Rhodium‐Catalyzed [(3+2)+2] Carbocyclization of Alkynylidenecyclopropanes with Substituted Allenes: Stereoselective Construction of Tri‐ and Tetrasubstituted Exocyclic Olefins

Abstract

Abstract The development of the stereoselective rhodium‐catalyzed [(3+2)+2] carbocyclization of alkynylidenecyclopropanes (ACPs) with substituted allenes is described. This work demonstrates that activated and unactivated allenes preferentially undergo carbometalation at the distal terminus to generate tri‐ and tetrasubstituted exocyclic olefins with a neutral rhodium catalyst. In addition, this method provides a strategy for the total synthesis of the guaiane family of sesquiterpenes, which are not directly accessible using alkynes as exogenous π‐components. Finally, the preparation of the bicyclo[5.4.0]undecane ring system using a homologated ACP tether serves to further illustrate the versatility of this approach.