Patent ID: 7767824

Claim:
A heterocyclic compound represented by the formula I: wherein represents R 1 represents a hydrogen atom, C 1 -C 6 alkyl or benzyloxy; R 2 represents methyl or nil; R 3 represents a hydrogen atom, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 3 -C 8 cycloalkyl or —CH 2 R 5 [wherein R 5 represents phenyl (which may be substituted with C 1 -C 6 alkyl, halogen atom or cyano) or thienyl]; R 4 represents C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 3 -C 8 cycloalkyl or —CH 2 R 6 [wherein R 6 represents phenyl (which may be substituted with C 1 -C 6 alkyl, halogen atom or cyano), naphtyl or thienyl].