Abstract: Disclosed are a novel phosphorylating reagent and related methods. Specifically disclosed is a compound represented by general formula (A). In the formula, WG1 and WG2 independently represent a cyano group, a nitro group, a halogen atom, an alkylsulfonyl group or an arylsulfonyl group; X1, X2, X3 and X4 independently represent CR or N; and R represents H, a methyl group, a halogen atom, a trifluoromethyl group, a cyano group, a nitro group, an alkoxycarbonyl group, a carbamoyl group, a monoalkylcarbamoyl group, a dialkylcarbamoyl group, a sulfamoyl group, a monoalkylsulfamoyl group, a dialkylsulfamoyl group, or an alkylsulfonyl group.