Patent ID: 7491705

Claim:
A compound represented by the formula (I) wherein R 1 is (1) a group represented by the formula (IIb) in which n is an integer of 2 to 5, (2) a straight or branched C 1-6 alkyl substituted by a pyridyl group optionally having a C 1-3 alkyl substituent on the pyridine ring, or (3) a tetrahydrofuranyl group or a tetrahydropyranyl group; R 2 is a straight or branched C 1-6 alkyl, optionally substituted by a phenyl; and R 3 is hydrogen, a straight or branched C 1-6 alkyl or is selected from the group consisting of cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl.