Visible Light-Mediated Intermolecular C-H Functionalization of Electron-Rich Heterocycles with Malonates

The photoredox-mediated direct intermolecular C-H functionalization of substituted indoles, pyrroles, and furans with diethyl bromomalonate is described, utilizing the visible light-induced reductive quenching pathway of Ru(bpy)(3)Cl(2). An analysis of reductive quenchers and mechanistic considerations has led to an optimized protocol for the heteroaromatic alkylations, providing products in good yields and regioselectivities, as well as successfully eliminating previously observed competitive side reactions. This methodology is highlighted by its neutral conditions, activity at ambient temperatures, low catalyst loading, functional group tolerance, and chemoselectivity.