5 NEW MODIFIED 6,7-SECOLABDANE DITERPENOIDS FROM CLUYTIA-RICHARDIANA

The aerial parts of Cluytia richardiana yielded five new modified 6,7- secolabdane diterpene derivatives, saudinolide (4), dihydrosaudinplide (5), 5 beta-hydroxyrichardianidin 1 (6), and 5 beta-hydroxyrichardian idin 2 (7), and the 6,7-seco-6,11-cyclo-20-norlabdane cluytene F (8). The structural assignments of the diterpenoids were based on their spe ctral data, including 2D NMR experiments, and chemical derivatization. X-ray crystallographic analyses provided unambiguous characterization of the structures and relative stereochemistries of 4, 6, 7, and 1-O- acetylcluytene F (10).