z)-C(O)-NH-(CH 2 ) 2 -NH- where Z is 4-(n-octyl)-phenyl -HN-(CH 2 )-Z-O-(CH 2 ) 6 -O-Z-(CH 2 )-NH- where Z is 1,4-phenyl -HN-(CH 2 ),-NH-C(O)-(CH 2 ) 2 -NH-C(O)-(CH 2 ) 3 -C(O)-NH-(CH 2 ) 2 -C(0)-NH- (CH 2 ) 2 -NH- -HN-(CH 2 ) 2 -NH-C(O)-(CH 2 ) 2 -CH(NH-C(O)-Ph)-C(0)-NH-(CH 2 ) 2 -NH- -HN-(CH 2 ) 2 -NH-C(O)-(CH 2 )-N+((CH 2 ) 9 -CH 3 )(CH 2 -C(0)-NH-(CH 2 ) ,-NH,)- (CH 2 )-C(O)-NH-(CH 2 ) 2 -NH- -HN-(CH 2 ) 2 -NH-C(O)-(CH 2 )-N((CH 2 ) 9 -CH 3 )-(CH 2 )-C(O)-NH-(CH 2 ) 2 -NH- -HN-(CH 2 ) 2 -NH-C(O)-(CH 2 ) 2 -NH-C(O)-(CH 2 ) ,-NH-C(O)-(CH,) 3 -C(0)-NH- (CH 2 ) 2 -C(O)-NH-(CH 2 ) 2 -C(0)-NH-(CH 2 ) 2 -NH- -HN-(CH 2 ) 2 -NH-C(O)-Z-C(O)-NH-(CH 2 ) 2 -NH- where Z is 5-hydroxy-l,3-phenyl In another embodiment of this invention, the linker (i.e., X, X' or X") has the formula: wherein each R a is independently selected from the group consisting of a covalent bond, alkylene, substituted alkylene and arylene; each R b is independently selected from the group consisting of hydrogen, alkyl and substituted alkyl; and n ' is an integer ranging from 1 to about 20. In view of the above description of the linker, it is understood that the term "linker" when used in combination with the term "multibinding compound" includes both a covalently contiguous single linker (e.g., L-X-L) and multiple covalently non-contiguous linkers (L-X-L-X-L) within the multibinding compound. Ligands Any compound which is an agonist, partial agonist, inverse agonist or antagonist of the D, receptors and which can be covalently linked to a linker can be used as a ligand to prepare the compounds described herein. Such ligands are well known to those of skill in the art. The most prefeπed ligands are agonists of the D, receptors. Examples of D, ligands which can be used as ligands to prepare the compounds ofthe present invention include dopamine, apomorphine, SKF 75670, CY 208-243, fenoldopam, abeorphine, A C6H12, dihydrexidinem and analogues and prodrugs thereof. Analogs (for these and other known compounds which bind to the D, receptors) which can be used include alkylated, acylated, carboxy lated, amidated, sulfonated, phosphorylated, aminated, hydroxylated, thiolated, and halogenated derivatives. Prefeπed ligands, L, in the multibinding compounds are independently selected from a compound of formula IA-F: and analogs thereof, wherein A is H, alkyl or a direct link to the linker, M, 20 are, independently, H or a direct link to the linker, wherein only one of A or M, 20 is a link to the linker, and analogs thereof Suitable analogs include alkylated, acylated, ammated, thiolated, hydroxylated, amidated, carboxylated, phosphorylated, sulfonated, and halogenated analogs thereof Ligands of formula 1A-F (and the precursors and analogs thereof) are well- known in the art and can be readily prepared using art-recognized starting matenals, reagents and reaction conditions By way of illustration, the following patents and publications disclose compounds, intermediates and procedures useful in the preparation of ligands of formulas 1A-F or related compounds suitable for use m this invention Alkorta and Villar, J. Comp. Aided Mol. Design, 7 659-670 (1993) Brogden and Markham, Drugs, 54(4) 634-650 (1997) Brooks et al , J. Pharmacol. And Exp. Therapeutics, 254(3) 1084-1089 (1990) Felder et al , ΔIt 3(6) 96S-99S (1990) Fisher et al , Bioorgamc and Medicinal Chem. Lett., 5(20) 2371-2376 (1995) Hegde and Lokhandwala, A.TH, 3(6) 78S-81S (1990) Holcslaw and Beck, AJH, 3(6) 120S-125S (1990) Missale et al , Physiological Reviews, 78(1 ) 189-213 (Jan 1998) Nichols et al , A.TH, 3(6) 1 16S-119S (1990) Pfeiffer et al , J. Med. Chem, 25 352-358 (1982) Post and Fnshman, I. Clin. Pharmacol.. 38 2-13 (1998) Smit, ΔJiL 3(6) 75S-77S (1990) Wemstock et al , I. Med. Chem, 23 975-976 ( 1980) Yamaguchi et al , Hypertension, 29(4) 962-968 (1997) U S Patent No 4,963,568 to Schoenleber, et al Each of these patents and publications is incorporated herein by reference in its entirety to the same extent as if each individual patent or publication was specifically and individually indicated to be incoφorated by reference in its entirety Preparation of Multibinding Compounds The multibinding compounds of this invention can be prepared from readily available starting matenals using the following general methods and procedures It will be appreciated that where typical or prefeπed process conditions (I e , reaction temperatures, times, mole ratios of reactants, solvents, pressures, etc ) are given, other process conditions can also be used unless otherwise stated Optimum reaction conditions may vary with the particular reactants or solvent used, but such conditions can be determined by one skilled in the art by routine optimization procedures Additionally, as will be apparent to those skilled in the art, conventional protecting groups may be necessary to prevent certain functional groups from undergoing undesired reactions The choice of a suitable protecting group for a particular functional group as well as suitable conditions for protection and deprotection are well known in the art For example, numerous protecting groups, and their introduction and removal, are descnbed in T W Greene and G M Wuts, Protecting Groups in Organic Synthesis, Second Edition, Wiley, New York, 1991 , and references cited therein Any compound which is an agonist, partial agonist, inverse agonist or antagonist of the D, receptors, preferably agonists of the D, receptors, can be used as a ligand in this invention As discussed above, numerous such receptor agonists, partial agonists, inverse agonists and antagonists are known in the art and any of these known compounds or denvatives thereof may be employed as ligands in this invention Typically, a compound selected for use as a ligand will have at least one functional group, such as an amino, hydroxyl, thiol or carboxyl group and the like, which allows the compound to be readily coupled to the linker Compounds having such functionality are either known m the art or can be prepared by routine modification of known compounds using conventional reagents and procedures The patents and publications set forth above provide numerous examples of suitably functionahzed agonists, partial agonists and antagonists of the D j receptors, and intermediates thereof, which may be used as ligands in this invention The ligands can be covalently attached to the linker through any available position on the ligands, provided that when the ligands are attached to the linker at least one of the ligands retains its ability to bind to the D, receptors Certain sites of attachment of the linker to the ligand are prefeπed based on known structure- activity relationships Preferably, the linker is attached to a site on the ligand where structure-activity studies show that a wide vanety of substituents are tolerated without loss of receptor activity It will be understood by those skilled m the art that the following methods may be used to prepare other multibinding compounds of this invention Ligand precursors, for example, ligands containing a leaving group or a nucleophilic group, can be covalently linked to a linker precursor containing a nucleophilic group or a leaving group, using conventional reagents and conditions Other methods are well known to those of skill m the art for coupling molecules such as the ligands descnbed herein with the linker molecules described herein For example, two equivalents of ligand precursor with a halide, tosylate, or other leaving group, can be readily coupled to a linker precursor containing two nucleophilic groups, for example, amme groups, to form a dimer The leaving group employed in this reaction may be any conventional leaving group including, by way of example, a halogen such as chloro, bromo or lodo, or a sulfonate group such as tosyl, mesyl and the like When the nucleophilic group is a phenol, any base which effectively deprotonates the phenolic hydroxyl group may be used, including, by way of illustration, sodium carbonate, potassium carbonate, cesium carbonate, sodium hydnde, sodium hydroxide, potassium hydroxide, sodium ethoxide, triethylamine, dnsopropylethylamme and the like Nucleophilic substition reactions are typically conducted in an inert diluent, such as tetrahydrofuran, N,N-dιmethylformamιde, N,N-dιmethylacetamιde, acetone, 2- butanone, l-methyl-2-pyrrohdιnone and the like After the reaction is complete, the dimer is typically isolated using conventional procedures, such as extraction, filtration, chromatography and the like By way of further illustration, dimers with a hydrophihc linker can be formed using a ligand precursor containing nucleophilic groups and a polyoxyethylene linker containing leaving groups for example, poly(oxyethylene) dibromide (where the number of oxyethylene units is typically an integer from 1 to about 20) In this reaction, two molar equivalents of the ligand precursor are reacted with one molar equivalent ofthe poly(oxyethylene) dibromide in the presence of excess potassium carbonate to afford a dimer This reaction is typically conducted in N,N-dιmethylformamιde at a temperature ranging from about 25 °C to about 100°C for about 6 to about 48 hours Alternatively, the linker connecting the ligands may be prepared m several steps Specifically, a ligand precursor can first be coupled to an "adapter", l e , a bifunctional group having a leaving group at one end and another functional group at the other end which allows the adapter to be coupled to a intermediate linker group In some cases, the functional group used to couple to the intermediate linker is temporanly masked with a protecting group ("PG") Representative examples of adapters include, by way of illustration, fert-butyl biomoacetate, 1 - Fmoc-2-bromoethylamme, l-tπtyl-2-bromoethanethιol, 4-ιodobenzyl bromide, propargyl bromide and the like After the hgand precursor is coupled to the adapter and the protecting group is removed from the adapter's functional group (if a protecting group is present) to form an intermediate, two molar equivalents of the intermediate are then coupled with an intermediate linker to form a dimer Ligand precursors can be coupled with adapters which include both leaving groups and protecting groups to form protected intermediates The leaving group employed in this reaction may be any conventional leaving group including, by way of example, a halogen such as chloro, bromo or lodo, or a sulfonate group such as tosyl, mesyl and the like Similarly, any conventional protecting group may be employed including, by way of example, esters such as the methyl, tert- butyl, benzyl ("Bn") and 9-fluorenyImethyl ("Fm") esters Protected intermediates can then be deprotected using conventional procedures and reagents to afford deprotected intermediates For example, tert- butyl esters are readily hydrolyzed with 95% trifluoroacetic acid in dichloromethane, methyl ester can be hydrolyzed with lithium hydroxide in tetrahydrofuran water, benzyl esters can be removed by hydrogenolysis in the presence of a catalyst, such as palladium on carbon, and 9-fluorenylmethyl esters are readily cleaved using 20% pipeπdme in DMF If desired, other well-known protecting groups and deprotectmg procedures may be employed in these reactions to form deprotected intermediates Similarly, ligand precursors having an adapter with an amme functional group can be prepared Ligand precursors can be coupled with adapters which include leaving groups and protected amme groups to afford protected intermediates The leaving group employed in this reaction may be any conventional leaving group Similarly, any conventional amme protecting group may be employed including, by way of example, tπtyl, tβrt-butoxycarbonyl ("Boc"), benzyloxycarbonyl ("CBZ") and 9-fluorenylmethoxy-carbonyl ("Fmoc") After coupling the adapter to the ligand precursor, the resulting protected intermediate is deprotected to afford a ligand precursor including an amme group using conventional procedures and reagents For example, a tntyl group is readily removed using hydrogen chloride in acetone; a Boc group is removed using 95% trifluoroacetic acid in dichloromethane; a CBZ group can be removed by hydrogenolysis in the presence of a catalyst, such as palladium on carbon; and a 9- fluorenylmethoxycarbonyl group is readily cleaved using 20% piperidine in DMF to afford the deblocked amine. Other well-known amine protecting groups and deprotectmg procedures may be employed in these reactions to foπri amine- containing intermediates and related compounds. Ligand precursors having an adapter, for example, one including a free carboxylic acid group or a free amine group, can be readily coupled to intermediate linkers having complementary functional groups to form multibinding compounds as described herein. For example, when one component includes a carboxylic acid group, and the other includes an amine group, the coupling reaction typically employs a conventional peptide coupling reagent and is conducted under conventional coupling reaction conditions, typically in the presence of a trialkylamine, such as ethyldiisopropylamine. Suitable coupling reagents for use in this reaction include, by way of example, carbodiimides, such as ethyl-3-(3- dimethylamino)propylcarboiimide (EDC), dicyclohexylcarbodiimide (DCC), diisopropylcarbodiimide (DIC) and the like, and other well-known coupling reagents, such as N,N'-carbonyldiimidazole, 2-ethoxy-l-ethoxycarbonyl-l ,2- dihydroquinoline (EEDQ), benzotriazol- 1 -yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP), O-(7-azabenzotriazol-l-yl)-N,N,N',N'- tetramethyluronium hexafluorophosphate (HATU) and the like. Optionally, well- known coupling promoters, such N-hydroxysuccinimide, 1-hydroxybenzotriazole (HOBT), 1 -hydroxy-7-azabenzotriazole (HOAT), N,N-dimethylaminopyridine (DMAP) and the like, may be employed in this reaction. Typically, this coupling reaction is conducted at a temperature ranging from about 0°C to about 60 °C for about 1 to about 72 hours in an inert diluent, such as THF, to afford the dimer. The multibinding compounds described herein can also be prepared using a wide variety of other synthetic reactions and reagents. For example, ligand precursors having aryhodide, carboxylic acid, amme and boromc acid functional groups can be prepared Pyπoles can be readily coupled under Mitsunobu reaction conditions to vaπous phenols to provide, after deprotection, functionahzed intermediates The Mitsunobu reaction is typically conducted by reacting hydroxymethyl pyrrole and the appropnate phenol using diethyl azodicarboxylate (DEAD) and tnphenylphosphine at ambient temperature for about 48 hours Deprotection, if necessary, using conventional procedures and reagents then affords the functionahzed intermediates The functionahzed intermediates can be employed in the synthesis of multibinding compounds For example, aryhodide intermediates can be coupled with bis-boromc acid linkers to provide dimers Typically, this reaction is conducted by contacting two molar equivalents of the aryhodide and one molar equivalent of the bis-boromc acid in the presence of tetrakιs(tnphenylphosphme)palladιum(0), sodium carbonate and water m refluxing toluene Aryhodide intermediates can also be coupled with acrylate intermediates or alkyne intermediate to afford dimers These reactions are typically conducted by contacting two molar equivalents of aryhodide intermediates with one molar equivalent of either acrylates or alkynes m the presence of dιchlorobιs(tnphenylphosphme)palladιum (II), copper (I) iodide and dπsopropylethylamine in N,N-dιmethylformamιde to afford the respective dimers As will be readily apparent to those of ordinary skill m the art, the synthetic procedures descnbed herein or those known in the art may be readily modified to afford a wide vanety of compounds withm the scope of this invention Combinatonal Libraries The methods described herein lend themselves to combinatonal approaches for identifying multimeπc compounds which possess multibinding properties Specifically, factors such as the proper juxtaposition of the individual ligands of a multibinding compound with respect to the relevant aπay of binding sites on a target or targets is important in optimizing the interaction ofthe multibinding compound with its target(s) and to maximize the biological advantage through multivalency One approach is to identify a library of candidate multibinding compounds with properties spanning the multibinding parameters that are relevant for a particular target These parameters include (1) the identity of hgand(s), (2) the oπentation of ligands, (3) the valency of the construct, (4) linker length, (5) linker geometry, (6) linker physical properties, and (7) linker chemical functional groups Libraries of multimeπc compounds potentially possessing multibinding properties (1 e , candidate multibinding compounds) and compnsing a multiplicity of such vanables are prepared and these libraries are then evaluated via conventional assays corresponding to the hgand selected and the multibinding parameters desired Considerations relevant to each of these variables are set forth below Selection of Lιgand(s) A single ligand or set of ligands is (are) selected for incoφoration into the hbraπes of candidate multibinding compounds which library is directed against a particular biological target or targets, I e , binding of D, receptors The only requirement for the ligands chosen is that they are capable of interacting with the selected target(s) Thus, ligands may be known drugs, modified forms of known drugs, substructures of known drugs or substrates of modified forms of known drugs (which are competent to interact with the target), or other compounds Ligands are preferably chosen based on known favorable properties that may be projected to be earned over to or amplified in multibinding forms Favorable properties include demonstrated safety and efficacy in human patients, appropnate PK/ADME profiles, synthetic accessibility, and desirable physical properties such as solubility, logP, etc However, it is crucial to note that ligands which display an unfavorable property from among the previous list may obtain a more favorable property through the process of multibinding compound formation, 1 e , ligands should not necessarily be excluded on such a basis For example, a ligand that is not sufficiently potent at a particular target so as to be efficacious in a human patient may become highly potent and efficacious when presented in multibinding form A ligand that is potent and efficacious but not of utility because of a non- mechamsm-related toxic side effect may have increased therapeutic index (increased potency relative to toxicity) as a multibinding compound Compounds that exhibit short in vivo half-lives may have extended half-lives as multibinding compounds Physical properties of ligands that limit their usefulness (e g poor bioavailabihty due to low solubility, hydrophobicity, hydrophihcity) may be rationally modulated in multibinding forms, providing compounds with physical properties consistent with the desired utility Orientation. Selection of Ligand Attachment Points and Linking Chemistry Several points are chosen on each ligand at which to attach the hgand to the linker The selected points on the hgand/hnker for attachment are functionahzed to contain complementary reactive functional groups This permits probing the effects of presenting the ligands to their target binding sιte(s) in multiple relative oπentations, an important multibinding design parameter The only requirement for choosing attachment points is that attaching to at least one of these points does not abrogate activity ofthe ligand Such points for attachment can be identified by structural information when available For example, inspection of a co-crystal structure of a ligand bound to its target allows one to identify one or more sites where linker attachment will not preclude the ligand/target interaction Alternatively, evaluation of ligand/target binding by nuclear magnetic resonance will permit the identification of sites non-essential for ligand/target binding See, for example, Fesik, et al , U S Patent No 5,891 ,643, the disclosure of which is incoφorated herein by reference in its entirety When such structural information is not available, utilization of structure-activity relationships (SAR) for ligands will suggest positions where substantial structural vaπations are and are not allowed In the absence of both structural and SAR information, a library is merely selected with multiple points of attachment to allow presentation ofthe ligand in multiple distinct oπentations Subsequent evaluation of this library will indicate what positions are suitable for attachment It is important to emphasize that positions of attachment that do abrogate the activity of the monomeπc ligand may also be advantageously included in candidate multibinding compounds in the library provided that such compounds bear at least one ligand attached m a manner which does not abrogate intrinsic activity This selection denves from, for example, heterobivalent interactions withm the context of a single target molecule For example, consider a ligand bound to its target, and then consider modifying this ligand by attaching to it a second copy ofthe same ligand with a linker which allows the second ligand to interact with the same target at sites proximal to the first binding site, which include elements ofthe target that are not part ofthe formal ligand binding site and/or elements ofthe matrix surrounding the formal binding site, such as the membrane Here, the most favorable oπentation for interaction of the second ligand molecule may be achieved by attaching it to the linker at a position which abrogates activity of the ligand at the first binding site Another way to consider this is that the SAR of individual ligands withm the context of a multibinding structure is often different from the SAR of those same hgands in momomenc form The foregoing discussion focused on bivalent interactions of dimenc compounds beanng two copies of the same ligand joined to a single linker through different attachment points, one of which may abrogate the binding/activity of the monomeπc ligand It should also be understood that bivalent advantage may also be attained with heteromeπc constructs beaπng two different ligands that bind to common or different targets Once the ligand attachment points have been chosen, one identifies the types of chemical linkages that are possible at those points The most prefeπed types of chemical linkages are those that are compatible with the overall structure ofthe ligand (or protected forms of the ligand) readily and generally formed, stable and intπnsically innocuous under typical chemical and physiological conditions, and compatible with a large number of available linkers Amide bonds, ethers, ammes, carbamates, ureas, and sulfonamides are but a few examples of prefeπed linkages Linker Selection In the library of linkers employed to generate the library of candidate multibinding compounds, the selection of linkers employed in this library of linkers takes into consideration the following factors Valency. In most instances the library of linkers is initiated with divalent linkers The choice of ligands and proper juxtaposition of two hgands relative to their binding sites permits such molecules to exhibit target binding affinities and specificities more than sufficient to confer biological advantage Furthermore, divalent linkers or constructs are also typically of modest size such that they retain the desirable biodistπbution properties of small molecules Linker Length. Linkers are chosen m a range of lengths to allow the spanning of a range of mter-hgand distances that encompass the distance preferable for a given divalent interaction In some instances the prefeπed distance can be estimated rather precisely from high-resolution structural information of targets In other instances where high-resolution structural information is not available, one can make use of simple models to estimate the maximum distance between binding sites either on adjacent receptors or at different locations on the same receptor In situations where two binding sites are present on the same target (or target subunit for multisubumt targets), prefeπed linker distances are 2-20 A, with more prefeπed linker distances of 3-12 A In situations where two binding sites reside on separate target sites, prefeπed linker distances are 20-100 A, with more prefeπed distances of 30-70 A. Linker Geometry and Rigidity: The combination of ligand attachment site, linker length, linker geometry, and linker rigidity determine the possible ways in which the ligands of candidate multibinding compounds may be displayed in three dimensions and thereby presented to their binding sites. Linker geometry and rigidity are nominally determined by chemical composition and bonding pattern, which may be controlled and are systematically varied as another spanning function in a multibinding aπay. For example, linker geometry is varied by attaching two ligands to the ortho, meta, and para positions of a benzene ring, or in cis- or trα«s-arrangements at the 1,1- vs. 1,2- vs. 1,3- vs. 1,4- positions around a cyclohexane core or in cis- or tra«s-arrangements at a point of ethylene unsaturation. Linker rigidity is varied by controlling the number and relative energies of different conformational states possible for the linker. For example, a divalent compound bearing two ligands joined by 1,8-octyl linker has many more degrees of freedom, and is therefore less rigid than a compound in which the two ligands are attached to the 4,4' positions of a biphenyl linker. Linker Physical Properties: The physical properties of linkers are nominally determined by the chemical constitution and bonding patterns of the linker, and linker physical properties impact the overall physical properties of the candidate multibinding compounds in which they are included. A range of linker compositions is typically selected to provide a range of physical properties (hydrophobicity, hydrophihcity, amphiphilicity, polarization, acidity, and basicity) in the candidate multibinding compounds. The particular choice of linker physical properties is made within the context of the physical properties of the ligands they join and preferably the goal is to generate molecules with favorable PK/ADME properties. For example, linkers can be selected to avoid those that are too hydrophihc or too hydrophobic to be readily absorbed and/or distributed in vivo. Linker Chemical Functional Groups: Linker chemical functional groups are selected to be compatible with the chemistry chosen to connect linkers to the ligands and to impart the range of physical properties sufficient to span initial examination of this parameter. Combinatorial Synthesis Having chosen a set of n ligands (n being determined by the sum ofthe number of different attachment points for each ligand chosen) and m linkers by the process outlined above, a library of (n )m candidate divalent multibinding compounds is prepared which spans the relevant multibinding design parameters for a particular target. For example, an aπay generated from two ligands, one which has two attachment points (Al, A2) and one which has three attachment points (Bl, B2, B3) joined in all possible combinations provide for at least 15 possible combinations of multibinding compounds: Al-Al A1-A2 Al-Bl A1-B2 A1-B3 A2-A2 A2-B1 A2-B2 A2-B3 Bl-Bl B1-B2 B1-B3 B2-B2 B2-B3 B3-B3 When each of these combinations is joined by 10 different linkers, a library of 150 candidate multibinding compounds results. Given the combinatorial nature ofthe library, common chemistries are preferably used to join the reactive functionalies on the ligands with complementary reactive functionalities on the linkers. The library therefore lends itself to efficient parallel synthetic methods. The combinatorial library can employ solid phase chemistries well known in the art wherein the ligand and/or linker is attached to a solid support. Alternatively and preferably, the combinatorial libary is prepared in the solution phase. After synthesis, candidate multibinding compounds are optionally purified before assaying for activity by, for example, chromatographic methods (e.g., HPLC). Analysis ofthe Library Vaπous methods are used to characterize the properties and activities ofthe candidate multibinding compounds in the library to determine which compounds possess multibinding properties Physical constants such as solubility under vaπous solvent conditions and logD/clogD values can be determined A combination of NMR spectroscopy and computational methods is used to determine low-energy conformations of the candidate multibinding compounds in fluid media The ability ofthe members ofthe library to bind to the desired target and other targets is determined by vanous standard methods, which include radiohgand displacement assays for receptor and ion channel targets, and kinetic inhibition analysis for many enzyme targets In vitro efficacy, such as for receptor agonists and antagonists, ion channel blockers, and antimicrobial activity, can also be determined Pharmacological data, including oral absoφtion, everted gut penetration, other pharmacokinetic parameters and efficacy data can be determined in appropriate models In this way, key structure-activity relationships are obtained for multibinding design parameters which are then used to direct future work The members of the library which exhibit multibinding properties, as defined herein, can be readily determined by conventional methods First those members which exhibit multibinding properties are identified by conventional methods as descnbed above including conventional assays (both in vitro and in vivo) Second, ascertaining the structure of those compounds which exhibit multibinding properties can be accomplished via art recognized procedures For example, each member ofthe library can be encrypted or tagged with appropnate information allowing determination ofthe structure of relevant members at a later time See, for example, Dower, et al , International Patent Application Publication No WO 93/06121, Brenner, et al , Proc. Natl. Acad. Sci., USA, 89 5181 (1992), Gallop, et al , U S Patent No 5,846,839, each of which are incoφorated herein by reference in its entirety. Alternatively, the structure of relevant multivalent compounds can also be determined from soluble and untagged libaries of candidate multivalent compounds by methods known in the art such as those described by Hindsgaul, et al, Canadian Patent Application No. 2,240,325 which was published on July 11, 1998. Such methods couple frontal affinity chromatography with mass spectroscopy to determine both the structure and relative binding affinities of candidate multibinding compounds to receptors. The process set forth above for dimeric candidate multibinding compounds can, of course, be extended to trimeric candidate compounds and higher analogs thereof. Follow-up Synthesis and Analysis of Additional Libraries Based on the information obtained through analysis of the initial library, an optional component ofthe process is to ascertain one or more promising multibinding "lead" compounds as defined by particular relative ligand orientations, linker lengths, linker geometries, etc. Additional libraries can then be generated around these leads to provide for further information regarding structure to activity relationships. These arrays typically bear more focused variations in linker structure in an effort to further optimize target affinity and/or activity at the target (antagonism, partial agonism, etc.), and/or alter physical properties. By iterative redesign/ analysis using the novel principles of multibinding design along with classical medicinal chemistry, biochemistry, and pharmacology approaches, one is able to prepare and identify optimal multibinding compounds that exhibit biological advantage towards their targets and as therapeutic agents. To further elaborate upon this procedure, suitable divalent linkers include, by way of example only, those derived from dicarboxylic acids, disulfonylhalides, dialdehydes, diketones, dihalides, diisocyanates,diamines, diols, mixtures of carboxylic acids, sulfonylhalides, aldehydes, ketones, halides, isocyanates, amines and diols. In each case, the carboxylic acid, sulfonylhalide, aldehyde, ketone, halide, isocyanate, amine and diol functional group is reacted with a complementary functionality on the ligand to form a covalent linkage. Such complementary functionality is well known in the art. Exemplary linkers include the following linkers identified as X-1 through X-418 as set forth below : -12- Pharmaceutical Formulations When employed as pharmaceuticals, the compounds of this invention are usually administered m the form of pharmaceutical compositions These compounds can be administered by a variety of routes including oral, rectal, transdermal, subcutaneous, intravenous, intramuscular, and intranasal These compounds are effective as both injectable and oral compositions Such compositions are prepared in a manner well known in the pharmaceutical art and compπse at least one active compound This invention also includes pharmaceutical compositions which contain, as the active ingredient, one or more of the compounds described herein associated with pharmaceutically acceptable carriers In making the compositions of this invention, the active ingredient is usually mixed with an excipient, diluted by an excipient or enclosed withm such a earner which can be in the form of a capsule, sachet, paper or other container When the excipient serves as a diluent, it can be a solid, semi-solid, or liquid material, which acts as a \ ehicle, carrier or medium foi the active ingredient Thus, the compositions can be in the form of tablets, pills, powders, lozenges, sachets, cachets, elixirs, suspensions, emulsions, solutions, syrups, aerosols (as a solid or in a liquid medium), ointments containing, for example, up to 10% by weight ofthe active compound, soft and hard gelatin capsules, suppositones, stenle injectable solutions, and stenle packaged powders In prepanng a formulation, it may be necessary to mill the active compound to provide the appropnate particle size pnor to combining with the other ingredients If the active compound is substantially insoluble it ordinarily is milled to a particle size of less than 200 mesh If the active compound is substantially water soluble, the particle size is normally adjusted by milling to provide a substantially uniform distnbution m the formulation, e g about 40 mesh Some examples of suitable excipients include lactose, dextrose, sucrose, sorbitol, mannitol, starches, gum acacia, calcium phosphate, algmates, tragacanth, gelatm, calcium silicate, microcrystalhne cellulose, polyvinylpyrrolidone, cellulose, sterile water, syrup, and methyl cellulose The formulations can additionally include lubncatmg agents such as talc, magnesium stearate, and mineral oil, wetting agents, emulsifying and suspending agents, preserving agents such as methyl- and propylhydroxy-benzoates, sweetening agents, and flavoring agents The compositions ofthe invention can be formulated so as to provide quick, sustained or delayed release of the active ingredient after administration to the patient by employing procedures known in the art The compositions are preferably formulated in a unit dosage form, each dosage containing from about 0 001 to about 1 g, more usually about 1 to about 30 mg, ofthe active ingredient The term "unit dosage forms" refers to physically discrete units suitable as unitary dosages for human subjects and other mammals, each unit containing a predetermined quantity of active material calculated to produce the desired therapeutic effect, in association with a suitable pharmaceutical excipient Preferably, the compound of formula I above is employed at no more than about 20 weight percent ofthe pharmaceutical composition, more preferably no more than about 15 weight percent, with the balance being inert carner(s) The active compound is effective over a wide dosage range and is geneialh administered m a pharmaceutically effective amount It, will be understood, however, that the amount of the compound actually administered will be determined by a physician, in the light ofthe relevant circumstances, including the condition to be treated, the chosen route of administration, the actual compound administered and its relative activity, the age, weight, and response of the individual patient, the seventy of the patient's symptoms, and the like For preparing solid compositions such as tablets, the pnncipal active ingredient is mixed with a pharmaceutical excipient to form a solid preformulation composition containing a homogeneous mixture of a compound ofthe present vention When referring to these preformulation compositions as homogeneous, it is meant that the active ingredient is dispersed evenly throughout the composition so that the composition may be readily subdivided into equally effective unit dosage forms such as tablets, pills and capsules This solid preformulation is then subdivided into unit dosage forms ofthe type descnbed above containing from, far example, 0 1 to about 500 mg of the active ingredient of the present invention The tablets or pills ofthe present invention may be coated or otherwise compounded to provide a dosage form affording the advantage of prolonged action For example, the tablet or pill can compnse an inner dosage and an outer dosage component, the latter being in the form of an envelope over the former The two components can be separated by an entenc layer which serves to resist disintegration in the stomach and permit the inner component to pass intact into the duodenum or to be delayed in release A vanety of matenals can be used for such entenc layers oi coatings, such matenals including a number of polymenc acids and mixtures of polymenc acids with such matenals as shellac, cetyl alcohol, and cellulose acetate The liquid forms m which the novel compositions of the present invention may be incorporated for administration orally or by injection include aqueous solutions, suitably flavored syrups, aqueous or oil suspensions, and flavored emulsions with edible oils such as corn oil, cottonseed oil, sesame oil, coconut oil, or peanut oil, as well as elixirs and similar pharmaceutical vehicles Compositions for inhalation or insufflation include solutions and suspensions in pharmaceutically acceptable, aqueous or organic solvents, or mixtures thereof, and powders The liquid or solid compositions may contain suitable pharmaceutically acceptable excipients as descnbed supra Preferably the compositions are administered by the oral or nasal respiratory route for local or systemic effect Compositions m preferably pharmaceutically acceptable solvents may be nebulized by use of inert gases Nebulized solutions may be inhaled directly from the nebulizing device or the nebulizing device may be attached to a face mask tent, or intermittent positive pressure breathing machine Solution, suspension, or powder compositions may be administered, preferably orally or nasally, from devices which deliver the formulation m an appropnate manner The following formulation examples illustrate representative pharmaceutical compositions ofthe present invention Formulation Example 1 Hard gelatin capsules containing the following ingredients are prepared Quantity Ingredient (mg/capsule) Active Ingredient 30 0 Starch 305 0 Magnesium stearate 5 0 The above ingredients are mixed and filled into hard gelatin capsules in 340 mg quantities Formulation Example 2 A tablet formula is prepared using the ingredients below Quantity Ingredient (mg/tablet) Active Ingredient 25 0 Cellulose, micro crystalline 200 0 Colloidal silicon dioxide 10 0 Steanc acid 5 0 The components are blended and compressed to form tablets, each weighing 240 mg Formulation Example 3 A dry powder inhaler formulation is prepared containing the following components Ingredient Weight % Active Ingredient 5 Lactose 95 The active ingredient is mixed with the lactose and the mixture is added to a dry powder inhaling appliance Formulation Example 4 Tablets, each containing 30 mg of active ingredient, are prepared as follows Quantity Ingredient Active Ingredient 30 0 mg Starch 45 0 mg Microcrystalhne cellulose 35 0 mg Polyvinylpyrrolidone (as 10% solution in stenle water) 4 0 mg Sodium carboxymethyl starch 4 5 mg Magnesium stearate 0 5 mg Talc 1 ,0 mg Total 120 me The active ingredient, starch and cellulose are passed through a No 20 mesh U S sieve and mixed thoroughly The solution of polvvmylpyrrohdone is mixed with the resultant powders, which are then passed through a 16 mesh U S sieve The granules so produced are dned at 50° to 60° C and passed through a 16 mesh U S sieve The sodium carboxymethyl starch, magnesium stearate, and talc, previously passed through a No 30 mesh U S sieve, are then added to the granules which, after mixing, are compressed on a tablet machine to yield tablets each weighing 120 mg Formulation Example 5 Capsules, each containing 40 mg of medicament are made as follows Quantity Ingredient (mg/capsule) Active Ingredient 40 0 mg Starch 109 O mg Magnesium stearate 1 .0 mg Total 150 O mg The active ingredient, starch, and magnesium stearate are blended, passed through a No 20 mesh U S sieve, and filled into hard gelatin capsules in 150 mg quantities Eormulation Example 6 Suppositones, each containing 25 mg of active ingredient are made as follows Ingredient Amount Active Ingredient 25 mg Saturated fatty acid glycendes to 2,000 mg The active ingredient is passed through a No 60 mesh U S sieve and suspended in the saturated fatty acid glycendes previously melted using the minimum heat necessary The mixture is then poured into a suppository mold of nominal 2 0 g capacity and allowed to cool Formulation Example 7 Suspensions, each containing 50 mg of medicament per 5 0 mL dose are made as follows Ingredient Amount Active Ingredient 50 O mg Xanthan gum 4 O mg Sodium carboxymethyl cellulose (11%) Microcrystallme cellulose (89%) 50 O mg Sucrose 1 75 g Sodium benzoate 10 O mg Flavor and Color q v Punfied water to 5 O mL The active ingredient, sucrose and xanthan gum are blended, passed through a No. 10 mesh U.S. sieve, and then mixed with a previously made solution of the microcrystalline cellulose and sodium carboxymethyl cellulose in water. The sodium benzoate, flavor, and color are diluted with some of the water and added with stirring. Sufficient water is then added to produce the required volume. Formulation Example 8 A formulation may be prepared as follows: Quantity Ingredient (mg/capsule) Active Ingredient 15.0 mg Starch 407.0 mg Magnesium stearate 3.0 mg Total 425.0 mg The active ingredient, starch, and magnesium stearate are blended, passed through a No. 20 mesh U.S. sieve, and filled into hard gelatin capsules in 425.0 iru quantities. Formulation Example 9 A formulation may be prepared as follows: Ingredient Quantity Active Ingredient 5.0 mg Corn Oil 1.0 mL Formulation Example 10 A topical formulation may be prepared as follows: Ingredient Quantity Active Ingredient 1-lO g Emulsifying Wax 30 g Liquid Paraffin 20 g White Soft Paraffin to 100 g The white soft paraffin is heated until molten. The liquid paraffin and emulsifying wax are incorporated and st red until dissolved. The active ingredient IS added and stirnng is continued until dispersed The mixture is then cooled until solid Another preferred formulation employed in the methods of the present invention employs transdermal delivery devices ("patches") Such transdermal patches may be used to provide continuous or discontinuous infusion of the compounds ofthe present invention in controlled amounts The construction and use of transdermal patches for the delivery of pharmaceutical agents is well known in the art See, e g , U S Patent 5,023,252, issued June 1 1, 1991, herein incorporated by reference m its entirety Such patches may be constructed for continuous, pulsatile, or on demand delivery of pharmaceutical agents Other suitable formulations for use in the present invention can be found in Remington's Pharmaceutical Sciences, Mace Publishing Company, Philadelphia, PA, 17th ed (1985) Utility The multibinding compounds of this invention are agonists, partial agonists, inverse agonists or antagonists of the D, receptors, preferably antagonists of the D,A receptors, which are known to mediate numerous disorders Accordingly, the multibinding compounds and pharmaceutical compositions of this invention are useful in the treatment and prevention of various disorders mediated by D, receptors Examples of disorders which can be treated using the compounds descnbed herein include hypertension, angina, congestive heart failure, renal failure (including chronic and acute renal failure), impotence, psychosexual disorders, Parkinson's disease and the like When used in treating or ameliorating such conditions, the compounds of this invention are typically delivered to a patient m need of such treatment by a pharmaceutical composition compnsmg a pharmaceutically acceptable diluent and an effective amount of at least one compound of this invention The amount of compound administered to the patient will vary depending upon what compound and/or composition is being administered, the purpose of the administration, such as prophylaxis or therapy, the state of the patient, the manner of administration, and the like In therapeutic applications, compositions are administered to a patient already suffenng from, for example, renal failure, in an amount sufficient to at least partially reduce the symptoms Amounts effective for this use will depend on the judgment of the attending clinician depending upon factors such as the degree or seventy of the disorder m the patient, the age, weight and general condition of the patient, and the like The pharmaceutical compositions of this invention may contain more than one compound ofthe present invention Typically, dosages useful for treating renal failure are less than those used to treat cardiac disorders As noted above, the compounds admimsteied to a patient are in the form of pharmaceutical compositions described above which can be administered by a variety of routes including oral, rectal, transdermal, subcutaneous, intravenous, intramuscular, etc These compounds are effective as both injectable and oral deliverable pharmaceutical compositions Such compositions are prepared in a manner well known in the pharmaceutical art and comprise at least one active compound The multibinding compounds of this invention can also be administered in the form of pro-drugs, l e , as derivatives which are converted into a biologicallv active compound in vι\ o Such pro-drugs w ill typicallv include compounds in which, for example, a carboxylic acid group, a hydroxyl group or a thiol group is converted to a biologically liable group, such as an ester, lactone or thioester group which will hydrolyze in vivo to reinstate the respective group Combinatorial Chemistry The compounds can be assayed to identify which of the multimenc ligand compounds possess multibinding properties First, one identifies a ligand or mixture of ligands which each contain at least one reactive functionality and a library of linkers which each include at least two functional groups having complementary reactivity to at least one of the reactive functional groups of the ligand Next one prepares a multimenc ligand compound library by combining at least two stoichiometnc equivalents ofthe ligand or mixture of ligands with the library of linkers under conditions wherein the complementary functional groups react to form a covalent linkage between the linker and at least two of the ligands The multimenc ligand compounds produced in the library can be assayed to identify multimenc hgand compounds which possess multibinding properties The method can also be performed using a library of hgands and a linker or mixture of linkers The preparation ofthe multimenc ligand compound library can be achieved by either the sequential or concurrent combination of the two or more stoichiometric equivalents of the ligands with the linkers The multimeπc ligand compounds can be dimeπc, for example, homomenc or heteromeπc A heteromeπc hgand compound library can be prepared by sequentially adding a first and second hgand Each member of the multimenc ligand compound library can be isolated from the library, for example, by preparative liquid chromatography mass spectrometry (LCMS) The linker or linkers can be flexible linkers, ngid linkers, hydrophobic linkers, hydrophihc linkers, linkers of different geometry, acidic linkers, basic linkers, linkers of different polanzation and/or polanzabihty or amphiphihc linkers The linkers can include linkers of different chain lengths and/or which have different complementary reactive groups In one embodiment the linkers are selected to have different linker lengths ranging from about 2 to 100A The hgand or mixture of hgands can have reactive functionality at different sites on the ligands The reactive functionality can be, for example, carboxylic acids, carboxylic acid halides, carboxyl esters, am es, halides, pseudohahdes, isocyanates, vmyl unsaturation, ketones, aldehydes, thiols, alcohols, anhydndes, boronates, and precursors thereof, as long as the reactive functionality on the ligand is complementary to at least one ofthe reactive groups on the linker so that a covalent linkage can be formed between the linker and the ligand A library of multimenc ligand compounds can thus be formed which possesses multivalent properties Multimenc ligand compounds possessing multibinding pioperties can be identified in an iterative method by prepanng a first collection or iteration of multimenc compounds by contacting at least two stoichiometric equivalents of the ligand or mixture of ligands which target the D, receptors with a linker or mixture of linkers, where the ligand or mixture of hgands includes at least one reactive functionality and the linker or mixture of linkers includes at least two functional groups having complementary reactivity to at least one of the reactive functional groups ofthe ligand The hgand(s) and hnker(s) are reacted under conditions which form a covalent linkage between the linker and at least two of the ligands The first collection or iteration of multimenc compounds can be assayed to assess which if any of the compounds possess multibinding properties The process can be repeated until at least one multimeπc compound is found to possess multibinding properties By evaluating the particular molecular constraints which are imparted or are consistent with imparting multibinding properties to the multimenc compound or compounds in the first iteration, a second collection or iteration of multimenc compounds which elaborates upon the particular molecular constraints can be assayed, and the steps optionally repeated to furthei elaborate upon said molecular constraints For example, the steps can be repeated from between 2 and 50 times, more preferably, between 5 and 50 times The following synthetic and biological examples are offered to illustrate this invention and are not to be construed in any way as limiting the scope of this invention Unless otherwise stated, all temperatures are in degrees Celsius EXAMPLES In the examples below, the following abbreviations have the following meanings If an abbreviation is not defined, it has its generally accepted meaning A Angstroms cm centimeter DCC dicyclohexyl carbodiimide DMF N N-dimethyl formamide DMSO dimethylsulfoxide EDTA ethylenediammetetraacetic acid σ gram HPLC high performance liquid chromatography MEM minimal essential medium milligram MIC minimum inhibitory concentration mm minute mL milhhter mm millimeter mmol milhmol N normal THF tetrahydrofuran μL microhters μm = microns ANALYTIC AT. EXAMPLES Example 1: In vitro Radioligand binding studies. Receptor binding assays for the D, and D2 receptors can be performed on rat membrane preparations by competitive binding studies using displacement of 0 2 nM [ H]SCH 23390 (Hytell, Eur J Pharmacol , 91 153 (1983)) and 0 2 nM [ 3 H]spιperone (Seeman et al , J L Mol Pharmacol , 28 391 (1985)), respectively In general, after rapid decapitation and dissection of the appropnate brain tissue, crude membrane pellets are prepared by homogemzation and centrifugation Ahquots of membrane homogenate are added to test tubes containing buffer, radiohgand, and various concentrations of inhibitor Nonspecific binding is determined using an excess ofthe specified inhibitor for the receptor of interest Following the appropnate incubation conditions, the reactions are terminated bv separating the membrane bound from free radiohgand by rapid filtration over Whatman GF/C filters Bound radiohgand is quantified by scintillation spectroscopy The percent inhibition of radiohgand binding at each test concentration is calculated, and an IC 50 is determined by log-probit analysis Example 2: In vivo assays predicting efficacy Useful bioassays for determining the efficacy of the compounds, as well as their side effect profiles, include hexabarbitol induced sleep, neurological defect pentalene tetrazole induced seizures, electroshock induced seizures and observations of general mice behavior Renal vasodilator activity can be measured according to the methods disclosed in Wemstock et al , I. Med. Chem., 23 973 (1980), the contents of which are hereby incorporated by reference Bnefly renal vasodilator activity can be measured in anesthetized dogs surgically prepared for electromagnetic measurement of renal blood flow Blood pressure can be measured, for example from the carotid artery Drugs can be infused into a suitable v em, for example an antecubital vein RVR can be calculated as the ratio of mean arterial blood pressure to mean renal blood flow Stimulation of DA-sensitive adenylate cyclase can be measured using homogenates of rat stnatum using the procedures described m Kebabian et al Pioc Natl. Acad. Sci., US A 69 2145 (1972) and Fujita and Saito, NeuropharmacQJ. 17 1089 (1978), the contents of which are hereby incorporated by reference The EC 50 is the molar concentration of the compound which provides 50% of the maximal increase of cAMP production over the range of concentrations tested Preparative Examples Example 1 Preparation of (103), a compound of Formula I. A solution of 20 mmols of 6-chloro-7,8-dιmethoxy-l-(4-methoxyphenyl)- 2,3,4,5-tetrahydro-lH-3-benzazepme (100) in DMF with 10 mmols of 1,3- dibromopropane (120) and 20 mmols of potassium carbonate is heated as necessary and the reaction followed by TLC When judged complete, the mixture is partitioned between ethyl acetate and water and the organic phase washed with water, dned over sodium sulfate and the solvent removed in vacuo The residue is punfied by chromatography to afford the desired product (102). To a solution of (102) (4 6 mmol) in dry CH 2 C1 2 at -10°C, under argon, is added BBr 3 (12 8 mmol, 8 mL of a solution of 1 g of BBr 3 per 2 5 mL of CH 2 C1 2 ) The solution is allowed to come to 25 °C duπng the course of 30 mm and the reaction is followed by TLC The reaction is quenched by the addition of excess methanol, concentrated, and the residue is triturated with ethyl acetate, filtered, and dissolved in warm water The solution is adjusted to pH 8 with aqueous ammonia Precipitated solid is filtered and washed with cold water The solid is slurned in methanol and 98% methanesulfomc acid is added to give pH 1 Ethyl acetate is added to the resulting solution and then ethei is added until the solution becomes cloudy After cooling, crystallization affords the title product The preparation of compound (100) is descnbed in J Med Chem 1982, 25, 352-358 and also in J Med Chem 1980, 23, 973-975 The chemistry is shown below (103) Example 2: Preparation of (107), a compound of Formula I. A solution of (S)-7,8-dimethoxy-l-phenyl-2,3,4,5-tetrahydro-lH-3- benzazepine (104) (2 mmols), prepared from resolution of the racemic mixture following the procedure described in Acta Phar. Suec. (1983) Issue Suppl. 2, Dopamine Receptor: Agonists 2, 132-150, and benzene- 1 ,4-bisacetic acid (105) (lmmol) in methylene chloride is prepared under argon in a flask equipped with magnetic stirrer and drying tube. To this solution is added dicyclohexylcarbodiimide (2.1 mmols) while stirring at room temperature. The course of the reaction is followed by TLC. When reaction has occuned, the reaction solution is diluted with ethyl acetate and washed with water and with aqueous Na 2 CO 3 . The organic layer is dried (Na 2 S0 4 ), filtered and concentrated under reduced pressure to give the crude product. Purification of the crude product by use of HPLC affords the desired product (106). To a solution of (106) (4.6 mmol) in dry CH 2 C1 2 at -10 °C, under argon, is added BBr 3 (12.8 mmol, 8 mL of a solution of 1 g of BBr 3 per 2.5 mL of CH 2 C1 2 ). The solution is allowed to come to 25 °C during the course of 30 min and the reaction is followed by TLC. The reaction is quenched by the addition of excess methanol, concentrated, and the residue is triturated with ethyl acetate, filtered, and dissolved in wanri water. The solution is adjusted to pH 8 with aqueous ammonia. Precipitated solid is filtered and washed with cold water. The solid is slurried in methanol and 98% methanesulfonic acid is added to give pH 1. Ethyl acetate is added to the resulting solution and then ether is added until the solution becomes cloudy. After cooling, crystallization affords the title product. The preparation of compound (104) is described in J. Med. Chem. 1982, 25, 352-358. The chemistry is shown below. (107) Example 3. Preparation of (110), a compound of Formula II. A solution of 20 mmols of (108) in DMF with 10 mmols of 1,4- dibromobutane (101) and 20 mmols of potassium carbonate is heated as necessary and the reaction followed by TLC When judged complete, the mixture is partitioned between ethyl acetate and water and the organic phase washed with water, dried over sodium sulfate and the solvent removed in vacuo The residue is punfied by chromatography to afford the desired product (109). To a solution of (109) (4 6 mmol) in dry CH 2 C1 2 at -10 °C, under argon, is added BBr 3 (12 8 mmol, 8 mL of a solution of 1 g of BBr 3 per 2 5 mL of CH 2 C1,) The solution is allowed to come to 25 °C dunng the course of 30 mm and the reaction is followed by TLC The reaction is quenched by the addition of excess methanol, concentrated, and the residue is triturated with ethyl acetate, filtered, and dissolved in warm water The solution is adjusted to pH 8 with aqueous ammonia Precipitated solid is filtered and washed with cold water The solid is slurned in methanol and 98% methanesulfomc acid is added to give pH 1 Ethyl acetate is added to the resulting solution and then ether is added until the solution becomes cloudy After cooling, crystallization affords the title product The preparation of compound (108) is descnbed in Example 5 The chemistry is shown below W wOυ 9 v9/ / 6o3 j 9 y 9 y 3 j PCT US9 9 /12 7 78 -97- Example 4 Preparation of (114), a compound of Formula III. A solution of 20 mmols of (108) in DMF with 20 mmols of 1,5- dibromopentane (121) and 20 mmols of potassium carbonate is heated as necessary and the reaction followed by TLC When judged complete, the mixture is partitioned between ethyl acetate and water and the organic phase washed with water, dried over sodium sulfate and the solvent removed in vacuo The residue is punfied by chromatography to afford the desired product (112) A solution of 20 mmols of (112) in DMF with 20 mmols of (111) and 20 mmols of potassium carbonate is heated as necessary and the reaction followed by TLC When judged complete, the mixture is partitioned between ethyl acetate and water and the organic phase washed with water, dned over sodium sulfate and the solvent removed in vacuo The residue is punfied by chromatography to afford the desired product (113). To a solution of (113) (4 6 mmol) in dry CH 2 C1 2 at -10 °C, under argon, is added BBr 3 (12 8 mmol, 8 mL of a solution of 1 g of BBr 3 per 2 5 mL of CH 2 C1 2 ) The solution is allowed to come to 25 °C dunng the course of 30 mm and the reaction is followed by TLC The reaction is quenched by the addition of excess methanol, concentrated, and the residue is tnturated with ethyl acetate, filtered, and dissolved m warm water The solution is adjusted to pH 8 with aqueous ammonia Precipitated solid is filtered and washed with cold water The solid is slurned in methanol and 98% methanesulfomc acid is added to give pH 1 Ethyl acetate is added to the resulting solution and then ether is added until the solution becomes cloudy After cooling, crystallization affords the title product The preparation of compound (108) is descnbed in Example 5 Compound (111) is descnbed in Acta Phar Suec (1983) Issue Suppl 2, Dopamine Receptor Agonists 2, 132-150 The chemistry is shown below (113) (114) Example 5 Preparation of (108) A suspension of 50% NaH (0 28 mmol) m mineral oil in 300 mL of Me 2 SO is heated at 65-70 °C for 80 mm Then 150 mL of dry THF is added and the mixture is cooled in ice water A solution of tnmethylsulfomum iodide (0 28 mmol) in 400 mL of Me 2 SO is added over 10 mm After the mixture is stirred for an additional 5 min, a solution of 3-hydroxybenzaldehyde (115) in 150 mL of THF is added over 10 mm The mixture is stirred at 0 °C for 15 mm and then at 25 °C for 2 h, diluted with 4 L of ice water, and extracted several times with ethyl acetate, and the extracts are washed with brine The dned crude oxirane is mixed with 2-(2-chloro- 3,4-dιmethoxyphenyl)ethylamme (116) and heated at 1 10 °C for 18 h under nitrogen The cooled reaction mixture is tnturated with ethyl acetate to give a voluminous solid, which is collected and washed with ethyl acetate/petroleum ether Punfication via column chromatography affords the desired product (117) In 50 mL of CF 3 COOH is dissolved 0 02 mmol of (117), and then 2 5 mL of H 2 S0 4 is added The solution is refluxed for 2 h, concentrated in vacuo, basified with cold NaOH solution and extracted with ethyl acetate After the solution is washed with water, the dried, concentrated product is converted to the hydrochloride salt with ethereal HCl to afford the desired product as (118)«HC1 A solution of 8 5 mmol of (118), 15 mL of 37% HCHO, and 18 mL of 88% HCOOH is heated on the steam bath for 4 5 h, diluted with ice, and basified with NaOH solution, and the product is extracted into ethyl acetate and washed with water The crude matenal is punfied by chromatography to afford the desired product (119) Resolution of the racemic mixture is achieved using the procedure described in Acta Phar Suec (1983) Issue Suppl 2, Dopamine Receptor Agonists 2, 132- 150 to afford the title structure The chemistry is shown below H 2 S0 4 , TFA While the above examples are described with respect to particular D, receptor antagonists, the chemistry is applicable to all of the hgands described herein. The chemistry outlined above in Examples 1-5 is further illustrated in Figures 6-8 where the generic linkers are shown. In Figure 6, one equivalent of a ligand with an amine group is reacted with a linker molecule with two leaving groups (X) to provide a dimeric compound. In Figure 7, one equivalent of a ligand with a nucleophilic group (YH) is reacted with a linker molecule with two leaving groups (X) to form a dimeric compound. In Figure 3, one equivalents of a ligand with an amine group are reacted with one equivalent of a linker with two leaving groups (X) to form an intermediate containing a leaving group (X). This intermediate is reacted with a second ligand containing a nucleophilic group (YH) to form a mixed dimer.

Claims: WHAT IS CLAIMED IS: 1 A multibinding compound comprising from 2 to 10 ligands covalently attached to one or more linkers wherein each of said ligands independently comprises an agonist, partial agonist, inverse agonist or antagonist of the D, receptors, and pharmaceutically-acceptable salts thereof 2 A multibinding compound of formula I (L) p (X) q I wherein each L is independently a hgand which is an agonist, partial agonist inverse agonist or antagonist of the D receptors, each X is independently a linker, p is an integer of from 2 to 10, and q is an integer of from 1 to 20, and phannaceutically-acceptable salts thereof 3 The multibinding compound of Claim 2 wherein q is less than/? 4 The multibinding compound of Claim 3 herein each hgand is independently selected from a compound of formula IA-F and analogs thereof, wherein A is H, alkyl or a direct link to the linker; and Mι .20 are, independently, H or a direct link to the linker, wherein only one of A or M, .20 is a link to the linker. 5. The multibinding compound of Claim 4 wherein each linker independently has the formula: -X a -Z-(Y a -Z) m -Y b -Z-X a - wherein m is an integer of from 0 to 20; X a at each separate occunence is selected from the group consisting of -0-, -S-, -NR-, -C(O)-, -C(O)O-, -C(O)NR-, -C(S), -C(S)O-, -C(S)NR- or a covalent bond where R is as defined below; Z is at each separate occurrence is selected from the group consisting of alkylene, substituted alkylene, cycloalkylene, substituted cylcoalkylene, alkenylene, substituted alkenylene, alkynylene, substituted alkynylene, cycloalkenylene, substituted cycloalkenylene, arylene, heteroarylene, heterocyclene, or a covalent bond; Y a and Y b at each separate occurrence are selected from the group consisting of -C(0)NR\ -NR'C(O)-, -NR'C(O)NR'-, -C(=NR')-NR'-, -NR'-C(=NR')-, -NR'-C(O)-0-, -N=C(X a )-NR'-, -P(0)(OR')-0-, -S(O) n CR'R"-, -S(O) n -NR'-, -S-S- and a covalent bond; where n is 0, 1 or 2; and R, R' and R" at each separate occurrence are selected from the group consisting of hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, substituted alkenyl, cycloalkenyl, substituted cycloalkenyl, alkynyl, substituted alkynyl, aryl, heteroaryl and heterocyclic. 6 A multibinding compound of formula II L'— X'— L' II wherein each L' is independently a ligand compnsmg an agonist, partial agonist, inverse agonist or antagonist of the D, receptors and X' is a linker, and pharmaceutically-acceptable salts thereof 7 The multibinding compound of Claim 6 wherein each ligand is independently selected from the group consisting of compounds of formula 1A-F and analogs thereof 8 The multibinding compound of Claim 6 wherein X' has the formula -X a -Z-(Y a -Z) m -Y b -Z-X α - wherein m is an integer of from 0 to 20, X a at each separate occurrence is selected from the group consisting of -O-, -S-, -NR-, -C(O)-, -C(O)0-, -C(O)NR-, -C(S), -C(S)0-, -C(S)NR- or a covalent bond where R is as defined below, Z is at each separate occurrence is selected from the group consisting of alkylene, substituted alkylene, cycloalkylene, substituted cylcoalkylene, alkenylene, substituted alkenylene, alkynylene, substituted alkynylene, cycloalkenylene, substituted cycloalkenylene, arylene, heteroarylene, heterocyclene, or a covalent bond, Y a and Y b at each separate occunence are selected from the group consisting of -C(O)NR'-, -NR'C(O)-, -NR'C(O)NR'-, -C(=NR')-NR'-, -NR'-C(=NR'K -NR'-C(O)-0-, -N=C(X a )-NR\ -P(0)(OR')-0-, -S(O) n CR'R"-, -S(O) n -NR'-, -S-S- and a covalent bond, where n is 0, 1 or 2, and R, R' and R" at each separate occunence are selected from the group consisting of hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, substituted alkenyl, cycloalkenyl, substituted cycloalkenyl, alkynyl, substituted alkynyl aryl, heteroaryl and heterocyclic. 9. A multibinding compound of claim 6 wherein the ligand is an agonist or partial agonist of the D, receptors. 10. A pharmaceutical composition comprising a pharmaceutically acceptable carrier and an effective amount of a multibinding compound of formula II: L'— X'— L' II wherein each L' is independently a ligand comprising an agonist, partial agonist, inverse agonist or antagonist of the D, receptors; and X' is a linker; and pharmaceutically-acceptable salts thereof. 1 1. The pharmaceutical composition of Claim 10 wherein each ligand is independently selected from the group consisting of compounds of formulas 1 A-F 12 The pharmaceutical composition of Claim 10 wherein X' has the formula: -X a -Z-(Y a -Z) m -Y b -Z-X a - wherein m is an integer of from 0 to 20; X a at each separate occurrence is selected from the group consisting of -0-, -S-. -NR-, -C(O)-, -C(O)0-, -C(O)NR-, -C(S), -C(S)0-, -C(S)NR- or a covalent bond where R is as defined below; Z is at each separate occunence is selected from the group consisting of alkylene, substituted alkylene, cycloalkylene, substituted cylcoalkylene, alkenylene, substituted alkenylene, alkynylene, substituted alkynylene, cycloalkenylene, substituted cycloalkenylene, arylene, heteroarylene, heterocyclene, or a covalent bond, Y a and Y b at each separate occurrence are selected from the group consisting of -C(O)NR'-, -NR'C(O)-, -NR'C(O)NR'-, -C(=NR')-NR'-, -NR'-C(=NR')-, -NR'-C(O)-O-, -N=C(X a )-NR\ -P(O)(OR')-O-, -S(O) n CR'R"-, -S(O) n -NR'-, -S-S- and a covalent bond, where n is 0, 1 or 2, and R, R' and R" at each separate occurrence are selected from the group consisting of hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, substituted alkenyl, cycloalkenyl, substituted cycloalkenyl, alkynyl, substituted alkynyl, aryl, heteroaryl and heterocyclic 13 A method for treating hypertension, angina, congestive heart failure, renal failure, impotence, psychosexual disorders, or Parkinson's disease compnsmg administenng an effective amount of he compound of claim 1 to a patient in need of treatment thereof 14 The method of Claim 13 wherein the compound is a compound of formula I 15 The method of Claim 14 wherein q is less than p 16 The method of Claim 13 wherein each hgand is independently selected from a compound of formula IA-F W wOυ 9 y 9 y /6o3 j 9 y 9 y 3 j PCT/US99/12778 -111- and analogs thereof, wherein A is H, alkyl or a direct link to the linker; and M, 20 are, independently, H or a direct link to the linker, wherein only one of A or M, 20 is a link to the linker 17 The method of Claim 16 wherein each linker independently has the formula -X a -Z-(Y a -Z) m -Y b -Z-X a - wherein m is an integer of from 0 to 20, X a at each separate occunence is selected from the group consisting of -O-, -S-, -NR-, -C(O)-, -C(O)O-, -C(O)NR-, -C(S), -C(S)O-, -C(S)NR- or a covalent bond where R is as defined below, Z is at each separate occurrence is selected from the group consisting of alkylene, substituted alkylene, cycloalkylene, substituted cylcoalkylene, alkenylene, substituted alkenylene, alkynylene, substituted alkynylene, cycloalkenylene, substituted cycloalkenylene, arylene, heteroarylene, heterocyclene, or a covalent bond, Y a and Y b at each separate occunence are selected from the group consisting of -C(0)NR'-, -NR'C(O)-, -NR'C(O)NR'-, -C(=NR')-NR'-, -NR'-C(=NR')-, -NR'-C(O)-0-, -N=C(X a )-NR\ -P(O)(OR')-O-, -S(O) n CR'R"-, -S(0) n -NR'-, -S-S- and a covalent bond, where n is 0, 1 or 2, and R, R' and R" at each separate occunence are selected from the group consisting of hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, substituted alkenyl, cycloalkenyl, substituted cycloalkenyl, alkynyl, substituted alkynyl, aryl, heteroaryl and heterocyclic 18 The method of claim 13 wherein the compound is a compound of formula II 19 The method of Claim 18 wherein each ligand is independently selected from the group consisting of compounds of formula 1A-F and analogs thereof 20 The method of Claim 19 wherein X' has the formula -X a -Z-(Y a -Z) m -Y b -Z-X a - wherein m is an integer of from 0 to 20, X a at each separate occurrence is selected from the group consisting of -0-, -S-, -NR-, -C(O)-, -C(O)O-, -C(O)NR-, -C(S), -C(S)O-, -C(S)NR- or a covalent bond where R is as defined below, Z is at each separate occunence is selected from the group consisting of alkylene, substituted alkylene, cycloalkylene, substituted cylcoalkylene, alkenylene, substituted alkenylene, alkynylene, substituted alkynylene, cycloalkenylene, substituted cycloalkenylene, arylene, heteroarylene, heterocyclene, or a covalent bond, Y a and Y b at each separate occurrence are selected from the group consisting of -C(O)NR\ -NR'C(O)-, -NR'C(O)NR'-, -C(=NR')-NR'-, -NR'-C(=NR')-, -NR'-C(O)-0-, -N=C(X a )-NR\ -P(O)(OR')-0-, -S(0) p CR'R"-, -S(0) n -NR'-, -S-S- and a covalent bond, where n is 0, 1 or 2, and R, R and R" at each separate occunence are selected from the group consisting of hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, substituted alkenyl, cycloalkenyl, substituted cycloalkenyl, alkynyl, substituted alkynyl, aryl, heteroaryl and heterocyclic 21 The method of Claim 13 wherein the ligand is an agonist or partial agonist of the D [ receptors 22 A method for identifying multimenc hgand compounds possessing multibinding properties which method compnses (a) identifying a ligand or a mixture of ligands wherein each ligand is an agonist, partial agonist, inverse agonist, partial inverse agonist, or antagonist ofthe D, receptors and contains at least one reactive functionality, (b) identifying a library of linkers wherein each linker in said library compnses at least two functional groups having complementary reactivity to at least one of the reactive functional groups of the ligand, (c) preparing a multimenc ligand compound library by combining at least two stoichiometnc equivalents ofthe ligand or mixture of ligands identified in (a) with the library of linkers identified in (b) under conditions wherein the complementary functional groups react to form a covalent linkage between said linker and at least two of said ligands; and (d) assaying the multimenc ligand compounds produced in the library prepared in (c) above to identify multimenc ligand compounds possessing multibinding properties 23 A method for identifying multimenc ligand compounds possessing multibinding properties which method compnses (a) identifying a library of ligands wherein each ligand is an agonist, partial agonist, inverse agonist, partial inverse agonist, or antagonist of the D j receptors and contains at least one reactive functionality, (b) identifying a linker or mixture of linkers wherein each linker compnses at least two functional groups having complementary reactivity to at least one of the reactive functional groups ofthe ligand, (c) preparing a multimenc ligand compound library by combining at least two stoichiometnc equivalents ofthe library of ligands identified m (a) with the linker or mixture of linkers identified in (b) under conditions wherein the complementary functional groups react to form a covalent linkage between said linker and at least two of said ligands, and (d) assaying the multimenc ligand compounds produced m the library prepared in (c) above to identify multimenc ligand compounds possessing multibinding properties 24 The method according to Claim 22 or 23 wherein the preparation of the multimenc ligand compound library is achieved by either the sequential or concureent combination of the two or more stoichiometnc equivalents of the ligands identified in (a) with the linkers identified in (b) 25 The method according to Claim 24 wherein the multimenc hgand compounds compnsmg the multimenc ligand compound library are dimenc 26 The method according to Claim 25 wherein the dimeric ligand compounds compnsmg the dimenc ligand compound library are heteromeπc 27 The method according to Claim 26 wherein the heteromenc ligand compound library is prepared by sequential addition of a first and second hgand 28 The method according to Claim 22 or 23 wherein, prior to procedure (d), each member of the multimeπc ligand compound library is isolated from the library 29 The method according to Claim 28 wherein each member of the library is isolated by preparative liquid chromatography mass spectrometry (LCMS) 30 The method according to Claim 22 or 23 wherein the linker or linkers employed are selected from the group comprising flexible linkers, ngid linkers hydrophobic linkers, hydrophihc linkers, linkers of different geometry, acidic linkers, basic linkers, linkers of different polanzation and/or polanzabihty and amphiphihc linkers 31 The method according to Claim 30 wherein the linkers comprise linkers of different chain length and/or having different complementary reactiv e groups 32 The method according to Claim 31 wherein the linkers are selected to have different linker lengths ranging from about 2 to 100A 33 The method according to Claim 22 or 23 wherein the ligand or mixture of ligands is selected to have reactive functionality at different sites on said ligands 34 The method according to Claim 33 wherein said reactive functionality is selected from the group consisting of carboxylic acids, carboxylic acid halides, carboxyl esters, ammes, halides, pseudohahdes, isocyanates, vinyl unsaturation, ketones, aldehydes, thiols, alcohols, anhydndes, boronates, and precursors thereof wherein the reactive functionality on the hgand is selected to be complementary to at least one ofthe reactive groups on the linker so that a covalent linkage can be formed between the linker and the ligand 35 The method according to Claim 22 or 23 wherein the multimenc ligand compound library compnses homomeπc hgand compounds 36 The method according to Claim 22 or 23 wherein the multimenc ligand compound library compnses heteromeπc hgand compounds 37 A library of multimenc ligand compounds which may possess multivalent properties which library is prepared by the method compnsmg (a) identifying a ligand or a mixture of ligands wherein each ligand is an agonist, partial agonist, inverse agonist, partial inverse agonist, or antagonist of the D, receptors and contains at least one reactive functionality, (b) identifying a library of linkers wherein each linker said library compnses at least two functional groups having complementary reactivity to at least one ofthe reactive functional groups ofthe ligand, and (c) prepanng a multimenc ligand compound library by combining at least two stoichiometnc equivalents of the ligand or mixture of ligands identified in (a) with the library of linkers identified in (b) under conditions wherein the complementary functional groups react to form a covalent linkage between said linker and at least two of said ligands. 38. A library of multimeric ligand compounds which may possess multivalent properties which library is prepared by the method comprising: (a) identifying a library of ligands wherein each ligand is an agonist, partial agonist, inverse agonist, partial inverse agonist, or antagonist of the D1 receptors and contains at least one reactive functionality; (b) identifying a linker or mixture of linkers wherein each linker comprises at least two functional groups having complementary reactivity to at least one of the reactive functional groups of the hgand; and (c) preparing a multimeric ligand compound library by combining at least two stoichiometric equivalents of the library of ligands identified in (a) with the linker or mixture of linkers identified in (b) under conditions wherein the complementary functional groups react to form a covalent linkage between said linker and at least two of said ligands. 39. The library according to Claim 37 or 38 wherein the linker or linkers employed are selected from the group comprising flexible linkers, rigid linkers, hydrophobic linkers, hydrophihc linkers, linkers of different geometry, acidic linkers, basic linkers, linkers of different polarization and/or polarizability and amphiphilic linkers. 40. The library according to Claim 39 wherein the linkers comprise linkers of different chain length and/or having different complementary reactive groups. 41. The library according to Claim 40 wherein the linkers are selected to have different linker lengths ranging from about 2 to 100A. 42 The library according to Claim 37 or 38 wherein the ligand or mixture of hgands is selected to have reactive functionality at different sites on said ligands 43 The library according to Claim 42 wherein said reactive functionality is selected from the group consisting of carboxylic acids, carboxylic acid halides, carboxyl esters, ammes, halides, pseudohahdes, isocyanates, vinyl unsaturation, ketones, aldehydes, thiols, alcohols, anhydndes, boronates, and precursors thereof wherein the reactive functionality on the hgand is selected to be complementary to at least one of the reactive groups on the linker so that a covalent linkage can be formed between the linker and the ligand 44 The library according to Claim 38 or 39 wherein the multimenc ligand compound library compnses homomenc ligand compounds 45 The library according to Claim 37 or 38 wherein the multimenc ligand compound library comprises heteromeπc ligand compounds 46 An iterative method for identifying multimenc ligand compounds possessing multibinding properties which method compnses (a) preparing a first collection or iteration of multimenc compounds which is prepared by contacting at least two stoichiometnc equivalents of the ligand or mixture of hgands which are agonists, partial agonists, inverse agonists, partial inverse agonists, or antagonists of the D, receptors and with a linker or mixture of linkers wherein said ligand or mixture of ligands compnses at least one reactive functionality and said linker or mixture of linkers comprises at least two functional groups having complementary reactivity to at least one of the reactive functional groups of the ligand wherein said contacting is conducted under conditions wherein the complementary functional groups react to form a covalent linkage between said linker and at least two of said ligands, (b) assaying said first collection or iteration of multimenc compounds to assess which if any of said multimenc compounds possess multibinding properties (c) repeating the process of (a) and (b) above until at least one multimeπc compound is found to possess multibinding properties, (d) evaluating what molecular constraints imparted or are consistent with imparting multibinding properties to the multimeπc compound or compounds found in the first iteration recited in (a)- (c) above, (e) creating a second collection or iteration of multimenc compounds which elaborates upon the particular molecular constraints imparting multibinding properties to the multimenc compound or compounds found m said first iteration, (f) evaluating what molecular constraints imparted or are consistent with imparting enhanced multibinding properties to the multimenc compound or compounds found in the second collection or iteration recited m (e) above, (g) optionally repeating steps (e) and (f) to further elaborate upon said molecular constraints 47 The method according to Claim 46 wherein steps (e) and (f) are repeated from 2-50 times 48 The method according to Claim 47 wherein steps (e) and (f) are repeated from 5-50 times

Inventors: GRIFFIN JOHN H, THOMAS G ROGER, YANG GUANG, GRIFFIN, JOHN, H., THOMAS, G., ROGER, YANG, GUANG
Applicants: ADVANCED MEDICINE INC, GRIFFIN JOHN H, THOMAS G ROGER, YANG GUANG, ADVANCED MEDICINE, INC., GRIFFIN, JOHN, H., THOMAS, G., ROGER, YANG, GUANG
Application year: 1999
Main classification: A61K31
IPC codes: A61K31, A61K38, A61K45, A61K47, A61P9, A61P11, A61P13, A61P15, A61P17, A61P21, A61P25, A61P27, A61P43, C07B61, C07C215, C07C217, C07C237, C07C271, C07C311, C07C323, C07D207, C07D209, C07D211, C07D213, C07D215, C07D221, C07D223, C07D235, C07D239, C07D241, C07D249, C07D257, C07D263, C07D265, C07D277, C07D295, C07D401, C07D403, C07D413, C07D417, C07D471, C07D487, C07D495, C07D519, C07K1, C07K2, C07K4, C07K7, C07K16, C40B20, G01N33, G01N37