Stereoselective lithiation and alkylation and aldol reactions of chiral 5-methyl-3-(o-aryl)-oxazolidinones

Alkylation and aldol reactions carried out on axially chiral, diastereoenriched oxazolidinedione derivatives were found to be highly stereoselective with respect to substitution at the 5-position of the oxazolidindione ring. Thus, diastereoenriched 5-methyl-3-(o-iodophenyl)-2-thioxo-4-oxazolidinone and 5-methyl-3-(o-aryl)-2,4-oxazolidinediones were prepared and lithiated at C-5 of the oxazolidine ring and the subsequent electrophilic quench with alkyl halides or benzaldehyde yielded products with the same diastereomer ratios as the starting materials.