Patent ID: 7872040

Claim:
A method for blocking α 2 receptor comprising administering an effective amount of a compound represented by formula (I) or a pharmaceutically acceptable salt thereof to a subject in need thereof: wherein R 1 represents a hydrogen atom, substituted or unsubstituted C 1-6 alkyl group, substituted or unsubstituted C 2-6 alkenyl group, substituted or unsubstituted C 2-6 alkynyl group, substituted or unsubstituted aromatic group, substituted or unsubstituted aralkyl group, substituted or unsubstituted acyl group, substituted or unsubstituted arylsulfonyl group, substituted or unsubstituted C 1-6 alkylsulfonyl group, or substituted or unsubstituted hydroxyl group; R 2 represents a C 4-21 aliphatic hydrocarbon group which may be substituted by one or more substituents selected from a C 1-6 alkyl group, C 2-6 alkenyl group, C 2-6 alkynyl group, aromatic group, acyl group, hydroxyl group, carboxyl group, halogen atom, and C 1-6 alkoxy group; R 3 , R 4 , R 6 , and R 7 are the same or different and represent a hydrogen atom, halogen atom, substituted or unsubstituted C 1-6 alkyl group, or substituted or unsubstituted C 1-6 alkoxy group; R 5 represents a hydrogen atom; R 8 represents a hydrogen atom or substituted or unsubstituted acyl group; n represents an integer of 1 to 6; and a and b are the same or different and represent 1 or 0.