The reaction between N-methyl-p-toluohydroxamic acid and tervalent phosphorous compounds: a thermal PIII→ PV rearrangement proceeding by a radical mechanism

Abstract

N-Methyl-p-toluohydroxamic acid (6) reacts rapidly with phosphorus compounds XYPCl (X = Ph, Y = OEt and X, Y = OCH₂CH₂O) at –60 °C in the presence of pyridine to give the P^III intermediates (7) which have been characterised by ¹H, ¹³C, and ³¹P n.m.r. spectroscopy. The intermediates decompose at ambient temperatures with homolysis of the N–O bond to give the isomeric N-phosphine oxides (8), accompanied by varying amounts of O-phosphonylhydroxamic acids (9)N-methyl-4-toluamide, (4) and phosphoryl-radical related products. Evidence for a radical-cage process (at least in part) is obtained from ¹H and ³¹P CIDNP studies.