Patent ID: 8058280

Claim:
A compound of the formula (I): wherein R 1 is a C 1-4 alkyl; R 2 is a 5- to 7-membered nitrogen-containing heterocyclic group which may have a substituent selected from the group consisting of (1â€²) a halogen, (2â€²) a hydroxy group, (3â€²) a C 1-4 alkyl and (4â€²) a C 1-4 alkoxy; R 3 is a C 1-4 alkyl; R 4 is (1) a hydrogen atom, (2) a C 1-4 alkoxy, (3) a C 6-10 aryl, (4) a Nâ€”C 1-4 alkyl-Nâ€”C 1-4 alkylsulfonylamino, (5) a hydroxyl group, or (6) a 5- to 7-membered nitrogen-containing heterocyclic group which may have a substituent selected from the group consisting of (1â€²) oxo, (2â€²) a C 1-4 alkyl, (3â€²) a hydroxy-C 1-4 alkyl, (4â€²) a C 1-4 alkoxy-carbonyl, (5â€²) a mono-C 1-4 alkyl-carbamoyl and (6â€²) a C 1-4 alkylsulfonyl; n is an integer of 1 to 4; or a salt thereof.