Compounds for enzyme inhibition

1. A method for the treatment of lung fibrosis in a patient, comprising administering to the patient a compound having a structure of formula (I) or a pharmaceutically acceptable salt thereof,

wherein

each A is independently selected from C═O, C═S, and SO 2 ; or

A is optionally a covalent bond when adjacent to an occurrence of Z;

B is absent or is N(R 9 )R 10 ;

L is absent or is selected from C═O, C═S, and SO 2 ;

M is C 1-12 alkyl;

Q is absent or is selected from O, NH, and N—C 1-6 alkyl;

X is selected from O, S, NH, and N—C 1-6 alkyl;

each Z is independently selected from O, S, NH, and N—C 1-6 alkyl; or

Z is optionally a covalent bond when adjacent to an occurrence of A;

R 1 is selected from H, —C 1-6 alkyl-B, C 1-6 hydroxyalkyl, C 1-6 alkoxyalkyl, aryl, and C 1-6 aralkyl;

R 2 and R 3 are each independently selected from aryl, C 1-6 aralkyl, heteroaryl, and C 1-6 heteroaralkyl;

R 4 is N(R 5 )L-Q-R 6 ;

R 5 is selected from hydrogen, OH, aryl C 1-6 alkyl, and C 1-6 alkyl;

R 6 is selected from an N-terminal protecting group, heterocyclylMZAZC 1-6 alkyl-, heterocyclylM-, and carbocyclylM;

R 7 and R 8 are independently selected from hydrogen, C 1-6 alkyl, and C 1-6 aralkyl;

R 9 is selected from hydrogen, OH, and C 1-6 alkyl; and

R 10 is an N-terminal protecting group; and

R 15 is selected from C 1-6 alkyl and C 1-6 hydroxyalkyl;

provided that in any occurrence of the sequence ZAZ, at least one member of the sequence must be other than a covalent bond.

2. The method of claim 1 , wherein the lung fibrosis is selected from the group consisting of: idiopathic pulmonary fibrosis, collagen vascular disease, sarcoidosis, interstitial lung diseases and extrinsic lung disorders.

3. The method of claim 1 , wherein L is C═O, Q is absent, M is C 1-8 alkyl and R 6 is heterocyclylM- and the heterocyclyl moiety is morpholino.

4. The method of claim 1 , wherein R 7 and R 8 are independently selected from hydrogen and C 1-6 aralkyl.

5. The method of claim 4 , wherein R 7 and R 8 are both hydrogen.

6. The method of claim 5 , wherein R 15 is selected from methyl, ethyl, hydroxymethyl, and 2-hydroxyethyl.

7. The method of claim 1 , wherein R 5 is hydrogen.

8. The method of claim 1 , wherein L and Q are absent.

9. The method of claim 1 , wherein R 6 is an N-terminal protecting group.

10. The method of claim 9 , wherein R 6 is selected from t-butoxycarbonyl and benzyloxycarbonyl.

11. The method of claim 1 , wherein the carbon bearing R 1 has a D stereochemical configuration.

12. The method of claim 11 , wherein R 1 is selected from methyl, ethyl, isopropyl, carboxymethyl, and benzyl.

13. The method of claim 1 , wherein R 2 is selected from C 1-6 alkyl-phenyl, C 1-6 alkyl-indolyl, C 1-6 alkyl-thienyl, C 1-6 alkyl-thiazolyl, and C 1-6 alkyl-isothiazolyl.

14. The method of claim 1 , wherein R 2 is selected from

wherein D is selected from hydrogen, methoxy, t-butoxy, hydroxy, cyano, trifluoromethyl, and C 1-4 -alkyl, wherein C 1-4 -alkyl may be substituted or not with substituents selected from the group consisting of a halogen, a hydroxyl, a carbonyl, a thiocarbonyl, an alkoxyl, a phosphoryl, a phosphate, a phosphonate, a phosphinate, an amino, an amido, an amidine, an imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, a sulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, a heterocyclyl, an aralkyl, or an aromatic or heteroaromatic moiety; and

R is hydrogen or a suitable protecting group.

15. The method of claim 1 , wherein R 3 is selected from C 1-6 alkyl-phenyl and C 1-6 alkyl-indolyl.

16. The method of claim 15 , wherein R 3 is selected from

wherein D is selected from hydrogen, methoxy, t-butoxy, hydroxy, cyano, trifluoromethyl, and C 1-4 -alkyl, wherein C 1-4 -alkyl may be substituted or not with substituents selected from the group consisting of a halogen, a hydroxyl, a carbonyl, a thiocarbonyl, an alkoxyl, a phosphoryl, a phosphate, a phosphonate, a phosphinate, an amino, an amido, an amidine, an imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, a sulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, a heterocyclyl, an aralkyl, or an aromatic or heteroaromatic moiety; and

R is hydrogen or a suitable protecting group.

17. The method of claim 1 , wherein R 6 is selected from heterocyclylMZAZ-C 1-8 alkyl-, heterocyclylM-, and carbocyclylM-.

18. The method of claim 17 , wherein R 6 is heterocyclylMZAZ-C 1-8 alkyl-, and heterocyclylM-.

19. The method of claim 1 , wherein L is C═O, Q is absent, M is C 1-8 alkyl and R 6 is heterocyclylM- and the heterocyclyl moiety is selected from morpholino, piperidino, piperazino, and pyrrolidino.

20. The method of claim 1 , wherein an EC 50 ratio of the compound in an assay of constitutive proteasome activity as compared to the EC 50 of the compound in an assay of immunoproteasome activity is greater than 1.0.

21. The method of claim 20 , wherein the EC 50 ratio is greater than 3.0.

22. A method for treating a pulmonary disease in a patient, comprising administering to the patient a compound having a structure of formula (I) or a pharmaceutically acceptable salt thereof,

wherein

each A is independently selected from C═O, C═S, and SO 2 ; or

A is optionally a covalent bond when adjacent to an occurrence of Z;

B is absent or is N(R 9 )R 10 ;

L is absent or is selected from C═O, C═S, and SO 2 ;

M is C 1-12 alkyl;

Q is absent or is selected from O, NH, and N—C 1-6 olkyl;

X is selected from O, S, NH, and N—C 1-6 alkyl;

each Z is independently selected from O, S, NH, and N—C 1-6 alkyl; or

Z is optionally a covalent bond when adjacent to an occurrence of A;

R 1 is selected from H, C 1-6 hydroxyalkyl, C 1-6 alkoxyalkyl, aryl, and C 1-6 aralkyl;

R 2 and R 3 are each independently selected from aryl, C 1-6 aralkyl, heteroaryl, and C 1-6 heteroaralkyl;

R 4 is N(R 5 )L-Q-R 6 ;

R 5 is selected from hydrogen, OH, aryl C 1-6 olkyl, and C 1-6 olkyl;

R 6 is selected from an N-terminal protecting group, heterocyclylMZAZC 1-6 alkyl-, heterocyclylM-, and carbocyclylM;

R 7 and R 8 are independently selected from hydrogen, C 1-6 alkyl, and C 1-6 aralkyl;

R 9 is selected from hydrogen, OH, and C 1-6 alkyl; and

R 10 is an N-terminal protecting group; and

R 15 is selected from C 1-6 alkyl and C 1-6 hydroxyalkyl;

provided that in any occurrence of the sequence ZAZ, at least one member of the sequence must be other than a covalent bond.

23. The method of claim 22 , wherein the pulmonary disease is selected from the group consisting of: bronchitis, bronchiectasis, and fibrosis.

24. The method of claim 22 , wherein L is C═O, Q is absent, M is C 1-8 alkyl and R 6 is heterocyclylM- and the heterocyclyl moiety is morpholino.

25. The method of claim 22 , wherein R 7 and R 8 are independently selected from hydrogen and C 1-6 aralkyl.

26. The method of claim 25 , wherein R 7 and R 8 are both hydrogen.

27. The method of claim 26 , wherein R 15 is selected from methyl, ethyl, hydroxymethyl, and 2-hydroxyethyl.

28. The method of claim 22 , wherein R 5 is hydrogen.

29. The method of claim 22 , wherein L and Q are absent.

30. The method of claim 22 , wherein R 6 is an N-terminal protecting group.

31. The method of claim 30 , wherein R 6 is selected from t-butoxycarbonyl and benzyloxycarbonyl.

32. The method of claim 22 , wherein the carbon bearing R 1 has a D stereochemical configuration.

33. The method of claim 32 , wherein R 1 is selected from methyl, ethyl, isopropyl, carboxymethyl, and benzyl.

34. The method of claim 22 , wherein R 2 is selected from C 1-6 alkyl-phenyl, C 1-6 alkyl-indolyl, C 1-6 alkyl-thienyl, C 1-6 alkyl-thiazolyl, and C 1-6 alkyl-isothiazolyl.

35. The method of claim 22 , wherein R 2 is selected from

wherein D is selected from hydrogen, methoxy, t-butoxy, hydroxy, cyano, trifluoromethyl, and C 1-4 -alkyl, wherein C 1-4 -alkyl may be substituted or not with substituents selected from the group consisting of a halogen, a hydroxyl, a carbonyl, a thiocarbonyl, an alkoxyl, a phosphoryl, a phosphate, a phosphonate, a phosphinate, an amino, an amido, an amidine, an imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, a sulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, a heterocyclyl, an aralkyl, or an aromatic or heteroaromatic moiety; and

R is hydrogen or a suitable protecting group.

36. The method of claim 22 , wherein R 3 is selected from C 1-6 alkyl-phenyl and C 1-6 alkyl-indolyl.

37. The method of claim 36 , wherein R 3 is selected from

wherein D is selected from hydrogen, methoxy, t-butoxy, hydroxy, cyano, trifluoromethyl, and C 1-4 -alkyl, wherein C 1-4 -alkyl may be substituted or not with substituents selected from the group consisting of a halogen, a hydroxyl, a carbonyl, a thiocarbonyl, an alkoxyl, a phosphoryl, a phosphate, a phosphonate, a phosphinate, an amino, an amido, an amidine, an imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, a sulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, a heterocyclyl, an aralkyl, or an aromatic or heteroaromatic moiety; and

R is hydrogen or a suitable protecting group.

38. The method of claim 22 , wherein R 6 is selected from heterocyclylMZAZ-C 1-8 alkyl-, heterocyclylM-, and carbocyclylM-.

39. The method of claim 38 , wherein R 6 is heterocyclylMZAZ-C 1-8 alkyl-, and heterocyclylM-.

40. The method of claim 22 , wherein L is C═O, Q is absent, M is C 1-8 alkyl and R 6 is heterocyclylM- and the heterocyclyl moiety is selected from morpholino, piperidino, piperazino, and pyrrolidino.

41. The method of claim 22 , wherein an EC 50 ratio of the compound in an assay of constitutive proteasome activity as compared to the EC 50 of the compound in an assay of immunoproteasome activity is greater than 1.0.

42. The method of claim 41 , wherein the EC 50 ratio is greater than 3.0.

43. A method for the treatment of lung fibrosis in a patient, comprising administering to the patient a compound having the structure:

or a pharmaceutically acceptable salt thereof.

44. The method of claim 43 , wherein the lung fibrosis is selected from the group consisting of: idiopathic pulmonary fibrosis, collagen vascular disease, sarcoidosis, interstitial lung diseases and extrinsic lung disorders.

45. A method for the treatment of a pulmonary disease in a patient, comprising administering to the patient a compound having the structure:

or a pharmaceutically acceptable salt thereof.

46. The method of claim 45 , wherein the pulmonary disease is selected from the group consisting of: bronchitis, bronchiectasis, and fibrosis.