Visible-light Photoredox-Catalyzed Carboxylation of Aryl Epoxides with CO2

Herein, we report the first visible-light photoredox-catalyzed carboxylation of aryl epoxides with CO2 to synthesize hydroxy acid derivatives. A variety of valuable β-, γ-, δ-, ε-hydroxy acid derivatives are obtained in moderate to high yields under mild conditions. This protocol shows noteworthy functional-group compatibility, high chemo- and regioselectivities under transition-metal-free conditions with an inexpensive organo-dye as photosensitizer. Mechanistic studies indicate that the benzylic carbanion is generated as an intermediate via the sequential single electron transfer (SSET) process.