Absolute configuration of 2,3-dihydroxy-3-methylpentanoic acid, an intermediate in the biosynthesis of isoleucine, and its identity with the esterifying acid of the pyrrolizidine alkaloid strigosine

Abstract

The (–)-erythro- and (–)-threo-isomers of 2,3-dihydroxy-3-methylpentanoicacid (I) have been synthesised. The (–)-erythro-isomer has been shown to have the absolute configuration 2R,3R and to be identical with the naturally occurring (–)-acid, a precursor of isoloucine (II), and with the esterifying acid of the pyrrolizidine alkaloid Strigosine.