CHIRAL AMINE-BORANES DERIVED FROM EPHEDRI NE AND PSEUDOEPHEDRINE AS ASYMMETRIC REDUCTION AND HYDROBORATION REAGENTS - STERICAL RELATIONSHIPTO THE MECHANISM OF THE REACTIONS

The aminoborane adducts derived from N-methyl-O-isopropyl-(+)- and (-) -ephedrine, and N-methyl-O-isopropyl-(+)- and (-)-pseudoephedrine redu ce ketones to alcohols enantioselectively when the reactions were carr ied out in the presence of Lewis acids. These aminoborane adducts also react with stilbene leading to 1,2-diphenylethanol enantiomerically e nriched. Altough the optical yields are low, these reactions give ster eochemical information about the reaction mechanisms.