Paclitaxel enhancer compound

1. A compound represented by the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein:

Y is a covalent bond or a substituted or unsubstituted straight chained hydrocarbyl group;

R 1 is an aliphatic group, a substituted aliphatic group, a non-aromatic heterocyclic ring, or a substituted non-aromatic heterocyclic ring;

R 2 is —H, an aliphatic group, a substituted aliphatic group, a non-aromatic heterocyclic ring, a substituted non-aromatic heterocyclic ring, an aryl group or a substituted aryl group;

R 3 and R 4 are independently an aliphatic group, a substituted aliphatic group, a non-aromatic heterocyclic ring, a substituted non-aromatic heterocyclic ring, an aryl group or a substituted aryl group, or R 1 and R 3 taken together with the carbon and nitrogen atoms to which they are bonded, and/or R 2 and R 4 taken together with the carbon and nitrogen atoms to which they are bonded, form a non-aromatic heterocyclic ring optionally fused to an aromatic ring;

R 5 -R 6 are independently —H, an aliphatic group, a substituted aliphatic group, an aryl group or a substituted aryl group; and

Z is ═O or ═S;

provided that when Y is —CH 2 , R 3 and R 4 are both phenyl and R 5 -R 6 are all —H, then R 1 and R 2 are not both methyl.

2. The compound of claim 1 wherein:

Y is a covalent bond or a substituted or unsubstituted straight chained hydrocarbyl group;

R 1 is an aliphatic group or a substituted aliphatic group;

R 2 is —H, an aliphatic group, a substituted aliphatic group, an aryl group or a substituted aryl group

R 3 and R 4 are independently an aliphatic group, a substituted aliphatic group, an aryl group or a substituted aryl group, or R 1 and R 3 taken together with the carbon and nitrogen atoms to which they are bonded, and/or R 2 and R 4 taken together with the carbon and nitrogen atoms to which they are bonded, form a non-aromatic heterocyclic ring optionally fused to an aromatic ring.

3. The compound of claim 2 wherein the compound is represented by the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein Y′ is a covalent bond or —CR 7 R 8 — and R 7 and R 8 are each independently —H, an aliphatic or substituted aliphatic group, or R 7 is —H and R 8 is a substituted or unsubstituted aryl group, or, R 7 and R 8 , taken together, are a C2-C6 substituted or unsubstituted alkylene group.

4. The compound of claim 1 wherein the compound is represented by the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein Y′ is a covalent bond or —CR 7 R 8 —, at least one of R 1 -R 2 is an aliphatic group, a substituted aliphatic group, a non-aromatic heterocyclic ring, or a substituted non-aromatic heterocyclic ring and R 5 -R 8 are all —H.

5. The compound of claim 1 wherein the compound is represented by the following structural formula:

wherein Y′ is a covalent bond or —CR 7 R 8 —, at least one of R 1 -R 2 is an unsubstituted C3-C8 cyclic aliphatic group, a substituted C3-C8 cyclic aliphatic group, a substituted straight chained or branched aliphatic group, a substituted non-aromatic heterocyclic ring, or an unsubstituted non-aromatic heterocyclic ring and R 7 and R 8 are each independently —H, an aliphatic or substituted aliphatic group, or R 7 is —H and R 8 is a substituted or unsubstituted aryl group, or, R 7 and R 8 , taken together, are a C2-C6 substituted or unsubstituted alkylene group.

6. The compound of claim 3 wherein the compound is represented by the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein Y″ is a covalent bond or —CH 2 —.

7. The compound of claim 6 wherein R 1 and R 2 are the same.

8. The compound of claim 6 wherein the compound is represented by the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein Y″ is a covalent bond or —CH 2 — and R 1 is a substituted or unsubstituted aliphatic group and R 2 is a substituted or unsubstituted aryl group.

9. The compound of claim 6 wherein R 1 and R 2 are the same and R 3 and R 4 are the same.

10. The compound of claim 9 wherein R 1 and R 2 are both lower alkyl or a substituted lower alkyl groups.

11. The compound of claim 10 wherein R 1 and R 2 are both methyl, ethyl, n-propyl, n-butyl n-pentyl or cyclopropyl.

12. The compound of claim 10 wherein R 1 and R 2 are both 1-methylcyclopropyl, 2-methylcyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl.

13. The compound of claim 10 wherein R 1 and R 2 are both a C3-C8 cyclic alkyl group substituted with at least one lower alkyl group.

14. The compound of claim 9 wherein R 1 and R 2 are both a substituted or unsubstituted C3-C8 cyclic aliphatic group.

15. The compound of claim 14 wherein R 1 and R 2 are both a cyclopropyl group or a substituted cyclopropyl group.

16. The compound of claim 14 wherein R 1 and R 2 are both a C3-C8 cyclic aliphatic group substituted with one or more groups selected from —OH, —Br, —Cl, —I, —F, —OR a , —O—COR a , —COR a , —CN, —NO 2 , —COOH, —SO 3 H, —NH 2 , —NHR a , —N(R a R b ), —COOR a , —CHO, —CONH 2 , —CONHR a , —CON(R a R b ), —NHCOR a , —NRCOR a , —NHCONH 2 , —NHCONR a H, —NHCON(R a R b ), —NR c CONH 2 , —NR c CONR a H, —NR c CON(R a R b ), —C(═NH)—NH 2 , —C(═NH)—NHR a , —C(═NH)—N(R a R b ), —C(═NR c )—NH 2 , —C(═NR c )—NHR a , —C(═NR c )—N(R a R b ), —NH—C(═NH)—NH 2 , —NH—C(═NH)—NHR a , —NH—C(═NH)—N(R a R b ), —NH—C(═NR c )—NH 2 , —NH—C(═NR c )—NHR a , —NH—C(═NR c )—N(R a R b ), —NR d —C(═NH)—NH 2 , —NR d —C(═NH)—NHR a , —NR d —C(═NH)—N(R a R b ), —NR d —C(═NR c )—NH 2 , —NR d —C(═NR c )—NHR a , —NR d —C(═NR c )—N(R a R b ), —NHNH 2 , —NHNHR a , —NHNR a R b , —SO 2 NH 2 , —SO 2 NHR a , —SO 2 NR a R b , —CH═CHR a , —CH═CR a R b , —CR c ═CR a R b , —CR c ═CHR a , —CR c ═CR a R b , —CCR a , —SH, —SR a , —S(O)R a , —S(O) 2 R a , alkyl group, non-aromatic heterocyclic ring, benzyl group, aryl group wherein R a -R d are each independently an alkyl group, benzyl, aromatic group, or, —N(R a R b ), taken together, can also form a non-aromatic heterocyclic ring.

17. The compound of claim 1 wherein the compound is represented by the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein Y′ is a covalent bond or —CR 7 R 8 —.

18. The compound of claim 17 wherein R 7 and R 8 are different.

19. The compound of claim 17 where R 1 and R 2 are the same; and R 3 and R 4 are the same.

20. A compound represented by the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein:

Y′ is a covalent bond or —CR 7 R 8 —;

R 1 and R 2 are both a substituted or unsubstituted aliphatic group;

R 3 and R 4 are both methyl or ethyl; and

R 7 is —H and R 8 is —H or methyl.

21. The compound of claim 20 wherein R 1 and R 2 are both C3-C8 cyclic aliphatic group substituted with one or more groups selected from —OH, —Br, —Cl, —I, —F, —OR a , —O—COR a , —COR a , —CN, —NO 2 , —COOH, —SO 3 H, —NH 2 , —NHR a , —N(R a R b ), —COOR a , —CHO, —CONH 2 , —CONHR a , —CON(R a R b ), —NHCOR a , —NRCOR a , —NHCONH 2 , —NHCONR a H, —NHCON(R a R b ), —NR c CONH 2 , —NR c CONR a H, —NR c CON(R a R b ), —C(═NH)—NH 2 , —C(═NH)—NHR a , —C(═NH)—N(R a R b ), —C(═NR c )—NH 2 , —C(═NR c )—NHR a , —C(═NR c )—N(R a R b ), —NH—C(═NH)—NH 2 , —NH—C(═NH)—NHR a , —NH—C(═NH)—N(R a R b ), —NH—C(═NR c )—NH 2 , —NH—C(═NR c )—NHR a , —NH—C(═NR c )—N(R a R b ), —NR d —C(═NH)—NH 2 , —NR d− C(═NH)—NHR a , —NR d− C(═NH)—N(R a R b ), —NR d− C(═NR c )—NH 2 , —NR d− C(═NR c )—NHR a , —NR d− C(═NR c )—N(R a R b ), —NHNH 2 , —NHNHR a , —NHNR a R b , —SO 2 NH 2 , —SO 2 NHR a , —SO 2 NR a R b , —CH═CHR a , —CH═CR a R b , —CR c ═CR a R b , —CR c ═CHR a , —CR c ═CR a R b , —CCR a , —SH, —SR a , —S(O)R a , —S(O) 2 R a , alkyl group, non-aromatic heterocyclic ring, benzyl group, aryl group wherein R a -R d are each independently an alkyl group, benzyl, aromatic group, or, —N(R a R b ), taken together, can also form a non-aromatic heterocyclic ring.

22. The compound of claim 3 wherein R 5 and R 6 are the same.

23. The compound of claim 22 wherein the compound is represented by the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein Y″ is a covalent bond or —CH 2 .

24. The compound of claim 23 wherein R 5 and R 6 are both a lower alkyl group or a phenyl group.

25. The compound of claim 24 wherein R 5 and R 6 are both a methyl group.

26. A compound represented by the following structural formula:

or a pharmaceutically acceptable salt thereof.

27. A compound represented by the following structural formula:

or a pharmaceutically acceptable salt thereof.

28. A pharmaceutical composition comprising a pharmaceutically acceptable carrier or diluent and a compound represented by the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein:

Y is a covalent bond or a substituted or unsubstituted straight chained hydrocarbyl group;

R 1 is an aliphatic group, a substituted aliphatic group, a non-aromatic heterocyclic ring, or a substituted non-aromatic heterocyclic ring;

R 2 is —H, an aliphatic group, a substituted aliphatic group, a non-aromatic heterocyclic ring, a substituted non-aromatic heterocyclic ring, an aryl group or a substituted aryl group;

R 3 and R 4 are independently an aliphatic group, a substituted aliphatic group, a non-aromatic heterocyclic ring, a substituted non-aromatic heterocyclic ring, an aryl group or a substituted aryl group, or R 1 and R 3 taken together with the carbon and nitrogen atoms to which they are bonded, and/or R 2 and R 4 taken together with the carbon and nitrogen atoms to which they are bonded, form a non-aromatic heterocyclic ring optionally fused to an aromatic ring;

R 5 -R 6 are independently —H, an aliphatic group, a substituted aliphatic group, an aryl group or a substituted aryl group; and

Z is ═O or ═S;

provided that when Y is —CH 2 , R 3 and R 4 are both phenyl and R 5 R are all —H, then R 1 and R 2 are not both methyl.

29. The pharmaceutical composition of claim 28 wherein the compound is represented by the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein Y′ is a covalent bond or —CR 7 R 8 —, at least one of R 1 -R 2 is an unsubstituted C3-C8 cyclic aliphatic group, a substituted C3-C8 cyclic aliphatic group, a substituted straight chained or branched aliphatic group, a substituted non-aromatic heterocyclic ring, or an unsubstituted non-aromatic heterocyclic ring and R 7 and R 8 are each independently —H, an aliphatic or substituted aliphatic group, or R 7 is —H and R 8 is a substituted or unsubstituted aryl group, or, R 7 and R 8 , taken together, are a C2-C6 substituted or unsubstituted alkylene group.

30. The pharmaceutical composition of claim 28 wherein the compound is represented by the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein:

Y″ is a covalent bond or —CH 2 —;

R 1 is an aliphatic group or a substituted aliphatic group;

R 2 is —H, an aliphatic group, a substituted aliphatic group, an aryl group or a substituted aryl group; and

R 3 and R 4 are independently an aliphatic group, a substituted aliphatic group, an aryl group or a substituted aryl group, or R 1 and R 3 taken together with the carbon and nitrogen atoms to which they are bonded, and/or R 2 and R 4 taken together with the carbon and nitrogen atoms to which they are bonded, form a non-aromatic heterocyclic ring optionally fused to an aromatic ring.

31. The pharmaceutical composition of claim 28 , wherein the compound is represented by the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein:

Y′ is a covalent bond or —CR 7 R 8 —;

R 1 and R 2 are both a substituted or unsubstituted aliphatic group;

R 3 and R 4 are both methyl or ethyl; and

R 7 is —H and R 8 is —H or methyl.

32. The pharmaceutical composition of claim 28 , wherein the compound is represented by a structural formula selected from:

or a pharmaceutically acceptable salt thereof.