PHOTOREACTIONS OF IMINOPHOSPHORANES

The irradiation of N-aryltriphenyliminophosphoranes in inert solvents leads to efficient production of triphenylphosphine and the diaryl azo compounds derived from the N-aryl ylide substituent. The irradiation of N-alkyltriphenyliminophosphoranes leads to rearrangements of the N-alkyl substituent analogous to those observed during the irradiation of the corresponding azides. Triphenyliminophosphoranes which possess N-substituents capable of strong delocalization of the nitrogen lone pair (e.g. benzene sulfonyl, benzoyl) are photostable. Since all attempts to trap nitrene intermediates suspected to be formed during the photoreactions of the photolabile iminophosphoranes were unsuccessful, the reactions are considered to proceed via excited ylide intermediates.