Synthesis of tricyclo[7.2.1.09,10]dodecan-11-one core ring systems of norditerpenoid alkaloids and racemulosine

A robust and convergent synthetic approach for the rapid assembly of common bridged tricyclic BCD-ring systems of norditerpenoid alkaloids as well as racemulosine has been developed. The synthesis features an efficient Au(i)-catalyzed [2 + 2] enyne cycloaddition and an exquisite pinacol rearrangement in a highly exclusive manner to generate the unique bicyclo[3.2.1]octane moiety of the CD-ring on the seven-membered B-ring.