A new 9,10-dihydrophenanthrenedione from Cannabis sativa

The structure of a new 9,10-dihydrophenanthrenedione, which was isolated from the leaves and branches of Cannabis sativa L., was elucidated as 9,10-dihydro-2,3,5,6-tetramethoxyphenanthrene-1,4-dione (1) on the basis of MS, 1 H NMR, and 13 C NMR methods, especially 2D NMR techniques (HMBC and NOESY).