Mild Three-Step Consecutive C-H Activations.

Herein, the Rh-catalyzed consecutive C-H bond olefination/annulation/olefination cascade, tandemly directed by sulfonamide and ester groups, has been developed under mild conditions with the assistance of 1-adamantane carboxylic acid. A seven-membered metallacycle including an ester group was preferred to the five-membered one including a sulfonamide group for the third C-H activation. In this transformation, the Rh catalyst exhibits its high reactivity by catalyzing a triple C-H activation process with a low catalyst loading at 50 °C. This method can be applied in the construction of various pharmaceutical derivatives.