Asymmetric Reactions. III. Stereoselectivity Difference between Grignard and Alkyllithium Reactions with 2,3-O-Substituted-d-glyceraldehydes

Abstract
Stereoselectivity has been investigated in addition reactions of 2,3-O-isopropylidene-d-glyceraldehyde (I) or 2,3-di-O-benzyl-d-glyceraldehyde (II) with phenylmagnesium bromide or phenyllithium. Stereoselectivity difference between the Grignard and phenyllithium reactions occurred in the case of compound (I): the phenyllithium reaction gives threo and the Grignard reaction erythro products predominantly. On the other hand, no difference in stereoselectivity has been observed between the reactions with 2,3-di-O-benzyl-d-glyceraldehyde (II): both reactions gave threo product predominantly.