Inhibitors of iap   

Abstract: The invention provides novel inhibitors of IAP that are useful as therapeutic agents for treating malignancies where the compounds have the general formula (I): wherein Q, X1, X2, Y, Z1, Z2, Z3, Z4, R1, R2, R3, R3′, R4, R4′, R5, R6, R6′, and n are as described herein.

This application claims priority to provisional U.S. patent application No. 60/751,801 filed Dec. 19, 2005, the entirety of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to organic compounds useful for therapy and/or prophylax is in a mammal, and in particular to inhibitors of IAP proteins useful for treating cancers.

BACKGROUND OF THE INVENTION

Apoptosis or programmed cell death is a genetically and biochemically regulated mechanism that plays an important role in development and homeostasis in invertebrates as well as vertebrates. Aberrancies in apoptosis that lead to premature cell death have been linked to a variety of developmental disorders. Deficiencies in apoptosis that result in the lack of cell death have been linked to cancer and chronic viral infections (Thompson et al., (1995) Science 267, 1456-1462).

One of the key effector molecules in apoptosis are the caspases (cysteine containing aspartate specific proteases). Caspases are strong proteases, cleaving after aspartic acid residues and once activated, digest vital cell proteins from within the cell. Since caspases are such strong proteases, tight control of this family of proteins is necessary to prevent premature cell death. In general, caspases are synthesized as largely inactive zymogens that require proteolytic processing in order to be active. This proteolytic processing is only one of the ways in which caspases are regulated. The second mechanism is through a family of proteins that bind and inhibit caspases.

A family of molecules that inhibit caspases are the Inhibitors of Apoptosis (IAP) (Deveraux et al., J Clin Immunol (1999), 19:388-398). IAPs were originally discovered in baculovirus by their functional ability to substitute for P35 protein, an anti-apoptotic gene (Crook et al. (1993) J Virology 67, 2168-2174). IAPs have been described in organisms ranging from Drosophila to human. Regardless of their origin, structurally, IAPs comprise one to three Baculovirus IAP repeat (BIR) domains, and most of them also possess a carboxyl-terminal RING finger motif. The BIR domain itself is a zinc binding domain of about 70 residues comprising 4 alpha-helices and 3 beta strands, with cysteine and histidine residues that coordinate the zinc ion (Hinds et al., (1999) Nat. Struct. Biol. 6, 648-651). It is the BIR domain that is believed to cause the anti-apoptotic effect by inhibiting the caspases and thus inhibiting apoptosis. As an example, human X-chromosome linked IAP (XIAP) inhibits caspase 3, caspase 7 and the Apaf-1-cytochrome C mediated activation of caspase 9 (Deveraux et al., (1998) EMBO J. 17, 2215-2223). Caspases 3 and 7 are inhibited by the BIR2 domain of XIAP, while the BIR3 domain of XIAP is responsible for the inhibition of caspase 9 activity. XIAP is expressed ubiquitously in most adult and fetal tissues (Liston et al, Nature, 1996, 379(6563):349), and is overexpressed in a number of tumor cell lines of the NCI 60 cell line panel (Fong et al, Genomics, 2000, 70:113; Tamm et al, Clin. Cancer Res. 2000, 6(5):1796). Overexpression of XIAP in tumor cells has been demonstrated to confer protection against a variety of pro-apoptotic stimuli and promotes resistance to chemotherapy (LaCasse et al, Oncogene, 1998, 17(25):3247). Consistent with this, a strong correlation between XIAP protein levels and survival has been demonstrated for patients with acute myelogenous leukemia (Tamm et al, supra). Down-regulation of XIAP expression by antisense oligonucleotides has been shown to sensitize tumor cells to death induced by a wide range of pro-apoptotic agents, both in vitro and in vivo (Sasaki et al, Cancer Res., 2000, 60(20):5659; Lin et al, Biochem J., 2001, 353:299; Hu et al, Clin. Cancer Res., 2003, 9(7):2826). Smac/DIABLO-derived peptides have also been demonstrated to sensitize a number of different tumor cell lines to apoptosis induced by a variety of pro-apoptotic drugs (Arnt et al, J. Biol. Chem., 2002, 277(46):44236; Fulda et al, Nature Med., 2002, 8(8):808; Guo et al, Blood, 2002, 99(9):3419; Vucic et al, J. Biol. Chem., 2002, 277(14):12275; Yang et al, Cancer Res., 2003, 63(4):831).

Melanoma IAP (ML-IAP) is an IAP not detectable in most normal adult tissues but is strongly upregulated in melanoma (Vucic et al., (2000) Current Bio 10:1359-1366). Determination of protein structure demonstrated significant homology of the ML-IAP BIR and RING finger domains to corresponding domains present in human XIAP, C-IAP1 and C-IAP2. The BIR domain of ML-IAP appears to have the most similarities to the BIR2 and BIR3 of XIAP, C-IAP1 and C-IAP2, and appears to be responsible for the inhibition of apoptosis, as determined by deletional analysis. Furthermore, Vucic et al., demonstrated that ML-IAP could inhibit chemotherapeutic agent induced apoptosis. Agents such as adriamycin and 4-tertiary butylphenol (4-TBP) were tested in a cell culture system of melanomas overexpressing ML-IAP and the chemotherapeutic agents were significantly less effective in killing the cells when compared to a normal melanocyte control. The mechanism by which ML-IAP produces an anti-apoptotic activity is in part through inhibition of caspase 3 and 9. ML-IAP did not effectively inhibit caspases 1, 2, 6, or 8.

Since apoptosis is a strictly controlled pathway with multiple interacting factors, the discovery that IAPs themselves are regulated was not unusual. In the fruit fly Drosophila, the Reaper (rpr), Head Involution Defective (hid) and GRIM proteins physically interact with and inhibit the anti-apoptotic activity of the Drosophila family of IAPs. In the mammal, the proteins SMAC/DIABLO act to block the IAPs and allow apoptosis to proceed. It was shown that during normal apoptosis, SMAC is processed into an active form and is released from the mitochondria into the cytoplasm where it physically binds to IAPs and prevents the IAP from binding to a caspase. This inhibition of the IAP allows the caspase to remain active and thus proceed with apoptosis. Interestingly, sequence homology between the IAP inhibitors shows that there is a four amino acid motif in the N-terminus of the processed, active proteins. This tetrapeptide appears to bind into a hydrophobic pocket in the BIR domain and disrupts the BIR domain binding to caspases (Chai et al., (2000) Nature 406:855-862, Liu et al., (2000) Nature 408:1004-1008, Wu et al., (2000) Nature 408 1008-1012).

SUMMARY

In one aspect of the present invention there is provided novel inhibitors of IAP proteins having the general formula (I)

wherein X1 and X2 are each independently O or S; Y is a bond, (CR7R7)n, O or S; Z1 is NR8, O, S, SO or SO2; Z2, Z3 and Z4 are independently CQ or N; Q is H, halogen, hydroxyl, carboxyl, amino, nitro, cyano, alkyl, a carbocycle, a heterocycle; wherein one or more CH2 or CH groups of an alkyl is optionally replaced with —O—, —S—, —S(O)—, S(O)2, —N(R8)—, —C(O)—, —C(O)—NR8—, —NR8—C(O)—, —SO2—NR8—, —NR8—SO2—, —NR8—C(O)—NR8—, —NR8—C(NH)—NR8—, —NR8—C(NH)—, —C(O)—O— or —O—C(O)—; and an alkyl, carbocycle and heterocycle is optionally substituted with one or more hydroxyl, alkoxy, acyl, halogen, mercapto, oxo, carboxyl, acyl, halo-substituted alkyl, amino, cyano nitro, amidino, guanidino an optionally substituted carbocycle or an optionally substituted heterocycle; R1 is H, OH or alkyl; or R1 and R2 together form a 5-8 member heterocycle; R2 is alkyl, a carbocycle, carbocyclylalkyl, a heterocycle or heterocyclylalkyl each optionally substituted with halogen, hydroxyl, oxo, thione, mercapto, carboxyl, alkyl, haloalkyl, acyl, alkoxy, alkylthio, sulfonyl, amino and nitro, wherein said alkyl, acyl, alkoxy, alkylthio and sulfonyl are optionally substituted with hydroxy, mercapto, halogen, amino, alkoxy, hydroxyalkoxy and alkoxyalkoxy; R3 is H or alkyl optionally substituted with halogen or hydroxyl; or R3 and R4 together form a 3-6 heterocycle; R3′ is H, or R3 and R3′ together foil a 3-6 carbocycle; R4 and R4′ are independently H, hydroxyl, amino, alkyl, carbocycle, carbocycloalkyl, carbocycloalkyloxy, carbocycloalkyloxycarbonyl, heterocycle, heterocycloalkyl, heterocycloalkyloxy or heterocycloalkyloxycarbonyl; wherein each alkyl, carbocycloalkyl, carbocycloalkyloxy, carbocycloalkyloxycarbonyl, heterocycle, heterocycloalkyl, heterocycloalkyloxy and heterocycloalkyloxycarbonyl is optionally substituted with halogen, hydroxyl, mercapto, carboxyl, alkyl, alkoxy, amino, imino and nitro; or R4 and R4′ together form a heterocycle; R5 is H or alkyl; R6, and R6′ are each independently H, alkyl, aryl or aralkyl; R7 is H, cyano, hydroxyl, mercapto, halogen, nitro, carboxyl, amidino, guanidino, alkyl, a carbocycle, a heterocycle or —U—V; wherein U is —O—, —S—, —S(O)—, S(O)2, —N(R8)—, —C(O)—, —C(O)—NR8—, —NR8—C(O)—, —SO2—NR8—, —NR8—SO2—, —NR8—C(O)—NR8—, —NR8—C(NH)—NR8—, —NR8—C(NH)—, —C(O)—O— or —O—C(O)— and V is alkyl, a carbocycle or a heterocycle; and wherein one or more CH2 or CH groups of an alkyl is optionally replaced with —O—, —S—, —S(O)—, S(O)2, —N(R8)—, —C(O)—, —C(O)—NR8—, —NR8—C(O)—, —SO2—NR8—, —NR8—SO2—, —NR8—C(O)—NR8—, —C(O)—O— or —O—C(O)—; and an alkyl, carbocycle and heterocycle is optionally substituted with hydroxyl, alkoxy, acyl, halogen, mercapto, oxo, carboxyl, acyl, halo-substituted alkyl, amino, cyano nitro, amidino, guanidino an optionally substituted carbocycle or an optionally substituted heterocycle; R8 is H, alkyl, a carbocycle or a heterocycle wherein one or more CH2 or CH groups of said alkyl is optionally replaced with —O—, —S—, —S(O)—, S(O)2, —N(R8), or —C(O)—; and said alkyl, carbocycle and heterocycle is optionally substituted with hydroxyl, alkoxy, acyl, halogen, mercapto, oxo (═O), carboxyl, acyl, halo-substituted alkyl, amino, cyano nitro, amidino, guanidino an optionally substituted carbocycle or an optionally substituted heterocycle; and n is 0 to 4.

In another aspect of the invention, there are provided compositions comprising compounds of formula I and a carrier, diluent or excipient.

In another aspect of the invention, there is provided a method of inducing apoptosis in a cell comprising introducing into said cell a compound of formula I.

In another aspect of the invention, there is provided a method of sensitizing a cell to an apoptotic signal comprising introducing into said cell a compound of formula I.

In another aspect of the invention, there is provided a method for inhibiting the binding of an IAP protein to a caspase protein comprising contacting said IAP protein with a compound of formula I.

In another aspect of the invention, there is provided a method for treating a disease or condition associated with the overexpression of an IAP protein in a mammal, comprising administering to said mammal an effective amount of a compound of formula I.

DETAILED DESCRIPTION

“Acyl” means a carbonyl containing substituent represented by the formula —C(O)—R in which R is H, alkyl, a carbocycle, a heterocycle, carbocycle-substituted alkyl or heterocycle-substituted alkyl wherein the alkyl, alkoxy, carbocycle and heterocycle are as defined herein. Acyl groups include alkanoyl (e.g. acetyl), aroyl (e.g. benzoyl), and heteroaroyl.

“Alkyl” means a branched or unbranched, saturated or unsaturated (i.e. alkenyl, alkynyl) aliphatic hydrocarbon group, having up to 12 carbon atoms unless otherwise specified. When used as part of another term, for example “alkylamino”, the alkyl portion may be a saturated hydrocarbon chain, however also includes unsaturated hydrocarbon carbon chains such as “alkenylamino” and “alkynylamino. Examples of particular alkyl groups are methyl, ethyl, n-propyl, isopropyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, 2-methylbutyl, 2,2-dimethylpropyl, n-hexyl, 2-methylpentyl, 2,2-dimethylbutyl, n-heptyl, 3-heptyl, 2-methylhexyl, and the like. The terms “lower alkyl” “C1-C4 alkyl” and “alkyl of 1 to 4 carbon atoms” are synonymous and used interchangeably to mean methyl, ethyl, 1-propyl, isopropyl, cyclopropyl, 1-butyl, sec-butyl or t-butyl. Unless specified, substituted, alkyl groups may contain one, for example two, three or four substituents which may be the same or different. Examples of substituents are, unless otherwise defined, halogen, amino, hydroxyl, protected hydroxyl, mercapto, carboxy, alkoxy, nitro, cyano, amidino, guanidino, urea, sulfonyl, sulfinyl, aminosulfonyl, alkylsulfonylamino, arylsulfonylamino, aminocarbonyl, acylamino, alkoxy, acyl, acyloxy, a carbocycle, a heterocycle. Examples of the above substituted alkyl groups include, but are not limited to; cyanomethyl, nitromethyl, hydroxymethyl, trityloxymethyl, propionyloxymethyl, aminomethyl, carboxymethyl, carboxyethyl, carboxypropyl, alkyloxycarbonylmethyl, allyloxycarbonylaminomethyl, carbamoyloxymethyl, methoxymethyl, ethoxymethyl, t-b utoxymethyl, acetoxymethyl, chloromethyl, bromomethyl, iodomethyl, trifluoromethyl, 6-hydroxyhexyl, 2,4-dichloro(n-butyl), 2-amino(iso-propyl), 2-carbamoyloxyethyl and the like. The alkyl group may also be substituted with a carbo cycle group. Examples include cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl, and cyclohexylmethyl groups, as well as the corresponding -ethyl, -propyl, -butyl, -pentyl, -hexyl groups, etc. Substituted alkyls include substituted methyls e.g. a methyl group substituted by the same substituents as the “substituted Cn-Cm alkyl” group. Examples of the substituted methyl group include groups such as hydroxymethyl, protected hydroxymethyl (e.g. tetrahydropyranyloxymethyl), acetoxymethyl, carbamoyloxymethyl, trifluoromethyl, chloromethyl, carboxymethyl, bromomethyl and iodomethyl.

“Amidine” means the group —C(NH)—NHR in which R is H, alkyl, a carbocycle, a heterocycle, carbocycle-substituted alkyl or heterocycle-substituted alkyl wherein the alkyl, alkoxy, carbocycle and heterocycle are as defined herein. A particular amidine is the group —NH—C(NH)—NH2.

“Amino” means primary (i.e. —NH2), secondary (i.e. —NRH) and tertiary (i.e. —NRR) amines in which R is H, alkyl, a carbocycle, a heterocycle, carbocycle-substituted alkyl or heterocycle-substituted alkyl wherein the alkyl, alkoxy, carbocycle and heterocycle are as defined herein. Particular secondary and tertiary amines are alkylamine, dialkylamine, arylamine, diarylamine, aralkylamine and diaralkylamine wherein the alkyl is as herein defined and optionally substituted. Particular secondary and tertiary amines are methylamine, ethylamine, propylamine, isopropylamine, phenylamine, benzylamine dimethylamine, diethylamine, dipropylamine and disopropylamine.

“Amino-protecting group” as used herein refers to a derivative of the groups commonly employed to block or protect an amino group while reactions are carried out on other functional groups on the compound. Examples of such protecting groups include carbamates, amides, alkyl and aryl groups, imines, as well as many N-heteroatom derivatives which can be removed to regenerate the desired amine group. Particular amino protecting groups are Boc, Fmoc and Cbz. Further examples of these groups are found in T. W. Greene and P. G. M. Wuts, “Protective Groups in Organic Synthesis”, 2nd ed., John Wiley & Sons, Inc., New York, N.Y., 1991, chapter 7; E. Haslam, “Protective Groups in Organic Chemistry”, J. G. W. McOmie, Ed., Plenum Press, New York, N.Y., 1973, Chapter 5, and T. W. Greene, “Protective Groups in Organic Synthesis”, John Wiley and Sons, New York, N.Y., 1981. The term “protected amino” refers to an amino group substituted with one of the above amino-protecting groups.

“Aryl” when used alone or as part of another term means a carbocyclic aromatic group whether or not fused having the number of carbon atoms designated or if no number is designated, up to 14 carbon atoms. Particular aryl groups are phenyl, naphthyl, biphenyl, phenanthrenyl, naphthacenyl, and the like (see e.g. Lang\'s Handbook of Chemistry (Dean, J. A., ed) 13th ed. Table 7-2 [1985]). A particular aryl is phenyl. Substituted phenyl or substituted aryl means a phenyl group or aryl group substituted with one, two, three, four or five, for example 1-2, 1-3 or 1-4 substituents chosen, unless otherwise specified, from halogen (F, Cl, Br, I), hydroxy, protected hydroxy, cyano, nitro, alkyl (for example C1-C6 alkyl), alkoxy (for example C1-C6 alkoxy), benzyloxy, carboxy, protected carboxy, carboxymethyl, protected carboxymethyl, hydroxymethyl, protected hydroxymethyl, aminomethyl, protected aminomethyl, trifluoromethyl, alkylsulfonylamino, alkylsulfonylaminoalkyl, arylsulfonylamino, arylsulonylaminoalkyl, heterocyclylsulfonylamino, heterocyclylsulfonylaminoalkyl, heterocyclyl, aryl, or other groups specified. One or more methyne (CH) and/or methylene (CH2) groups in these substituents may in turn be substituted with a similar group as those denoted above. Examples of the term “substituted phenyl” includes but is not limited to a mono- or di(halo)phenyl group such as 2-chlorophenyl, 2-bromophenyl, 4-chlorophenyl, 2,6-dichlorophenyl, 2,5-dichlorophenyl, 3,4-dichlorophenyl, 3-chlorophenyl, 3-bromophenyl, 4-bromophenyl, 3,4-dibromophenyl, 3-chloro-4-fluorophenyl, 2-fluorophenyl and the like; a mono- or di(hydroxy)phenyl group such as 4-hydroxyphenyl, 3-hydroxyphenyl, 2,4-dihydroxyphenyl, the protected-hydroxy derivatives thereof and the like; a nitrophenyl group such as 3- or 4-nitrophenyl; a cyanophenyl group, for example, 4-cyanophenyl; a mono- or di(lower alkyl)phenyl group such as 4-methylphenyl, 2,4-dimethylphenyl, 2-methylphenyl, 4-(iso-propyl)phenyl, 4-ethylphenyl, 3-(n-propyl)phenyl and the like; a mono or di(alkoxy)phenyl group, for example, 3,4-dimethoxyphenyl, 3-methoxy-4-benzyloxyphenyl, 3-methoxy-4-(1-chloromethyl)benzyloxy-phenyl, 3-ethoxyphenyl, 4-(isopropoxy)phenyl, 4-(t-butoxy)phenyl, 3-ethoxy-4-methoxyphenyl and the like; 3- or 4-trifluoromethylphenyl; a mono- or dicarboxyphenyl or (protected carboxy)phenyl group such 4-carboxyphenyl; a mono- or di(hydroxymethyl)phenyl or (protected hydroxymethyl)phenyl such as 3-(protected hydroxymethyl)phenyl or 3,4-di(hydroxymethyl)phenyl; a mono- or di(aminomethyl)phenyl or (protected aminomethyl)phenyl such as 2-(aminomethyl)phenyl or 2,4-(protected aminomethyl)phenyl; or a mono- or di(N-(methylsulfonylamino))phenyl such as 3-(N-methylsulfonylamino))phenyl. Also, the term “substituted phenyl” represents disubstituted phenyl groups where the substituents are different, for example, 3-methyl-4-hydroxyphenyl, 3-chloro-4-hydroxyphenyl, 2-methoxy-4-bromophenyl, 4-ethyl-2-hydroxyphenyl, 3-hydroxy-4-nitrophenyl, 2-hydroxy-4-chlorophenyl, and the like, as well as trisubstituted phenyl groups where the substituents are different, for example 3-methoxy-4-benzyloxy-6-methyl sulfonylamino, 3-methoxy-4-benzyloxy-6-phenyl sulfonylamino, and tetrasubstituted phenyl groups where the substituents are different such as 3-methoxy-4-benzyloxy-5-methyl-6-phenyl sulfonylamino. Particular substituted phenyl groups include the 2-chlorophenyl, 2-aminophenyl, 2-bromophenyl, 3-methoxyphenyl, 3-ethoxy-phenyl, 4-benzyloxyphenyl, 4-methoxyphenyl, 3-ethoxy-4-benzyloxyphenyl, 3,4-diethoxyphenyl, 3-methoxy-4-benzyloxyphenyl, 3-methoxy-4-(1-chloromethyl)benzyloxy-phenyl, 3-methoxy-4-(1-chloromethyl)benzyloxy-6-methyl sulfonyl aminophenyl groups. Fused aryl rings may also be substituted with any, for example 1, 2 or 3, of the substituents specified herein in the same manner as substituted alkyl groups.

“Carbocyclyl”, “carbocyclylic”, “carbocycle” and “carbocyclo” alone and when used as a moiety in a complex group such as a carbocycloalkyl group, refers to a mono-, bi-, or tricyclic aliphatic ring having 3 to 14 carbon atoms, for example 3 to 7 carbon atoms, which may be saturated or unsaturated, aromatic or non-aromatic. Particular saturated carbocyclic groups are cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl groups. A particular saturated carbocycle is cyclopropyl. Another particular saturated carbocycle is cyclohexyl. Particular unsaturated carbocycles are aromatic e.g. aryl groups as previously defined, for example phenyl. The terms “substituted carbocyclyl”, “carbocycle” and “carbocyclo” mean these groups substituted by the same substituents as the “substituted alkyl” group.

“Carboxy-protecting group” as used herein refers to one of the ester derivatives of the carboxylic acid group commonly employed to block or protect the carboxylic acid group while reactions are carried out on other functional groups on the compound. Examples of such carboxylic acid protecting groups include 4-nitrobenzyl, 4-methoxybenzyl, 3,4-dimethoxybenzyl, 2,4-dimethoxybenzyl, 2,4,6-trimethoxybenzyl, 2,4,6-trimethylbenzyl, pentamethylbenzyl, 3,4-methylenedioxybenzyl, benzhydryl, 4,4′-dimethoxybenzhydryl, 2,2′,4,4′-tetramethoxybenzhydryl, alkyl such as t-butyl or t-amyl, trityl, 4-methoxytrityl, 4,4′-dimethoxytrityl, 4,4′,4″-trimethoxytrityl, 2-phenylprop-2-yl, trimethylsilyl, t-butyldimethylsilyl, phenacyl, 2,2,2-trichloroethyl, beta-(trimethylsilyl)ethyl, beta-(di(n-butyl)methylsilyl)ethyl, p-toluenesulfonylethyl, 4-nitrobenzylsulfonylethyl, allyl, cinnamyl, 1-(trimethylsilylmethyl)prop-1-cn-3-yl, and like moieties. The species of carboxy-protecting group employed is not critical so long as the derivatized carboxylic acid is stable to the condition of subsequent reaction(s) on other positions of the molecule and can be removed at the appropriate point without disrupting the remainder of the molecule. In particular, it is important not to subject a carboxy-protected molecule to strong nucleophilic bases, such as lithium hydroxide or NaOH, or reductive conditions employing highly activated metal hydrides such as LiAlH4. (Such harsh removal conditions are also to be avoided when removing amino-protecting groups and hydroxy-protecting groups, discussed below.) Particular carboxylic acid protecting groups are the alkyl (e.g. methyl, ethyl, t-butyl), allyl, benzyl and p-nitrobenzyl groups. Similar carboxy-protecting groups used in the cephalosporin, penicillin and peptide arts can also be used to protect a carboxy group substituents. Further examples of these groups are found in T. W. Greene and P. G. M. Wuts, “Protective Groups in Organic Synthesis”, 2nd ed., John Wiley & Sons, Inc., New York, N.Y., 1991, chapter 5; E. Haslam, “Protective Groups in Organic Chemistry”, J. G. W. McOmie, Ed., Plenum Press, New York, N.Y., 1973, Chapter 5, and T. W. Greene, “Protective Groups in Organic Synthesis”, John Wiley and Sons, New York, N.Y., 1981, Chapter 5. The term “protected carboxy” refers to a carboxy group substituted with one of the above carboxy-protecting groups.

“Guanidine” means the group —NH—C(NH)—NHR in which R is H, alkyl, a carbocycle, a heterocycle, carbocycle-substituted alkyl or heterocycle-substituted alkyl wherein the alkyl, alkoxy, carbocycle and heterocycle are as defined herein. A particular guanidine is the group —NH—C(NH)—NH2.

“Hydroxy-protecting group” as used herein refers to a derivative of the hydroxy group commonly employed to block or protect the hydroxy group while reactions are carried out on other functional groups on the compound. Examples of such protecting groups include tetrahydropyranyloxy, benzoyl, acetoxy, carbamoyloxy, benzyl, and silylethers (e.g. TBS, TBDPS) groups. Further examples of these groups are found in T. W. Greene and P. G. M. Wuts, “Protective Groups in Organic Synthesis”, 2nd ed., John Wiley & Sons, Inc., New York, N.Y., 1991, chapters 2-3; E. Haslam, “Protective Groups in Organic Chemistry”, J. G. W. McOmie, Ed., Plenum Press, New York, N.Y., 1973, Chapter 5, and T. W. Greene, “Protective Groups in Organic Synthesis”, John Wiley and Sons, New York, N.Y., 1981. The term “protected hydroxy” refers to a hydroxy group substituted with one of the above hydroxy-protecting groups.

“Heterocyclic group”, “heterocyclic”, “heterocycle”, “heterocyclyl”, or “heterocyclo” alone and when used as a moiety in a complex group such as a heterocycloalkyl group, are used interchangeably and refer to any mono-, bi-, or tricyclic, saturated or unsaturated, aromatic (heteroaryl) or non-aromatic ring having the number of atoms designated, generally from 5 to about 14 ring atoms, where the ring atoms are carbon and at least one heteroatom (nitrogen, sulfur or oxygen), for example 1 to 4 heteroatoms. Typically, a 5-membered ring has 0 to 2 double bonds and 6- or 7-membered ring has 0 to 3 double bonds and the nitrogen or sulfur heteroatoms may optionally be oxidized (e.g. SO, SO2), and any nitrogen heteroatom may optionally be quaternized. Particular non-aromatic heterocycles are morpholinyl (morpholino), pyrrolidinyl, oxiranyl, oxetanyl, tetrahydrofuranyl, 2,3-dihydrofuranyl, 2H-pyranyl, tetrahydropyranyl, thiiranyl, thietanyl, tetrahydrothietanyl, aziridinyl, azetidinyl, 1-methyl-2-pyrrolyl, piperazinyl and piperidinyl. A “heterocycloalkyl” group is a heterocycle group as defined above covalently bonded to an alkyl group as defined above. Particular 5-membered heterocycles containing a sulfur or oxygen atom and one to three nitrogen atoms are thiazolyl, in particular thiazol-2-yl and thiazol-2-yl N-oxide, thiadiazolyl, in particular 1,3,4-thiadiazol-5-yl and 1,2,4-thiadiazol-5-yl, oxazolyl, for example oxazol-2-yl, and oxadiazolyl, such as 1,3,4-oxadiazol-5-yl, and 1,2,4-oxadiazol-5-yl. Particular 5-membered ring heterocycles containing 2 to 4 nitrogen atoms include imidazolyl, such as imidazol-2-yl; triazolyl, such as 1,3,4-triazol-5-yl; 1,2,3-triazol-5-yl, 1,2,4-triazol-5-yl, and tetrazolyl, such as 1H-tetrazol-5-yl. Particular benzo-fused 5-membered heterocycles are benzoxazol-2-yl, benzthiazol-2-yl and benzimidazol-2-yl. Particular 6-membered heterocycles contain one to three nitrogen atoms and optionally a sulfur or oxygen atom, for example pyridyl, such as pyrid-2-yl, pyrid-3-yl, and pyrid-4-yl; pyrimidyl, such as pyrimid-2-yl and pyrimid-4-yl; triazinyl, such as 1,3,4-triazin-2-yl and 1,3,5-triazin-4-yl; pyridazinyl, in particular pyridazin-3-yl, and pyrazinyl. The pyridine N-oxides and pyridazine N-oxides and the pyridyl, pyrimid-2-yl, pyrimid-4-yl, pyridazinyl and the 1,3,4-triazin-2-yl groups, are a particular group. Substituents for “optionally substituted heterocycles”, and further examples of the 5- and 6-membered ring systems discussed above can be found in W. Druckheimer et al., U.S. Pat. No. 4,278,793. In a particular embodiment, such optionally substituted heterocycle groups are substituted with hydroxyl, alkyl, alkoxy, acyl, halogen, mercapto, oxo, carboxyl, acyl, halo-substituted alkyl, amino, cyano, nitro, amidino and guanidino.

“Heteroaryl” alone and when used as a moiety in a complex group such as a heteroaralkyl group, refers to any mono-, bi-, or tricyclic aromatic ring system having the number of atoms designated where at least one ring is a 5-, 6- or 7-membered ring containing from one to four heteroatoms selected from the group nitrogen, oxygen, and sulfur, and in a particular embodiment at least one heteroatom is nitrogen (Lang\'s Handbook of Chemistry, supra). Included in the definition are any bicyclic groups where any of the above heteroaryl rings are fused to a benzene ring. Particular heteroaryls incorporate a nitrogen or oxygen heteroatom. The following ring systems are examples of the heteroaryl (whether substituted or unsubstituted) groups denoted by the term “heteroaryl”: thienyl, furyl, imidazolyl, pyrazolyl, thiazolyl, isothiazolyl, oxazolyl, isoxazolyl, triazolyl, thiadiazolyl, oxadiazolyl, tetrazolyl, thiatriazolyl, oxatriazolyl, pyridyl, pyrimidyl, pyrazinyl, pyridazinyl, thiazinyl, oxazinyl, triazinyl, thiadiazinyl, oxadiazinyl, dithiazinyl, dioxazinyl, oxathiazinyl, tetrazinyl, thiatriazinyl, oxatriazinyl, dithiadiazinyl, imidazolinyl, dihydropyrimidyl, tetrahydropyrimidyl, tetrazolo[1,5-b]pyridazinyl and purinyl, as well as benzo-fused derivatives, for example benzoxazolyl, benzofuryl, benzothiazolyl, benzothiadiazolyl, benzotriazolyl, benzoimidazolyl and indolyl. A particular “heteroaryl” is: 1,3-thiazol-2-yl, 4-(carboxymethyl)-5-methyl-1,3-thiazol-2-yl, 4-(carboxymethyl)-5-methyl-1,3-thiazol-2-yl sodium salt, 1,2,4-thiadiazol-5-yl, 3-methyl-1,2,4-thiadiazol-5-yl, 1,3,4-triazol-5-yl, 2-methyl-1,3,4-triazol-5-yl, 2-hydroxy-1,3,4-triazol-5-yl, 2-carboxy-4-methyl-1,3,4-triazol-5-yl sodium salt, 2-carboxy-4-methyl-1,3,4-triazol-5-yl, 1,3-oxazol-2-yl, 1,3,4-oxadiazol-5-yl, 2-methyl-1,3,4-oxadiazol-5-yl, 2-(hydroxymethyl)-1,3,4-oxadiazol-5-yl, 1,2,4-oxadiazol-5-yl, 1,3,4-thiadiazol-5-yl, 2-thiol-1,3,4-thiadiazol-5-yl, 2-(methylthio)-1,3,4-thiadiazol-5-yl, 2-amino-1,3,4-thiadiazol-5-yl, 1H-tetrazol-5-yl, 1-methyl-1H-tetrazol-5-yl, 1-(1-(dimethylamino)eth-2-yl)-1H-tetrazol-5-yl, 1-(carboxymethyl)-1H-tetrazol-5-yl, 1-(carboxymethyl)-1H-tetrazol-5-yl sodium salt, 1-(methylsulfonic acid)-1H-tetrazol-5-yl, 1-(methylsulfonic acid)-1H-tetrazol-5-yl sodium salt, 2-methyl-1H-tetrazol-5-yl, 1,2,3-triazol-5-yl, 1-methyl-1,2,3-triazol-5-yl, 2-methyl-1,2,3-triazol-5-yl, 4-methyl-1,2,3-triazol-5-yl, pyrid-2-yl N-oxide, 6-methoxy-2-(n-oxide)-pyridaz-3-yl, 6-hydroxypyridaz-3-yl, 1-methylpyrid-2-yl, 1-methylpyrid-4-yl, 2-hydroxypyrimid-4-yl, 1,4,5,6-tetrahydro-5,6-dioxo-4-methyl-as-triazin-3-yl, 1,4,5,6-tetrahydro-4-(formylmethyl)-5,6-dioxo-as-triazin-3-yl, 2,5-dihydro-5-oxo-6-hydroxy-as-triazin-3-yl, 2,5-dihydro-5-oxo-6-hydroxy-as-triazin-3-yl sodium salt, 2,5-dihydro-5-oxo-6-hydroxy-2-methyl-as-triazin-3-yl sodium salt, 2,5-dihydro-5-oxo-6-hydroxy-2-methyl-as-triazin-3-yl, 2,5-dihydro-5-oxo-6-methoxy-2-methyl-as-triazin-3-yl, 2,5-dihydro-5-oxo-as-triazin-3-yl, 2,5-dihydro-5-oxo-2-methyl-as-triazin-3-yl, 2,5-dihydro-5-oxo-2,6-dimethyl-as-triazin-3-yl, tetrazolo[1,5-b]pyridazin-6-yl and 8-aminotetrazolo[1,5-b]-pyridazin-6-yl. An alternative group of “heteroaryl” includes; 4-(carboxymethyl)-5-methyl-1,3-thiazol-2-yl, 4-(carboxymethyl)-5-methyl-1,3-thiazol-2-yl sodium salt, 1,3,4-triazol-5-yl, 2-methyl-1,3,4-triazol-5-yl, 1H-tetrazol-5-yl, 1-methyl-1H-tetrazol-5-yl, 1-(1-(dimethylamino)eth-2-yl)-1H-tetrazol-5-yl, 1-(carboxymethyl)-1H-tetrazol-5-yl, 1-(carboxymethyl)-1H-tetrazol-5-yl sodium salt, 1-(methylsulfonic acid)-1H-tetrazol-5-yl, 1-(methylsulfonic acid)-1H-tetrazol-5-yl sodium salt, 1,2,3-triazol-5-yl, 1,4,5,6-tetrahydro-5,6-dioxo-4-methyl-as-triazin-3-yl, 1,4,5,6-tetrahydro-4-(2-formylmethyl)-5,6-dioxo-as-triazin-3-yl, 2,5-dihydro-5-oxo-6-hydroxy-2-methyl-as-triazin-3-yl sodium salt, 2,5-dihydro-5-oxo-6-hydroxy-2-methyl-as-triazin-3-yl, tetrazolo[1,5-b]pyridazin-6-yl, and 8-aminotetrazolo[1,5-b]pyridazin-6-yl. Heteroaryl groups are optionally substituted as described for heterocycles.

“Inhibitor” means a compound which reduces or prevents the binding of IAP proteins to caspase proteins or which reduces or prevents the inhibition of apoptosis by an IAP protein. Alternatively, “inhibitor” means a compound which prevents the binding interaction of X-IAP with caspases or the binding interaction of ML-IAP with SMAC.

“Optionally substituted” unless otherwise specified means that a group may be unsubstituted or substituted by one or more (e.g. 0, 1, 2, 3 or 4) of the substituents listed for that group in which said substituents may be the same or different. In an embodiment an optionally substituted group has 1 substituent. In another embodiment an optionally substituted group has 2 substituents. In another embodiment an optionally substituted group has 3 substituents.

“Pharmaceutically acceptable salts” include both acid and base addition salts. “Pharmaceutically acceptable acid addition salt” refers to those salts which retain the biological effectiveness and properties of the free bases and which are not biologically or otherwise undesirable, formed with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, carbonic acid, phosphoric acid and the like, and organic acids may be selected from aliphatic, cycloaliphatic, aromatic, araliphatic, heterocyclic, carboxylic, and sulfonic classes of organic acids such as formic acid, acetic acid, propionic acid, glycolic acid, gluconic acid, lactic acid, pyruvic acid, oxalic acid, malic acid, maleic acid, maloneic acid, succinic acid, fumaric acid, tartaric acid, citric acid, aspartic acid, ascorbic acid, glutamic acid, anthranilic acid, benzoic acid, cinnamic acid, mandelic acid, embonic acid, phenylacetic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, salicyclic acid and the like.

“Pharmaceutically acceptable base addition salts” include those derived from inorganic bases such as sodium, potassium, lithium, ammonium, calcium, magnesium, iron, zinc, copper, manganese, aluminum salts and the like. Particularly base addition salts are the ammonium, potassium, sodium, calcium and magnesium salts. Salts derived from pharmaceutically acceptable organic nontoxic bases includes salts of primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines and basic ion exchange resins, such as isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, ethanolamine, 2-diethylaminoethanol, trimethamine, dicyclohexylamine, lysine, arginine, histidine, caffeine, procaine, hydrabamine, choline, betaine, ethylenediamine, glucosamine, methylglucamine, theobromine, purines, piperizine, piperidine, N-ethylpiperidine, polyamine resins and the like. Particularly organic non-toxic bases are isopropylamine, diethylamine, ethanolamine, trimethamine, dicyclohexylamine, choline, and caffeine.

“Sulfonyl” means a —SO2—R group in which R is H, alkyl, a carbocycle, a heterocycle, carbocycle-substituted alkyl or heterocycle-substituted alkyl wherein the alkyl, alkoxy, carbocycle and heterocycle are as defined herein. Particular sulfonyl groups are alkylsulfonyl (i.e. —SO2-alkyl), for example methylsulfonyl; arylsulfonyl, for example phenylsulfonyl; aralkylsulfonyl, for example benzylsulfonyl.

The phrase “and salts and solvates thereof” as used herein means that compounds of the inventions may exist in one or a mixture of salts and solvate forms. For example a compound of the invention may be substantially pure in one particular salt or solvate form or else may be mixtures of two or more salt or solvate forms.

The present invention provides novel compounds having the general formula I:

wherein Q, X1, X2, Y, Z1, Z2, Z3, Z4, R1, R2, R3, R3′, R4, R4′, R5, R6, R6′ and n are as described herein. Compounds of the invention include salts, solvates and polymorphs thereof unless otherwise specified.

X1 and X2 are each independently O or S. In a particular embodiment, X1 and X2 are both O. In another particular embodiment X1 and X2 are both S. In another particular embodiment, X1 is S while X2 is O. In another particular embodiment, X1 is O while X2 is S.

Y is a bond, (CR7R7)n, O or S. In an embodiment Y is a bond, (CR7R7)n, O or S; wherein n is 1 or 2 and R7 is as defined herein or is H, halogen, alkyl, aryl, aralkyl, amino, arylamino, alkylamino, aralkylamino, alkoxy, aryloxy or aralkyloxy. In a particular embodiment, Y is (CHR7)n, O or S; wherein n is 1 or 2 and R7 is H, halogen, alkyl, aryl, aralkyl, amino, arylamino, alkylamino, aralkylamino, alkoxy, aryloxy or aralkyloxy. In a particular embodiment, Y is CH2. In a particular embodiment n is 1. In a particular embodiment Y is a bond. In a particular embodiment n is 1 and Y is CHR7 wherein R7 is aralkyloxy, for example benzyloxy. In a particular embodiment n is 1 and Y is CHR7 wherein R7 is F. In a particular embodiment n is 1 and Y is CHR7 wherein R7 is aralkylamino, for example benzylamino. In another particular embodiment Y is O. In another particular embodiment Y is S.

Z1 is NR8, O, S, SO or SO2; wherein R8 is defined herein. In an embodiment, Z1 is NR8, O or S. In an embodiment, Z1 is NR8 wherein R8 is H, alkyl, aryl or aralkyl. In a particular embodiment, Z1 is NR8 wherein R8 is benzyl. In a particular embodiment, Z1 is NR8 wherein R8 is Me. In a particular embodiment, Z1 is NR8 wherein R8 is H. In a particular embodiment, Z1 is O. In a particular embodiment, Z1 is S.

Z2, Z3 and Z4 are independently CQ or N. In a particular embodiment, Z2 is N. In a particular embodiment, Z3 is N. In a particular embodiment, Z4 is N. In an embodiment, Z2, Z3 and Z4 are CQ. In an embodiment, Z2 is N, Z3 is CQ and Z4 is CQ. In an embodiment, Z2 is CQ, Z3 is N and Z4 is CQ. In an embodiment, Z2 is CQ, Z3 is CQ and Z4 is N. In an embodiment, Z2 is N, Z3 is CQ and Z4 is N.

Q is H, halogen, hydroxyl, carboxyl, amino, nitro, cyano, alkyl, a carbocycle, a heterocycle; wherein one or more CH2 or CH groups of an alkyl is optionally replaced with —O—, —S—, —S(O)—, S(O)2, —N(R8)—, —C(O)—, —C(O)—NR8—, —NR8—C(O)—, —SO2—NR8—, —NR8—SO2—, —NR8—C(O)—NR8—, —NR8—C(NH)—NR8—, —NR8—C(NH)—, —C(O)—O— or —O—C(O)—; and wherein any of the foregoing alkyl, carbocycle and heterocycle is optionally substituted with one or more hydroxyl, alkoxy, acyl, halogen, mercapto, oxo, carboxyl, acyl, halo-substituted alkyl, amino, cyano nitro, amidino, guanidino an optionally substituted carbocycle or an optionally substituted heterocycle. Substituents of the “optionally substituted carbocycle” and “optionally substituted heterocycle” are as defined herein. In a particular embodiment such carbocycle and heterocycle groups are substituted with hydroxyl, alkyl, alkoxy, acyl, halogen, mercapto, oxo, carboxyl, acyl, halo-substituted alkyl, amino, cyano, nitro, amidino and guanidino. In a particular embodiment Q is a carbocycle or heterocycle optionally substituted with halogen, amino, oxo, alkyl, a carbocycle or a heterocycle; wherein one or more CH2 or CH groups of an alkyl is optionally replaced with —O—, —S—, —S(O)—, S(O)2, —N(R8)—, —C(O)—, —C(O)—NR8—, —NR8—C(O)—, —SO2—NR8—, —NR8—SO2—, —NR8—C(O)—NR8—, —NR8—C(NH)—NR8—, —NR8—C(NH)—, —C(O)—O— or —O—C(O)—; and wherein said alkyl, carbocycle or heterocycle is optionally substituted with halogen, amino, hydroxyl, mercapto, carboxyl, alkoxy, alkoxyalkoxy, hydroxyalkoxy, alkylthio, acyloxy, acyloxyalkoxy, alkylsulfonyl, alkylsulfonylalkyl, alkylsulfinyl, and alkylsulfinylalkyl. In a particular embodiment at least one instance of Q is a carbocycle or a heterocycle as defined herein which is optionally substituted as described herein while any other instances of Q are independently selected from the group consisting of H, halogen, carboxyl, amino, nitro and cyano. In a particular embodiment one instance of Q is aryl or heteroaryl while any other instances of Q are independently selected from the group consisting of H, halogen, carboxyl, amino, nitro and cyano. In a particular embodiment such other instances of Q are H. In another particular embodiment, such other instances of Q are H, halogen or alkyl.

In a particular embodiment, Q is a carbocycle or heterocycle selected from the group consisting of III-1-III-16

wherein n is 1-4, for example 1-3, for example 1-2, for example 1; T is O, S, NR8 or CR7R7; W is O, NR8 or CR7R7; and R7 and R8 are as defined herein. In an embodiment, compounds of the invention comprise one Q group having the general formulae III-1 to III-16. In another embodiment, compounds of the invention have one Q group having the general formulae III-1 to III-16 while other instances of Q are independently selected from the group consisting of H, halogen, carboxyl, amino, nitro and cyano. In a particular embodiment such other instances of Q are H. In another particular embodiment, such other instances of Q are H, halogen or alkyl.

In a particular embodiment, Q is a carbocycle or heterocycle selected from the group consisting of IIIa-IIIs:

wherein n is 1-4, for example 1-3, for example 1-2, for example 1; T is O, S, NR8 or CR7R7; W is O, NR8 or CR7R7; and R7 and R8 are as defined herein. In a particular embodiment Q is any one of IIIa-IIIi wherein R8 is H and R7 is selected from the group consisting of H, F, Cl, Me, methoxy, hydroxyethoxy, methoxyethoxy, acetoxyethoxy, methylsulfonyl methylsulfonylmethyl, phenyl and morpholin-4-yl. In another particular embodiment Q is IIId. In a particular embodiment Q is IIId which is substituted at the 4-position with R7. In another particular embodiment Q is IIId which is substituted at the 5-position with R7. In a particular embodiment Q is F, Me, iPr, phenyl, phenyl substituted as follows: 2-Cl, 3-Cl, 4-Cl, 2-F, 3-F or 4-F substituted, benzyl, pyrid-3-yl or pyrid-4-yl. In an embodiment, compounds of the invention comprise one Q group having the general formulae IIIa to IIIs. In another embodiment, compounds of the invention have one Q group having the general formulae IIIa to IIIs while other instances of Q are independently selected from the group consisting of H, halogen, carboxyl, amino, nitro and cyano. In a particular embodiment such other instances of Q are H. In another particular embodiment, such other instances of Q are H, halogen or alkyl.

R1 is H, OH or alkyl; or R1 and R2 together form a 5-8 member heterocycle. In a particular embodiment, R1 is H. In a particular embodiment, R1 and R2 together form a 6-member ring. In a particular embodiment, R1 and R2 together form a 7-member ring. In another particular embodiment, R1 and R2 together form an 8-member ring. In another particular embodiment, R1 and R2 together form a 7-member ring while Y is S. In another particular embodiment, R1 is H, while Y is CH2. In another particular embodiment, R1 is H, while Y is S. In another particular embodiment, R1 is H, while Y is O.

R2 is alkyl, a carbocycle, carbocyclylalkyl, a heterocycle or heterocyclylalkyl each optionally substituted with halogen, hydroxyl, oxo, thione, mercapto, carboxyl, alkyl, haloalkyl, acyl, alkoxy, alkylthio, sulfonyl, amino and nitro, wherein said alkyl, acyl, alkoxy, alkylthio and sulfonyl are optionally substituted with hydroxy, mercapto, halogen, amino, alkoxy, hydroxyalkoxy and alkoxyalkoxy. In an embodiment, R2 is alkyl, a carbocycle, carbocyclylalkyl, a heterocycle or heterocyclylalkyl each optionally substituted with halogen, hydroxyl, oxo, thione, mercapto, carboxyl, alkyl, haloalkyl, alkoxy, alkylthio, sulfonyl, amino and nitro. In a particular embodiment R2 is alkyl, a carbocycle, carbocyclylalkyl, a heterocycle or heterocyclylalkyl each optionally substituted with halogen, hydroxyl, oxo, mercapto, thione, carboxyl, alkyl, haloalkyl, alkoxy, acyl, alkylthio, acyl, hydroxyacyl, methoxyacyl, sulfonyl, amino and nitro. In an embodiment R2 is alkyl, a carbocycle, carbocyclylalkyl, a heterocycle or heterocyclylalkyl each optionally substituted with halogen, hydroxyl, mercapto, carboxyl, alkyl, alkoxy, acyl, amino and nitro. In a particular embodiment R2 is alkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, a heterocycle or heterocyclylalkyl. In a particular embodiment R2 is alkyl, cycloalkyl or a heterocycle. In a particular embodiment R2 is selected from the group consisting of t-butyl, isopropyl, cyclohexyl, tetrahydropyran-4-yl, N-methylsulfonylpiperidin-4-yl, tetrahydrothiopyran-4-yl, tetrahydrothiopyran-4-yl (in which the S is in oxidized form SO or SO2), cyclohexan-4-one, 4-hydroxycyclohexane, 4-hydroxy-4-methylcyclohexane, 1-methyl-tetrahydropyran-4-yl, 2-hydroxyprop-2-yl, but-2-yl, thiophen-3-yl, piperidin-4-yl, N-acetylpiperidin-4-yl, N-hydroxyethylpiperidin-4-yl, N-(2-hydroxyacetyl)piperidin-4-yl, N-(2-methoxyacetyl)piperidin-4-yl, pyridin-3-yl, phenyl, tetrahydrofuran-2-yl-carbonyl, methoxyethanone, 2-methoxyethoxyethanone and 1-hydroxyeth-1-yl. In an embodiment of the invention R2 is t-butyl, isopropyl, cyclohexyl, cyclopentyl, phenyl or tetrahydropyran-4-yl. In a particular embodiment, R2 is phenyl. In a particular embodiment, R2 is cyclohexyl. In another embodiment R2 is tetrahydropyran-4-yl. In another particular embodiment, R2 is isopropyl (i.e. the valine amino acid side chain). In another particular embodiment, R2 is t-butyl. In a particular embodiment R2 is oriented such that the amino acid, or amino acid analogue, which it comprises is in the L-configuration.

R3 is H or alkyl optionally substituted with halogen or hydroxyl; or R3 and R4 together form a 3-6 heterocycle. In an embodiment R3 is H or alkyl; or R3 and R4 together form a 3-6 heterocycle. In an embodiment R3 is H or methyl, ethyl, propyl or isopropyl. In a particularly particular embodiment R3 is H or methyl. In another particular embodiment R3 is methyl. In another particular embodiment R3 is fluoromethyl. In another particular embodiment, R3 is ethyl. In another particular embodiment R3 is hydroxyethyl. In a particular embodiment R3 is fluoromethyl. In a particular embodiment R3 is hydroxyethyl. In another embodiment R3 is oriented such that the amino acid, or amino acid analogue, which it comprises is in the L-configuration. In a particular embodiment R3 and R4 together with the atoms from which they depend form a 3-6 heterocycle. In a particular embodiment R3 and R4 together form an azetidine ring. In a particular embodiment R3 and R4 together form a pyrrolidine.

R3′ is H, or R3 and R3′ together form a 3-6 carbocycle. In an embodiment, R3′ is H. In another embodiment R3 and R3′ together form a 3-6 carbocycle, for example a cyclopropyl ring. In a particular embodiment R3 and R3′ are both methyl.

R4 and R4′ are independently H, hydroxyl, amino, alkyl, carbocycle, carbocycloalkyl, carbocycloalkyloxy, carbocycloalkyloxycarbonyl, heterocycle, heterocycloalkyl, heterocycloalkyloxy or heterocycloalkyloxycarbonyl; wherein each alkyl, carbocycloalkyl, carbocycloalkyloxy, carbocycloalkyloxycarbonyl, heterocycle, heterocycloalkyl, heterocycloalkyloxy and heterocycloalkyloxycarbonyl is optionally substituted with halogen, hydroxyl, mercapto, carboxyl, alkyl, alkoxy, amino, imino and nitro; or R4 and R4′ together form a heterocycle. In an embodiment R4 and R4′ are independently H, hydroxyl, amino, alkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, heteroaryl, or heteroarylalkyl wherein each alkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, heteroaryl and heteroarylalkyl is optionally substituted with halogen, hydroxyl, mercapto, carboxyl, alkyl, alkoxy, amino and nitro; or R4 and R4′ together form a heterocycle. In a particular embodiment R4 and R4′ together foil a heterocycle, for example an azetidine ring, or a pyrrolidine ring. In a particular embodiment R4 and R4′ are both H. In another particular embodiment R4 is methyl and R4′ is H. In a particular embodiment one of R4 and R4′ is hydroxyl (OH) while the other is H. In another embodiment, one of R4 and R4′ is amino, such as NH2, NHMe and NHEt, while the other is H. In a particular embodiment, R4′ is H and R4 is H, alkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, heteroaryl or heteroarylalkyl. In a particular embodiment R4 is a group selected from the group consisting of:

R5 is H or alkyl. In a particular embodiment, R5 is H or methyl. In a particular embodiment, R5 is H. In another particular embodiment, R5 is methyl.

R6, and R6′ are each independently H, alkyl, aryl or aralkyl. In a particular embodiment, R6 is alkyl, for example methyl. In another particular embodiment R6 is aryl, for example phenyl. In another particular embodiment R6 is aralkyl, for example benzyl. In a particular embodiment R6 and R6′ are the same, for example both alkyl, e.g. both methyl. In another particular embodiment R6 is methyl and R6′ is H.

R7 in each occurrence is independently H, cyano, hydroxyl, mercapto, halogen, nitro, carboxyl, amidino, guanidino, alkyl, a carbocycle, a heterocycle or —U—V; wherein U is —O—, —S—, —S(O)—, S(O)2, —N(R8)—, —C(O)—, —C(O)—NR8—, —NR8—C(O)—, —SO2—NR8—, —NR8—SO2—, —NR8—C(O)—NR8—, —NR8—C(NH)—NR8—, —NR8—C(NH)—, —C(O)—O— or —O—C(O)— and V is alkyl, a carbocycle or a heterocycle; and wherein one or more CH2 or CH groups of an alkyl is optionally replaced with —O—, —S—, —S(O)—, S(O)2, —N(R8)—, —C(O)—, —C(O)—NR8—, —NR8—C(O)—, —SO2—NR8—, —NR8—SO2—, —NR8—C(O)—NR8—, —NR8—C(NH)—NR8—, —NR8—C(NH)—, —C(O)—O— or —O—C(O)—; and an alkyl, carbocycle and heterocycle is optionally substituted with hydroxyl, alkoxy, acyl, halogen, mercapto, oxo, carboxyl, acyl, halo-substituted alkyl, amino, cyano, nitro, amidino, guanidino an optionally substituted carbocycle or an optionally substituted heterocycle. Substituents of the “optionally substituted carbocycle” and “optionally substituted heterocycle” are as defined herein. In a particular embodiment such carbocycle and heterocycle groups are substituted with hydroxyl, alkyl, alkoxy, acyl, halogen, mercapto, oxo, carboxyl, acyl, halo-substituted alkyl, amino, cyano, nitro, amidino and guanidino. In an embodiment R7 is H, halogen, alkyl, aryl, aralkyl, amino, arylamino, alkylamino, aralkylamino, alkoxy, aryloxy or aralkyloxy.

R8 is H, alkyl, a carbocycle or a heterocycle wherein one or more CH2 or CH groups of said alkyl is optionally replaced with —O—, —S—, —S(O)—, S(O)2, —N(R8), or —C(O)—; and said alkyl, carbocycle and heterocycle is optionally substituted with hydroxyl, alkoxy, acyl, halogen, mercapto, oxo (═O), carboxyl, acyl, halo-substituted alkyl, amino, cyano nitro, amidino, guanidino an optionally substituted carbocycle or an optionally substituted heterocycle. Substituents of the “optionally substituted carbocycle” and “optionally substituted heterocycle” are as defined herein. In a particular embodiment such carbocycle and heterocycle groups are substituted with hydroxyl, alkyl, alkoxy, acyl, halogen, mercapto, oxo, carboxyl, acyl, halo-substituted alkyl, amino, cyano, nitro, amidino and guanidino. In a particular embodiment R8 is H, alkyl, or acyl. In an embodiment R8 is methyl. In another embodiment R8 is acetyl. In a particular embodiment R8 is H. In an embodiment R7 is H, halogen, amino, hydroxyl, carboxyl, alkyl, haloalkyl or aralkyl. In a particular embodiment R7 is halogen, for example Cl or F. In a particular embodiment R7 is H. It is understood that substitutions defined for R7 and R8 as well as all other variable groups herein are subject to permissible valency.

n is 0 to 4. In an embodiment n is 0. In an embodiment n is 1. In an embodiment n is 2. In an embodiment n is 3. In an embodiment n is 4.

Compounds of the invention contain one or more asymmetric carbon atoms. Accordingly, the compounds may exist as diastereomers, enantiomers or mixtures thereof. The syntheses of the compounds may employ racemates, diastereomers or enantiomers as starting materials or as intermediates. Diastereomeric compounds may be separated by chromatographic or crystallization methods. Similarly, enantiomeric mixtures may be separated using the same techniques or others known in the art. Each of the asymmetric carbon atoms may be in the R or S configuration and both of these configurations are within the scope of the invention. In a particular embodiment, compounds of the invention have the following stereochemical configuration of formula I′

wherein X1, X2, Y, Z1, Z2, Z3, Q R1, R2, R3, R4, R4′, R5, R6 and R6′ are as described herein.

In particular embodiments, compounds of the invention have the general formula IIa-IIe

wherein X1, X2, Y, Z1, Q R1, R2, R3, R4, R4′, R5, R6 and R6′ are as described herein.

The invention also encompasses prodrugs of the compounds described above. Suitable prodrugs where applicable include known amino-protecting and carboxy-protecting groups which are released, for example hydrolyzed, to yield the parent compound under physiologic conditions. A particular class of prodrugs are compounds in which a nitrogen atom in an amino, amidino, aminoalkyleneamino, iminoalkyleneamino or guanidino group is substituted with a hydroxy (OH) group, an alkylcarbonyl (—CO—R) group, an alkoxycarbonyl (—CO—OR), an acyloxyalkyl-alkoxycarbonyl (—CO—O—R—O—CO—R) group where R is a monovalent or divalent group and as defined above or a group having the formula —C(O)—O—CP1P2-haloalkyl, where P1 and P2 are the same or different and are H, lower alkyl, lower alkoxy, cyano, halo lower alkyl or amyl. In a particular embodiment, the nitrogen atom is one of the nitrogen atoms of the amidino group of the compounds of the invention. These prodrug compounds are prepared reacting the compounds of the invention described above with an activated acyl compound to bond a nitrogen atom in the compound of the invention to the carbonyl of the activated acyl compound. Suitable activated carbonyl compounds contain a good leaving group bonded to the carbonyl carbon and include acyl halides, acyl amines, acyl pyridinium salts, acyl alkoxides, in particular acyl phenoxides such as p-nitrophenoxy acyl, dinitrophenoxy acyl, fluorophenoxy acyl, and difluorophenoxy acyl. The reactions are generally exothermic and are carried out in inert solvents at reduced temperatures such as −78 to about 50 C. The reactions are usually also carried out in the presence of an inorganic base such as potassium carbonate or sodium bicarbonate, or an organic base such as an amine, including pyridine, triethylamine, etc. One manner of preparing prodrugs is described in U.S. Ser. No. 08/843,369 filed Apr. 15, 1997 (corresponding to PCT publication WO9846576) the contents of which are incorporated herein by reference in their entirety.

Particular compounds of formula I include the following:

Compounds of the invention may exist in different resonance forms and that all such resonance forms are within the scope of the invention herein.

Compounds of the invention are prepared using standard organic synthetic techniques from commercially available starting materials and reagents. It will be appreciated that synthetic procedures employed in the preparation of compounds of the invention will depend on the particular substituents present in a compound and that various protection and deprotection steps that are standard in organic synthesis may be required but may not be illustrated in the following general schemes. In a particular general synthetic scheme, compounds of the invention may be prepared by coupling amino acid residue analogues employing typical amide coupling procedures. In scheme 1, wherein Q, Y, Z1, Z2, Z3, Z4, R1, R6 and R6′ are as defined herein and Pr is a suitable protecting group, amine-protected amino acid residue analogues are coupled and deprotected sequentially to give the final compounds.

It will be appreciated that the amino acid analogs may be coupled in any order and may be prepared using solid phase support which is routine in the art. For example, Scheme 2 illustrates an alternative amino acid residue analogue coupling route in which R4 or R4′ is an amino-protecting group or other group as defined herein which renders the amine non-reactive with carboxyl groups.

Thiazole intermediates for preparing compounds of the invention in which Z1 is S may be prepared according to scheme 3 wherein Q, Y, Z1, Z2, Z3, Z4, R1, R6 and R6′ are as defined herein and Pr is a suitable protecting group.

Amine a is coupled with b using standard amide formation procedures, to form amide c which is converted to the corresponding thiamide d by reacting with Lawesson\'s reagent. Thioamide d is cyclized, for example with K3Fe(CN)6 in EtOH to form e which is deprotected to give the desired thiazole f to be used in preparing compounds of the invention.

Alternatively, thiazole intermediates for preparing compounds of the invention in which Z1 is S may be prepared according to Scheme 4.

Chloro-substituted amine a is coupled with acid chloride b to give amide c which is reacted with Lawesson\'s reagent and heated to give cyclized compound d. Compound d is then deprotected to give the desired thiazole intermediate e to be used in preparation of compounds of the invention.

Oxazole intermediates for preparing compounds of the invention in which Z1 is O may be prepared according to the procedures described by Wang et al. (Bioorganic & Medicinal Chemistry (2004), 12(1):17-21) as illustrated in Scheme 5.

Similar to schemes 3 and 4, an acid chloride b is coupled with amine a to give amide c. However, amide c is refluxed in a solution of p-toluenesulfonic acid in toluene to give d and the protecting group Pr is removed to give the desired oxazole e to be used in preparing compounds of the invention.

Alternatively, oxazole intermediates for preparing compounds of the invention in which Z1 is O may be prepared according to the procedures described by Kauffman et al. (Journal of Heterocyclic Chemistry (2002), 39(5), 981-988) illustrated in Scheme 6.

Acid a with dioxane, thionylchloride and N-methylpyrrolidinone are refluxed under inert gas and the resulting acid chloride is coupled with hydroxy/amine b to give amide c. This is then heated with boric acid in dibutylcarbitol to give e and the protecting group Pr is removed to give the desired oxazole intermediate e which may be used for preparing compounds of the invention.

Imidazole intermediates for preparing compounds of the invention in which Z1 is NH may be prepared according to the procedures described by Kumar et al. (Bioorganic & Medicinal Chemistry (2002), 10(12), 3997-4004) as illustrated in Scheme 7.

Acid chloride a is coupled with nitro/amine b to give amide c. The nitro group of amide c is reduced to the corresponding amine, for example with iron, and is then cyclized by heating with acetic acid to give d. The protecting group Pr of d is removed to give the desired imidazole intermediate e which may be used in preparing compounds of the invention.

Compounds of the invention in which R4 or R4′ are other than H may be prepared according to standard organic chemistry techniques, for example by reductive amination in which a starting amino acid residue analog e.g. NH2—CH(R3)—C(O)—OH is reacted with a suitable aldehyde or ketone to give the desired R4 and R4′ substituents. See scheme 8. The resulting R4/R4′ substituted amino acid intermediate can then be conjugated to the next amino acid intermediate or the remainder of the compound using standard peptide coupling procedures.

In a particular embodiment, alanine is reacted with 1-methylindole-2-carboxaldehyde and reduced with sodium cyanoborohydride dissolved in 1% HOAc/DMF to give the N-substituted alanine residue which may be used in preparing compounds of the invention. See scheme 9.

Alternatively, the reductive amination procedure to introduce R4/R4′ substituents is the final step in the preparation of the compound.

When compounds of the invention incorporate R4 or R4′ substituents other than H, they may also be prepared by substitution of a suitable acid intermediate which incorporates a leaving group with a desired amine. For example Br—CH(R3)—C(O)—OH is substituted with an amine R4—NH2 or R4—NH—R4′ according to scheme 10.

Alternatively, the substitution reaction introducing R4 or R4′ substituents may be performed as a final step in the preparation of the compound as illustrated in scheme 11.

In a particular embodiment, 2-bromopropionic acid is reacted with the following amines dissolved in DMF and bubbled for until substitution is complete to form N-substituted alanine residues:

Compounds of the invention in which either X1 or X2 is sulfur, i.e. the compound incorporates a thioamide, may be prepared according to established organic chemistry techniques. For example, compounds in which X2 is sulfur can be prepared according to scheme 12 starting from an Fmoc protected amino acid residue analog NH2—CH(R2)—COOH which is dissolved in THF and cooled to −25° C., with addition of DIPEA followed by addition of isobutylchloroformate. After 10 minutes, the diamine, 4-nitrobenzene-1,2-diamine, is added and the reaction mixture is continuously stirred at −25° C. for 2 hours, then at room temperature overnight. THF is vacuumed off and the mixture is then subjected to flash chromatography using 50% EtOAc/Hexane to yield the product. The Fmoc-alanine derivative, phosphorus pentasulfide and sodium carbonate are mixed in THF and stirred overnight. The solution is concentrated and direct chromatography using 80% EtOAc/Hexane yields the activated thioalanine. The activated thioalanine and sodium nitrite are then mixed in acetic acid and diluted with H2O. The resulting precipitant is filtered and dried to yield the product. The thioalanine is coupled to an A ring substituted proline amino acid residue analog by dissolving both in DMF. The thioamide product may then be deprotected with 20% PIP/DMA for 15 minutes and used to conjugate to the R4/R4′—N—C(R3)(R3′)—COOH.

Alternatively the Fmoc-protected thioamide is first coupled to the A ring substituted proline amino acid residue analog followed by Fmoc deprotection and subsequent coupling to the R4/R4′—R4/R4′—N—C(R3)(R3′)—COOH amino acid residue analog.

The compounds of the invention inhibit the binding of IAP proteins to caspases, in particular X-IAP binding interaction with caspases 3 and 7. The compounds also inhibit the binding of ML-IAP to Smac protein. Accordingly, the compounds of the invention are useful for inducing apoptosis in cells or sensitizing cells to apoptotic signals, in particular cancer cells. Compounds of the invention are useful for inducing apoptosis in cells that overexpress IAP proteins. Alternatively, compounds of the invention are useful for inducing apoptosis in cells in which the mitochondrial apoptotic pathway is disrupted such that release of Smac from ML-IAP proteins is inhibited, for example by up regulation of Bcl-2 or down regulation of Bax/Bak. More broadly, the compounds can be used for the treatment of all cancer types which fail to undergo apoptosis. Examples of such cancer types include neuroblastoma, intestine carcinoma such as rectum carcinoma, colon carcinoma, familiarly adenomatous polyposis carcinoma and hereditary non-polyposis colorectal cancer, esophageal carcinoma, labial carcinoma, larynx carcinoma, hypopharynx carcinoma, tong carcinoma, salivary gland carcinoma, gastric carcinoma, adenocarcinoma, medullary thyroidea carcinoma, papillary thyroidea carcinoma, renal carcinoma, kidney parenchym carcinoma, ovarian carcinoma, cervix carcinoma, uterine corpus carcinoma, endometrium carcinoma, chorion carcinoma, pancreatic carcinoma, prostate carcinoma, testis carcinoma, breast carcinoma, urinary carcinoma, melanoma, brain tumors such as glioblastoma, astrocytoma, meningioma, medulloblastoma and peripheral neuroectodermal tumors, Hodgkin lymphoma, non-Hodgkin lymphoma, Burkitt lymphoma, acute lymphatic leukemia (ALL), chronic lymphatic leukemia (CLL), acute myeloid leukemia (AML), chronic myeloid leukemia (CML), adult T-cell leukemia lymphoma, hepatocellular carcinoma, gall bladder carcinoma, bronchial carcinoma, small cell lung carcinoma, non-small cell lung carcinoma, multiple myeloma, basalioma, teratoma, retinoblastoma, choroidea melanoma, seminoma, rhabdomyo sarcoma, craniopharyngeoma, osteosarcoma, chondrosarcoma, myosarcoma, liposarcoma, fibrosarcoma, Ewing sarcoma and plasmocytoma.

Compounds of the invention are useful for sensitizing cells to apoptotic signals. Accordingly, the compounds may be administered prior to, concomitantly with, or following administration of radiation therapy or cytostatic or antineoplastic chemotherapy. Suitable cytostatic chemotherapy compounds include, but are not limited to (i) antimetabolites, such as cytarabine, fludarabine, 5-fluoro-2′-deoxyuiridine, gemcitabine, hydroxyurea or methotrexate; (ii) DNA-fragmenting agents, such as bleomycin, (iii) DNA-crosslinking agents, such as chlorambucil, cisplatin, cyclophosphamide or nitrogen mustard; (iv) intercalating agents such as adriamycin (doxorubicin) or mitoxantrone; (v) protein synthesis inhibitors, such as L-asparaginase, cycloheximide, puromycin or diphtheria toxin; (Vi) topoisomerase I poisons, such as camptothecin or topotecan; (vii) topoisomerase II poisons, such as etoposide (VP-16) or teniposide; (viii) microtubule-directed agents, such as colcemid, colchicine, paclitaxel, vinblastine or vincristine; (ix) kinase inhibitors such as flavopiridol, staurosporin, STI571 (CPG 57148B) or UCN-01 (7-hydroxystaurosporine); (x) miscellaneous investigational agents such as thioplatin, PS-341, phenylbutyrate, ET-18- OCH3, or farnesyl transferase inhibitors (L-739749, L-744832); polyphenols such as quercetin, resveratrol, piceatannol, epigallocatechine gallate, theaflavins, flavanols, procyanidins, betulinic acid and derivatives thereof; (xi) hormones such as glucocorticoids or fenretinide; (xii) hormone antagonists, such as tamoxifen, finasteride or LHRH antagonists. In a particular embodiment, compounds of the present invention are coadministered with a cytostatic compound selected from the group consisting of cisplatin, doxorubicin, taxol, taxotere and mitomycin C. In a particular embodiment, the cytostatic compound is doxorubicin.

Another class of active compounds which can be used in the present invention are those which are able to sensitize for or induce apoptosis by binding to death receptors (“death receptor agonists”). Such agonists of death receptors include death receptor ligands such as tumor necrosis factor a (TNF-α), tumor necrosis factor β (TNF-β, lymphotoxin-α), LT-β (lymphotoxin-β), TRAIL (Apo2L, DR4 ligand), CD95 (Fas, APO-1) ligand, TRAMP (DR3, Apo-3) ligand, DR6 ligand as well as fragments and derivatives of any of said ligands. In an embodiment, the death receptor ligand is TNF-α. In a particular embodiment, the death receptor ligand is Apo2L/TRAIL. Furthermore, death receptors agonists comprise agonistic antibodies to death receptors such as anti-CD95 antibody, anti-TRAIL-R1 (DR4) antibody, anti-TRAIL-R2 (DR5) antibody, anti-TRAIL-R3 antibody, anti-TRAIL-R4 antibody, anti-DR6 antibody, anti-TNF-R1 antibody and anti-TRAMP (DR3) antibody as well as fragments and derivatives of any of said antibodies.