Heterocycle substituted ketone derivatives as histone deacetylase (HDAC) inhibitors

A compound of formula I:

• wherein:
• b is 0, 1, 2, 3, 4 or 5;
• q is 1, 2, 3 or 4;
• Y is C═O, (C═O)NR7, O(C═O)NR7 or (CH2)aO;
• a is 0, 1, 2 or 3;
• Het is imidazolyl, oxazolyl, thienyl, thiazolyl or pyrazolyl optionally substituted by one or more groups independently chosen from cyano, halogen, hydroxy, oxo, nitro, amino, C1-6alkylamino, di(C1-6alkyl)amino, C1-6alkyl, haloC1-6alkyl, C1-6alkoxy, haloC1-6alkoxy, C3-10cycloalkyl, C2-6alkenyl, C2-6alkynyl and C6-10aryl;
• R1 is hydrogen, C1-6alkyl, haloC1-6alkyl, C6-10aryl, 5 membered unsaturated heterocycle containing 1, 2, 3 or 4 heteroatoms independently selected from O, N and S, but not more than one of which is O or S, 6 membered unsaturated heterocycle containing 1, 2 or 3 nitrogen atoms, or 8-10 membered unsaturated or partially saturated heterocycle containing heteroatoms independently selected from O, N and S;
• any of which rings being optionally substituted by one or more groups independently chosen from cyano, halogen, nitro, oxo, hydroxy, C1-6alkyl, haloC1-6alkyl, C1-6alkoxy, haloC1-6alkoxy, C1-6alkylcarbonyl, C1-6alkoxycarbonyl, carboxy, C6-10aryl, C6-10aryloxy, C6-10arylcarbonyl and N(Ra)2 wherein Ra is independently selected from hydrogen, C1-6alkyl, C6-10aryl, C1-6alkylcarbonyl and C6-10arylcarbonyl;
• R2 is C1-6alkyl;
• R3 is hydrogen, halogen, hydroxy, cyano, C1-6alkyl, haloC1-6alkyl, C1-6alkoxy, haloC1-6alkoxy, C3-10cycloalkyl, haloC3-10cycloalkyl, C2-10alkenyl, C2-10alkynyl, nitro, N(Rd)2 wherein Rd is independently selected from hydrogen, C1-6alkyl and C1-6alkylcarbonyl;
• C6-10aryl, C6-10arylC1-6alkyl, C6-10arylC1-6alkoxy, 4, 5 or 6 membered saturated or partially saturated heterocycle containing 1, 2 or 3 heteroatoms independently selected from N, O and S, optionally bridged by a C1-4alkyl group;
• 5 membered unsaturated heterocycle containing 1, 2, 3 or 4 heteroatoms independently selected from N, O and S, but not more than one of which is O or S;
• 6 membered unsaturated heterocycle containing 1, 2 or 3 nitrogen atoms;
• or a 7-13 membered saturated, partially saturated or unsaturated heterocycle containing heteroatoms independently selected from N, O or S;
• any of which rings being optionally substituted by one or more groups independently chosen from Rb;
• R4 is hydrogen or C1-6alkyl;
• or
• R5 and R6 are independently hydrogen or C1-6alkyl;
• R7 is hydrogen or C1-6alkyl;
• each Rb is halogen, hydroxy, cyano, C1-6alkyl, haloC1-6alkyl, haloC1-6alkylcarbonyl, haloC1-6alkylcarbonyloxy, C1-6alkoxy, haloC1-6alkoxy, carboxy, C1-6alkylcarbonyl, C1-6alkoxycarbonyl, nitro, oxo, SO2N(Rc)2, N(Rc)2 wherein Rc is independently selected from hydrogen, C1-6alkyl, C1-6alkylcarbonyl, carboxy and C1-6alkoxycarbonyl, or C6-10aryl, C6-10arylC1-6alkyl, 5 or 6 membered saturated or partially saturated heterocycle containing 1, 2 or 3 heteroatoms independently selected from N, O or S, optionally bridged by a C1-4alkyl group;
• 5 membered unsaturated heterocycle containing 1, 2, 3 or 4 heteroatoms independently selected from N, O and S, but not more than one of which is O or S;
• or a 6 membered unsaturated heterocycle containing 1, 2 or 3 nitrogen atoms;
• any of which rings may be optionally substituted by one or more groups independently chosen from halogen, hydroxy, amino, cyano, C1-6alkyl, haloC1-6alkyl, C1-6alkoxy and haloC1-6alkoxy;
• or a pharmaceutically acceptable salt or tautomer thereof.