A highly stereoselective synthesis of optically active trisubstituted 1,2-ethylenediamines:: The first example of Grignard addition to N-diphenylphosphinoyl ketimines derived from amino acids

The efficient synthesis of optically active trisubstituted 1,2-ethylenediamines is described. Addition of aryl and/or alkyl Grignard reagents to a-amino N-diphenylphosphinoyl ketimines derived from a-amino acids was demonstrated to afford the desired trisubstituted 1,2-ethylenediamines in good yields and with high diastereoselectivities. Subsequent removal of the diphenyphosphinoyl group from the adduct was smoothly accomplished in reasonable yield without racemization under newly developed reductive conditions.