Formation of phospholimine and novel preparation of benzofurazans by thermolytic rearrangement of N-(o-nitroaryl)-1,2,5-triphenylphospholimines

Abstract

Reactions of 1,2,5-triphenylphosphole with aryl-, arylsulphonyl-, methylsulphonyl-, ethoxycarbonyl-, and diphenylphosphinyl-azides readily give the novel 1,2,5-triphenylphospholimines (I; X = Ar, ArSO₂, MeSO₂, EtO₂C, Ph₂PO) which are thermally stable except for N-o-nitroaryl derivatives, e.g.(III), which give benzofurazans and 1,2,5-triphenylphosphole oxide, a reaction which does not occur with the corresponding P-triphenyl-or P-trithoxy-derivatives [Ph₃P = NAr or (EtO)₃P = NAr].