N,O-, N,N-, N,S-, and N,N,S-Heterocycles with an Exocyclic Amino Group in the Synthesis of 1,5,3,7-Diazadiphosphacyclooctanes

Abstract

New 1,5,3,7-diazadiphosphacyclooctanes with N,O-, N,N-, N,S-, and N,N,S-heterocyclic substituents at the nitrogen atoms have been synthesized. The influence of the nature of amines containing sp²-hybridized nitrogen atom in the ortho-position of the heterocyclic substituent on the result of Mannich condensation in phosphine–paraformaldehyde–primary amine system has been revealed. The stabilization of intermediate acyclic products—aminomethyl(hydroxymethyl)arylphosphines and bis(aminomethyl)arylphosphines—due to amino–imine tautomerism is responsible for the low yield of the target cyclic diphosphines based on the above amines.