Enantiospecific Synthesis of Analogues of the Diketide Intermediate of the Erythromycin Polyketide Synthase (PKS).

The four stereoisomers of 3-hydroxy-2-methylpentanoic acid (1a–d) and the structurally modified acids 1e–j have been synthesised enantiospecifically and converted into p-nitrophenyl ester and thioester derivatives; as the activated derivatives; they are available for investigations into the substrate selectivity of polyketide synthase (PKS) domains.