Phosphoric Acid Catalyzed Desymmetrization of Bicyclic Bislactones Bearing an All-Carbon Stereogenic Center: Total Syntheses of (-)-Rhazinilam and (-)-Leucomidine B

In the presence of a catalytic amount of an imidodiphosphoric acid, enantioselective desymmetrization of bicyclic bislactones by reaction with alcohols took place smoothly to afford enantiomerically enriched monoacids having an all-carbon stereogenic center. Concise catalytic enantioselective syntheses of both (-)-rhazinilam and (-)-leucomidineB were subsequently developed using (S)-methyl 4-ethyl-4-formylpimelate monoacid as a common starting material.