# Patent

## Title
1-aryl- or 1-alkylsulfonyl-heterocyclylbenzazoles as 5-hydroxytryptamine-6 ligands

## Abstract

The present invention provides a compound of formula I and the use thereof in the therapeutic treatment of disorders related to or affected by the 5-HT6 receptor

## Background
This is a divisional of application Ser. No. 10/759,595 filed on Jan. 16, 2004 (now U.S. Pat. No. 7,034,029), which application is a continuation-in-part application of application Ser. No. 10/003,015, filed on Nov. 1, 2001 (now abandoned) which claims the benefit of provisional application Ser. No. 60/245,118, filed on Nov. 2, 2000, the entire disclosure of each application is hereby incorporated by reference.


BACKGROUND OF THE INVENTION
Compounds capable of forming 5-HT6 receptor ligands are potentially useful in the treatment of a number of central nervous system disorders such as anxiety, depression, epilepsy obsessive compulsive disorders, migraine, cognitive disorders, sleep disorders, feeding disorders, panic attacks, disorders resulting from withdrawal from drug abuse, schizophrenia, or certain gastrointestinal disorders such as irritable bowel syndrome. Significant efforts are being made to understand the recently identified 5HT-6 receptor and its possible role in neuropsychiatric and neurodegenerative functions. To that end, new compounds which demonstrate a binding affinity for the 5HT-6 receptor are earnestly sought, particularly as potential potent therapeutic agents.
Therefore, it is an object of this invention to provide compounds which are useful as therapeutic agents in the treatment of a variety of conditions related to or affected by the 5-HT6 receptor.
It is another object of this invention to provide methods and compositions useful for the treatment of psychoses (e.g., schizophrenia, anxiety, or depression), motor disorders (e.g., Parkinson's disease), anxiety, depression, obsessive compulsive disorder, attention deficit disorder, or any condition which is known to be related to or affected by the 5-HT6 receptor.
These and other objects and features of this invention will become more apparent by the detailed description set forth hereinbelow.
SUMMARY OF THE INVENTION
The present invention provides a compound of formula I




    
    
        wherein
        A is C, CR10 or N;
        X is CR11 or N;
        Y is CR7 or N with the proviso that when X is N, then Y must be CR7;
        R1 is H, C1-C6alkylcarbonyl, C1-C6alkylcarbonyloxy or an C1-C6alkyl, C1-C6alkenyl, C1-C6alkynl or C5-C7cycloheteroalkyl group each optionally substituted;
        R2, R3, R4, R5 and R6 are each independently H, halogen, OH or an optionally substituted C1-C6alkyl group;
        R7 and R11 are each independently H, halogen or an C1-C6alkyl, aryl, heteroaryl or C1-C6alkoxy group each optionally substituted;
        R8 is an C1-C6alkyl, aryl or heteroaryl group each optionally substituted;
        R9 is H, halogen or a C1-C6alkyl, C1-C6alkoxy, C1-C6alkenyl, aryl or heteroaryl group each optionally substituted;
        R10 is H, OH or an optionally subsituted alkoxy group;
        m is an integer of 1, 2 or 3;
        n is 0 or an integer of 1, 2 or 3; and
         represents a single bond or a double bond; or

a pharmaceutically acceptable salt thereof.

    
    


The present invention also provides methods and compositions useful in the treatment of central nervous system disorders.


DETAILED DESCRIPTION OF THE INVENTION
The 5-hydroxytryptamine-6 (5-HT6) receptor is one of the most recent receptors to be identified by molecular cloning. Its ability to bind a wide range of therapeutic compounds used in psychiatry, coupled with its intriguing distribution in the brain has stimulated significant interest in new compounds which are capable of interacting with or affecting said receptor. At present, there are no known fully selective agonists. Significant efforts are being made to understand the possible role of the 5-HT6 receptor in psychiatry, cognitive dysfunction, motor function and control, memory, mood and the like. To that end, compounds which demonstrate a binding affinity for the 5-HT6 receptor are earnestly sought both as an aid in the study of the 5-HT6 receptor and as potential therapeutic agents in the treatment of central nervous system disorders.
Surprisingly, it has now been found that 1-alkyl- or 1-arylsulfonyl-heterocyclylbenzazoles of formula I demonstrate 5-HT6 affinity along with significant sub-type selectivity. Advantageously, said formula I benzazoles are effective therapeutic agents for the treatment of central nervous system disorders associated with or affected by the 5-HT6 receptor. Accordingly, the present invention provides 1-alkyl- or 1-arylsulfonyl-heterocyclylbenzazole compounds of formula I




    
    
        wherein
        A is C, CR10 or N;
        X is CR11 or N;
        Y is CR7 or N with the proviso that when X is N, then Y must be CR7;
        R1 is H, C1-C6alkylcarbonyl, C1-C6alkylcarbonyloxy or a C1-C6alkyl, C1-C6alkenyl, C1-C6alkynl or cycloheteroalkyl group each optionally substituted;
        R2, R3, R4, R5 and R6 are each independently H, halogen, OH or an optionally substituted C1-C6alkyl group;
        R7 and R11 are each independently H, halogen or an C1-C6alkyl, aryl, heteroaryl or alkoxy group each optionally substituted;
        R8 is an C1-C6alkyl, aryl or heteroaryl group each optionally substituted;
        R9 is H, halogen or an C1-C6alkyl, C1-C6alkoxy, C1-C6alkenyl, aryl or heteroaryl group each optionally substituted;
        R10 is H, OH or an optionally subsituted alkoxy group;
        m is an integer of 1, 2 or 3;
        n is O or an integer of 1, 2 or 3; and
         represents a single bond or a double bond; or

a pharmaceutically acceptable salt thereof.

    
    


As used in the specification and claims, the term halogen designates Br, Cl, I or F; the term aryl designates phenyl or naphthyl; and the term cycloheteroalkyl designates a C5-C7cycloalkyl ring system containing 1 or 2 heteroatoms, which may be the same or different, selected from N, O or S and optionally containing one double bond. Exemplary of the cycloheteroalkyl ring systems included in the term as designated herein are the following rings wherein Y is NR, O or S and R is H or an optional substituent as described hereinbelow.




Similarly, as used in the specification and claims, the term heteroaryl designates a C5-C10 aromatic ring system containing 1 to 3 heteroatoms, which may be the same or different, selected from N, O or S. Such heteroaryl ring systems include pyrrolyl, azolyl, oxazolyl, thiazolyl, imidazolyl, furyl, thienyl, quinolinyl, isoquinolinyl, indolinyl, benzothienyl, benzofuranyl, benzisoxazolyl and the like; the term haloalkyl designates a CnH2n+1 group having from one to 2n+1 halogen atoms which may be the same or different; and the term haloalkoxy designates an OCnH2n+1 group having from one to 2n+1 halogen atoms which may be the same or different.
In the specification and claims, when the terms C1-C6alkyl, C2-C6alkenyl, C2-C6alkynyl, C2-C6alkynyl, C3-C7cycloalkyl, cycloheteroalkyl, aryl or heteroaryl are designated as being optionally substituted, the substituent groups which are optionally present include halogen atoms, nitro, cyano, thiocyanato, cyanate, hydroxyl, alkyl, haloalkyl, alkoxy, haloalkoxy, amino, alkylamino, dialkylamino, formyl, alkoxycarbonyl, carboxyl, alkanoyl, alkylthio, alkylsuphinyl, alkylsulphonyl, carbamoyl, alkylamido, phenyl, phenoxy, benzyl, benzyloxy, heteroaryl, cycloheteroalkyl or cycloalkyl groups, preferably halogen atoms or lower alkyl groups. Typically, 0-3 substituents may be present. When any of the foregoing substituents represents or contains an alkyl substituent group, this may be linear or branched and may contain up to 12, preferably up to 6, more preferably up to 4 carbon atoms.
Pharmaceutically acceptable salts may be any acid addition salt formed by a compound of formula I and a pharmaceutically acceptable acid such as phosphoric, sulfuric, hydrochloric, hydrobromic, citric, maleic, succinic, fumaric, acetic, lactic, nitric, sulfonic, p-toluene sulfonic, methane sulfonic acid or the like.
Preferred compounds of the invention are those compounds of formula I wherein A is N and m is 2. Also preferred are those compounds of formula I wherein R8 is an optionally substituted phenyl group and R1 is H or a C1-C6alkyl or C5-C7cycloheteroalkyl group each optionally substituted. Further preferred compounds of the invention are those compounds of formula I wherein R2, R3, R4, R5 and R6 are H and n is 0.
More preferred compounds of the invention are those compounds of formula I wherein A is N; m is 2 and R1 is H or a C1-C4alkyl or C5-C7cycloheteroalkyl group each optionally substituted. Another group of more preferred compounds of the invention are those compounds of formula I wherein A is N; m is 2; R1 is H or a C1-C4alkyl or C5-C7cycloheteroalkyl group each optionally substituted; and R8 is an optionally substituted phenyl group.
Among the preferred compounds of the invention are:

    1-(phenylsulfonyl)-4-piperazin-1-yl-1H-indole;
    1-[(2-bromophenyl)sulfonyl]-4-piperazin-1-yl-1H-indole;
    1-[(6-chloroimidazo[2,1-b][1,3]thiazol-5-yl)sulfonyl]-4-piperazin-1-yl-1H-indole;
    1-[(3,4-dimethoxyphenyl)sulfonyl]-4-piperazin-1-yl-1H-indole;
    1-[(5-chloro-3-methyl-1-benzothien-2-yl)sulfonyl]-4-piperazin-1-yl-1H-indole;
    1-[(4-bromophenyl)sulfonyl]-4-piperazin-1-yl-1H-indole;
    1-[(5-bromothien-2-yl)sulfonyl]-4-piperazin-1-yl-1H-indole;
    1-[(4,5-dichlorothien-2-yl)sulfonyl]-4-piperazin-1-yl-1H-indole;
    methyl 4-[(4-piperazin-1-yl-1H-indol-1-yl)sulfonyl]phenyl ether;
    4-piperazin-1-yl-1-{[4-(trifluoromethoxy)phenyl]sulfonyl}-1H-indole;
    4-(4-benzylpiperazin-1-yl)-1-(phenylsulfonyl)-1H-indole;
    4-(4-benzylpiperazin-1-yl)-1-[(2-bromophenyl)sulfonyl]-1H-indole;
    4-(4-benzylpiperazin-1-yl)-1-[(6-chloroimidazo[2,1-b][1,3]thiazol-5-yl)sulfonyl]-1H-indole;
    4-(4-benzylpiperazin-1-yl)-1-[(3,4-dimethoxyphenyl)sulfonyl]-1H-indole;
    4-[4-(3-methoxybenzyl)piperazin-1-yl]-1-(phenylsulfonyl)-1H-indole;
    1-(phenylsulfonyl)-4-[4-(pyridin-4-ylmethyl)piperazin-1-yl]-1H-indole;
    1-(phenylsulfonyl)-4-[4-(pyridin-3-ylmethyl)piperazin-1-yl]-1H-indole;
    1-[(2-bromophenyl)sulfonyl]-4-[4-(3-methoxybenzyl)piperazin-1-yl]-1H-indole;
    1-[(2-bromophenyl)sulfonyl]-4-[4-(pyridin-4-ylmethyl)piperazin-1-yl]-1H-indole;
    1-[(2-bromophenyl)sulfonyl]-4-[4-(pyridin-3-ylmethyl)piperazin-1-yl]-1H-indole;
    1-(phenylsulfonyl)-5-piperazin-1-yl-1H-indazole;
    1-(phenylsulfonyl)-6-piperazin-1-yl-1H-indazole;
    1-[(2-bromophenyl)sulfonyl]-6-piperazin-1-yl-1H-indazole;
    1-[(4-bromophenyl)sulfonyl]-5-piperazin-1-yl-1H-indazole;
    1-[(4-bromophenyl)sulfonyl]-6-piperazin-1-yl-1H-indazole;
    1-[(5-bromothien-2-yl)sulfonyl]-5-piperazin-1-yl-1H-indazole;
    1-[(5-bromothien-2-yl)sulfonyl]-6-piperazin-1-yl-1H-indazole;
    1-[(4-fluorophenyl)sulfonyl]-5-piperazin-1-yl-1H-indazole;
    1-[(4-fluorophenyl)sulfonyl]-6-piperazin-1-yl-1H-indazole;
    methyl 4-[(5-piperazin-1-yl-1H-indazol-1-yl)sulfonyl]phenyl ether;
    1-phenylsulfonyl-4-(4-propylpiperazin-1-yl)-1H-indazole;
    1-phenylsulfonyl-4-piperazin-1-yl-1H-indazole;
    1-phenylsulfonyl-4-(4-phenethylpiperazin-1-yl)-1H-indazole;
    1-phenylsulfonyl-4-[4-(3-phenylpropyl)piperazin-1-yl]-1H-indazole; and

the pharmaceutically acceptable salts thereof.



Compounds of the invention may be prepared using conventional synthetic methods and, if required, standard separation and isolation techniques. For example, 4-(piperazin-1-yl)indole compounds of formula II may be readily prepared by the catalytic hydrogenation of the 4-nitroindole precursor of formula III to the corresponding 4-aminoindole of formula IV and reacting said formula IV indole with a bis-alkylating agent such as bis(2-chloroethyl)amine to give the desired formula II intermediate. The reaction is illustrated in flow diagram I.




The formula II intermediate may then be converted to a compound of formula I wherein A is N, m is 2; R1 is H; R2, R3, and R4 are H;  represents a single bond; and the heterocyclyl group is in the 4-position, by reacting the formula II intermediate with a protecting group, G, for example di-t-butyl dicarbonate, to selectively protect the piperazine basic N atom to give the compound of formula V and sequentially reacting said formula V compound with a base such as NaH and a sulfonyl chloride, R8SO2Cl to give the protected 4-(piperazin-1-yl)-1-(substituted-sulfonyl)indole and deprotecting said indole to give the desired compound of formula Ia. Reaction of said formula Ia compound with a reagent R1-Hal, wherein R1 is defined hereinabove for formula I and Hal is Cl, Br or I in the presence of a base gives compounds of formula Ib wherein R1 is other than H. The reaction sequence is shown in flow diagram II.




Corresponding compounds of the invention wherein A is CR10 may be obtained, for example, by lithiating a protected 4-bromoindole of formula VI wherein G is benzyl, and displacing the lithium group with a cyclic ketone such as an N-protected-4-piperidone to give the hydroxy intermediate of formula VII, which may then be dehydrated and sulfonylated in the manner described hereinabove to give the protected compound of formula VIII. Catalytic hydrogenation and simultaneous deprotection of said formula VIII compound gives the desired compounds of formula I wherein  represents a single bond (formula Id). The reaction sequence is shown in flow diagram III.




These and other literature procedures may be utilized to prepare the formula I compounds of the invention. Employing a 5-, 6- or 7-haloindole, -haloindazole or -halobenzimidazole substrate as starting material and using essentially the same procedures illustrated in flow diagrams I, II and III hereinabove enables the construction of the corresponding compounds of formula I wherein the heterocyclyl group is in the 5-, 6-, or 7-position and X or Y is N.
Advantageously, the inventive compound of formula I may be utilized in the treatment of central nervous system disorders relating to or affected by the 5-HT6 receptor such as motor, mood, psychiatric, cognitive, neurodegenerative or the like disorders. Accordingly, the present invention provides a method for the treatment of a disorder of the central nervous system (CNS) related to or affected by the 5-HT6 receptor in a patient in need thereof which comprises administering to said patient a therapeutically effective amount of a compound of formula I as described hereinabove. The compounds may be administered orally or parenterally or in any common manner known to be an effective administration of a therapeutic agent to a patient in need thereof.
The therapeutically effective amount administered in the treatment of a specific CNS disorder may vary according to the specific condition(s) being treated, the size, age and response pattern of the patient, the severity of the disorder, the judgment of the attending physician and the like. In general, effective amounts for daily oral administration may be about 0.01 to 1,000 mg/kg, preferably about 0.5 to 500 mg/kg and effective amounts for parenteral administration may be about 0.1 to 100 mg/kg, preferably about 0.5 to 50 mg/kg.
In actual practice, the compounds of the invention are administered in a solid or liquid form, either neat or in combination with one or more conventional pharmaceutical carriers or excipients. Accordingly, the present invention provides a pharmaceutical composition which comprises a pharmaceutically acceptable carrier and an effective amount of a compound of formula I as described hereinabove.
Solid carriers suitable for use in the composition of the invention include one or more substances which may also act as flavoring agents, lubricants, solubilizers, suspending agents, fillers, glidants, compression aids, binders, tablet-disintegrating agents or encapsulating materials. In powders, the carrier may be a finely divided solid which is in admixture with a finely divided compound of formula I. In tablets, the formula I compound is mixed with a carrier having the necessary compression properties in suitable proportions and compacted in the shape and size desired. Said powders and tablets may contain up to 99% by weight of the formula I compound. Solid carriers suitable for use in the composition of the invention include calcium phosphate, magnesium stearate, talc, sugars, lactose, dextrin, starch, gelatin, cellulose, methyl cellulose, sodium carboxymethyl cellulose, polyvinylpyrrolidine, low melting waxes and ion exchange resins.
Any pharmaceutically acceptable liquid carrier suitable for preparing solutions, suspensions, emulsions, syrups and elixirs may be employed in the composition of the invention. Compounds of formula I may be dissolved or suspended in a pharmaceutically acceptable liquid carrier such as water, an organic solvent, or a pharmaceutically acceptable oil or fat, or a mixture thereof. Said liquid composition may contain other suitable pharmaceutical additives such as solubilizers, emulsifiers, buffers, preservatives, sweeteners, flavoring agents, suspending agents, thickening agents, coloring agents, viscosity regulators, stabilizers, osmo-regulators, or the like. Examples of liquid carriers suitable for oral and parenteral administration include water (particularly containing additives as above, e.g., cellulose derivatives, preferably sodium carboxymethyl cellulose solution), alcohols (including monohydric alcohols and polyhydric alcohols, e.g., glycols) or their derivatives, or oils (e.g., fractionated coconut oil and arachis oil). For parenteral administration the carrier may also be an oily ester such as ethyl oleate or isopropyl myristate.
Compositions of the invention which are sterile solutions or suspensions are suitable for intramuscular, intraperitoneal or subcutaneous injection. Sterile solutions may also be administered intravenously. Inventive compositions suitable for oral administration may be in either liquid or solid composition form.
For a more clear understanding, and in order to illustrate the invention more clearly, specific examples thereof are set forth hereinbelow. The following examples are merely illustrative and are not to be understood as limiting the scope and underlying principles of the invention in any way.
Unless otherwise stated, all parts are parts by weight. The terms HPLC and NMR designate high performance liquid chromatography and nuclear magnetic resonance, respectively.
EXAMPLE 1
Preparation of 1-(Phenylsulfonyl)-4-piperazin-1-yl-1H-indole Hydrochloride




A mixture of 1H-indol-4-ylpiperazine (4.0 g, 20 mmol), di-t-butyl dicarbonate (4.8 g, 22 mmol) and NaOH (0.8 g, 20 mmol) in 40% dioxane is stirred at room temperature for 10 hours and treated with water. The reaction mixture is extracted with ethyl acetate. The extracts are combined, dried over Na2SO4 and concentrated in vacuo to give t-butyl 4-(1H-indol-4-yl)piperazine-1-carboxylate as a colorless solid, mp 137° C., identified by mass spectral and elemental analyses.
A portion of the t-butyl 4-(1H-indol-1-yl)-piperazine-1-carboxylate (1.05 g, 3.5 mmol) is added to a suspension of NaH (3.8 mmol) in tetrahydrofuran at 0° C. under N2. The resultant mixture is stirred for 0.5 hr, treated with benzenesulfonyl chloride (0.616 g, 3.5 mmol), stirred for 16 hr and treated with water. The aqueous reaction mixture is extracted with ethyl acetate. The extracts are combined, dried over Na2SO4 and concentrated in vacuo to give a residue. The residue is chromatographed (SiO2, CH2Cl2) to give t-butyl 4-(1-phenylsulfonyl-(1H-indol-4-yl)piperazine-1-carboxylate as a light yellow solid, 1.25 g (81% yield), mp 64-65° C., identified by mass spectral and elemental analyses.
A portion of the t-butyl 4-(1-benzenesulfonyl-1H-indol-4-yl)piperazine-1-carboxylate (0.85 g) is stirred in a mixture of 4N HCl and dioxane at room temperature for 2 hrs and filtered. The filtercake is dried to give the title product as a while solid, 0.64 g (99% yield) mp 60° C. identified by mass spectral and NMR analyses.
EXAMPLES 2-13
Preparation of 1-Arylsulfonyl-4-piperazin-1-yl)-1H-Indole Hydrochloride




Using essentially the same procedure described in Example 1 and substituting the appropriate arylsulfonyl chloride, the following compounds listed in Table I are obtained and identified by HPLC and mass spectral analyses.







TABLE I













 









Ex.

LCMS1










No.
R8
Min.
M + H













2
o-bromophenyl
2.58
422


3
6-chloroimidazo[2,1-b]thiasol-5-yl
2.48
422


4
3,4-dimethoxyphenyl
2.52
402


5
4-aminophenyl
2.26
357


6
benzo-2,1,3-thiazol-4-yl


7
benzofurazan-4-yl


8
3-bromo-5-chlorothien-2-yl


9
5-chloro-3-methylbenzo(b)thien-2-yl


10
Dansyl


11
2,5-dichlorothien-3-yl


12
3,5-dimethylisoxasol-4-yl


13
1-methylimidazol-4-yl





1LCMS conditions: Hewlett Packard 1100 MSD; YMC ODS-AM 2.0 mm × 50 mm 5 u column at 23° C.; 3 uL injection; Solvent A: 0.02% TFA/water; Solvent B: 0.02% TFA/acetonitrile; Gradient: Time 0:95% A; 0.3 min: 95% A; 4.7 min: 10% A, 4.9 min: 95% A; Post time 1 min. Flow rate 1.5 mL/min; Detection: 254 nm DAD; API-ES Scanning Mode Positive 150-700; Fragmentor 70 mV.






EXAMPLE 14
Preparation of 4-[4-(4,5-Dihydro-1H-imidazol-2-yl)-piperazin-1-yl]-1-(phenylsulfonyl)-1H-indole




A solution of 1-(phenylsulfonyl)-4-piperzin-1-yl-1H-indole (71 mg, 0.18 mmol) in dioxane is treated with 2-methylthio-2-imidazoline hydroiodide (52.7 mg, 0.22 mmol) and N,N-diisopropylethylamine (62 μl, 0.36 mmol), heated at 50° C. for 16 hr., cooled and concentrated in vacuo to give a residue. The residue is purified by HPLC to give the title product, 15 mg, identified by HPLC and mass spectral analyses (2.57 min; 410 M+H) using the LCMS conditions described in Table I.
EXAMPLES 15-18
Preparation of 4-Heterocyclyl-1-(arylsulfonyl)indole Compounds




Using essentially the same procedure described in Example 14 and substituting the appropriate 1-(arylsulfonyl)indole substrate, the following compounds shown in Table II are obtained and identified by HPLC and mass spectral analyses.







TABLE II













 









Ex.

LCMS1










No.
R8
Min.
M + H













15
2-bromophenyl
2.79
490


16
6-chloroimidazo[2,1-b]thiazol-5-yl
2.68
490


17
3,4-dimethoxyphenyl
2.64
470


18
4-aminophenyl
2.46
425





1LCMS conditions: same as for Table I






EXAMPLE 19
Preparation of 4-(4-Benzylpiperazin-1-yl)-1-(phenylsulfonyl)-1H-indole




A solution of 1-(phenylsulfonyl)-4-piperazin-1-yl-1H-indole (71 mg, 0.18 mmol) in tetrahydrofuran is treated sequentially with benzyl bromide (21 μl) and triethyl-amine (75 μl), shaken at room temperature for 16 hr and concentrated in vacuo to give a residue. The residue is purified by RP-HPLC to give the title product, 37 mg, identfied by HPLC and mass spectral analyses (2.81 min; 432 M+H) using the LCMS conditions described in Table I.
EXAMPLES 20-53
Preparation of 4-Heteroaryl-1-arylsulfonylindole Compounds




Using essentially the same procedure described in Example 19 and employing the appropriate 4-(piperazin-1-yl)-1-(arylsulfonyl)indole substrate and a suitable aryl, alkyl or acyl halide, the following compounds shown in Table III are obtained and identified by HPLC and mass spectral analyses.







TABLE III













 










Ex.


LCMS1











No.
R1
R8
Min.
M + H














20
2-chloro-5-
phenyl
3.07
472



thienylmethyl


21
3-nitrobenzyl
phenyl
2.95
477


22
Acetyl
phenyl
3.18
384


23
Benzyl
2-bromophenyl
2.99
512


24
2-chloro-5-
2-bromophenyl
3.08
550



thienylmethyl


25
3-nitrobenzyl
2-bromophenyl
3.08
550


26
Acetyl
2-bromophenyl
2.97
557


27
Benzyl
6-choroimidazol[2,1-b]
2.91
512




thiazol-5-yl


28
2-chloro-5-
6-choroimidazol[2,1-b]
3.00
553



thienylmethyl
thiazol-5-yl


29
3-nitrobenzyl
6-choroimidazol[2,1-b]
2.87
557




thiazol-5-yl


30
Acetyl
6-choroimidazol[2,1-b]
3.23
464




thiazol-5-yl


31
Benzyl
3,4-dimethoxyphenyl
2.76
492


32
2-chloro-5-
3,4-dimethoxyphenyl
2.90
532



thienylmethyl


33
3-nitrobenzyl
3,4-dimethoxyphenyl
2.82
537


34
Acetyl
3,4-dimethoxyphenyl
3.10
442


35
benzyl
4-aminophenyl
2.64
447


36
methyl
4-aminophenyl
2.28
371


37
2-chloro-5-
4-aminophenyl
2.82
487



thienylmethyl


38
3-nitrobenzyl
4-aminophenyl
2.72
492


39
3-methoxybenzyl
Phenyl
2.88
462


40
4-pyridylmethyl
Phenyl
2.40
433


41
3-pyridylmethyl
Phenyl
2.42
433


42
3-methoxybenzyl
2-bromophenyl
2.99
542


43
4-pyridylmethyl
2-bromophenyl
2.51
513


44
3-pyridylmethyl
2-bromophenyl
2.52
513


45
3-methoxybenzyl
6-chloroimidazo[2,1-b]
2.93
542




thiazol-5-yl


46
4-pyridylmethyl
6-chloroimidazo[2,1-b]
2.48
513




thiazol-5-yl


47
3-pyridylmethyl
6-chloroimidazo[2,1-b]
2.48
513




thiazol-5-yl


48
3-methoxybenzyl
3,4-dimethoxyphenyl
2.82
522


49
4-pyridylmethyl
3,4-dimethoxyphenyl
2.47
493


50
3-pyridylmethyl
3,4-dimethoxyphenyl
2.45
493


51
3-methoxybenzyl
4-aminophenyl
2.75
477


52
4-pyridylmethyl
4-aminophenyl
2.24
448


53
3-pyridylmethyl
4-aminophenyl
2.26
448





1LCMS conditions are the same as that for Table I






EXAMPLE 54
Preparation of 4-(Homopiperazin-1-yl)-1-(phenylsulfonyl)-benzimidazole hydrochloride




A suspension of 4-bromobenzimidazole (42 mmol), homopiperazine (256 mmol) and NaOt-Bu (59 mmol) in dry oxylene, under N2, is treated with a catalytic amount of Pd(OCOCH3)2.P(t-Bu)3 (P/Pd=4), heated at 120° C. for 3 hr, cooled to room temperature and diluted with water. The aqueous mixture is extracted with ethyl acetate. The extracts are combined, dried over MgSO4 and concentrated in vacuo to give a residue. The residue is purified by flash chromotography to give 4-(homopiperazin-1-yl)benzimidazole.
A mixture of 4-(homopiperazin-1-yl)benzimidazole (4.3 g, 20 mmol), di-t-butyl dicarbonate (4.8 g, 22 mmol) and NaOH (0.8 g, 20 mmol) in 40% aqueous dioxane is stirred at room temperature for 10 hrs and diluted with water. The aqueous mixture is extracted with ethyl acetate. The extracts are combined, dried over NaSO4 and concentrated in vacuo to give t-butyl 4-(benzimidazol-4-yl)homopiperazine-1-carboxylate.
A suspension of NaH (3.8 mmol) in tetrahydrofuran at 0° C., under N2, is treated with t-butyl 4-(benzimidazol-4-yl)-homopiperazine-1-carboxylate (1.1 g, 3.5 mmol), stirred for 0.5 hr, treated with benzenesulfonyl chloride (0.616 g, 3.5 mmol), stirred for 16 hours at room temperature and diluted with water. The aqueous mixture is extracted with ethyl acetate. The extracts are combined, dried over Na2SO4 and concentrated in vacuo to give a residue. The residue is purified by flash chromatography to give t-butyl 4-(1-phenylsulfonyl)-benzimidazol-4-yl)homopiperazin-1-carboxylate.
A mixture of the thus-obtained carboxylate in 4N HCl and dioxane is stirred at room temperature for 2 hrs and filtered. The filtercake is washed with ethyl acetate and dried in vacuo to afford the title product.
EXAMPLE 56
Preparation of 4-(4-Benzylpiperazin-1-yl)-1H-indazole




A stirred solution of 4-benzyl-1-(3-fluoro-2-carboxyphenyl)-piperazine (5.96 g, 20.0 mmol) in dimethylsulfoxide (10 mL) and hydrazine (10 mL) is heated at 95° C. under nitrogen for 4 days. The cooled reaction is diluted with ether and washed with a mixture of water and saturated aqueous sodium bicarbonate. The organic layer is further washed sequentially with water and brine dried over MgSO4 and concentrated in vacuo to give a residue. The residue is chromatographed using ethyl acetate as the eluant. The resulting oil is reconcentrated from ether to give a white foam which is stirred under hexanes/ether overnight. The resulting white powder is isolated by suction filtration and washed with hexane to give the title compound 3.11 g, (53% yield), identified by HNMR.
EXAMPLE 57
Preparation of 4-(4-Benzylpiperazin-1-yl)-1-(phenylsulfonyl)-1H-indazole hydrochloride




A solution of 4-(4-benzylpiperazin-1-yl)-1H-indazole (2.34 g, 8.00 mmol) in dry dimethyl formamide is treated with 0.48 g unwashed 60% NaH in mineral oil (12.0 mmol of NaH). After stirring under nitrogen for 15 min, the reaction is treated with benzenesulfonylchloride (1.53 mL, 12.0 mmol), stirred for 24 hr at ambient temperature, treated with saturated aqueous NaHCO3 and water and extracted with ether. The organic layer is washed sequentially with water and brine, dried over MgSO4 and concentrated in vacuo to give a residue. The residue is purified by flash chromatography on silica gel using 1:1 ethyl acetate:hexanes as eluant to afford the free amine of the title compound as an oil (3.14 g, 91%). A portion of this oil (432 mg, 1.0 mmol) is dissolved in ether and treated with 1.0M HCl in ether (1.1 mL, 1.1 mmol). The resulting solid is filtered, washed with ether, and dried under vacuum to provide the title compound as a light tan solid, mp 208-209° C., identified by HNMR and mass spectral analyses.
EXAMPLE 58
Preparation of 1-(Phenylsulfonyl)-4-(1-piperazinyl)-1H-indazole hydrochloride




A solution of 1-phenylsulfonyl-4-(4-benzylpiperazin-1-yl)-1H-indazole (433 mg, 1.0 mmol) in 1,2-dichloroethane is treated with 1-chloroethyl chloroformate (0.27 mL, 2.5 mmol) heated at reflux temperature for 2 hr, and concentrated in vacuo. The resultant residue is heated at reflux temperature in methanol for 1.5 hr, cooled, concentrated in vacuo and reconcentrated from ether. The resulting tan solid is triturated with ether and crystallized from hot ethanol to give the title compound as a tan solid 237 mg (63% yield), mp 203-205° C., identified by HNMR and mass spectral analyses.
EXAMPLE 59
Preparation of 4-[4-(2-phenylethyl)piperazin-1-yl]-1-(phenylsulfonyl)-1H-indazole hydrochloride




A mixture of 1-phenylsulfonyl-4-piperazin-1-yl-1H-indazole (190 mg, 0.50 mmol) and K2CO3 (138 mg, 1.0 mmol) in dry acetonitrile is treated with phenethylbromide (0.55 mL, 2.0 mmol), heated at reflux temperature under nitrogen for 8.5 h, treated with water and extracted with methylene chloride. The combined extracts are dried over MgSO4 and chromatographed on an SCX column (Varian SCX Mega Bond Elut, 5 g) eluting with ethyl acetate to remove non-basic organic material and then with 1:99 triethylamine:ethyl acetate to afford, after concentration, the free amine of the title compound as a slightly yellow oil (198 mg, 89%). The oil is dissolved in ether with a small amount of ethanol to aid solubility and treated with 1.0M HCl in ether. The solution is concentrated in vacuo and the resulting tan solid is treated with ether and suction filtered to afford the title compound as a light tan solid 209 mg, (87% yield), mp 230-232° C. (dec), identified by NMR and mass spectral analyses.
EXAMPLES 60-72
Preparation of 4-Heteroaryl-1-arylsulfonylindazole Compounds




Using essentially the same procedures described in Examples 56-59 and employing the appropriate indazole substrate and suitable aryl, alkyl or acyl halide or arylsulfonyl chloride, the following compounds shown in Table IV are obtained and identified by NMR and mass spectral analyses.







TABLE IV













 











Ex.


mp



No.
R1
R8
° C.
M + H














60
2(p-fluorophenoxy)ethyl-
Phenyl
184-186
481


61
p-flourophenyl-CO-(CH2)3—
Phenyl
—
507


62
phenyl-CO-CH2—
phenyl
202-205
461


63
3-phenylpropyl-
phenyl
188-190
461


64
n-propyl-
phenyl
258-260
385


65
benzyl
phenyl-CH═CH—
233-235
459


66
benzyl
p-fluorophenyl
240-241
451


67
benzyl
p-chlorophenyl
238-239
467


68
benzyl
naphthyl
147-149
483


69
benzyl
p-methoxyphenyl
206-209
463


70
benzyl
p-(trifluoro-methoxy)
229-231
517




phenyl


71
benzyl
2-(4,5-dichloro-
235-237
507




thienyl)-


72
benzyl
p-tolyl
215-217
447









EXAMPLE 73
Preparation of 1-(4-Aminophenylsulfonyl)-5-piperazin-1-yl-1H-indole hydrochloride




A solution of 5-aminoindole (6.23 g, 47 mmol), bis(2-chloroethyl)amine hydrochloride (16.8 g, 96 mmol) and triethylamine (19 mL, 141 mmol) in butanol is heated at 100° C. for 8 hours, cooled to room temperature and concentrated in vacuo to give 9.46 g of 5-piperazin-1-yl-1H-indole.
A solution of said indole in acetone and water is treated with di-tert-butyl dicarbonate (11.3 g, 47 mmol) and potassium carbonate (13 g, 96 mmol). The mixture is stirred at room temperature overnight, the acetone evaporated and the remaining aqueous phase extracted with ethyl acetate. The extracts are dried over MgSO4 and concentrated in vacuo to give a residue. The residue is purified by flash chromatography to give 4-(1H-indol-5-yl)-piperazine-1-carboxylic acid tert-butyl ester.
A solution of said ester (60 mg, 0.2 mmol) in tetrahydrofuran is treated with sodium hydride (30 mg, 0.5 mmol) followed by N-acetylsulfanilyl chloride (25 uL, 0.2 mmol), shaken at room temperature for 16 hours and concentrated in vacuo to give 4-[1-(4-acetylaminophenylsulfonyl)-1H-indol-5-yl]-piperazine-1-carboxylic acid tert-butyl ester.
The thus-obtained ester is dissolved in methanol, treated with concentrated hydrochloric acid (100 uL), shaken at 60° C. for 2 hours and concentrated in vacuo to give a residue. The residue is purified by HPLC to give the title product, 15 mg, identified by HPLC and mass spectral analyses (r.t. 2.37 min., M+H 357).
EXAMPLES 74-102
Preparation of Piperazinyl-1-arylsulfonylindazole and indole Compounds




Using essentially the same procedures described in Example 73 and employing the appropriate aminoindole or aminoindazole substrate and suitable arylsulfonylchloride reagents, the following compounds shown in Table V are obtained and identified by HPLC and mass spectral analyses.







TABLE V













 










Piperazinyl












Ex.
Ring


LCMS1












No.
Position
Y
R8
Min.
M + H















74
5
N
phenyl
1.98
343


75
6
N
phenyl
1.96
343


76
5
CH
benzo-2,1,3-thiadiazol-4-yl
2.56
400


77
6
N
benzo-2,1,3-thiadiazol-4-yl
2.01
401


78
6
N
2-bromophenyl
2.21
423


79
5
N
p-bromophenyl
2.39
423


80
6
N
p-bromophenyl
2.34
423


81
5
N
5-bromothien-2-yl
2.33
429


82
6
N
5-bromothien-2-yl
2.25
429


83
5
CH
p-(n-butoxy)phenyl
3.23
414


84
5
N
p-(n-butoxy)phenyl
2.79
415


85
6
N
p-(n-butoxy)phenyl
2.73
415


86
5
CH
5-chloro-1,3-dimethyl-
2.49
395





pyrazol-4-yl


87
5
N
5-chloro-1,3-dimethyl-
1.88
396





pyrazol-4-yl


88
5
N
5-chloro-3-methylbenzo-
2.88
448





[b]thien-2-yl


89
6
N
5-chloro-3-methylbenzo-
3.10
448





[b]thien-2-yl


90
5
N
2,3-dichlorothien-5-yl
2.59
418


91
6
N
2,3,-dichlorothien-5-yl
2.77
418


92
5
N
p-fluorophenyl
2.08
361


93
6
N
p-fluorophenyl
2.40
361


94
5
N
p-methoxyphenyl
2.11
373


95
5
CH
2-naphthyl
2.92
392


96
6
N
2-naphthyl
2.43
393


97
5
CH
p-(trifluoromethoxy)phenyl
2.97
426


98
5
N
p-(trifluoromethoxy)phenyl
2.57
427


99
6
N
p-(trifluoromethoxy)phenyl
2.54
427


100
5
CH
p-iodophenyl
2.92
468


101
5
N
p-iodophenyl
2.48
469


102
6
N
p-iodophenyl
2.67
469









EXAMPLE 103
Comparative Evaluation of 5-HT6 Binding Affinity of Test Compounds
The affinity of test compounds for the serotonin 5-HT6 receptor is evaluated in the following manner. Cultured Hela cells expressing human cloned 5-HT6 receptors are harvested and centrifuged at low speed (1,000×g) for 10.0 min to remove the culture media. The harvested cells are suspended in half volume of fresh physiological phosphate buffered saline solution and recentrifuged at the same speed. This operation is repeated. The collected cells are then homogenized in ten volumes of 50 mM Tris.HCl (pH 7.4) and 0.5 mM EDTA. The homogenate is centrifuged at 40,000×g for 30.0 min and the precipitate is collected. The obtained pellet is resuspended in 10 volumes of Tris.HCl buffer and recentrifuged at the same speed. The final pellet is suspended in a small volume of Tris.HCl buffer and the tissue protein content is determined in aliquots of 10-25 μl volumes. Bovine Serum Albumin is used as the standard in the protein determination according to the method described in Lowry et al., J. Biol. Chem., 193:265 (1951). The volume of the suspended cell membranes is adjusted to give a tissue protein concentration of 1.0 mg/ml of suspension. The prepared membrane suspension (10 times concentrated) is aliquoted in 1.0 ml volumes and stored at −70° C. until used in subsequent binding experiments.
Binding experiments are performed in a 96 well microtiter plate format, in a total volume of 200 μl. To each well is added the following mixture: 80.0 μl of incubation buffer made in 50 mM Tris.HCl buffer (pH 7.4) containing 10.0 mM MgCl2 and 0.5 mM EDTA and 20 μl of [3H]-LSD (S.A., 86.0 Ci/mmol, available from Amersham Life Science), 3.0 nM. The dissociation constant, KD of the [3H]LSD at the human serotonin 5-HT6 receptor is 2.9 nM, as determined by saturation binding with increasing concentrations of [3H]LSD. The reaction is initiated by the final addition of 100.0 μl of tissue suspension. Nonspecific binding is measured in the presence of 10.0 μM methiothepin. The test compounds are added in 20.0 μl volume.
The reaction is allowed to proceed in the dark for 120 min at room temperature, at which time, the bound ligand-receptor complex is filtered off on a 96 well unifilter with a Packard Filtermate® 196 Harvester. The bound complex caught on the filter disk is allowed to air dry and the radioactivity is measured in a Packard TopCount® equipped with six photomultiplier detectors, after the addition of 40.0 μl Microscint®-20 scintillant to each shallow well. The unifilter plate is heat-sealed and counted in a PackardTopCount® with a tritium efficiency of 31.0%.
Specific binding to the 5-HT6 receptor is defined as the total radioactivity bound less the amount bound in the presence of 10.0 μM unlabeled methiothepin. Binding in the presence of varying concentrations of test compound is expressed as a percentage of specific binding in the absence of test compound. The results are plotted as log % bound versus log concentration of test compound. Nonlinear regression analysis of data points with a computer assisted program Prism® yielded both the IC50 and the Ki values of test compounds with 95% confidence limits. A linear regression line of data points is plotted, from which the IC50 value is determined and the Ki value is determined based upon the following equation:

Ki=IC50/(1+L/KD)

where L is the concentration of the radioactive ligand used and KD is the dissociation constant of the ligand for the receptor, both expressed in nM.

Using this assay, the following Ki values are determined and compared to those values obtained by representative compounds known to demonstrate binding to the 5-HT6 receptor. The data are shown in Table VI, below.










TABLE VI









Test Compound
5-HT6 binding Ki



(Ex. No.)
(nM)














1
1.0



2
2.0



3
1.0



4
15.0



5
1.0



14
24.0



18
6.0



27
56.0



30
220.0



33
45.0



35
15.0



36
3.0



37
59.0



38
5.0



40
4.0



41
7.0



42
4.0



43
7.0



44
1.0



46
5.0



47
6.0



48
14.0



49
10.0



50
17.0



51
7.0



52
25.0



53
4.0



57
14



58
0.3



59
1.0



60
306



61
3.0



62
12



63
6.0



64
2.0



65
172



66
84



67
87



68
14



69
116



70
251



71
81



72
56



73
34



79
19



81
44



83
38



86
44



89
24



90
30



91
6



96
37



101
18














Comparative Examples
5-HT6 binding Ki







Clozapine
6.0



Loxapine
41.4



Bromocriptine
23.0



Methiothepin
8.3



Mianserin
44.2



Olanzepine
19.5










As can be seen from the results set forth above, the compounds of the present invention have a high degree of affinity for the serotonin 5-HT6 receptor sub-type. Although two of the comparison compounds (clozapine and methiothepin) have similar 5-HT6 receptor affinity, they do not have the selectivity of the compounds of the present invention. The examples disclosed above demonstrate up to 50-fold selectivity for the 5-HT6 receptor when compared to their affinity at the 5-HT7 receptor.

## Claims

1. A compound of formula I




wherein
A is N;
X is CR11 or N;
Y is CR7 or N with the proviso that when X is N, then Y must be CR7 and with the further proviso that one of X and Y must be N;
R1 is H, C1-C6alkylcarbonyl, C1-C6alkylcarbonyloxy or an C1-C6alkyl, C2-C6alkenyl, C2-C6alkynl or cycloheteroalkyl group each optionally substituted;
R2, R3, R4, R5 and R6 are each independently H, halogen, OH or an optionally substituted C1-C6alkyl group;
R7 and R11 are each independently H, halogen or an C1-C6alkyl, aryl, heteroaryl or C1-C6alkoxy group each optionally substituted;
R8 is an C1-C6alkyl, aryl or heteroaryl group each optionally substituted;
R9 is H, halogen or an C1-C6alkyl, C1-C6alkoxy, C1-C6alkenyl, aryl or heteroaryl group each optionally substituted;
m is an integer of 3;
n is 0 or an integer of 1, 2 or 3; and
 represents a single bond or a double bond; or

a pharmaceutically acceptable salt thereof.

2. The compound according to claim 1 wherein X is CR11 and Y is N.

3. The compound according to claim 1 wherein R8 is an optionally substituted phenyl group.

4. The compound according to claim 1 wherein R2, R3, R4, R5 and R6 are H.

5. The compound according to claim 2 wherein R1 is H or a C1-C6alkyl or cycloheteroalkyl group each optionally substituted.

6. A method for the treatment of a disorder of the central nervous system related to or affected by the 5-HT6 receptor selected from schizophrenia and depression in a patient in need thereof which comprises administering to said patient a therapeutically effective amount of a compound of formula I as described in claim 1.

7. A pharmaceutical composition which comprises a pharmaceutically acceptable carrier and an effective amount of a compound of formula I




wherein
A is N;
X is CR11 or N;
Y is CR7 or N with the proviso that when X is N, then Y must be CR7 and with the further proviso that one of X and Y must be N;
R1 is H, C1-C6alkylcarbonyl, C1-C6alkylcarbonyloxy or an C1-C6alkyl, C2-C6alkenyl, C2-C6alkynl or cycloheteroalkyl group each optionally substituted;
R2, R3, R4, R5 and R6 are each independently H, halogen, OH or an optionally substituted C1-C6alkyl group;
R7 and R11 are each independently H, halogen or an C1-C6alkyl, aryl, heteroaryl or C1-C6alkoxy group each optionally substituted;
R8 is an C1-C6alkyl, aryl or heteroaryl group each optionally substituted;
R9 is H, halogen or an C1-C6alkyl, C1-C6alkoxy, C1-C6alkenyl, aryl or heteroaryl group each optionally substituted;
m is an integerof 3;
n is 0 or an integer of 1, 2 or 3; and
 represents a single bond or a double bond; or

a pharmaceutically acceptable salt thereof.

8. The composition according to claim 7 wherein R8 is an optionally substituted phenyl group.

9. The composition according to claim 7 wherein X is CR11 and Y is N.

10. A method for the preparation of a compound of formula




wherein
A is N;
X is CR11, or N;
Y is CR7 or N with the proviso that when X is N, then Y must be CR7 and with the further proviso that one of X and Y must be N;
R1 is H, C1-C6alkylcarbonyl, C1-C6alkylcarbonyloxy or an C1-C6alkyl, C2-C6alkenyl, C2-C6alkynl or cycloheteroalkyl group each optionally substituted;
R2, R3, R4, R5 and R6are each independently H, halogen, OH or an optionally substituted C1-C6alkyl group;
R7 and R11 are each independently H, halogen or an C1-C6alkyl, aryl, heteroaryl or C1-C6alkoxy group each optionally substituted;
R8 is an C1-C6alkyl, aryl or heteroaryl group each optionally substituted;
R9 is H, halogen or an C1-C6alkyl, C1-C6alkoxy, C1-C6alkenyl, aryl or heteroaryl group each optionally substituted;
m is an integer of 3;
n is 0 or an integer of 1, 2 or 3; and
 represents a single bond or a double bond

said method which comprises reacting a compound of formula Ia




wherein A, X, R2, R3, R4, R5, R6, R7, R8, R9, m and n are as defined hereinabove for formula I with a compound R1-Hal wherein R1 is as defined hereinabove for formula I and Hal is CI, Br or I.