A FORMAL SYNTHESIS OF (-)-KAINIC ACID BY MEANS OF SmI2-MEDIATED RADICAL CYCLIZATION

A formal synthesis of (-)-kainic acid (1) starting from the known D-serine derivative 9 has been established in 14 steps. Construction of all the stereogenic centers on the pyrrolidine core of 1 was successfully achieved by application of SmI2-mediated radical cyclization to the alpha,beta-unsaturated ester having an alkyne moiety, followed by hydroxy group directed diastereoselective hydrogenation over Wilkinson's catalyst.