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.