Stereoselective reduction of α-hydroxy ketones

Reduction of α-hydroxy ketones with zinc horohydride afforded the erythro-glycols in high stereoselectivity, while reduction of their α-(t-butyldiphenylsily)oxy derivatives with sodium bis(2-methoxyethoxy)aluminum hydride gave the isomeric threoglycols. The structure-stereoselectivity relationship has been discussed.