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

摘要

Total 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.