Insertion of benzynes into the P═N Bond of P-alkenyl(alkynyl)-λ5-phosphazenes.

Benzynes, generated from 2-(trimethylsilyl)phenyl triflates, have been found to react with P-Alkenyl-λ(5)-phosphazenes via a formal π-insertion into the P═N bond. A subsequent retro [2 + 2] cycloaddition/6π electrocyclization/protonation cascade explains the formation of the resulting 1,4-benzazaphosphorinium triflates. P-Alkynyl λ(5)-phosphazenes and phosphane sulfides undergo similar transformations.