Self-catalytic photochemical sulfonylation of phenothiazines

Herein, we disclose a novel self-catalytic photochemical sulfonylation of phenothiazines, in which phenothiazine functions as both a substrate and a photosensitizer. The reaction proceeds under visible-light irradiation without an extra photocatalyst and additives and presents a green synthetic approach to access valuable mono- and di-sulfonylated phenothiazines. This late-stage modification process massively enriches the library of phenothiazine-based organophotocatalysts and features operational simplicity, broad functional group compatibility, and high product diversity.