| abstract |
Disclosed is a method for producing a compound (III), a salt thereof or a solvate of them by reacting a compound (I), a salt thereof or a solvate of them with a compound (II) in a toluene solvent in the presence of an additive such as water or an alcohol. Also disclosed is a method for producing a compound (IV) wherein the thus-obtained compound (III) is hydrolyzed if necessary, and then oxidized. (In the formulae, R1 represents a hydrogen, an optionally substituted lower alkyl, an optionally substituted aryl or an optionally substituted aryl-lower alkyl; and R2 represents an optionally substituted lower alkyl, an optionally substituted cycloalkyl or an optionally substituted aryl-lower alkyl.) |