SYNTHESIS OF MANOOL-RELATED LABDANE DITERPENES AS PLATELET-AGGREGATION INHIBITORS

Enantioselective total synthesis of the labdane diterpene (-)-1, was a chieved starting from the R-(-)-enantiomer of the Wieland-Miescher ket one (3). The enantiomer (+)-1 was obtained by partial synthesis via mi crobial transformation of sclareol (24). These results established tha t the natural compound (+)-1, a platelet aggregation inhibitor, has a normal absolute stereochemistry like that of manool (2). The B-norlabd ane-related compound 44 was also synthesized using a novel ring contra ction reaction.