Studies on phosphoroheterocycle chemistry II: A simple and new route to 1,3,2-diazaphospholidine-4-thione 2-sulfide derivatives

A simple and new method for the synthesis of phosphoroheterocycles 1,3,2-di azaphospholidine-4-thione 2-sulfide derivatives by treatment of Lawesson's reagent (LR) with a variety of alpha -aminonitriles has been developed. The same methodology was also used in the preparation of fused phosphorohetero cycle 6 from 5-amino-4-cyano-3-methylthia-1-phenylpyrazole. The possible me chanism of the reaction involving addition of P-SH to the nitrile and subse quent rearrangement is proposed.