Patent ID: 8093248

Claim:
A compound of formula (I) or a pharmaceutically acceptable salt thereof, wherein: X 1 is selected from N and CH; R 1 is selected from hydrogen, C 1-6 -alkyl which is unsubstituted or optionally substituted with one or more substituents independently selected from halogen, hydroxy, cyano and C 1-6 -alkoxy, and C 1-6 -acyl which is unsubstituted or optionally substituted with one or more substituents independently selected from halogen, hydroxy and C 1-6 -alkoxy attached to an atom other than the carbonyl carbon atom of the C 1-6 -acyl; each R 4 is independently selected from halogen, hydroxy, cyano, nitro, CF 3 , C 1-6 -alkyl and C 1-6 -alkoxy; c is 0, 1, 2 or 3; f is 0, 1, 2 or 3; and g is 0, 1 or 2; with the proviso that the compound or pharmaceutically acceptable salt thereof is not 2-(4-piperidinyl)ethyl 4-phenylpiperazine-1-carboxylate or a pharmaceutically acceptable salt thereof.