Eosin Y as a direct hydrogen-atom transfer photocatalyst for the C3-H acylation of quinoxalin-2(1H)-ones.

[Display omitted] • Visible light promoted eosin Y catalyzed selective C3-H acylation of quinoxalin-2(1H)-ones. • Neutral eosin Y as the actual hydrogen-atom transfer catalyst in a green and sustainable manner. • Readily available aldehyde as the radical precursor for the generation of acyl radical. Visible light promoted eosin Y catalyzed selective C3-H acylation of quinoxalin-2(1H)-ones has been developed in a green and sustainable manner. In contrast to the conventional anionic eosin Y-based photoredox process, neutral eosin Y acts as the actual catalyst, which was responsible for the hydrogen-atom transfer (HAT) process to generate the acyl radical with readily available aldehydes as the radical precursor. [ABSTRACT FROM AUTHOR]