A stereodivergent approach to (-)-α-kainic acid and (+)-α-allokainic acid utilizing the complementarity of alkyne and allene cyclizations

A formal synthesis of (+)-alpha-allokainic acid and a total synthesis of (-)-alpha-kainic acid were carried out using a short, efficient, and highly stereoselective approach. From an alkyne precursor, a nickel-catalyzed cyclization and a palladium-catalyzed rearrangement were utilized in the synthesis of (+)-alpha-allokainic acid. From an allene precursor, a nickel-catalyzed cyclization was utilized in the synthesis of (-)-alpha-kainic acid. The allene cyclization used in the latter sequence was the first example of a metal-catalyzed cyclization of this type.