First examples of methylene insertion into the phosphorus(III)–nitrogen bond

The reaction of N-substituted phosphinous amides with paraformaldehyde leads to methylene insertion into the P–N bond, followed by the oxidation of phosphorus from P(III) to P(V) state. The product, Ph2P(O)CH2NHPh was characterised by a single-crystal X-ray diffraction study. The reaction not only depends on the acidic proton on the nitrogen, but also on the oxidation state of phosphorus and it is considered to proceed through Staudinger–Wittig pathway.