Synthesis of optically pure gomisi lignans: The total synthesis of (+)-schizandrin, (+)-gomisin A, and (+)-isoschizandrin in naturally occurring forms

Article abstract of DOI:10.1021/jo00119a010

The total syntheses of (+)-schizandrin (1), (+)-gomisin A (2), and (+)-isoschizandrin (3) having natural configurations were accomplished. Optically pure butyrolactones ((-)-9, (-)-31) were transformed to α-benzylidenebutyrolactones ((+)-10, (+)-32, (+)-35). By a highly efficient iron(III) perchlorate-mediated oxidative coupling reaction of 10, 32, and 35, the key intermediates with biphenyl skeletons ((-)-11, (-)-33) were constructed with high stereoselectivity. Several methods for the stereoselective introduction of the C6-hydroxyl group were examined. For the synthesis of schizandrin and gomisin A, the Mukaiyama hydration reaction of (-)-11 and(-)-33 provided the desired products with satisfactory selectivity. For the synthesis of isoschizandrin, the stereoselective epoxidation of allylic alcohol (+)-48 was successfully utilized taking advantage of its conformational features.