AEI: Diastereoselective nucleophilic additions to 2-keto-4-methyl-1,3-dioxanes: 1,3-Dioxanes as chiral auxiliaries

ORGN 98

Daniel R. Clark and William F. Bailey. Department of Chemistry, University of Connecticut, 55 N Eagleville Rd., Unit 3060, Storrs, CT 06269-3060
The diastereofacial selectivity of the reaction of various metal hydrides and Grignard reagents with 2-keto-4-methyl-1,3-dioxanes 1 has been investigated. Diastereoselectivities in excess of 90:10 favoring formation of alcohol 2 are observed for additions involving metal hydrides and Grignard reagents that are capable of reasonably strong coordination with the carbonyl oxygen and the dioxane oxygen remote from the 4-methyl group. Application of this simple methodology to the enantioselective preparation of a-hydroxy acids will be discussed.