Visible-Light-Induced Regioselective Cascade Radical Cyclization of α-Bromocarbonyls: Access to Benzazepine Derivatives
Nengneng Zhou, Fangli Zhao, Lei Wang, Xiang Gao, Xiaowei Zhao, Man Zhang
Abstract
Visible-light-induced regioselective cascade radical cyclization of α-bromocarbonyls for the synthesis of benzazepine derivatives is described. In the presence of fac -Ir(ppy) 3 (2.0 mol %) as a photocatalyst, 2,6-lutidine as a base, and dichloromethane as a solvent, the reactions proceed smoothly to afford seven-membered rings in good yields. This protocol features a broad substrate scope, excellent functional group tolerance, and mild reaction conditions. Preliminary mechanistic studies reveal that the generation of the α-carbon radical is more prone to react with the 1,1-diphenylethylene tethered acrylamide to generate the stable seven-membered heterocycle.
Topics & Concepts
ChemistryRegioselectivityRadical cyclizationDichloromethaneCascade reactionBenzazepineSubstrate (aquarium)Functional groupFree-radical reactionCombinatorial chemistryMedicinal chemistrySolventPhotochemistryOrganic chemistryRadicalCatalysisPolymerOceanographyGeologyRadical Photochemical ReactionsCatalytic C–H Functionalization MethodsSulfur-Based Synthesis Techniques