Rhodium-catalyzed formal [2 + 2 + 1] annulation of arylboronic acids with alkynes†
Abstract
A Rh(I)-catalyzed formal [2 + 2 + 1] annulation between arylboronic acids and alkynes for the expedient synthesis of indenes is described. A reaction process involving intermolecular carborhodation, 1,4-Rh migration, and intramolecular carborhodation, which forges three C–C bonds of the indene core, is proposed for the reaction outcome.