Non-thiazolidinedione antihyperglycaemic agents. Part 5: Asymmetric aldol synthesis of (S)-(−)-2-oxy-3-arylpropanoic acids

Abstract Boron-mediated asymmetric aldol reactions of substituted benzaldehyde 5 with 2-oxyethanoyloxazolidinones 4a – e , containing electron withdrawing, chelating, and bulky alkoxy and aryloxy groups, gave variable yields of syn -aldol adducts 6a – e in high diastereoisomeric excess. Dehydroxylation of these adducts afforded 7a – e in a sequence which complements the traditional Evans asymmetric alkylation strategy. Cleavage of the auxiliary from 7a – e afforded antihyperglycaemic ( S )-(−)-2-oxy-3-arylpropanoic acids 3a – e in excellent enantiomeric excess.