Total Synthesis and Revision of Stereochemistry of a Natural Benzo[ g ]isochromene Stereodiad Isolated from Rubia philippinensis .

This study presents a total synthesis and revision of the stereochemical configuration of the conformationally flexible natural product benzo[ g ]isochromene stereodiad alongside its diastereomeric counterparts. The highlights of the synthesis are the TiCl 4 -mediated diastereoselective aldol reaction, Pd-catalyzed lactonization, and Schmidt glycosidation. Our efforts using total synthesis disclosed herein proved that a previously assigned structure required revision.