Chiral synthesis of (+)-8′-demethyl abscisic acid

An enantioselective synthesis of (+)-8′-demethyl ABA ( 2 ) is described. The chiral intermediate 7 was prepared by yeast reduction of a substituted monoprotected cyclohexa-2,5-dien-1,4-dione ( 9 ) synthesized through a phenol oxidation. The scope and limitations of the phenol oxidation is described. 8′-Demethyl ABA shows ABA-like activity in wheat embryo germination inhibition, showing that the 8′-methyl group is not essential for biological activity. Key words: abscisic acid, phenol oxidation, yeast reduction.