Stereoselective total syntheses of (-)-hygrophorone A, 4--acetyl-hygrophorone A and (+)-hygrophorone B.

Total syntheses of anti-fungal cyclopentenones (-)-hygrophorone A12, 4-O-acetyl-hygrophorone A12 and (+)-hygrophorone B12 were achieved in high overall yields from d-(-)-tartaric acid. The key feature of these syntheses is the aqueous KOH-mediated diastereoselective intramolecular aldol reaction to form β-hydroxy ketone with three contiguous chiral centres, which was further elaborated to (-)-hygrophorone A12 and (+)-hygrophorone B12. The synthetic route reported here is operationally simple and highly diastereoselective and is amenable for the synthesis of several analogues of hygrophorones.