Four New Dibenzocyclooctadiene Lignans from Schisandra rubriflora

From the aerial parts of Schisandra rubriflora (FRANCH) REHD. et WILS., four new dibenzocyclooctadiene lignans, methylgomisin R (1), (+)-14-tigloylgomisin K(3) (2), 12-demethylwuweilignan I (3), schisandrene A (4), together with 13 known lignans, were isolated. The structures of four new compounds were elucidated by spectroscopic methods including extensive 1D- and 2D-NMR techniques.