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 a-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 ((-)-ll, (-)-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 (-)-ll 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.

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Synthesis of Optically Pure Gomisi Lignans:The Total Synthesis of (+)-Schizandrin (VIIIa), (+)-Gomisin A (VIIIb), and (+)-Isoschizandrin (XI) in Naturally Occurring Forms.--(TANAKA, M.; MUKAIYAMA, C.; MITSUHASHI, H.; MARUNO, M.; WAKAMATSU, T.; J.