Patent ID: 7632950

Claim:
A compound represented by the following formula (I) or a salt thereof; wherein R1 represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, an aryloxy group, a formyl group, a carboxyl group, a carbonyl group, an oxycarbonyl group, a sulfonyl group, a carbamoyl group, a sulfamoyl group, a thiol group, an alkylthio group, an arylthio group, a thiocarbonyl group, a ureido group, an amino group, a carbonylamino group, a sulfonylamino group, a cyano group, a heterocycle residue, a fluorine atom, a bromine atom or an iodine atom, R2 represents a hydrogen atom or an alkyl group, and R3 represents a hydrogen atom, an alkyl group, a formyl group, a carboxyl group, a carbonyl group, an oxycarbonyl group, a sulfonyl group, a carbamoyl group or a sulfamoyl group.