Histone deacetylase inhibitors

1. A compound of the formula

or a pharmaceutically acceptable salt thereof, wherein:

each R′ is independently H or QR 1 ;

each Q is independently selected from the group consisting of: a bond, CO, CO 2 , NH, S, SO, SO 2 and O;

each R 1 is independently selected from the group consisting of: H, C 1 -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 10 alkynyl, aryl, heteroaryl, C 3 -C 10 cycloalkyl, halogen, C 1 -C 10 alkylaryl, C 1 -C 10 alkyl heteroaryl and C 1 -C 10 heterocycloalkyl;

each L is a 5 to 10-membered nitrogen-containing heteroaryl, wherein at least one L is pyrazinyl;

W is

each R 2 is independently hydrogen or C 1 to C 6 alkyl;

R 3 is an aryl or heteroaryl;

each aryl or heteroaryl may be substituted by up to three substituents selected from the group consisting of C 1 -C 6 alkyl, hydroxy, C 1 -C 3 hydroxyalkyl, C 1 -C 3 alkoxy, C 1 -C 3 haloalkoxy, amino, C 1 -C 3 mono alkylamino, C 1 -C 3 bis alkylamino, C 1 -C 3 acylamino, C 1 -C 3 aminoalkyl, mono (C 1 -C 3 alkyl) amino C 1 -C 3 alkyl, bis(C 1 -C 3 alkyl) amino C 1 -C 3 alkyl, C 1 -C 3 alkyl sulfonylamino, halo, nitro, cyano, trifluoromethyl, carboxy, C 1 -C 3 alkoxycarbonyl, aminocarbonyl, mono C 1 -C 3 alkyl aminocarbonyl, bis C 1 -C 3 alkyl aminocarbonyl, —SO 3 H, C 1 -C 3 alkylsulfonyl, aminosulfonyl, mono C 1 -C 3 alkyl aminosulfonyl and bis C 1 -C 3 -alkyl aminosulfonyl; and

each alkyl, alkenyl or alkynyl may be substituted with a substituent selected from the group consisting of halogen, NH 2 , NO 2 and hydroxyl.

2. The compound of claim 1 , wherein in both L groups, the atom that is directly bonded to the N is a carbon, and at least one nitrogen atom is directly bonded to said carbon.

3. The compound of claim 1 , wherein R 3 is phenylene or phenylene substituted with a halogen.

4. The compound of claim 1 , wherein at least one of R 2 is H.

5. The compound of claim 1 , wherein R′ that is attached to L is independently selected from the group consisting of H, C 1 -C 10 alkyl, O—(C 1 -C 10 alkyl), halogen, C 1 -C 10 heterocycloalkyl, aryl, trifluoromethyl and heteroaryl.

6. The compound of claim 1 , wherein at least one of R′ is selected from the group consisting of H, halogen, CF 3 , C 1 -C 6 alkyl, aryl optionally substituted with halogen, heteroaryl optionally substituted with halogen, and heterocycloalkyl.

7. The compound of claim 1 , wherein at least one of the R′ that is attached to L is heterocycloalkyl.

8. The compound according to claim 7 , wherein R′ attached to R 3 is hydrogen or halogen.

9. The compound according to claim 7 , wherein at least one of R′ is C 1 -C 6 alkyl optionally substituted with a substituent selected from the group consisting of halogen, NH 2 , NO 2 and hydroxyl.

10. The compound according to claim 9 , wherein at least one of R′ is C 1 -C 6 alkyl optionally substituted with halogen.

11. A pharmaceutical composition comprising a compound of claim 1 and a pharmaceutically acceptable carrier.

12. A compound selected from the group consisting of: N-Hydroxy-4-((pyrazin-2-yl(pyridin-2-yl)amino)methyl)benzamide; 4-(((5-Fluoropyridin-2-yl)(pyrazin-2-yl)amino)methyl)-N-hydroxybenzamide; 4-(((4-(4-Fluorophenyl)pyridin-2-yl)(pyrazin-2-yl)amino)methyl)-N-hydroxybenzamide; N-Hydroxy-4-{[(pyrazin-2-yl)(pyrimidin-4-yl)amino]methyl}benzamide; 3-Fluoro-N-hydroxy-4-{[(pyrazin-2-yl)(pyrimidin-4-yl)amino]methyl}benzamide; N-Hydroxy-6-{[(pyrazin-2-yl)(pyrimidin-4-yl)amino]methyl}pyridine-3-carboxamide; 4-{[Bis(pyrazin-2-yl)amino]methyl}-N-hydroxybenzamide; 4-{[Bis(pyrazin-2-yl)amino]methyl}-3-fluoro-N-hydroxybenzamide; 6-{[Bis(pyrazin-2-yl)amino]methyl}-N-hydroxypyridine-3-carboxamide; N-Hydroxy-4-{[(3-methoxypyridin-2-yl)(pyrazin-2-yl)amino]methyl}benzamide; 3-Fluoro-N-hydroxy-4-{[(3-methoxypyridin-2-yl)(pyrazin-2-yl)amino]methyl}benzamide; N-Hydroxy-6-{[(3-methoxypyridin-2-yl)(pyrazin-2-yl)amino]methyl}pyridine-3-carboxamide; N-Hydroxy-4-{[(pyrazin-2-yl)(pyridazin-3-yl)amino]methyl}benzamide; 3-Fluoro-N-hydroxy-4-{[(pyrazin-2-yl)(pyridazin-3-yl)amino]methyl}benzamide; N-Hydroxy-4-{[(3-methyl-1,2,4-thiadiazol-5-yl)(pyrazin-2-yl)amino]methyl}benzamide; N-Hydroxy-4-{[(4-methoxypyridin-2-yl)(pyrazin-2-yl)amino]methyl}benzamide; N-Hydroxy-4-{[(pyrazin-2-yl) [6-(trifluoromethyl)pyrazin-2-yl]amino]methyl}benzamide; 4-({[5-(6-Aminopyridin-3-yl)pyridin-2-yl](pyrazin-2-yl)amino}methyl)-N-hydroxybenzamide; 4-({[5-(2-Aminopyridin-4-yl)pyridin-2-yl](pyrazin-2-yl)amino}methyl)-N-hydroxybenzamide; N-hydroxy-4-[({5-[2-(methylamino)pyridin-4-yl]pyridin-2-yl}(pyrazin-2-yl)amino)methyl]benzamide; N-hydroxy-4-{[(pyrazin-2-yl)[5-(pyridin-4-yl)pyridin-2-yl]amino]methyl}benzamide; and pharmaceutically acceptable salts thereof.