Herein, we report a rare example of rhodium-catalyzed
C–H
activation/[4 + 2] annulation of alkenyl amides with bicyclic alkenes
under mild and green conditions. The reactivity of the rhodium catalyst
in this study differed from that observed in cobalt-catalyzed C–H
activation/[3 + 2] annulation between vinylic amides and bicyclic
alkenes. In addition, the reaction was performed in EtOH at room temperature,
which also displayed excellent diastereoselectivity, good functional
group tolerance, and air compatibility. A series of novel bridged-ring
skeletons were obtained in good to excellent yields. Scale-up experiments
were carried out with 1 or 0.75 mol % rhodium catalyst, affording
the desired bridged-ring skeleton in excellent yields.