Preparation of Dialkyl 1-(Alkylamino)alkylphosphonates, Alkyl [1-(Alkylamino)alkyl]phenylphosphinates and [1-(Alkylamino)alkyl]diphenylphosphine Oxides via 'In Situ' Generated Iminium Ions

The reaction of trialkyl phosphites, dialkyl phenylphosphonites or alkyl diphenylphosphinites with N-alkylalkanimines in the presence of hydrogen chloride gives dialkyl 1-(alkylamino) alkylphosphonates, alkyl [1-(alkylamino)alkyl]phenylphosphinates or [1-(alkylamino) alkyl] diphenylphosphine oxides respectively, via Arbusov-like reaction of iminium salts generated 'in situ' from N-alkylalkanimines. This reaction is an alternative and competitive to known method of preparation based on the addition of H-P compounds to N-alkylalkanimines, because it gives higher yields, no heating is necessary, and the isolation of products is easy.