Rhodium(I)-Catalyzed Cycloisomerization of Benzylallene-Alkynes through C-H Activation

摘要

The efficient Rh~I-catalyzed cycloisomerization of benzylallene-alkynes produced the tricyclo[9.4.0.0~(3.8)]penta-decapentaene skeleton through a C_(sp2)-H bond activation in good yields. A plausible reaction mechanism proceeds via oxidative addition of the acetylenic C—H bond to Rh~I, an ene-type cyclization to the vinylidenecarbene-Rh~I intermediate, and an electrophilic aromatic substitution with the vinylidene-carbene species. It was proposed based on deuteration and competition experiments.