Cascade of C(sp<sup>2</sup>)–H Addition to Carbonyl and C(sp<sup>2</sup>)–CN/C(sp<sup>2</sup>)–H Coupling Enabled by Brønsted Acid: Construction of Benzo[<i>a</i>]carbazole Frameworks
Ling Tang, Shuangshuang Jiang, Xinmiao Huang, Zhiyong Song, Jian‐bo Wang, Ming Ma, Bo Chen, Yuanhong Ma
Abstract
Herein, we report an unprecedented cascade reaction of C(sp2)–H addition to carbonyl and the C(sp2)–CN/C(sp2)–H coupling of 2-(2-oxo-2-arylethyl)benzonitriles with indoles enabled by commercially available TsOH·H2O. The protocol represents the first metal-free C(sp2)–CN/C(sp2)–H coupling, affording a new route for the synthesis of various benzo[a]carbazole derivatives with a broad substrate scope, high yields, and simple conditions.
Topics & Concepts
ChemistrySubstrate (aquarium)CascadeCoupling (piping)CarbazoleMedicinal chemistryMetalStereochemistryOrganic chemistryChromatographyOceanographyEngineeringMechanical engineeringGeologyCatalytic C–H Functionalization MethodsCatalytic Cross-Coupling ReactionsRadical Photochemical Reactions