Vanadium(V)-catalyzed epimerization of isoleucine

Abstract

All stereoisomers of isoleucine were transformed to the mixtures of the corresponding epimers by epimerization in alkaline aqueous solution. The catalyst was formed in situ by condensation of salicylaldehyde and isoleucine followed by complexation with vanadate. No derivatization of the amino acid was necessary. The tetrabutylammonium salts of [VO2(N-salicylidene-isoleucinato)]− can be used for diastereomeric separation of the epimers providing low yields and moderate diastereoselectivities.