Total syntheses of the lignans isolated from Schisandra Chinensis

The total syntheses of wuweizisu C (4), gomisin J (6), gomisin N (7), and γ-schizandrin (8) having natural configuration were accomplished in a stereoselective manner. The catalytic hydrogenation or the metal mediated 1,4-reduction of the tetracyclic lactones (12, 17, 22, 30) played the significant role for the stereoselective introduction of C6, C7 dimethyl moiety. Furthermore, the neighboring carbonyl group assisted regioselective demethylation of 5 was essential for the synthesis of 6.