Total Synthesis of (±)‐Glyflavanone by a Rigid Quaternary Ammonium Salt

Abstract

AbstractTotal synthesis of (±)‐glyflavanones and glychalcones was accomplished starting from the known 1‐(5‐hydroxy‐7‐methoxy‐2,2‐dimethyl‐2H‐chromen‐6‐yl)ethanone (6). A new approach to synthesis of flavanones, based on a high yielding N‐benzylcinchoninium salt catalyzed chromane ring forming enantio‐selective cyclization process, is described. Also, synthesis of (+)‐glyflavanone 1, the natural enantiomer, was achieved through optical resolution of a key intermediate in racemic synthesis.