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[<i>c</i>]­azonine-1,5­(2<i>H</i>)-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