Catalytic Asymmetric Synthesis of Inherently Chiral Saddle‐Shaped Dibenzo[b,f][1,5]diazocines†

Comprehensive Summary Dibenzo[ b , f ][1,5]diazocines are a class of eight‐membered heterocycles, which exhibit unique rigid saddle‐shaped structure and possess inherent chirality. In this study, we report a convenient and straightforward method for the catalytic enantioselective synthesis of these unique chiral molecules through chiral phosphoric acid‐catalyzed dimerization of 2‐acylbenzoisocyanates. Notably, the addition of corresponding 2‐acylaniline as the co‐catalyst significantly improved the efficiency of these reactions, and a simple phase separation operation resulted in products with excellent enantiopurity. Experimental studies were performed to elucidate the mechanism behind these reactions, leading to the proposal of a plausible reaction mechanism based on the study findings.