Ruthenium-Catalyzed Intramolecular Hydroarylation of Arenes and Mechanistic Study: Synthesis of Dihydrobenzofurans, Indolines, and Chromans

A ruthenium-catalyzed, amide-directed intramolecular hydroarylation of alkene-tethered benzamide derivatives is discussed. This method proficiently constructs dihydrobenzofuran, indoline, and chroman skeletons of biological significance in good to excellent yields; the overall process is atom-economical and step-efficient. The reaction exhibits broad scope, tolerating common functional groups, labile protecting units, and heteroaryl motifs. The use of a catalytic amount of base suffices the need. Deuterium scrambling and kinetic studies offer valuable facts for understanding the reaction mechanism.