Michael Addition of P-Nucleophiles to Conjugated Nitrosoalkenes.

A general approach to various α-phosphorus-substituted oximes (β-oximinoalkyl-substituted phosphonates, phosphine oxides, phosphine-borane complexes, and phosphonium salts) was developed. The strategy exploits hitherto unknown Michael addition of PH-containing compounds (diphenylphosphine oxide, diisopropyl phosphite, phosphine-borane complexes, and triphenylphosphonium bromide) to unstable conjugated nitrosoalkenes, which are generated in situ from corresponding nitrosoacetals. The resulting α-phosphorus-substituted oximes can be considered as useful P-, N-, and O-ligands for catalysis and precursors to valuable β-aminophosphonates.