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.