Ruthenium-Catalyzed Alkyne−Propargyl Alcohol Addition. An Asymmetric Total Synthesis of (+)-α-Kainic Acid

A novel route to the neuroexcitatory amino acid, kainic acid, is developed. The key concept derives from a ruthenium-catalyzed cycloisomerization of a tethered alkyne−propargyl alcohol to form a cylic 2-vinyl-1-acyl compound. A single stereocenter introduced by an asymmetric reduction of a ketone sets the stage for all the other stereocenters. A novel 1,6-addition of silyl cuprate serves to install a hydroxyl group at the diene termines.