Patent Description:
The present technology generally relates to macrocyclic complexes of alpha-emitting radionuclides.

The following terms are used throughout as defined below.

As used herein and in the appended claims, singular articles such as "a" and "an" and "the" and similar referents in the context of describing the elements (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the embodiments and does not pose a limitation on the scope of the claims unless otherwise stated. No language in the specification should be construed as indicating any non-claimed element as essential.

Generally, reference to a certain element such as hydrogen or H is meant to include all isotopes of that element. For example, if an R group is defined to include hydrogen or H, it also includes deuterium and tritium. Compounds comprising radioisotopes such as tritium, C<NUM>, P<NUM> and S<NUM> are thus within the scope of the present technology. Procedures for inserting such labels into the compounds of the present technology will be readily apparent to those skilled in the art based on the disclosure herein.

In general, "substituted" refers to an organic group as defined below (e.g., an alkyl group) in which one or more bonds to a hydrogen atom contained therein are replaced by a bond to non-hydrogen or non-carbon atoms. Substituted groups also include groups in which one or more bonds to a carbon(s) or hydrogen(s) atom are replaced by one or more bonds, including double or triple bonds, to a heteroatom. Thus, a substituted group is substituted with one or more substituents, unless otherwise specified. In some embodiments, a substituted group is substituted with <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> substituents. Examples of substituent groups include: halogens (i.e., F, Cl, Br, and I); hydroxyls; alkoxy, alkenoxy, aryloxy, aralkyloxy, heterocyclyl, heterocyclylalkyl, heterocyclyloxy, and heterocyclylalkoxy groups; carbonyls (oxo); carboxylates; esters; urethanes; oximes; hydroxylamines; alkoxyamines; aralkoxyamines; thiols; sulfides; sulfoxides; sulfones; sulfonyls; pentafluorosulfanyl (i.e., SF<NUM>), sulfonamides; amines; N-oxides; hydrazines; hydrazides; hydrazones; azides; amides; ureas; amidines; guanidines; enamines; imides; isocyanates; isothiocyanates; cyanates; thiocyanates; imines; nitro groups; nitriles (i.e., CN); and the like.

Substituted ring groups such as substituted cycloalkyl, aryl, heterocyclyl and heteroaryl groups also include rings and ring systems in which a bond to a hydrogen atom is replaced with a bond to a carbon atom. Therefore, substituted cycloalkyl, aryl, heterocyclyl and heteroaryl groups may also be substituted with substituted or unsubstituted alkyl, alkenyl, and alkynyl groups as defined below.

As used herein, Cm-Cn, such as C<NUM>-C<NUM>, C<NUM>-C<NUM>, or C<NUM>-C<NUM> when used before a group refers to that group containing m to n carbon atoms.

Alkyl groups include straight chain and branched chain alkyl groups having from <NUM> to <NUM> carbon atoms, and typically from <NUM> to <NUM> carbons or, in some embodiments, from <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM> carbon atoms. Examples of straight chain alkyl groups include groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl groups. Examples of branched alkyl groups include, but are not limited to, isopropyl, iso-butyl, sec-butyl, tert-butyl, neopentyl, isopentyl, and <NUM>,<NUM>-dimethylpropyl groups. Alkyl groups may be substituted or unsubstituted. Representative substituted alkyl groups may be substituted one or more times with substituents such as those listed above, and include without limitation haloalkyl (e.g., trifluoromethyl), hydroxyalkyl, thioalkyl, aminoalkyl, alkylaminoalkyl, dialkylaminoalkyl, alkoxyalkyl, carboxyalkyl, and the like.

Cycloalkyl groups include mono-, bi- or tricyclic alkyl groups having from <NUM> to <NUM> carbon atoms in the ring(s), or, in some embodiments, <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>, <NUM>, or <NUM> carbon atoms. Exemplary monocyclic cycloalkyl groups include, but not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. In some embodiments, the cycloalkyl group has <NUM> to <NUM> ring members, whereas in other embodiments the number of ring carbon atoms range from <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>. Bi- and tricyclic ring systems include both bridged cycloalkyl groups and fused rings, such as, but not limited to, bicyclo[<NUM>. <NUM>]hexane, adamantyl, decalinyl, and the like. Cycloalkyl groups may be substituted or unsubstituted. Substituted cycloalkyl groups may be substituted one or more times with, non-hydrogen and non-carbon groups as defined above. However, substituted cycloalkyl groups also include rings that are substituted with straight or branched chain alkyl groups as defined above. Representative substituted cycloalkyl groups may be mono-substituted or substituted more than once, such as, but not limited to, <NUM>,<NUM>-, <NUM>,<NUM>-, <NUM>,<NUM>- <NUM>,<NUM>- or <NUM>,<NUM>-disubstituted cyclohexyl groups, which may be substituted with substituents such as those listed above.

Cycloalkylalkyl groups are alkyl groups as defined above in which a hydrogen or carbon bond of an alkyl group is replaced with a bond to a cycloalkyl group as defined above. In some embodiments, cycloalkylalkyl groups have from <NUM> to <NUM> carbon atoms, <NUM> to <NUM> carbon atoms, and typically <NUM> to <NUM> carbon atoms. Cycloalkylalkyl groups may be substituted or unsubstituted. Substituted cycloalkylalkyl groups may be substituted at the alkyl, the cycloalkyl or both the alkyl and cycloalkyl portions of the group. Representative substituted cycloalkylalkyl groups may be mono-substituted or substituted more than once, such as, but not limited to, mono-, di- or tri-substituted with substituents such as those listed above.

Alkenyl groups include straight and branched chain alkyl groups as defined above, except that at least one double bond exists between two carbon atoms. Alkenyl groups have from <NUM> to <NUM> carbon atoms, and typically from <NUM> to <NUM> carbons or, in some embodiments, from <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM> carbon atoms. In some embodiments, the alkenyl group has one, two, or three carbon-carbon double bonds. Examples include, but are not limited to vinyl, allyl, -CH=CH(CH<NUM>), -CH=C(CH<NUM>)<NUM>, -C(CH<NUM>)=CH<NUM>, -C(CH<NUM>)=CH(CH<NUM>), -C(CH<NUM>CH<NUM>)=CH<NUM>, among others. Alkenyl groups may be substituted or unsubstituted. Representative substituted alkenyl groups may be mono-substituted or substituted more than once, such as, but not limited to, mono-, di- or tri-substituted with substituents such as those listed above.

Cycloalkenyl groups include cycloalkyl groups as defined above, having at least one double bond between two carbon atoms. Cycloalkenyl groups may be substituted or unsubstituted. In some embodiments the cycloalkenyl group may have one, two or three double bonds but does not include aromatic compounds. Cycloalkenyl groups have from <NUM> to <NUM> carbon atoms, or, in some embodiments, <NUM> to <NUM> carbon atoms, <NUM> to <NUM> carbon atoms, or even <NUM>, <NUM>, <NUM>, or <NUM> carbon atoms. Examples of cycloalkenyl groups include cyclohexenyl, cyclopentenyl, cyclohexadienyl, cyclobutadienyl, and cyclopentadienyl.

Cycloalkenylalkyl groups are alkyl groups as defined above in which a hydrogen or carbon bond of the alkyl group is replaced with a bond to a cycloalkenyl group as defined above. Cycloalkenylalkyl groups may be substituted or unsubstituted. Substituted cycloalkenylalkyl groups may be substituted at the alkyl, the cycloalkenyl or both the alkyl and cycloalkenyl portions of the group. Representative substituted cycloalkenylalkyl groups may be substituted one or more times with substituents such as those listed above.

Alkynyl groups include straight and branched chain alkyl groups as defined above, except that at least one triple bond exists between two carbon atoms. Alkynyl groups have from <NUM> to <NUM> carbon atoms, and typically from <NUM> to <NUM> carbons or, in some embodiments, from <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM> carbon atoms. In some embodiments, the alkynyl group has one, two, or three carbon-carbon triple bonds. Examples include, but are not limited to - C≡CH, -C≡CCH<NUM>, -CH<NUM>C≡CCH<NUM>, -C≡CCH<NUM>CH(CH<NUM>CH<NUM>)<NUM>, among others. Alkynyl groups may be substituted or unsubstituted. Representative substituted alkynyl groups may be mono-substituted or substituted more than once, such as, but not limited to, mono-, di- or tri-substituted with substituents such as those listed above.

Aryl groups are cyclic aromatic hydrocarbons that do not contain heteroatoms. Aryl groups herein include monocyclic, bicyclic and tricyclic ring systems. Thus, aryl groups include, but are not limited to, phenyl, azulenyl, heptalenyl, biphenyl, fluorenyl, phenanthrenyl, anthracenyl, indenyl, indanyl, pentalenyl, and naphthyl groups. In some embodiments, aryl groups contain <NUM>-<NUM> carbons, and in others from <NUM> to <NUM> or even <NUM>-<NUM> carbon atoms in the ring portions of the groups. In some embodiments, the aryl groups are phenyl or naphthyl. Aryl groups may be substituted or unsubstituted. The phrase "aryl groups" includes groups containing fused rings, such as fused aromatic-aliphatic ring systems (e.g., indanyl, tetrahydronaphthyl, and the like). Representative substituted aryl groups may be mono-substituted or substituted more than once. For example, monosubstituted aryl groups include, but are not limited to, <NUM>-, <NUM>-, <NUM>-, <NUM>-, or <NUM>-substituted phenyl or naphthyl groups, which may be substituted with substituents such as those listed above.

Aralkyl groups are alkyl groups as defined above in which a hydrogen or carbon bond of an alkyl group is replaced with a bond to an aryl group as defined above. In some embodiments, aralkyl groups contain <NUM> to <NUM> carbon atoms, <NUM> to <NUM> carbon atoms, or <NUM> to <NUM> carbon atoms. Aralkyl groups may be substituted or unsubstituted. Substituted aralkyl groups may be substituted at the alkyl, the aryl or both the alkyl and aryl portions of the group. Representative aralkyl groups include but are not limited to benzyl and phenethyl groups and fused (cycloalkylaryl)alkyl groups such as <NUM>-indanylethyl. Representative substituted aralkyl groups may be substituted one or more times with substituents such as those listed above.

Heterocyclyl groups include aromatic (also referred to as heteroaryl) and non-aromatic ring compounds containing <NUM> or more ring members, of which one or more is a heteroatom such as, but not limited to, N, O, and S. In some embodiments, the heterocyclyl group contains <NUM>, <NUM>, <NUM> or <NUM> heteroatoms. In some embodiments, heterocyclyl groups include mono-, bi- and tricyclic rings having <NUM> to <NUM> ring members, whereas other such groups have <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM> ring members. Heterocyclyl groups encompass aromatic, partially unsaturated and saturated ring systems, such as, for example, imidazolyl, imidazolinyl and imidazolidinyl groups. The phrase "heterocyclyl group" includes fused ring species including those comprising fused aromatic and non-aromatic groups, such as, for example, benzotriazolyl, <NUM>,<NUM>-dihydrobenzo[<NUM>,<NUM>]dioxinyl, and benzo[<NUM>,<NUM>]dioxolyl. The phrase also includes bridged polycyclic ring systems containing a heteroatom such as, but not limited to, quinuclidyl. Heterocyclyl groups may be substituted or unsubstituted. Heterocyclyl groups include, but are not limited to, aziridinyl, azetidinyl, pyrrolidinyl, imidazolidinyl, pyrazolidinyl, thiazolidinyl, tetrahydrothiophenyl, tetrahydrofuranyl, dioxolyl, furanyl, thiophenyl, pyrrolyl, pyrrolinyl, imidazolyl, imidazolinyl, pyrazolyl, pyrazolinyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, thiazolyl, thiazolinyl, isothiazolyl, thiadiazolyl, oxadiazolyl, piperidyl, piperazinyl, morpholinyl, thiomorpholinyl, tetrahydropyranyl, tetrahydrothiopyranyl, oxathiane, dioxyl, dithianyl, pyranyl, pyridyl, pyrimidinyl, pyridazinyl, pyrazinyl, triazinyl, dihydropyridyl, dihydrodithiinyl, dihydrodithionyl, homopiperazinyl, quinuclidyl, indolyl, indolinyl, isoindolyl,azaindolyl (pyrrolopyridyl), indazolyl, indolizinyl, benzotriazolyl, benzimidazolyl, benzofuranyl, benzothiophenyl, benzthiazolyl, benzoxadiazolyl, benzoxazinyl, benzodithiinyl, benzoxathiinyl, benzothiazinyl, benzoxazolyl, benzothiazolyl, benzothiadiazolyl, benzo[<NUM>,<NUM>]dioxolyl, pyrazolopyridyl, imidazopyridyl (azabenzimidazolyl), triazolopyridyl, isoxazolopyridyl, purinyl, xanthinyl, adeninyl, guaninyl, quinolinyl, isoquinolinyl, quinolizinyl, quinoxalinyl, quinazolinyl, cinnolinyl, phthalazinyl, naphthyridinyl, pteridinyl, thianaphthyl, dihydrobenzothiazinyl, dihydrobenzofuranyl, dihydroindolyl, dihydrobenzodioxinyl, tetrahydroindolyl, tetrahydroindazolyl, tetrahydrobenzimidazolyl, tetrahydrobenzotriazolyl, tetrahydropyrrolopyridyl, tetrahydropyrazolopyridyl, tetrahydroimidazopyri dyl, tetrahydrotriazolopyridyl, and tetrahydroquinolinyl groups. Representative substituted heterocyclyl groups may be mono-substituted or substituted more than once, such as, but not limited to, pyridyl or morpholinyl groups, which are <NUM>-, <NUM>-, <NUM>-, <NUM>-, or <NUM>-substituted, or disubstituted with various substituents such as those listed above.

Heteroaryl groups are aromatic ring compounds containing <NUM> or more ring members, of which, one or more is a heteroatom such as, but not limited to, N, O, and S. Heteroaryl groups include, but are not limited to, groups such as pyrrolyl, pyrazolyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, thiazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, thiophenyl, benzothiophenyl, furanyl, benzofuranyl, indolyl, azaindolyl (pyrrolopyridinyl), indazolyl, benzimidazolyl, imidazopyridinyl (azabenzimidazolyl), pyrazolopyridinyl, triazolopyridinyl, benzotriazolyl, benzoxazolyl, benzothiazolyl, benzothiadiazolyl, imidazopyridinyl, isoxazolopyridinyl, thianaphthyl, purinyl, xanthinyl, adeninyl, guaninyl, quinolinyl, isoquinolinyl, tetrahydroquinolinyl, quinoxalinyl, and quinazolinyl groups. Heteroaryl groups include fused ring compounds in which all rings are aromatic such as indolyl groups and include fused ring compounds in which only one of the rings is aromatic, such as <NUM>,<NUM>-dihydro indolyl groups. Heteroaryl groups may be substituted or unsubstituted. Thus, the phrase "heteroaryl groups" includes fused ring compounds as well as includes heteroaryl groups that have other groups bonded to one of the ring members, such as alkyl groups. Representative substituted heteroaryl groups may be substituted one or more times with various substituents such as those listed above.

Heterocyclylalkyl groups are alkyl groups as defined above in which a hydrogen or carbon bond of an alkyl group is replaced with a bond to a heterocyclyl group as defined above. Heterocyclylalkyl groups may be substituted or unsubstituted. Substituted heterocyclylalkyl groups may be substituted at the alkyl, the heterocyclyl or both the alkyl and heterocyclyl portions of the group. Representative heterocyclyl alkyl groups include, but are not limited to, morpholin-<NUM>-yl-ethyl, furan-<NUM>-yl-methyl, imidazol-<NUM>-yl-methyl, pyridin-<NUM>-yl-methyl, tetrahydrofuran-<NUM>-yl-ethyl, and indol-<NUM>-yl-propyl. Representative substituted heterocyclylalkyl groups may be substituted one or more times with substituents such as those listed above.

Heteroaralkyl groups are alkyl groups as defined above in which a hydrogen or carbon bond of an alkyl group is replaced with a bond to a heteroaryl group as defined above. Heteroaralkyl groups may be substituted or unsubstituted. Substituted heteroaralkyl groups may be substituted at the alkyl, the heteroaryl or both the alkyl and heteroaryl portions of the group. Representative substituted heteroaralkyl groups may be substituted one or more times with substituents such as those listed above.

Groups described herein having two or more points of attachment (i.e., divalent, trivalent, or polyvalent) within the compound of the present technology are designated by use of the suffix, "ene. " For example, divalent alkyl groups are alkylene groups, divalent aryl groups are arylene groups, divalent heteroaryl groups are divalent heteroarylene groups, and so forth. Substituted groups having a single point of attachment to the compound of the present technology are not referred to using the "ene" designation. Thus, e.g., chloroethyl is not referred to herein as chloroethylene. Such groups may further be substituted or unsubstituted.

Alkoxy groups are hydroxyl groups (-OH) in which the bond to the hydrogen atom is replaced by a bond to a carbon atom of a substituted or unsubstituted alkyl group as defined above. Examples of linear alkoxy groups include but are not limited to methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, and the like. Examples of branched alkoxy groups include but are not limited to isopropoxy, sec-butoxy, tert-butoxy, isopentoxy, isohexoxy, and the like. Examples of cycloalkoxy groups include but are not limited to cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy, and the like. Alkoxy groups may be substituted or unsubstituted. Representative substituted alkoxy groups may be substituted one or more times with substituents such as those listed above.

The terms "alkanoyl" and "alkanoyloxy" as used herein can refer, respectively, to - C(O)-alkyl and -O-C(O)-alkyl groups, where in some embodiments the alkanoyl or alkanoyloxy groups each contain <NUM>-<NUM> carbon atoms. Similarly, the terms "aryloyl" and "aryloyloxy" respectively refer to -C(O)-aryl and -O-C(O)-aryl groups.

The terms "aryloxy" and "arylalkoxy" refer to, respectively, a substituted or unsubstituted aryl group bonded to an oxygen atom and a substituted or unsubstituted aralkyl group bonded to the oxygen atom at the alkyl. Examples include but are not limited to phenoxy, naphthyloxy, and benzyloxy. Representative substituted aryloxy and arylalkoxy groups may be substituted one or more times with substituents such as those listed above.

The term "carboxylic acid" as used herein refers to a compound with a -C(O)OH group. The term "carboxylate" as used herein refers to a -C(O)O- group. A "protected carboxylate" refers to a -C(O)O-G where G is a carboxylate protecting group. Carboxylate protecting groups are well known to one of ordinary skill in the art. An extensive list of protecting groups for the carboxylate group functionality may be found in<NPL>) which can be added or removed using the procedures set forth therein.

The term "ester" as used herein refers to -COOR<NUM> groups. R<NUM> is a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, alkynyl, aryl, aralkyl, heterocyclylalkyl or heterocyclyl group as defined herein.

The term "amide" (or "amido") includes C- and N-amide groups, i.e., -C(O)NR<NUM>R<NUM>, and -NR<NUM>C(O)R<NUM> groups, respectively. R<NUM> and R<NUM> are independently hydrogen, or a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl, aryl, aralkyl, heterocyclylalkyl or heterocyclyl group as defined herein. Amido groups therefore include but are not limited to carbamoyl groups (-C(O)NH<NUM>) and formamide groups (-NHC(O)H). In some embodiments, the amide is -NR<NUM>C(O)-(C<NUM>-<NUM> alkyl) and the group is termed "carbonylamino," and in others the amide is -NHC(O)-alkyl and the group is termed "alkanoylamino.

The term "nitrile" or "cyano" as used herein refers to the -CN group.

Urethane groups include N- and O-urethane groups, i.e., -NR<NUM>C(O)OR<NUM> and -OC(O)NR<NUM>R<NUM> groups, respectively. R<NUM> and R<NUM> are independently a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl, aryl, aralkyl, heterocyclylalkyl, or heterocyclyl group as defined herein. R<NUM> may also be H.

The term "amine" (or "amino") as used herein refers to -NR<NUM>R<NUM> groups, wherein R<NUM> and R<NUM> are independently hydrogen, or a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl, aryl, aralkyl, heterocyclylalkyl or heterocyclyl group as defined herein. In some embodiments, the amine is alkylamino, dialkylamino, arylamino, or alkylarylamino. In other embodiments, the amine is NH<NUM>, methylamino, dimethylamino, ethylamino, diethylamino, propylamino, isopropylamino, phenylamino, or benzylamino.

The term "sulfonamido" includes S- and N-sulfonamide groups, i.e., -SO<NUM>NR<NUM>R<NUM> and -NR<NUM>SO<NUM>R<NUM> groups, respectively. R<NUM> and R<NUM> are independently hydrogen, or a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl, aryl, aralkyl, heterocyclylalkyl, or heterocyclyl group as defined herein. Sulfonamido groups therefore include but are not limited to sulfamoyl groups (-SO<NUM>NH<NUM>). In some embodiments herein, the sulfonamido is -NHSO<NUM>-alkyl and is referred to as the "alkylsulfonylamino" group.

The term "thiol" refers to -SH groups, while sulfides include -SR<NUM> groups, sulfoxides include -S(O)R<NUM> groups, sulfones include -SO<NUM>R<NUM> groups, and sulfonyls include -SO<NUM>OR<NUM>. R<NUM>, R<NUM>, R<NUM>, and R<NUM> are each independently a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, alkynyl, aryl aralkyl, heterocyclyl or heterocyclylalkyl group as defined herein. In some embodiments the sulfide is an alkylthio group, -S-alkyl.

The term "urea" refers to -NR<NUM>-C(O)-NR<NUM>R<NUM> groups. R<NUM>, R<NUM>, and R<NUM> groups are independently hydrogen, or a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl, aryl, aralkyl, heterocyclyl, or heterocyclylalkyl group as defined herein.

The term "amidine" refers to -C(NR<NUM>)NR<NUM>R<NUM> and -NR<NUM>C(NR<NUM>)R<NUM>, wherein R<NUM>, R<NUM>, and R<NUM> are each independently hydrogen, or a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, alkynyl, aryl aralkyl, heterocyclyl or heterocyclylalkyl group as defined herein.

The term "guanidine" refers to -NR<NUM>C(NR<NUM>)NR<NUM>R<NUM>, wherein R<NUM>, R<NUM>, R<NUM> and R<NUM> are each independently hydrogen, or a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, alkynyl, aryl aralkyl, heterocyclyl or heterocyclylalkyl group as defined herein.

The term "enamine" refers to -C(R<NUM>)=C(R<NUM>)NR<NUM>R<NUM> and -NR<NUM>C(R<NUM>)=C(R<NUM>)R<NUM>, wherein R<NUM>, R<NUM>, R<NUM> and R<NUM> are each independently hydrogen, a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, alkynyl, aryl aralkyl, heterocyclyl or heterocyclylalkyl group as defined herein.

The term "halogen" or "halo" as used herein refers to bromine, chlorine, fluorine, or iodine. In some embodiments, the halogen is fluorine. In other embodiments, the halogen is chlorine or bromine.

The term "hydroxyl" as used herein can refer to -OH or its ionized form, -O-.

The term "imide" refers to -C(O)NR<NUM>C(O)R<NUM>, wherein R<NUM> and R<NUM> are each independently hydrogen, or a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, alkynyl, aryl aralkyl, heterocyclyl or heterocyclylalkyl group as defined herein.

The term "imine" refers to -CR<NUM>(NR<NUM>) and -N(CR<NUM>R<NUM>) groups, wherein R<NUM> and R<NUM> are each independently hydrogen or a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, alkynyl, aryl aralkyl, heterocyclyl or heterocyclylalkyl group as defined herein, with the proviso that R<NUM> and R<NUM> are not both simultaneously hydrogen.

The term "nitro" as used herein refers to an -NO<NUM> group.

The term "trifluoromethyl" as used herein refers to -CF<NUM>.

The term "trifluoromethoxy" as used herein refers to -OCF<NUM>.

The term "trialkyl ammonium" refers to a -N(alkyl)<NUM> group. A trialkylammonium group is positively charged and thus typically has an associated anion, such as halogen anion.

The term "trifluoromethyldiazirido" refers to
<CHM>.

The term "pentafluorosulfanyl" refers to -SF<NUM>.

As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as "up to," "at least," "greater than," "less than," and the like include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having <NUM>-<NUM> atoms refers to groups having <NUM>, <NUM>, or <NUM> atoms. Similarly, a group having <NUM>-<NUM> atoms refers to groups having <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> atoms, and so forth.

Pharmaceutically acceptable salts of compounds described herein are within the scope of the present technology and include acid or base addition salts which retain the desired pharmacological activity and is not biologically undesirable (e.g., the salt is not unduly toxic, allergenic, or irritating, and is bioavailable). When the compound of the present technology has a basic group, such as, for example, an amino group, pharmaceutically acceptable salts can be formed with inorganic acids (such as hydrochloric acid, hydroboric acid, nitric acid, sulfuric acid, and phosphoric acid), organic acids (e.g., alginate, formic acid, acetic acid, benzoic acid, gluconic acid, fumaric acid, oxalic acid, tartaric acid, lactic acid, maleic acid, citric acid, succinic acid, malic acid, methanesulfonic acid, benzenesulfonic acid, naphthalene sulfonic acid, and p-toluenesulfonic acid) or acidic amino acids (such as aspartic acid and glutamic acid). When the compound of the present technology has an acidic group, such as for example, a carboxylic acid group, it can form salts with metals, such as alkali and earth alkali metals (e.g., Na+, Li+, K+, Ca<NUM>+, Mg<NUM>+, Zn<NUM>+), ammonia or organic amines (e.g. dicyclohexylamine, trimethylamine, triethylamine, pyridine, picoline, ethanolamine, diethanolamine, triethanolamine) or basic amino acids (e.g., arginine, lysine and omithine). Such salts can be prepared in situ during isolation and purification of the compounds or by separately reacting the purified compound in its free base or free acid form with a suitable acid or base, respectively, and isolating the salt thus formed.

Those of skill in the art will appreciate that compounds of the present technology may exhibit the phenomena of tautomerism, conformational isomerism, geometric isomerism and/or stereoisomerism. As the formula drawings within the specification and claims can represent only one of the possible tautomeric, conformational isomeric, stereochemical or geometric isomeric forms, it should be understood that the present technology encompasses any tautomeric, conformational isomeric, stereochemical and/or geometric isomeric forms of the compounds having one or more of the utilities described herein, as well as mixtures of these various different forms.

"Tautomers" refers to isomeric forms of a compound that are in equilibrium with each other. The presence and concentrations of the isomeric forms will depend on the environment the compound is found in and may be different depending upon, for example, whether the compound is a solid or is in an organic or aqueous solution. For example, in aqueous solution, quinazolinones may exhibit the following isomeric forms, which are referred to as tautomers of each other:
<CHM>
As another example, guanidines may exhibit the following isomeric forms in protic organic solution, also referred to as tautomers of each other:
<CHM>.

Because of the limits of representing compounds by structural formulas, it is to be understood that all chemical formulas of the compounds described herein represent all tautomeric forms of compounds and are within the scope of the present technology.

Stereoisomers of compounds (also known as optical isomers) include all chiral, diastereomeric, and racemic forms of a structure, unless the specific stereochemistry is expressly indicated. Thus, compounds used in the present technology include enriched or resolved optical isomers at any or all asymmetric atoms as are apparent from the depictions. Both racemic and diastereomeric mixtures, as well as the individual optical isomers can be isolated or synthesized so as to be substantially free of their enantiomeric or diastereomeric partners, and these stereoisomers are all within the scope of the present technology.

The compounds of the present technology may exist as solvates, especially hydrates. Hydrates may form during manufacture of the compounds or compositions comprising the compounds, or hydrates may form over time due to the hygroscopic nature of the compounds. Compounds of the present technology may exist as organic solvates as well, including DMF, ether, and alcohol solvates among others. The identification and preparation of any particular solvate is within the skill of the ordinary artisan of synthetic organic or medicinal chemistry.

Although targeted radiotherapy has been practiced for some time using macrocyclic complexes of radionuclides, the macrocycles currently in use (e.g., DOTA) generally form complexes of insufficient stability with radionuclides, particularly for radionuclides of larger size, such as actinium, radium, bismuth, and lead isotopes. Such instability results in dissociation of the radionuclide from the macrocycle, and this results in a lack of selectivity to targeted tissue, which also results in toxicity to non-targeted tissue. Jensen et al. (DOI: <NUM>/ic500244p) disclose aqueous complexes for size-based separation of Americium from Curim. Wilson et al. (DOI: <NUM>/j. <NUM>) disclose nitrogen-rich macrocyclic ligands for chelation of therapeutic bismuth radioisotopes. Deal et al. (DOI: <NUM>/JM990141F) disclose actinium-<NUM> macrocyclic complexes. Wilbur (DOI: <NUM>/<NUM>) discloses chemical and radiochemical considerations in radiolabeling [alpha]-emitting radionuclides. Price et al. (DOI: <NUM>/C3CS60304K) discloses chelators and radiometals for radiopharmaceuticals.

The present technology provides new macrocyclic complexes that are substantially more stable than those of the conventional art. Thus, these new complexes can advantageously target cancer cells more effectively, with substantially less toxicity to non-targeted tissue than complexes of the art. Moreover, the new complexes can advantageously be produced at room temperature, in contrast to DOTA-type complexes, which generally require elevated temperatures (e.g., at least <NUM>) for complexation with the radionuclide. The present technology also specifically employs alpha-emitting radionuclides instead of beta radionuclides. Alpha-emitting radionuclides are of much higher energy, and thus substantially more potent, than beta-emitting radionuclides.

Thus, in one aspect, a composition of Formula I-b is provided:
<CHM>
or a pharmaceutically acceptable salt thereof, wherein.

Also provided is a compound that is of formula <NUM>:
<CHM>
Also provided is a compound that is of formula macropa-NCS:
<CHM>
Also provided is a compound that is of formula <NUM>:
<CHM>.

The examples herein are provided to illustrate advantages of the present technology and to further assist a person of ordinary skill in the art with preparing or using the compounds of the present technology or salts, pharmaceutical compositions, derivatives, prodrugs, or tautomeric forms thereof. The examples herein are also presented in order to more fully illustrate the preferred aspects of the present technology. The examples should in no way be construed as limiting the scope of the present technology, as defined by the appended claims. The examples can include or incorporate any of the variations, aspects or embodiments of the present technology described above. The variations, aspects or embodiments described above may also further each include or incorporate the variations of any or all other variations, aspects or embodiments of the present technology.

Materials and Instrumentation. All solvents and reagents, unless otherwise noted, were purchased from commercial sources and used as received without further purification. Solvents noted as "dry" were obtained following storage over <NUM>Å molecular sieves. Metal salts were purchased from Strem Chemicals (Newburyport, MA) and were of the highest purity available; Lu(ClO<NUM>)<NUM> was provided as an aqueous solution containing <NUM> wt% Lu. The bifunctional ligand p-SCN-Bn-DOTA was purchased from Macrocyclics (Plano, TX). NMe<NUM>OH was purchased as a <NUM> wt% solution in H<NUM>O (trace metals basis, Beantown Chemical, Hudson, NH). Hydrochloric acid (BDH Aristar Plus, VWR, Radnor, PA) and nitric acid (Optima, ThermoFisher Scientific, Waltham, MA) were of trace metals grade. Both Chelex <NUM> (sodium form, <NUM>-<NUM> mesh) and human serum used for <NUM>Ac-complex challenge assays were purchased from Sigma Aldrich (St. Louis, MO). Deionized water (≥<NUM> MΩ cm) was prepared on site using either Millipore Direct-Q® 3UV or Elga Purelab Flex <NUM> water purification systems.

Reactions were monitored by thin-layer chromatography (TLC, Whatman UV254 aluminum-backed silica gel). The HPLC system used for analysis and purification of compounds consisted of a CBM-20A communications bus module, an LC-20AP (preparative) or LC-20AT (analytical) pump, and an SPD-20AV UV/Vis detector monitoring at <NUM> (Shimadzu, Japan). Analytical chromatography was carried out using an Ultra Aqueous C18 column, <NUM>Å, <NUM>, <NUM> × <NUM> (Restek, Bellefonte, PA) at a flow rate of <NUM>/min, unless otherwise noted. Purification was performed with an Epic Polar preparative column, <NUM>Å, <NUM>, <NUM> × <NUM> (ES Industries, West Berlin, NJ) at a flow rate of <NUM>/min, unless otherwise noted. Gradient HPLC methods were employed using a binary mobile phase that contained H<NUM>O (A) and either MeOH (B) or ACN (C). HPLC Method A: <NUM>% B (<NUM>-<NUM>), <NUM>-<NUM>% B (<NUM>-<NUM>). Method B: <NUM>% C (<NUM>-<NUM>), <NUM>-<NUM>% C (<NUM>-<NUM>). Method C: <NUM>% C (<NUM>-<NUM>), <NUM>-<NUM>% C (<NUM>-<NUM>). Method D: <NUM>% C (<NUM>-<NUM>), <NUM>-<NUM>% C (<NUM>-<NUM>). The solvent systems contained <NUM>% trifluoroacetic acid (TFA), except for Method C, in which <NUM>% TFA was used. NMR spectra were recorded at ambient temperature on Varian Inova <NUM>, <NUM>, <NUM> or <NUM> spectrometers, or on a Bruker AV III HD <NUM> spectrometer equipped with a broadband Prodigy cryoprobe. Chemical shifts are reported in ppm. <NUM>H and <NUM>C NMR spectra were referenced to the TMS internal standard (<NUM> ppm), to the residual solvent peak, or to an acetonitrile internal standard (<NUM> ppm in D<NUM>O spectra). <NUM>F NMR spectra were referenced to a monofluorobenzene internal standard (-<NUM> ppm). The splitting of proton resonances in the reported <NUM>H spectra is defined as: s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet, dt = doublet of triplets, td = triplet of doublets, and br = broad. IR spectroscopy was performed on a KBr pellet of sample using a Nicolet Avatar <NUM> DTGS (ThermoFisher Scientific, Waltham, MA). High-resolution mass spectra (HRMS) were recorded on an Exactive Orbitrap mass spectrometer in positive ESI mode (ThermoFisher Scientific, Waltham, MA). UV/visible spectra were recorded on a Cary <NUM> UV-Vis (Agilent Technologies, Santa Clara, CA) using <NUM>-cm quartz cuvettes, unless otherwise noted. Elemental analysis (EA) was performed by Atlantic Microlab, Inc. (Norcross, GA).

Synthesis and Characterization of Macropa Complexes, Macropa-NCS, and Macropa-NHC(S)NHCH<NUM>. N,N'-bis[(<NUM>-carboxy-<NUM>-pyridil)methyl]-<NUM>,<NUM>-diaza-<NUM>-crown-<NUM> (H<NUM>macropa·2HCl·<NUM><NUM>O)[<NUM>,<NUM>] was prepared using <NUM>,<NUM>,<NUM>,<NUM>-tetraoxa-<NUM>,<NUM>-diazacyclooctadecane (<NUM>) that was either purchased from EMD Millipore (Darmstadt, Germany) or synthesized via literature protocols. [<NUM>] Chelidamic acid monohydrate (<NUM>) was purchased from TCI America (Portland, OR). Dimethyl <NUM>-chloropyridine-<NUM>,<NUM>-dicarboxylate (<NUM>),[<NUM>] dimethyl <NUM>-azidopyridine- <NUM>,<NUM>-dicarboxylate (<NUM>),[<NUM>] and <NUM>-chloromethylpyridine-<NUM>-carboxylic acid methyl ester (<NUM>),[<NUM>] were prepared via the indicated literature protocols.

<CHM>
To a suspension of H<NUM>macropa·2HCl·<NUM><NUM>O (<NUM>, <NUM> mmol) in <NUM>-propanol (<NUM>) was added triethylamine (<NUM>µL, <NUM> mmol). The pale-gold solution was heated at reflux for <NUM> before a solution of La(ClO<NUM>)<NUM>·<NUM><NUM>O (<NUM>, <NUM> mmol) in <NUM>-propanol (<NUM>) was added dropwise. A precipitate formed immediately. The cream suspension was stirred at reflux for an additional <NUM> before it was cooled and centrifuged. The supernatant was removed, and the pellet was washed with <NUM>-propanol (<NUM> × <NUM>) and then air-dried on filter paper to give the title complex as a pale-tan solid (<NUM>) containing <NUM> equiv of <NUM>-propanol. <NUM>H NMR (<NUM>, D<NUM>O, pD <NUM>) δ= <NUM> (t, J = <NUM>, <NUM>), <NUM> (d, J = <NUM>, <NUM>), <NUM> (d, J = <NUM>, <NUM>), <NUM> (d, J = <NUM>, <NUM>), <NUM> (t, J = <NUM>, <NUM>), <NUM> (t, J = <NUM>, <NUM>), <NUM> (t, J = <NUM>, <NUM>), <NUM> (d, J = <NUM>, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM> (d, J = <NUM>, <NUM>), <NUM> (td, J = <NUM>, <NUM>, <NUM>), <NUM> (d, J = <NUM>, <NUM>), <NUM> (d, J = <NUM>, <NUM>). <NUM>C{JH} APT NMR (<NUM>, D<NUM>O, pD ≈ <NUM>) δ= <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. EA Found: C, <NUM>; H, <NUM>; N, <NUM>. for C<NUM>H<NUM>LaN<NUM>O<NUM>·2ClO<NUM>·<NUM><NUM>O·<NUM>. 64iPrOH: C, <NUM>; H, <NUM>; N, <NUM>. IR (cm-<NUM>): <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. HPLC tR = <NUM> (Method A). HRMS (m/z): <NUM>, <NUM>; Calc for [C<NUM>H<NUM>LaN<NUM>O<NUM>]+ and [C<NUM>H<NUM>LaN<NUM>O<NUM>]<NUM>+, respectively: <NUM>, <NUM>.

<CHM>
To a suspension H<NUM>macropa·2HCl·<NUM><NUM>O (<NUM>, <NUM> mmol) in <NUM>-propanol (<NUM>) was added triethylamine (<NUM>µL, <NUM> mmol). The pale-gold solution was heated at reflux for <NUM> before a solution of aq. Lu(ClO<NUM>)<NUM> (<NUM>, <NUM> mmol Lu) in <NUM>-propanol (<NUM>) was added dropwise. A precipitate formed immediately. After stirring at reflux or an additional <NUM>, the cream suspension was triturated at RT for <NUM> and then centrifuged. The supernatant was removed, and the pellet was washed with <NUM>-propanol (<NUM> × <NUM>) and then air-dried on filter paper to give the title complex as a pale-tan solid (<NUM>) containing residual <NUM>-propanol and triethylamine salt. <NUM>H NMR (<NUM>, D<NUM>O, pD ≈ <NUM>-<NUM>) δ= <NUM> (t, J = <NUM>, <NUM>), <NUM> (d, J = <NUM>, <NUM>), <NUM> (d, J = <NUM>, <NUM>), <NUM> (d, J = <NUM>, <NUM>), <NUM> (td, J = <NUM>, <NUM>, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM> (d, J = <NUM>, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM> (td, J = <NUM>, <NUM>, <NUM>), <NUM> (m, <NUM>), <NUM> (d, J = <NUM>, <NUM>), <NUM> (dt, J = <NUM>, <NUM>, <NUM>). <NUM>C{<NUM>H} APT NMR (<NUM>, D<NUM>O, pD ≈ <NUM>-<NUM>) δ= <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. IR (cm-<NUM>): <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. HPLC tR = not stable (Method A). HRMS (m/z): <NUM>; Calc for [C<NUM>H<NUM>LuN<NUM>O<NUM>]+: <NUM>.

<CHM>
Dimethyl <NUM>-azidopyridine-<NUM>,<NUM>-dicarboxylate (<NUM>, <NUM>, <NUM> mmol), <NUM>% Pd/C (<NUM>), and DCM:MeOH (<NUM>:<NUM>, <NUM>) were combined in a round-bottom flask. After purging the flask with a balloon of H<NUM>, the reaction was stirred vigorously at room temperature under an H<NUM> atmosphere for <NUM>. The gray mixture was diluted with DMF (<NUM>) and filtered through a bed of Celite. Following a subsequent filtration through a <NUM> nylon membrane, the filtrate was concentrated at <NUM> under reduced pressure and further dried in vacuo to obtain <NUM> as a pale-tan solid (<NUM>, <NUM>% yield). <NUM>H NMR (<NUM>, DMSO-d<NUM>): δ= <NUM> (s, <NUM>), <NUM> (s, <NUM>), <NUM> (s, <NUM>). <NUM>C{<NUM>H} APT NMR (<NUM>, DMSO-d6): δ= <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. IR (cm-<NUM>): <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. HPLC tR = <NUM> (Method B). HRMS (m/z): <NUM> [M + H]+; Calc: <NUM>.

<CHM>
To a refluxing suspension of <NUM> (<NUM>, <NUM> mmol) in absolute EtOH (<NUM>) was added NaBH<NUM> (<NUM>, <NUM> mmol) portionwise over <NUM> to give a pale-yellow suspension. The reaction was then quenched with acetone (<NUM>) and concentrated at <NUM> under reduced pressure to a tan solid. The crude product was dissolved in H<NUM>O (<NUM>) and washed with ethyl acetate (<NUM> × <NUM>). The combined organics were dried over sodium sulfate and concentrated at <NUM> under reduced pressure. Further drying in vacuo yielded <NUM> as a pale-yellow solid (<NUM>, <NUM>% yield). <NUM>H NMR (<NUM>, DMSO-d<NUM>): δ= <NUM> (d, J = <NUM>, <NUM>), <NUM> (m, <NUM>), <NUM> (s, <NUM>), <NUM> (t, J = <NUM>, <NUM>), <NUM> (d, J = <NUM>, <NUM>), <NUM> (q, J = <NUM>, <NUM>), <NUM> (t, J = <NUM>, <NUM>). <NUM>C APT NMR (<NUM>, DMSO-d<NUM>) δ= <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. IR (cm-<NUM>): <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. HPLC tR = <NUM> (Method B). HRMS (m/z): <NUM> [M + H]+; Calc: <NUM>.

<CHM>
A mixture of thionyl chloride (<NUM>) and <NUM> (<NUM>, <NUM> mmol) was stirred in an ice bath for <NUM>, and then at RT for <NUM>. The yellow-orange emulsion was concentrated at <NUM> under reduced pressure to an oily residue. The residue was neutralized with sat. NaHCO<NUM> (<NUM>) and then extracted with ethyl acetate (<NUM>). The organic extract was washed with H<NUM>O (<NUM>), dried over sodium sulfate, and concentrated at <NUM> under reduced pressure. Further drying in vacuo gave <NUM> as an amber wax (<NUM>, <NUM>% yield, corrected for residual ethyl acetate). <NUM>H NMR (<NUM>, DMSO-d<NUM>) δ= <NUM> (d, J = <NUM>, <NUM>), <NUM> (d, J = <NUM>, <NUM>), <NUM> (br s, <NUM>), <NUM> (s, <NUM>), <NUM> (q, J = <NUM>, <NUM>), <NUM> (t, J = <NUM>, <NUM>). <NUM>C{<NUM>H} APT NMR (<NUM>, DMSO-d<NUM>) δ= <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. IR (cm-<NUM>): <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. HPLC tR = <NUM> (Method B). HRMS (m/z): <NUM> [M + H]+; Calc: <NUM>.

<CHM>
To a clear and colorless solution of <NUM>,<NUM>,<NUM>,<NUM>-tetraoxa-<NUM>,<NUM>-diazacyclooctadecane (<NUM>, <NUM>, <NUM> mmol) and diisopropylethylamine (<NUM>, <NUM> mmol) in dry ACN (<NUM>) at <NUM> was added dropwise a solution of <NUM> (<NUM>, <NUM> mmol) in dry ACN (<NUM>) over <NUM> <NUM>. The flask was then equipped with a condenser and drying tube, and the slightly-yellow solution was heated at reflux for <NUM>. Subsequently, the dark-gold solution containing fine, white precipitate was concentrated at <NUM> under reduced pressure to an amber oil. To the crude oil was added <NUM>% MeOH/H<NUM>O containing <NUM>% TFA (<NUM>). The slight suspension was filtered, and the filtrate was purified by preparative HPLC (Method A). Pure fractions were combined, concentrated at <NUM> under reduced pressure, and then lyophilized to give <NUM> (<NUM>, <NUM>% yield) as a pale-orange solid. <NUM>H NMR (<NUM>, DMSO-d<NUM>) δ= <NUM> (br s, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM> (dd, J = <NUM>, <NUM>, <NUM>), <NUM> (br s, <NUM>), <NUM> (s, <NUM>), <NUM> (br t, J = <NUM>, <NUM>), <NUM> (t, J = <NUM>, <NUM>), <NUM> (br s, <NUM>), <NUM> (br s, <NUM>), <NUM> (br t, J = <NUM>, <NUM>). <NUM>C{JH} APT NMR (<NUM>, DMSO-d<NUM>) δ <NUM>, <NUM>-<NUM> (q, TFA), <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>-<NUM> (q, TFA), <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. <NUM>F NMR (<NUM>, DMSO-d<NUM>) δ= -<NUM>. EA Found: C, <NUM>; H, <NUM>; N, <NUM>. for C<NUM>H<NUM>N<NUM>O<NUM>. 2CF<NUM>COOH·<NUM><NUM>O: C, <NUM>; H, <NUM>; N, <NUM>. HPLC tR = <NUM> (Method B). HRMS (m/z): <NUM> [M + H]+; Calc: <NUM>.

<CHM>
Into a round-bottom flask equipped with a condenser and drying tube were added <NUM> (<NUM>, <NUM> mmol), Na<NUM>CO<NUM> (<NUM>, <NUM> mmol), and dry ACN (<NUM>). The pale-yellow suspension was heated to reflux over <NUM>, after which <NUM> (<NUM>, <NUM> mmol, corrected for residual ethyl acetate) was added as a slight suspension in dry ACN (<NUM>). The mixture was heated at reflux for <NUM> and then filtered. The orange filtrate was concentrated at <NUM> under reduced pressure to an orange-brown oil (<NUM>), which was used in the next step without further purification. HRMS (m/z): <NUM> [M + H]+; Calc: <NUM>.

<CHM>
Compound <NUM> (<NUM>) was dissolved in <NUM> HCl (<NUM>) and heated at <NUM> for <NUM>. The orange-brown solution containing slight precipitate was concentrated at <NUM> under reduced pressure to a pale-tan solid. To this solid was added <NUM>% MeOH/H<NUM>O containing <NUM>% TFA (<NUM>). The slight suspension was filtered and the filtrate was purified by preparative HPLC using Method A. Pure fractions were combined, concentrated at <NUM> under reduced pressure, and then lyophilized to give <NUM> as an off-white solid (<NUM>, <NUM>% yield over <NUM> steps). <NUM>H NMR (<NUM>, DMSO-d<NUM>) δ= <NUM>-<NUM> (m, <NUM>), <NUM> (dd, J = <NUM>, <NUM>, <NUM>), <NUM> (br s), <NUM> (d, J = <NUM>, <NUM>), <NUM> (d, J = <NUM>, <NUM>), <NUM> (s, <NUM>), <NUM> (s, <NUM>), <NUM> (t, J = <NUM>, <NUM>), <NUM> (t, J = <NUM>, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM> (br t, J = <NUM>, <NUM>). <NUM>C{JH} NMR (<NUM>, DMSO-d<NUM>) δ <NUM>, <NUM>, <NUM>, <NUM>-<NUM> (q, TFA), <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>-<NUM> (q, TFA), <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. <NUM>F NMR (<NUM>, DMSO-d<NUM>) δ= -<NUM>. EA Found: C, <NUM>; H, <NUM>; N, <NUM>. for C<NUM>H<NUM>N<NUM>O<NUM>. 4CF<NUM>COOH: C, <NUM>; H, <NUM>; N, <NUM>. IR (cm-<NUM>): <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. HPLC tR = <NUM> (Method B); <NUM> (Method D). HRMS (m/z): <NUM> [M + H]+; Calc: <NUM>.

<CHM>
A white suspension of <NUM> (<NUM>, <NUM> mmol) and Na<NUM>CO<NUM> (<NUM>, <NUM> mmol) was heated at reflux in acetone (<NUM>) for <NUM> before the slow addition of CSCl<NUM> (<NUM>µL of CSCl<NUM>, <NUM>%, Acros Organics). The resulting orange suspension was heated at reflux for <NUM> and then concentrated at <NUM> under reduced pressure to a pale-orange solid. The solid was dissolved portionwise in <NUM>% ACN/H<NUM>O containing <NUM>% TFA (<NUM> total), filtered, and immediately purified by preparative HPLC using Method C. [<NUM>] Pure fractions were combined, concentrated at RT under reduced pressure to remove the organic solvent, and then lyophilized. Fractions that were not able to be concentrated immediately were frozen at -<NUM>. Isothiocyanate <NUM> was obtained as a mixture of white and pale-yellow solid (<NUM>) and was stored at -<NUM> in a jar of Drierite. Calculations from <NUM>H NMR and <NUM>F NMR spectra of a sample of <NUM> spiked with a known concentration of fluorobenzene estimated that <NUM> was isolated as a tetra-TFA salt. <NUM>H NMR (<NUM>, DMSO-d<NUM>) δ= <NUM>-<NUM> (m, <NUM>), <NUM> (s w/fine splitting, <NUM>), <NUM> (d, J = <NUM>, <NUM>), <NUM>-<NUM> (d w/fine splitting, J = <NUM>, <NUM>), <NUM> (s, <NUM>), <NUM> (s, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM>-<NUM> (m, <NUM>). <NUM>F NMR (<NUM>, DMSO-d<NUM>) δ= -<NUM>. IR (cm-<NUM>): ~<NUM>-<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. HPLC tR = <NUM> (Method B); <NUM> (Method D). HRMS (m/z): <NUM> [M + H]+; Calc: <NUM>.

<CHM>
Compound <NUM> was prepared as described above using <NUM> (<NUM> mmol) of <NUM>, except the purification step was omitted. Instead, directly to the crude solid was added <NUM> methylamine in THF (<NUM>). The tan-orange suspension was stirred at RT for <NUM> and then concentrated at RT under reduced pressure to a pale-peach solid. The solid was dissolved in <NUM>% ACN/H<NUM>O containing <NUM>% TFA (<NUM>), filtered, and purified by preparative HPLC using Method C. Pure fractions were combined, concentrated at <NUM> under reduced pressure to remove the organic solvent, and then lyophilized. The dark-gold, slightly sticky solid was then recrystallized from ACN with Et<NUM>O. The suspension was centrifuged, and the pellet was washed with Et<NUM>O (<NUM> × <NUM>) and dried in vacuo to give <NUM> as a tan powder (<NUM>, <NUM>% unoptimized yield from <NUM>). <NUM>H NMR (<NUM>, DMSO-d<NUM>) δ= <NUM> (s, <NUM>), <NUM> (br s, <NUM>), <NUM> (s, <NUM>), <NUM> (s, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM>-<NUM> (d, J = <NUM>, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM> (br s, <NUM>), <NUM> (br s, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM> (d, J = <NUM>, <NUM>). <NUM>C{JH} NMR (<NUM>, DMSO-d<NUM>) δ <NUM>, <NUM>, <NUM>, <NUM>-<NUM> (q, TFA), <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>-<NUM> (q, TFA), <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. <NUM>F NMR (<NUM>, DMSO-d<NUM>) δ= -<NUM>. EA Found: C, <NUM>; H, <NUM>; N, <NUM>. for C<NUM>H<NUM>N<NUM>O<NUM>S. 2CF<NUM>COOH. <NUM><NUM>O: C, <NUM>; H, <NUM>; N, <NUM>. HPLC tR = <NUM> (Method B). HRMS (m/z): <NUM> [M + H]+; Calc: <NUM>.

X-Ray Diffraction Studies. Single crystals of H<NUM>macropa·2HCl·<NUM><NUM>O suitable for x-ray diffraction were grown from a saturated H<NUM>O:acetone (<NUM>:<NUM>) solution upon standing at room temperature. Single crystals of [La(Hmacropa)(H<NUM>O)]·(ClO<NUM>)<NUM> were grown via vapor diffusion of THF into an aqueous solution made acidic (pH ~<NUM>) upon addition of the complex. Single crystals of [Lu(macropa)]·ClO<NUM>·DMF were grown via vapor diffusion of Et<NUM>O into a DMF solution of the complex.

X-ray diffraction data for H<NUM>macropa·2HCl·<NUM><NUM>O, [La(Hmacropa)(H<NUM>O)]·(ClO<NUM>)<NUM>, and [Lu(macropa)]·ClO<NUM>·DMF were collected on a Bruker APEX <NUM> CCD Kappa diffractometer (Mo Kα, λ = <NUM>Å) at <NUM>. The structures were solved through intrinsic phasing using SBELXT[<NUM>] and refined against F<NUM> on all data by full-matrix least squares with SHELXL[<NUM>] following established refinement strategies. [<NUM>] All non-hydrogen atoms were refined anisotropically. Hydrogen atoms were included in the model at geometrically calculated positions and refined using a riding model. Hydrogen atoms bound to nitrogen and oxygen were located in the difference Fourier synthesis and subsequently refined semi-freely with the help of distance restraints. The isotropic displacement parameters of all hydrogen atoms were fixed to <NUM> times the U value of the atoms they are linked to (<NUM> times for methyl groups). For [La(Hmacropa)(H<NUM>O)]·(ClO<NUM>)<NUM>, a partially occupied solvent molecule of water was included in the unit cell but could not be satisfactorily modeled. Therefore, that solvent was treated as a diffuse contribution to the overall scattering without using specific atom positions by the solvent masking function in Olex2.

La<NUM>+ and Lu<NUM>+ Titrations with Macropa. The pH of a <NUM> <NUM>-(N-morpholino)propanesulfonic acid (MOPS) buffer was adjusted to <NUM> using aqueous NMe<NUM>OH. The ionic strength was set at <NUM> using NMe<NUM>Cl. Stock solutions of LaCl<NUM>·<NUM><NUM>O (<NUM>) and LuCl<NUM>·<NUM><NUM>O (<NUM>) were prepared in <NUM> HCl. A stock solution of H<NUM>macropa·2HCl·<NUM><NUM>O (<NUM>) was prepared in MOPS buffer. From these stock solutions, titration solutions containing macropa (<NUM>) and either LaCl<NUM> or LuCl<NUM> were prepared in MOPS. Each metal ion titration was carried out at RT by adding <NUM>-<NUM>µL aliquots of titrant to a cuvette containing <NUM>µL of macropa (<NUM>) in MOPS. Each sample was allowed to equilibrate for <NUM> following every addition before a spectrum was acquired. Complexation of the metal ion was monitored by the decrease in absorbance at <NUM>, the λmax of macropa. Titrant was added until no further spectral changes were detected.

Kinetic Inertness of La<NUM>+ and Lu<NUM>+ Complexes of Macropa: Transchelation Challenge. A stock solution of ethylenediaminetetraacetic acid (EDTA, <NUM>) was made in MOPS buffer (prepared as described above) by adjusting the pH of the initial suspension to <NUM> using aqueous NMe<NUM>OH. A stock solution of diethylenetriaminepentaacetic acid (DTPA, <NUM>) was prepared in H<NUM>O by adjusting the pH to <NUM> as described for EDTA. This solution was serially diluted with H<NUM>O to yield <NUM> and <NUM> solutions of DTPA.

The preformed La<NUM>+ and Lu<NUM>+ complexes of macropa were challenged with EDTA. Challenges were initiated by adding an aliquot of solution containing EDTA (<NUM>) and macropa (<NUM>) in MOPS buffer to each solution of complex. The final ratios of M:macropa:EDTA were approximately <NUM>:<NUM>:<NUM> (La) and <NUM>:<NUM>:<NUM> (Lu). Solutions were repeatedly analyzed by UV spectroscopy over the course of <NUM> days for any spectral changes. The final pH of each solution was between <NUM> and <NUM>.

The complex formed in situ between La<NUM>+ and macropa was more rigorously challenged with excess DTPA. A solution containing <NUM> of complex, prepared using the LaCl<NUM> and macropa stock solutions described above, was left to equilibrate for <NUM>. Subsequently, it was portioned into cuvettes and diluted with either <NUM> DTPA, <NUM> DTPA, <NUM> DTPA, or MOPS to yield solutions containing <NUM>-, <NUM>-, <NUM>-, or <NUM>-fold excess DTPA and <NUM> concentration of macropa. These solutions were repeatedly analyzed by UV spectroscopy over the course of <NUM> days for any spectral changes. The final pH of each solution was between <NUM> and <NUM>.

<NUM>Ac and <NUM>Ra were produced by the spallation of uranium carbide, separated downstream from other radionuclides by a mass separator using the Isotope Separator and Accelerator (ISAC) isotope separation on-line (ISOL) facility at TRIUMF (Vancouver, BC, Canada), and were collected via literature protocols. [<NUM>,<NUM>] <NUM>Ac was then separated from <NUM>Ra via DGA column[<NUM>,<NUM>] (branched, <NUM>-<NUM>, Eichrom Technologies LLC) and obtained in <NUM> HNO<NUM> for use in radiolabeling experiments. Aluminum-backed TLC plates (silica gel <NUM>, F<NUM>, EMD Millipore, Darmstadt, Germany) were used to analyze <NUM>Ac radiolabeling reaction progress. Instant thin layer chromatography paper impregnated with silica gel (iTLC-SG, Agilent Technologies, Mississauga, ON, Canada) was used in La<NUM>+ and serum stability challenges. TLC plates were developed and then counted on a BioScan System <NUM> imaging scanner equipped with a BioScan Autochanger <NUM> and WinScan software at least <NUM> later to allow time for daughter isotopes to decay completely, ensuring that the radioactive signal measured was generated by parent <NUM>Ac. Quantitative radioactivity measurements of <NUM>Ac, <NUM>Fr, and <NUM>Bi were determined via gamma-spectroscopy using a high-purity germanium (HPGe) detector (Canberra GR1520, Meriden, CT) calibrated using a NIST-traceable mixed <NUM>Ba and <NUM>Eu source. Detector dead time was maintained below <NUM>% for all measurements. Data was analyzed using Genie <NUM> software (v3. <NUM>, Canberra, Meriden, CT).

Concentration Dependence. Various concentrations of macropa and DOTA were radiolabeled with <NUM>Ac<NUM>+ to determine the lowest concentration at which ><NUM>% radiolabeling still occurred. Stock solutions of H<NUM>macropa·2HCl·<NUM><NUM>O (<NUM>-<NUM>-<NUM>-<NUM> M) and H<NUM>DOTA (<NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>M) were prepared in H<NUM>O. For each radiolabeling reaction, ligand (<NUM>µL) and <NUM>Ac (<NUM>-<NUM> kBq, <NUM>-<NUM>µL) were sequentially added to NH<NUM>OAc buffer (pH <NUM>, <NUM>, <NUM>µL) to give final ligand concentrations of <NUM> × <NUM>-<NUM>-<NUM> × <NUM>-<NUM> M for macropa and <NUM> × <NUM>-<NUM>-<NUM> × <NUM>-<NUM> M for DOTA. The final pH of all labeling reactions was between <NUM> and <NUM>. The reaction solutions were maintained at ambient temperature or <NUM>. Reaction progress was monitored at <NUM> and <NUM> by spotting <NUM>-<NUM>µL of the reaction solution onto TLC plates. The plates were developed with a mobile phase of <NUM> sodium citrate (pH <NUM>) containing <NUM>% MeOH and then counted. Under these conditions, [<NUM>Ac(macropa)]+ and [<NUM>Ac(DOTA)]-remained at the baseline (RF=<NUM>) and any unchelated <NUM>Ac (<NUM>Ac-citrate) migrated with the solvent front (RF=<NUM>). Radiochemical yields (RCYs) were calculated by integrating area under the peaks on the radiochromatogram and dividing the counts associated with the <NUM>Ac-complex (RF=<NUM>) by the total counts integrated along the length of the TLC plate.

Stock solutions of La(NO<NUM>)<NUM> (<NUM> or <NUM>) were prepared in H<NUM>O. To the radiolabeled samples containing macropa (<NUM>µL of <NUM>-<NUM> M stock; <NUM> × <NUM>-<NUM> moles) or DOTA (<NUM>µL of <NUM>-<NUM> M stock; <NUM> × <NUM>-<NUM> moles) and <NUM>Ac (<NUM>µL, <NUM> kBq) in NH<NUM>OAc buffer (pH <NUM>, <NUM>, <NUM>µL), a <NUM>-fold mole excess of La<NUM>+ was added (<NUM>µL of <NUM> or <NUM> stock were added to solutions containing macropa and DOTA, respectively). The solutions were kept at room temperature and analyzed by iTLC at several time points over the course of <NUM> days. The iTLC plates were developed using citric acid (<NUM>, pH <NUM>) as the eluent. Under these conditions, [<NUM>Ac(macropa)]+ and [<NUM>Ac(DOTA)]- remained at the baseline (RF=<NUM>) and any unchelated <NUM>Ac (<NUM>Ac-citrate) migrated with the solvent front (RF=<NUM>). Percent of complex remaining intact was calculated by integrating area under the peaks on the radiochromatogram and dividing the counts associated with the <NUM> Ac-complex (RF=<NUM>) by the total counts integrated along the length of the iTLC plate.

Transmetalation by La<NUM>+. [<NUM>Ac(macropa)]+ and [<NUM>Ac(DOTA)]- were prepared using <NUM>-<NUM> M and <NUM>-<NUM> M stock solutions (<NUM>µL) of macropa and DOTA, respectively, to give final ligand concentrations of <NUM> × <NUM>-<NUM> M (macropa) and <NUM> × <NUM>-<NUM> M (DOTA). After confirming a radiochemical yield of ><NUM>% by TLC using <NUM> sodium citrate (pH <NUM>) containing <NUM>% MeOH as the mobile phase, <NUM>µL of human serum (an equal volume based on labeling reaction volume) were added to each radiolabeled solution. A control solution was also prepared in which water was substituted for ligand. The solutions were monitored over the course of <NUM> days by iTLC. The plates were developed with EDTA (<NUM>, pH <NUM>) as the eluent. Under these conditions, [<NUM>Ac(macropa)]+ and [<NUM>Ac(DOTA)]- complexes remained at the baseline (RF=<NUM>) and any <NUM>Ac (<NUM>Ac-EDTA) that had been transchelated by serum migrated with the solvent front (RF=<NUM>). Percent of complex remaining intact was calculated.

In Vivo Biodistribution of <NUM>Ac Complexes of Macropa and DOTA. All experiments were approved by the Institutional Animal Care Committee (IACC) of the University of British Columbia and were performed in accordance with the Canadian Council on Animal Care Guidelines. A total of <NUM> female C57BL/<NUM> mice (<NUM>-<NUM> weeks old, <NUM>-<NUM>) were used for the biodistribution study of each radiometal complex, n = <NUM> for each time point.

Macropa (<NUM>µL of a <NUM>/mL solution in NH<NUM>OAc) was diluted with <NUM>µL of NH<NUM>OAc (<NUM>, pH <NUM>), and an aliquot (<NUM>µL) of <NUM>Ac(NO<NUM>)<NUM> (-<NUM> kBq) was then added; the pH of this solution was adjusted to <NUM>-<NUM> by the addition of <NUM> NaOH (<NUM>µL, trace metal grade). After <NUM> at ambient temperature, the reaction solution was analyzed by TLC (<NUM> pH <NUM> sodium citrate as the eluent), which confirmed ><NUM>% radiochemical yield. The reaction was allowed to proceed overnight, and the radiochemical yield was again confirmed to be ><NUM>% the following morning. At this time, mice were anesthetized by <NUM>% isoflurane, and approximately <NUM>µL (<NUM>-<NUM> kBq) of the [<NUM>Ac(macropa)]+ complex were injected into the tail vein of each mouse. After injection, mice were allowed to recover and roam freely in their cages, and were euthanized by CO<NUM> inhalation at <NUM>, <NUM>, or <NUM> (n = <NUM> at each time point) post-injection. Blood was collected by cardiac puncture and placed into an appropriate test tube for scintillation counting. Tissues collected included heart, liver, kidneys, lungs, small intestine, large intestine, brain, bladder, spleen, stomach, pancreas, bone, thyroid, tail, urine, and feces. Tissues were weighed and then counted with a calibrated gamma counter (Packard, Cobra II model <NUM>) using three energy windows: <NUM>-<NUM> keV (window A), <NUM>-<NUM> keV (window B), and <NUM>-<NUM> keV (window C). Counting was performed both immediately after sacrifice and after <NUM> days; counts were decay corrected from the time of injection and then converted to the percentage of injected dose (% ID) per gram of tissue (% ID/g). No differences were noted between the data; therefore, the biodistributions are reported using the data acquired immediately using window A.

The biodistribution studies of [<NUM>Ac(DOTA)]- and <NUM>Ac(NO<NUM>)<NUM> were carried out as described above for [<NUM>Ac(macropa)]+, with the following modifications. [<NUM>Ac(DOTA)- was prepared by adding <NUM>Ac(NO<NUM>)<NUM> (<NUM>µL, <NUM> MBq) to a solution of DOTA (<NUM>µg, <NUM>/mL in H<NUM>O) in NH<NUM>OAc (<NUM>µL, <NUM>, pH <NUM>). The pH of the solution was adjusted to <NUM> using NH<NUM>OAc (<NUM>µL, <NUM>, pH <NUM>) and the solution was heated at <NUM> for <NUM>. RCY > <NUM>% was confirmed by TLC as described above. [<NUM>Ac(DOTA)]- was diluted with saline to a final concentration of <NUM> MBq/<NUM>µL, and <NUM>µL were injected into each mouse. <NUM>Ac(NO<NUM>)<NUM> (~<NUM>µL, <NUM> MBq) was diluted and injected in the same manner as [<NUM>Ac(DOTA)]-. One mouse that was to be euthanized at the <NUM> time point in the [<NUM>Ac(DOTA)]- study died shortly after injection. In the same manner, one mouse that was to be euthanized at the <NUM> time point in the <NUM>AC(NO<NUM>)<NUM> study died.

Hydrolysis of Macropa-NCS and p-SCN-Bn-DOTA. To screw-capped vials containing approximately <NUM> of macropa-NCS (compound <NUM>, n = <NUM>) or p-SCN-Bn-DOTA (n = <NUM>) was added <NUM> of <NUM> pH <NUM> NaHCO<NUM> buffer containing <NUM> NaCl, which had been passed through a column of pre-equilibrated Chelex. After stirring for <NUM>, each solution was filtered through a <NUM> PES or PTFE membrane. Five µL aliquots were removed from the vials at various time points over the course of <NUM>-<NUM> and analyzed by HPLC. Method D was employed for macropa-NCS. Method B was employed for p-SCN-Bn-DOTA using an Epic Polar C18 column, <NUM>Å, <NUM>, <NUM> × <NUM> (ES Industries, West Berlin, NJ) at a flow rate of <NUM>/min. Between samplings, the vials were stored at room temperature (<NUM> ± <NUM>) away from light. Hydrolysis was considered complete once the peak at <NUM> (corresponding to <NUM>) or <NUM> (corresponding to p-SCN-Bn-DOTA) had disappeared or had negligible integration. A linear regression performed on the plots of ln peak area versus time provided the pseudo-first order rate constant (kobs) as the negative slope. The half-life (t<NUM>/<NUM>) was calculated using the equation t<NUM>/<NUM> = <NUM>/kobs. The half-life of each compound is reported as the mean ± <NUM> standard deviation.

Titration of Macropa-NHC(S)NHCH<NUM> Conjugate with La<NUM>+. The titration of the macropa-NHC(S)NHCH<NUM> conjugate (<NUM>) with La<NUM>+ was carried out at pH <NUM> for macropa, except that the stock solution of <NUM> (<NUM>) was prepared in ACN instead of MOPS. The amount of ACN in the sample did not exceed <NUM>% by volume. A wait time of <NUM> after the addition of each aliquot was found to be sufficient for the sample to reach equilibrium before spectral acquisition. Complexation of the metal ion was monitored using the increase in absorbance at <NUM>. The pH of the solution at the end of the titration was <NUM>.

Kinetic Inertness of La-Macropa-NHC(S)NHCH<NUM>: Transchelation Challenge. Solutions of diethylenetriaminepentaacetic acid (DTPA; <NUM> and <NUM>) were prepared in MOPS buffer (pH <NUM>). A MOPS solution containing macropa-NHC(S)NHCH<NUM> (<NUM>, <NUM>% ACN by volume) and LaCl<NUM> (<NUM>) was prepared using the stock solutions described above and was left to equilibrate for <NUM>. Subsequently, it was portioned into cuvettes and diluted with either <NUM> DTPA, <NUM> DTPA, or MOPS to yield solutions containing <NUM>-, <NUM>-, or <NUM>-fold excess DTPA. The final concentration of macropa-NHC(S)NHCH<NUM> in each cuvette was <NUM>. These solutions were repeatedly analyzed by UV spectrophotometry over the course of <NUM> days for any spectral changes. The final pH of each solution was between <NUM> and <NUM>. The experiment was performed in triplicate.

All glassware was washed overnight in <NUM> HCl. Saline (<NUM> NaCl) and all buffer solutions were passed through a column of Chelex-<NUM> pre-equilibrated with the appropriate buffer. Trastuzumab (Tmab, Genentech) was purified using a Zeba spin desalting column (<NUM> or <NUM>, <NUM> MWCO, Thermo Scientific, Waltham, MA) according to the manufacturer's protocol, with saline as the mobile phase. The concentration of purified Tmab was calculated via the Beer-Lambert law using A<NUM> and an ε<NUM> of <NUM> mg-<NUM> cm-<NUM>. [<NUM>] Purified Tmab and Tmab conjugates were stored at <NUM>.

Conjugation of Macropa-NCS to Tmab. A stock solution containing <NUM>/mL of macropa-NCS (<NUM>) was prepared in <NUM> pH <NUM> NaHCO<NUM> buffer containing <NUM> NaCl and was stored at -<NUM>. The stability of <NUM> during storage was verified by analytical HPLC. To a portion of Tmab in saline (<NUM>µL) were added <NUM> (<NUM>µL) and NaHCO<NUM> buffer (<NUM>µL), so that the final concentrations of Tmab and <NUM> were <NUM>/mL and <NUM>/mL, respectively. Macropa-NCS was estimated to be in <NUM>-fold molar excess to Tmab based on a molecular weight of <NUM>/mol for <NUM> (tetra-TFA salt). The pH of this solution was between <NUM> and <NUM> by litmus paper. The solution was rocked gently at room temperature for <NUM> and then purified using a spin column.

Conjugation ofp-NCS-Bn-DOTA to Tmab. A stock solution containing <NUM>/mL ofp-NCS-Bn-DOTA was prepared in H<NUM>O and stored at -<NUM>. To a portion of Tmab in saline (<NUM>µL) were added p-NCS-Bn-DOTA (<NUM>µL) and NaHCO<NUM> buffer (<NUM>µL), so that the final concentrations of Tmab andp-NCS-Bn-DOTA were <NUM>/mL and <NUM>/mL (<NUM>-fold molar excess of L), respectively. The pH of this solution was between <NUM> and <NUM> by litmus paper. The solution was rocked gently at room temperature for <NUM> and then purified using a spin column.

Determination of Conjugate Protein Concentration by BCA Assay. The concentration of protein in macropa-Tmab and DOTA-Tmab conjugates was determined using the Pierce™ BCA Protein Assay kit (Thermo Scientific, Waltham, MA, microplate protocol). Tmab was employed as the protein standard. A stock solution of purified Tmab was diluted with saline and the concentration of this solution (<NUM>/mL) was determined using a NanoDrop <NUM> Spectrophotometer (Thermo Scientific, Waltham, MA). The standard curve was linear (r<NUM> = <NUM>) over the concentration range measured (<NUM>-<NUM>µg/mL). The protein concentration of each conjugate was calculated from two independent dilutions, each measured in triplicate, and the results were averaged to give a protein concentration of <NUM>/mL for macropa-Tmab and <NUM>/mL for DOTA-Tmab.

Ligand-to-Protein Ratio Analysis by MALDI-ToF. The average number of macropa or DOTA ligands conjugated to Tmab was determined by MALDI-ToF MS/MS on a Bruker autoflex speed at the Alberta Proteomics and Mass Spectrometry Facility (University of Alberta, Canada) using a procedure described elsewhere. [<NUM>] Purified Tmab and the conjugates were analyzed in duplicate, and the [M+H]+ mass signals from the chromatograms were averaged for each compound. The ligand-to-protein (L:P) ratio for each conjugate was obtained by subtracting the molecular weight of Tmab from the molecular weight of the conjugate, and subsequently dividing by the mass of the bifunctional ligand.

Instant thin layer chromatography paper impregnated with silica gel (iTLC-SG, Agilent Technologies, Mississauga, ON, Canada) was used to monitor the progress of <NUM>Ac radiolabeling reactions and to determine serum stability. TLC plates were developed as described below and then counted on a BioScan System <NUM> imaging scanner equipped with a BioScan Autochanger <NUM> and WinScan software at least <NUM> later to allow time for daughter isotopes to decay completely, ensuring that the radioactive signal measured was generated by parent <NUM>Ac.

<NUM>Ac Radiolabeling Studies. In a total reaction volume of <NUM>µL made up with NH<NUM>OAc buffer (pH <NUM>, <NUM>), <NUM>Ac (<NUM> or <NUM> kBq, <NUM>-<NUM>µL) was mixed with <NUM>-<NUM>µg of either macropa-Tmab (<NUM>-<NUM>µL) or DOTA-Tmab (<NUM>-<NUM>µL), and the pH was adjusted to ~<NUM> with NaOH. A control solution was also prepared in which unmodified Tmab (<NUM>µg) was substituted in place of conjugate. The reaction solutions were maintained at ambient temperature and analyzed at <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> by spotting <NUM>µL in triplicate on iTLC strips. The strips were developed with a mobile phase of <NUM> citric acid (pH <NUM>). Under these conditions, <NUM>Ac-macropa-Tmab and <NUM>Ac-DOTA-Tmab remained at the baseline of the plate (RF=<NUM>) and any unchelated <NUM>Ac (<NUM>Ac -citrate) migrated with the solvent front (RF=<NUM>). Radiochemical yields (RCYs) were calculated by integrating area under the peaks on the radiochromatogram and dividing the counts associated with the <NUM>Ac-complex (RF=<NUM>) by the total counts integrated along the length of the TLC plate.

Stability of <NUM>Ac-macropa-Tmab in Human Serum. A solution of <NUM>Ac-macropa-Tmab was prepared using <NUM>µg of protein. After confirmation by TLC that a RCY of ><NUM>% had been achieved, human serum was thawed to room temperature and added to the radiolabeled immunoconjugate to give a solution containing <NUM>% serum by volume. The sample was incubated at <NUM>. At various time points over the course of <NUM> days, aliquots (<NUM>-<NUM>µL) were removed from the sample and spotted in triplicate onto iTLC strips. The strips were developed using an EDTA (<NUM>, pH <NUM>) mobile phase and counted. Under these conditions, <NUM>Ac-macropa-Tmab remained at the baseline (RF=<NUM>) and any <NUM>Ac (<NUM>Ac-EDTA) that had been transchelated by serum migrated with the solvent front (RF=<NUM>). Percent of complex remaining intact was calculated.

As an additional challenge, separate aliquots (<NUM>µL) were also removed from the serum sample on days <NUM> and <NUM> and mixed with <NUM> DTPA (pH <NUM>, <NUM>µL) to challenge off any <NUM>Ac that was only loosely bound by the radioimmunoconjugate. After incubation of this solution at <NUM> for <NUM> minutes, an aliquot (<NUM>µL) was spotted in triplicate on iTLC plates and developed using an EDTA (<NUM>, pH <NUM>) mobile phase. Percent of complex remaining intact was calculated.

At the time points indicated in Table <NUM> below, an aliquot of complex in serum was removed and either directly analyzed by radio-TLC or first mixed with excess DTPA to remove any loosely-bound <NUM>Ac. The decay-corrected values shown represent % activity associated with the complex at RF=<NUM> on the TLC plate after exposure to an EDTA mobile phase. Reported uncertainties (± <NUM> SD) were derived from spotting TLC plates in triplicate at each time point. The % intact complex remaining was not significantly different for samples subjected to the DTPA challenge versus those that were not (p > <NUM>, <NUM>-tail t-test). The results demonstrate that <NUM>Ac remains strongly bound by macropa-Tmab in human serum over a <NUM>-day period.

Radium-<NUM> (<NUM>Ra) is the first therapeutic alpha (α)-emitting radionuclide to be approved for clinical use in cancer patients, and is effective in erradicating bone metastases. To harness the therapeutic potential of α-particles for soft-tissue metastases, the strategy of targeted alpha-particle therapy (TAT) has emerged, whereby lethal α-emitting radionuclides are conjugated to tumor-targeting vectors using bifunctional chelators to selectively deliver cytotoxic alpha radiation to cancer cells. Actinium-<NUM> (<NUM>Ac) was examined for use in TAT owing to its long <NUM>-day half-life that is compatible with antibody-based targeting vectors and <NUM> high-energy α-emissions that are extremely lethal to cells. The <NUM>-membered tetraaza macrocycle H<NUM>DOTA is currently the state of the art for the chelation of the <NUM>Ac<NUM>+ ion, however, the thermodynamic stabilities of complexes of H<NUM>DOTA decrease as the ionic radius of the metal ion increases, indicating that this ligand is not optimal for chelation of the of the Ac<NUM>+ ion (the largest +<NUM> ion on the periodic table). The macrocyclic complexes of the present technology provide a signifiant and unexpected improvement over known complexes, where the present examples (H<NUM>macropa and H<NUM>macropa-NCS; Scheme <NUM>) illustrate the improved <NUM>Ac bifunctional chelators according to the present technology.

Previous studies have shown that macropa, for which the thermodynamic affinity for the whole lanthanide series was evaluated, is selective for the larger metal ions La<NUM>+, Pb<NUM>+, and Am<NUM>+ over the smaller Lu<NUM>+, Ca<NUM>+, and Cm<NUM>+ ions. [<NUM>-<NUM>] Without wishing to be bound by theory it was believed that macropa would effectively chelate the large Ac<NUM>+ ion. Before assessing its Ac-chelation properties, complex formation was evaluated in situ between macropa and cold La<NUM>+ and Lu<NUM>+ ions. In these studies, La<NUM>+ was used as a non-radioactive surrogate for <NUM> Ac<NUM>+ because it is chemically similar albeit slightly smaller (<NUM>Å, CN <NUM>). Complexation of the smaller Lu<NUM>+ ion (<NUM>Å, CN <NUM>) by macropa was investigated to probe its size-selectivity. La<NUM>+ and Lu<NUM>+ titrations confirmed the high affinity of these metal ions for macropa at pH <NUM>, consistent with the previously measured stability constants (log KLaL = <NUM>, log KLuL = <NUM>). [<NUM>] The kinetic inertness of these complexes formed in situ was investigated by challenging them with an excess of either ethylenediaminetetraacetic acid (EDTA) or diethylenetriaminepentaacetic acid (DTPA) chelators that have a higher thermodynamic affinity than macropa for Lu<NUM>+ and La<NUM>+ ions. [<NUM>] The Lu<NUM>+ ion was transchelated within <NUM> upon the addition of only <NUM> equiv of EDTA, whereas the La<NUM>+ complex remained intact for up to <NUM> days in the presence of <NUM> equiv of DTPA. These results demonstrate that, despite a strong thermodynamic preference for DTPA to transchelate La<NUM>+, the high level of kinetic inertness of the macropa complex inhibits this process on a detectable time scale.

The La<NUM>+ and Lu<NUM>+ complexes of macropa were isolated and their solid-state structures were elucidated by X-ray crystallography (<FIG>). The La<NUM>+ and Lu<NUM>+ ions reside above the <NUM>-membered macrocycle, and the two picolinate arms are positioned on the same side of the macrocycle. The coordination sphere of the Lu<NUM>+ ion is satisfied by the ten donors of macropa with both picolinate arms deprotonated; by contrast, the larger La<NUM>+ ion forms an <NUM>-coordinate complex by the incorporation of an inner-sphere water molecule that penetrates the macrocycle. The ability of macropa to form stable <NUM>-coordinate complexes is of particular significance because recent EXAFS studies have demonstrated that Ac<NUM>+ prefers a coordination number of <NUM> in aqueous solutions. [<NUM>,<NUM>].

Macropa was examined for the chelation of the larger, radioactive <NUM>Ac<NUM>+ ion and compared to DOTA. Both ligands (<NUM>) were incubated with <NUM>Ac (<NUM> kBq) in <NUM> NH<NUM>OAc buffer at pH <NUM>-<NUM>, and the complexation reaction was monitored by radio-TLC after <NUM>. Remarkably, macropa complexed all the <NUM>Ac after merely <NUM> at RT, whereas DOTA only complexed <NUM>% under these conditions. At <NUM>-fold lower concentration (<NUM>) of macropa, a L:M ratio of only <NUM>, radiolabeling was still complete at RT in <NUM>. At this concentration, DOTA failed to form a complex with <NUM>Ac. Taken together, these studies reveal macropa to exhibit excellent radiolabeling kinetics at ambient temperature and submicromolar ligand concentration, conditions under which DOTA fails.

The long half-life of <NUM> Ac necessitates its stable complex retention in vivo to avoid off-target damage to normal tissues arising from the release of free <NUM>Ac<NUM>+. Furthermore, the stability of <NUM>Ac complexes against transmetalation and transchelation needs to be high. To determine the kinetic inertness, [<NUM>Ac(macropa)]+ was challeneged with La<NUM>+ because of the established high affinity of macropa for this metal ion. A <NUM>-fold excess of La<NUM>+ with respect to ligand concentration was added to <NUM>Ac-radiolabeled solutions of macropa (<NUM>) at RT. Over <NUM> days, <NUM>% of the <NUM>Ac complex remained intact by radio-TLC, signifying that a large molar equivalent of La<NUM>+ is unable to displace <NUM>Ac<NUM>+. The stability of [<NUM>Ac(macropa)]+ in human serum was also evaluated by radio-TLC and revealed that <NUM>Ac<NUM>+ remains complexed by macropa for at least <NUM> days.

The in vivo stability [<NUM>Ac(macropa)]+ was examined by comparing its biodistribution to those of <NUM>Ac(NO<NUM>)<NUM> and [<NUM>Ac(DOTA)]-. C57BL/<NUM> mice were injected via tail vein with <NUM>-<NUM> kBq of each radiometal complex and were sacrificed after <NUM>, <NUM>, or <NUM>. The amount of <NUM>Ac retained in each organ was quantified by gamma counting and reported as the percent of injected dose per gram of tissue (% ID/g). The results of these studies are compiled in Tables <NUM>-<NUM>. Inadequate stability of an <NUM>Ac complex leading to the loss of radioisotope in vivo is manifested by the accumulation of <NUM> Ac in the liver, spleen, and bone of mice. [<NUM>,<NUM>,<NUM>] <FIG> demonstrates slow blood clearance and excretion, coupled to large accumulation in the liver and spleen of the uncomplexed <NUM>Ac(NO<NUM>)<NUM>. The biodistribution profile of [<NUM>Ac(macropa)]+ (FIG. 3B) differs markedly from that of <NUM>Ac(NO<NUM>)<NUM>. [<NUM>Ac(macropa)]+ was rapidly cleared from mice, with very little activity measured in blood by <NUM> post injection. Most of the injected dose was renally excreted and subsequently detected in the urine, demonstrating the moderate kidney and bladder uptake of [<NUM>Ac(macropa)]+ observed in mice at <NUM> and <NUM> post injection. Of significance, [<NUM>Ac(macropa)]+ did not accumulate in any organ over the time course of the study, indicating that the complex does not release free <NUM>Ac<NUM>+ in vivo. Its biodistribution profile was similar to that of [<NUM>Ac(DOTA)- (FIG. 3C), which has been previously shown to retain <NUM>Ac<NUM>+ in vivo.

Due to the inherent stability of the [<NUM>Ac(macropa)]+ complexes, macropa was incorporated into into tumor-targeting constructs. To facilitate its conjugation, a reactive isothiocyanate functional group was installed onto one of the picolinate arms of macropa to give the novel bifunctional ligand macropa-NCS (Scheme <NUM>). As illustrated in vide supra, macropa-NCS was synthesized over <NUM> steps and characterized by conventional techniques. For one tumor-targeting construct, macropa-NCS was s conjugated to trastuzumab (Tmab), an FDA- approved monoclonal antibody that targets the human epidermal growth factor receptor <NUM> (HER2) in breast and other cancers. [<NUM>] With a biological half-life of several weeks,[<NUM>,<NUM>] Tmab is an ideal vector to shuttle the long-lived <NUM>Ac radionuclide to tumor cells. <NUM>Ac-macropa-Tmab displayed excellent stability in human serum at <NUM>; after <NUM> days, ><NUM>% of the complex remained intact (Table <NUM>). Together, these results highlight the efficacy of macropa as a chelator for <NUM>Ac in antibody constructs as well as other cancer-targeted constructs.

While certain embodiments have been illustrated and described, a person with ordinary skill in the art, after reading the foregoing specification, can effect changes, substitutions of equivalents and other types of alterations to the compounds of the present technology or salts, pharmaceutical compositions, tautomers or racemic mixtures thereof as set forth herein. Each aspect and embodiment described above can also have included or incorporated therewith such variations or aspects as disclosed in regard to any or all of the other aspects and embodiments.

The embodiments, illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms "comprising," "including," "containing," etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed technology. Additionally, the phrase "consisting essentially of" will be understood to include those elements specifically recited and those additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase "consisting of" excludes any element not specified.

Each of the narrower species and subgeneric groupings falling within the generic disclosure also form part of the invention. This includes the generic description of the invention with a proviso or negative limitation removing any subject matter from the genus, regardless of whether or not the excised material is specifically recited herein.

Claim 1:
A composition of Formula I-b
<CHM>
or a pharmaceutically acceptable salt thereof, wherein
M is an alpha-emitting radionuclide preferably selected from actinium-<NUM> (<NUM>Ac<NUM>+), radium-<NUM> (<NUM>Ra<NUM>+), bismuth-<NUM> (<NUM>Bi<NUM>+), lead-<NUM> (<NUM>Pb<NUM>+ and/or <NUM>Pb<NUM>+), terbium-<NUM> (<NUM>Tb<NUM>+), fermium-<NUM> (<NUM>Fm<NUM>+), thorium-<NUM> (<NUM>Th<NUM>+), thorium-<NUM> (<NUM>Th<NUM>+), astatine-<NUM> (<NUM>At+), astatine-<NUM> (<NUM>At+), and uranium-<NUM>;
R<NUM> and R<NUM> are -C(O)OH;
R<NUM> is NCS or NH<NUM>;
R<NUM>, R<NUM>, R<NUM>, R<NUM>, and R<NUM> are each H;
L<NUM> and L<NUM> are each -(CH<NUM>)p-, where p is a value of <NUM>;
r is <NUM>; and
s is <NUM>.