Insertion of Benzynes into the PN Bond of <i>P</i>-Alkenyl(alkynyl)-λ<sup>5</sup>-phosphazenes

Benzynes, generated from 2-(trimethylsilyl)phenyl triflates, have been found to react with <i>P</i>-Alkenyl-λ<sup>5</sup>-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. <i>P</i>-Alkynyl λ<sup>5</sup>-phosphazenes and phosphane sulfides undergo similar transformations.