Diarylphosphinic azides: Photochemical reactions including rearrangement in methanol

On photolysis in methanol the diarylphosphinic azides AR₂P(O)N₃ (Ar = phenyl,p-tolyl,p-anisyl,p-chlorophenyl) rearragement with loss of nitrogen to form (monemeric) metaphosphonimidates which are trapped by the solvent to give methyl NP-diarylphosphonamidates (7) (41–53%). Diarylphosphinic amides (18–42%) are also usually formed, presumably from (triplet) nitrenes. The limited evidence available suggests that the rearrangements take place directly from the photo-excited azides rather than via (singlet) nitrene intermediates. One of the products of rearrangement, methyl NP-di(p-chlorophenyl)phosphonamidate, suffers extensive photochemical dechlorination giving methyl N-phenyl-P-p-chlorophenylphosphonamidate.