Rh(III)-Catalyzed Diastereoselective Annulation of Amides with Quinone Monoacetals: Access to Bridged Nine-Membered Heterocycles via C–H Activation

An
unprecedented Rh­(III)-catalyzed annulation of various benzamides
and acrylamides with quinone monoacetals was developed for the facile
and efficient one-pot synthesis of bridged nine-membered benzo­[c]­azonine-1,5­(2H)-diones and 2-azabicyclo[4.3.1]­dec-4-ene-3,8-diones.
It is the first example of synthesis of nine-membered heterocycles
through Rh­(III)-catalyzed C–H bond functionalization, and both
aryl and vinyl C–H bonds are tolerant in this reaction. A plausible
mechanism is proposed on the basis of control experiments.