Neutral-Eosin Y-Catalyzed Regioselective Hydroacylation of Aryl Alkenes under Visible-Light Irradiation

Styrene derivatives were hydroacylated with exclusive anti-Markovnikov selectivity by using neutral eosin Y as a direct hydrogen-atom-transfer (HAT) catalyst under visible-light irradiation. Aldehydes and styrenes with various substituents were tolerated (>20 examples), giving the corresponding products in moderate to high yields. The key acyl radical intermediate was generated from a direct HAT process induced by photoexcited eosin Y. Subsequent addition to styrenes and a reverse HAT process generated the ketone products.

Automated summary

Styrene derivatives were hydroacylated with exclusive anti-Markovnikov selectivity using neutral eosin Y as a direct hydrogen-atom-transfer catalyst under visible-light irradiation, giving moderate to high yields of the corresponding products. The acyl radical intermediate was generated through a direct HAT process induced by photoexcited eosin Y, followed by subsequent addition to styrenes and a reverse HAT process to generate the ketone products.