Asymmetric synthesis of ephedrine analogs

Article abstract of DOI:10.1016/S0022-328X(00)99049-1

Addition of nitromethane to the chiral chromium tricarbonyl complex of o-tolualdehyde (1) gives, under conditions of kinetic control, the nitroalcohol 2 with ca. 95percent of asymmetric induction.Compound 2 then gives, in 3 steps, the corresponding aminoalcohol in about 40percent.Use of nitroethane gives the nitroalcohol with a small diastereoselectivity at C(2)-C(3) (d.e. = 30 and 55percent), but analogs of ephedrine and pseudoephedrine can be obtained optically pure by chromatography.