Convenient method for the synthesis of C-phosphorylated N-arylformamidines

C-Phosphorylated (P^V) arylformamidines have been prepared by the reaction of N-arylamidotrichloromethyl derivatives of phosphorus, thiophosphorus, and selenophosphorus acids with secondary amines. Dependence of the reaction on the nature of chalcogene, electronic and steric factors has been studied. By reduction of N-arylformamidinophosphonoselenides the corresponding C-phosphorylated (P^III) arylformamidines have been synthesized.