As shown in Scheme IX, amine Ip (where X1 and X2 are not hydrogen) can be reacted with diphenylcyanocarbonimidate either alone or in the presence of a base such as sodium hydride, sodium hexamethyldisilazide or dimethylaminopyridine in acetonitrile or tetrahydrofuran, dimethylformamide at room temperature or elevated temperature to form intermediate compound Iu which can be reacted with an amine (