This invention provides a compound of the formula (I):
1
wherein R
1
and R
2
independently represent a hydrogen atom or the like; X represents a covalent bond or the like: A represents a bicyclic, aromatic, saturated or partially unsaturated heterocyclic or carbocyclic group having from 8 to 12 ring atoms; or the like: B represents a phenyl group or a heteroaryl group having from 5 to 6 ring atoms or the like:
These compounds are useful for the treatment of disease conditions caused by overactivation of NMDA NR2B receptor such of pain, or the like in mammalian. This invention also provides a pharmaceutical composition comprising the above compound.