Isoxazolidine-based chiral auxiliaries for asymmetric syntheses

Abstract

Two types of chiral auxiliaries based on the isoxazolidine skeleton have been developed for asymmetric syntheses. The characteristic features of these auxiliaries are as follows: (1) acylation of the auxiliary with acid chloride and amine, or DCC condensation; (2) high reactivity for asymmetric alkylation; and (3) one-step transformation of the reaction products to the corresponding chiral alcohols, aldehydes and ketones without loss of the stereochemical integrity with recovery of the auxiliary. The synthetic utility and significance of these auxiliaries are demonstrated.