Stereoselective reactions of optically active derivatives of α-methylbenzylaminophosphine

A number of N+(alpha-methylbenzyl) phosphorus amides were synthesized, and their stereochemical properties were studied. Reactions of achiral chlorophosphines with optically active alpha-methylbenzylamine are accompanied by asymmetric induction at the phosphorus atom to give optically active diastereoisomers of N-(alpha-methylbenzyl)aminophosphines, which were isolated as the corresponding borane complexes with 100% optical purity. Stereochemically pure (R,S)-aminophosphines were obtained by decomposition of these complexes via treatment with diethylamine. Their oxidation, sulfurization, and alkylation with methyl iodide afforded optically active aminophosphine derivatives. Hydrolysis of (R,S)-aminophosphines gave optically active tert-butylphenylphosphine oxide and phosphonic acid amides. (R,S)- and (S,S)-Diastereoisomers of N-(alpha-methylbenzyl)phosphinic amides were separated by crystallization and flash chromatography, and their absolute configuration was established. Also, derivatives of bis- and tris(alpha-methylbenzylamino)phosphines were synthesized.