Rubriflorin A and B, Two Novel Partially Saturated Dibenzocyclooctene Lignans from Schisandra rubriflora

From the stems of Schisandra rubriflora , two novel partially saturated dibenzocyclooctene lignans, named rubriflorin A ( 1 ) and B ( 6 ), as well as the seven known partially saturated dibenzocyclooctene lignans kadsumarin A ( 2 ), kadsurin ( 3 ), heteroclitin B ( 4 ), heteroclitin C ( 5 ), heteroclitin D ( 7 ), interiorin ( 8 ), and interiorin B ( 9 ) were isolated. The structures of the new compounds 1 and 6 were established on the basis of spectral analysis as (5 R ,6 S ,7 R ,8 R ,13a S )‐8‐(acetyloxy)‐5,6,7,8‐tetrahydro‐1,2,3,13‐tetramethoxy‐6,7‐dimethylbenz([3,4]cycloocta[1,2‐ f ][1,3]benzodioxol‐5‐yl (2 Z )‐2‐methylbut‐2‐enoate and (6 R ,7 R ,12a S )‐7,8‐dihydro‐12‐hydroxy‐1,2,3,10,11‐pentamethoxy‐6,7‐dimethyl‐6 H ‐dibenzo[ a , c ]cycloocten‐5‐one, respectively.