Bioinspired syntheses of cryptoflavanones C and D, oboflavanones A and B, and cryptoyunnanones G and H enabled by an acid-triggered cascade sequence

Abstract

We herein present a concise synthetic route for the collective total syntheses of six flavanones named oboflavanones A and B, cryptoflavanones C and D, and cryptoyunnanones G and H, which were all isolated from the genus Cryptocarya. The key strategy of these syntheses involves a bioinspired acid-triggered olefin isomerization/hemiacetalization/dehydration/Friedel–Crafts alkylative formal [3 + 3]-type cycloaddition cascade process.