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.