DIRECT TRANSFORMATION OF PHOSPHINIC ACIDS IN THE 3-PHOSPHOLENE SERIES TO PHOSPHINAMIDES

Abstract

Tris(N,N-dialkylamino)phosphines undergo a transamination reaction with phosphinic acids containing the 3-phospholene ring. Yields of phosphinamides ranged from 66 to 93% for five different combinations. Products were characterized by ¹³C and ³¹P NMR. Transamination was not effected with diphenylphosphinic acid or methylphosphonic acid, but a low conversion of diethyl phosphate to its amide was achieved. With p-toluenesulfonic acid, tris(N,N-dimethylamino)phosphine was converted to a stable salt. The mechanism of the reaction with the phospholene acids was determined by ³¹P NMR studies to proceed through formation of a mixed anhydride R₂P(O)[sbnd]O[sbnd]P(NR^' ₂)₂; the displaced dialkylamino group then attacks at phosphoryl to give the phosphinamide.