Rh-Catalyzed Triple Allene Approach to Bicyclo[4.4.0]decene Derivatives and Its Application for the Stepwise Synthesis of Steroid-Like Tetracyclic Skeletons

The construction of a new type of bicyclo[4.4.0]decene products with a conjugated exocyclic diene unit was developed using Rh-catalyzed cyclization of 1,5-bisallenes in the presence of monoallenes. The steroid-like tetracyclic products could be obtained by applying an alkylation−Diels−Alder process.