A versatile synthesis of chiral beta-aminophosphines

A method for the preparation of chiral [small beta]-aminophosphines having substituted P-aryl groups is described. Ring-opening of cyclic sulfamidates with metal diarylphosphinites yields [small beta]-aminophosphine oxides, which are then reduced to the corresponding phosphines. Effects of the diarylphosphinite countercation on the regioselectivity of the ring-opening reaction (P- versus O-alkylation) are discussed. This method enables the introduction of electron-deficient, electron-rich and sterically hindered diarylphosphino groups, as demonstrated by the synthesis of a series of novel, P-aryl-substituted [small beta]-aminophosphines derived from tert-leucinol, valinol and phenylglycinol. Access to these derivatives will create new opportunities for steric and electronic tuning of [small beta]-aminophosphine-derived chiral ligands and organocatalysts.