Total Synthesis of (+)‐Erogorgiaene and the Pseudopterosin A−F Aglycone via Enantioselective Cobalt‐Catalyzed Hydrovinylation

Due to their pronounced bioactivity and limited availability from natural resources, metabolites of the soft coral Pseudopterogorgia elisabethae , such as erogorgiaene and the pseudopterosines, represent important target molecules for chemical synthesis. We have now developed a particularly short and efficient route towards these marine diterpenes exploiting an operationally convenient enantioselective cobalt‐catalyzed hydrovinylation as the chirogenic step. Other noteworthy C−C bond forming transformations include diastereoselective Lewis acid‐mediated cyclizations, a Suzuki coupling and a carbonyl ene reaction. Starting from 4‐methyl‐styrene the anti‐tubercular agent (+)‐erogorgiaene (>98 % ee) was prepared in only 7 steps with 46 % overall yield. In addition, the synthesis of the pseudopterosin A aglycone was achieved in 12 steps with 30 % overall yield and, surprisingly, was found to exhibit a similar anti‐inflammatory activity (inhibition of LPS‐induced NF‐κB activation) as a natural mixture of pseudopterosins A−D or iso ‐pseudopterosin A, prepared by β‐ D ‐xylosylation of the synthetic aglycone.