prov:value
| - The method as claimed in claim 4, wherein the substituent or the groups represented by each of R1 and R2 is a halogen atom, aryl group, alkoxy group, aryloxy group, sulfonyl group, sulfonamido group, sulfamoyl group, carbamoyl group, amido group, ureido group, alkoxycarbonylamino group, aryloxycarbonylamino group, alkoxycarbonyl group, aryloxycarbonyl group, cyano group, hydroxyl group, carboxyl g
|