Asymmetric synthesis of evoninic acid

Evoninic acid (3) is a component of a 14-membered bislactone of bioactive dihydro-β-agarofuran sesquiterpenoids. The unique structure of 3 is characterized by C2′,C3′-disubstituted pyridine and vicinal C7′S,C8′S-dimethyl groups. Here we report a new synthetic route to enantiopure 3. A chiral oxazolidinone controlled the stereochemical outcome of olefin hydrogenation, establishing the absolute configuration of the C7′S-methyl group. The C7′S-stereocenter then influenced the diastereoselectivity to install the C8′S-methyl group.