Green Approach for Visible-Light-Induced Direct Functionalization of 2-Methylquinolines

Abstract

A transition metal-and oxidant-free visible light-photoinduced protocol for direct functionalization of 2methylquinolines has been developed. This protocol enabled the C−H functionalization of substituted 2-methylquinolines with diacetyl or ethyl pyruvate, under environmentally friendly conditions. A mechanistic investigation based on density functional theory (DFT) calculations provided details about the origins of reactivity and selectivity.

Chemoselective bond activation by unidirectional and asynchronous PCET using ketone photoredox catalysts

“…S14 †), as determined by 1 H NMR spectroscopy. Surprisingly, several commonly employed photoinitiators, which have been extensively studied for their propensity to readily undergo C-H abstraction, such as diacetyl [61][62][63] and acetophenone [64][65][66] gave signicant yields of product, with the balance of the reaction being accounted for by unreacted starting material. These results demonstrate that chemoselectivity in hydroamidation photoredox transformations promoted by the PCET chemistry of triplet ketones is not limited to CQ.…”

Atmosphere- and Solvent-Controlled Coupling and Acetylation of Phenols Induced by Visible Light

“…Besides its use as a photosensitizer, diacetyl can take part in coupling reactions or undergo homolytic cleavage to give an acetyl radical under visible-light irradiation, whereas a labile X–Y bond is usually required in such a transformation, such as an O–N bond in Barton esters or a N–X (X = Cl, Br, I) bond in N -haloamides . It is much rarer and more difficult to achieve the direct cleavage of a strong chemical bond, such as a C–C bond, induced by visible light without catalysts .…”