Visible-Light-Promoted Tandem Defluorinative Annulation of Trifluoromethyl Benzamides to Access
Meng Guo1, Qi-Feng Wang1, Jie Gao1
1College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China.
Abstract:
A photocatalytic intramolecular defluorinative annulation of trifluoromethylbenzamide derivatives has been developed for the rapid assembly of dibenzo[b,e]azepin-6-ones. A series of readily accessible N-aryl-2-(trifluoromethyl)benzamides were facilely converted to the corresponding dibenzoazepinones under mild conditions in up to an 86% yield. Mechanistic investigations disclosed that the success of this transformation relies on rapid intramolecular radical cyclization, which inherently outcompetes the undesired hydrogen atom transfer of the difluoromethyl radical intermediate. The synthetic utility of this protocol is further underscored by its scalability, applicability to late-stage functionalization of complex molecules, and formal synthesis of bioactive compounds.
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