Synthesis of the C19 through C27 segment of okadaic acid using vinylogous urethane aldol chemistry: Part III

Abstract

The synthesis of the C-19 through C-27 segment of the marine natural product okadaic acid was accomplished employing a highly enantio- and diasteroselective aldol coupling reaction of a chiral vinylogous urethane lactone enolate. The remainder of the carbon skeleton of this segment was constructed by a diastereoselective γ-oxygenated allylstannane addition. Formation of the tetrahydropyran ring was achieved utilizing a stereoselective electrophilic cyclization.