Rapid Construction of [5−6−7] Tricyclic Ring Skeleton of <i>Calyciphylline</i> Alkaloid Daphnilongeranin B

Abstract

A concise photochemical [2 + 2] cycloaddition-Grob fragmentation sequence sets the common tricyclic ring skeletons of the Calyciphylline A-type alkaloids, particularly those in daphnilongeranins, daphniyunnines, and daphniglaucins.