Histone deacetylase inhibitors

1. A compound of the formula (I):

wherein:

Ar′/Het′ is:

phenyl which is optionally substituted with from 1-3 R p ; provided that the point of connection on said phenyl to U and the point of connection on said phenyl to the amide carbonyl do not result in a 1,2-relation to one another on said phenyl; wherein R p at each occurrence is, independently, selected from H, F, chloro, CH 3 , CF 3 , OCH 3 , OCF 3 , and OCHF 2 ;

R1 is:

(i) hydrogen; or

(ii) C6-C10 aryl, which is optionally substituted with from 1-3 R q ; or

(iii) monocyclic or bicyclic heteroaryl having from 5-10 ring atoms, which is optionally substituted with from 1-3 R q ; wherein from 1-4 of the ring atoms is/are a heteroatom independently selected from O, N, N—H, N—R q , and S; or

(iv) heterocyclyl having from 4-10 ring atoms, which is optionally substituted with from 1-3 R q ; wherein from 1-4 of the ring atoms is/are a heteroatom independently selected from O, N, N—H, N—R q , and S; and

each occurrence of R q is independently selected from the group consisting of:

(C1-C6 alkyl)NH—; (C1-C6 alkyl) 2 N—;

—N*(R q′ ) 2 , wherein R q′ —N*—R q′ together form a saturated ring having 5 or 6 ring atoms, in which 1 or 2 ring atoms is/are optionally a heteroatom independently selected from NH, N(alkyl), O, and S (—N*(R q′ ) 2 ;

formyl; formyl(C 1 -C 4 ) alkyl; cyano; cyano(C 1 -C 4 ) alkyl;

benzyl; benzyloxy;

heterocyclyl-(C0-C6) alkyl, wherein the heterocyclyl portion includes 5 or 6 ring atoms, in which 1 or 2 of the ring atoms is/are a heteroatom independently selected from NH, N(alkyl), O, and S, and when said alkyl portion is present, said alkyl portion serves as the point of attachment to R1; otherwise in the case of CO alkyl, a heterocyclyl carbon ring atom serves as the point of attachment of the heterocyclyl to R1;

phenyl or heteroaryl having from 5-6 ring atoms, wherein from 1-4 of the ring atoms is/are a heteroatom independently selected from O, N, N—H, N—R q″ , and S, each of which is optionally substituted with from 1-3 R q″ ;

SO 2 —(C1-C6)alkyl; SO—(C1-C6)alkyl; and

nitro;

each occurrence of R q″ is independently selected from the group consisting of:

halogen;

C1-C6 alkyl; fluoro(C1-C6)alkyl;

hydroxyl;

hydroxy(C 1 -C 4 )alkyl;

C1-C6 alkoxy; fluoro(C1-C6)alkoxy;

(C1-C6 alkyl)C(O)—;

(C1-C6 alkyl)NH—; (C1-C6 alkyl) 2 N—;

formyl; formyl(C1-C4) alkyl; cyano; cyano(C1-C4) alkyl;

benzyl; benzyloxy;

heterocyclyl)-(C0-C6) alkyl, wherein the heterocyclyl portion includes 5 or 6 ring atoms, in which 1 or 2 of the ring atoms is/are a heteroatom independently selected from NH, N(alkyl), O, and S, and when said alkyl portion is present, said alkyl portion serves as the point of attachment to R1; otherwise in the case of CO alkyl, a heterocyclyl carbon ring atom serves as the point of attachment of the heterocyclyl to R1;

phenyl or heteroaryl having from 5-6 ring atoms, wherein from 1-4 of the ring atoms is/are a heteroatom independently selected from O, N, N—H, N—(C1-C6 alkyl), and S;

SO 2 —(C1-C6)alkyl; SO—(C1-C6)alkyl; and

nitro;

U is ═CR r or U′—C(R s ) 2 — or C(R s ) 2 —U′;

wherein:

R r is hydrogen, F, C1-C6 alkyl, fluoro C1-C6 alkyl, C3-C6 cycloalkyl, C1-C6 alkoxy, C1-C6 fluoroalkoxy, or cyano;

each occurrence of R S is independently selected from H, F, OH, C1-C6 alkyl, C3-C6 cycloalkyl, NH 2 , OCO—(C1-C6 alkyl), OCO—(C3-C6 cycloalkyl), C1-C6 alkoxy C1-C6 fluoroalkoxy, and cyano; or

R s —C—R s together form C3-C6 cycloalkyl or heterocyclyl having 3-6 ring atoms, in which one of the heterocyclyl ring atoms is selected from O; S(O) m , (m=0-2); and NR u ; and m is 0-2;

each occurrence of R u is independently selected from H, C1-C6 alkyl, —C(═O)H, —C(═O)R v , C(═O)O(C1-C6 alkyl), C(═O)N(R w ) 2 , and SO 2 —R v ; wherein R v is selected from C1-C6 alkyl, CH 2 -(heteroaryl having 5-10 ring atoms), CH 2 —(C6-C10 aryl), and C6-C10 aryl; and each occurrence of R W is independently selected from H, C1-C6 alkyl, CH 2 -(heteroaryl having 5-10 ring atoms), CH 2 —(C6-C10 aryl), and C6-C10 aryl; wherein the aryl and heteroaryl portion in R v and R w are optionally substituted with one or more independently selected substituents selected from F, C1-C6 alkyl, fluoro C1-C6 alkyl, C3-C6 cycloalkyl, C1-C6 alkoxy, C1-C6 fluoroalkoxy, and cyano;

U′ is a bond; O; NR u ; S(O) m ; CH 2 ; or U″—CH 2 —; wherein U″ is O; NR u ; or S(O) m , and each m is independently 0-2;

Cy is C4-C10 cycloalkyl or saturated heterocyclyl having 4-10 ring atoms, each of which is optionally substituted with from 1-3 R x , in which from 1-3 heteroatoms are independently selected from O, N—H, NR′″, and S(O), wherein m is 0-2; wherein each occurrence of R x is independently selected from F, OH, C1-C6 alkyl, fluoro C1-C6 alkyl, C3-C6 cycloalkyl, C1-C6 alkoxy C1-C6 fluoroalkoxy, and cyano; wherein R x′ is defined as R q″ ; and

wherein when the heterocyclyl contains a secondary amine as part of its structure, then:

(i) V is linked through the nitrogen of the secondary amine portion of the heterocyclyl; and

(ii) U is linked to Cy via a Cy ring carbon atom; wherein the bond between U and the Cy ring carbon is a single or double bond;

V is:

(i) —V′—C(R y ) 2 — or —C(R y ) 2 —V′—; or

(ii) O, NR z , or S(O) m , and m is 0-2; or

(iii) —CH═CH—, C═O, C(R y ) 2 —C(═O), —C(═O)—C(R y ) 2 —, —SO 2 NR z , NR z SO 2 , —C(═O)NR z , or NR Z C(═O); wherein:

each occurrence of R y is independently selected from H, F, OH, C1-C6 alkyl, C3-C6 cycloalkyl, NH 2 , OCO—(C1-C6 alkyl), OCO—(C3-C6 cycloalkyl), C1-C6 alkoxy C1-C6 fluoroalkoxy, and cyano; or

R y —C—R y together form C3-C6 cycloalkyl or heterocyclyl having 3-6 ring atoms, in which one of the heterocyclyl ring atoms is selected from O; S(O) m , and NR aa ; and m is 0-2;

each occurrence of R z and R aa is independently selected from H, C1-C6 alkyl, —C(═O)H, —C(═O)R v , C(═O)O(C1-C6 alkyl), C(═O)N(R w ) 2 , and SO 2 —R v , wherein R v is selected from C1-C6 alkyl, CH 2 -(heteroaryl having 5-10 ring atoms), CH 2 —(C6-C10 aryl), and C6-C10 aryl; and each occurrence of R w is independently selected from H, C1-C6 alkyl, CH 2 -(heteroaryl having 5-10 ring atoms), CH 2 —(C6-C10 aryl), and C6-C10 aryl;

V′ is a bond; O; NR u ; S(O) m ; —C(O)—O—(CR y 2 ) 0-2 —, —(CR y 2 ) 0-2 —O—C(O)—, C(R y ) 2 , C(R y ) 2 —C(R y ) 2 ; —(R y ) 2 —V″; or V″—C(R Y ) 2 —; wherein V″ is O; NR z ; or S(O) m ; each occurrence of R y is independently defined as above; and each m is independently 0-2;

R2 is selected from H, F, CI, CF 3 , CF 2 CF 3 , CH 2 CF 3 , OCF 3 , OCHF 2 , phenyl; phenyl substituted with from 1-3 substituents independently selected from F, OH, C1-C6 alkyl, fluoro(C1-C6) alkyl C3-C6 cycloalkyl, NH 2 , C1-C6 alkoxy, C1-C6 fluoroalkoxy, and cyano; thienyl; thiazolyl; and pyrazol-1-yl; and

R3 is H, F, or Cl;

or a pharmaceutically acceptable salt thereof.

2. The compound or salt according to claim 1 , wherein Cy is a saturated heterocyclyl including 4-10 ring atoms, optionally substituted with from 1-3 R x , in which from 1-3 heteroatoms are independently selected from O, N—H, NR x″ , and S(O) m ; and m is 0-2.

3. The compound or salt according to claim 1 , wherein Cy is azetidinyl, pyrrolidinyl, piperidinyl, azepanyl, diazepanyl, isoxazolidinyl, thiazolidinonyl, imidazolidinonyl, pyrrolidinonyl.

4. The compound or salt according to claim 3 , wherein Cy is azetidinyl, pyrrolidinyl or piperidinyl.

5. The compound or salt according to claim 1 , wherein R1 is phenyl or naphthyl, which is optionally substituted with from 1-3 R q , and each R q is independently selected from F, OH, C1-C6 alkyl, fluoro(C1-C6) alkyl, C3-C6 cycloalkyl, NH 2 , C1-C6 alkoxy, C1-C6 fluoroalkoxy, and cyano.

6. The compound or salt according to claim 1 , wherein R1 is monocyclic or bicyclic heteroaryl having from 5-10 ring atoms, which is optionally substituted with from 1-3 R q ; wherein from 1-4 of the ring atoms is/are a heteroatom independently selected from O, N, N—H, N—R q , and S.

7. The compound or salt according to claim 1 , wherein R1 is H.

8. The compound or salt according to claim 1 , wherein V′ is a bond.

9. The compound or salt according to claim 1 , wherein U is ═CR r and R r is hydrogen.

10. The compound or salt according to claim 1 , wherein one of the following applies: (i) R2 is a substituent other than hydrogen, and R3 is hydrogen; or (ii) R2 is hydrogen, and R3 is a substituent other than hydrogen.

11. The compound or salt according to claim 1 , wherein each of R2 and R3 is hydrogen.

12. A compound selected from the group consisting of compounds

or a pharmaceutically acceptable salt thereof.

13. A pharmaceutical composition comprising a compound, or pharmaceutically acceptable salt thereof, as claimed in claim 1 and a pharmaceutically acceptable carrier.

14. A method of selectively inhibiting HDAC1, HDAC2, or HDAC3, the method comprising contacting a cell with an effective amount of a compound, or pharmaceutically acceptable salt thereof, as claimed in claim 1 .

15. A method of treating a neurological disorder selected from Friedreich's ataxia, myotonic dystrophy, spinal muscular atrophy, fragile X syndrome, Huntington's disease, spinocerebellar ataxia, Kennedy's disease, amyotrophic lateral sclerosis, spinal and bulbar muscular atrophy, and Alzheimer's disease in a patient in need thereof, the method comprising administering a compound, or pharmaceutically acceptable salt thereof, as claimed in claim 1 to said patient.

16. The method of claim 15 , wherein the neurological disorder is Friedreich's ataxia.