Vinyltriphenylphosphonium salt mediated serendipitous synthesis of aryliminophosphoranes

Crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine, dimethyl acetylenedicarboxylate and aromatic amines, such as aniline, 1-naphthylamine, p-toluidine, 4-bromoaniline, 4-nitroaniline, 4-acetylaniline, 2-aminopyridine, or 2-amino-5-bromopyridine. These stabilized phosphoranes undergo a smooth intramolecular reaction in boiling p-xylene or toluene to produce aryliminophosphoranes in excellent yields.