or one of them in an excess amount under cooling to heating under reflux, wherein it is preferable to carry out it under heating.The reaction may be carried out without solvent or in a solvent inert to the reaction, including an aromatic hydrocarbon such as benzene, toluene, xylene, mesitylene and the like, an ether such as diethyl ether, tetrahydrofuran, dimethoxyethane(DME) and the like, a halog