Visible-light photoredox-catalyzed carboxylation of benzyl halides with CO2: Mild and transition-metal-free

The visible-light photoredox-catalyzed carboxylation of benzyl chlorides and bromides with CO2 has been reported. With inexpensive organic dyes as photocatalysts and amines as electron donors, this carboxylation proceeds well in the absence of sensitive organometallic reagents, transition metal catalysts, or metallic reductants. A wide range of commercially available and inexpensive benzyl halides undergo such carboxylation to give valuable aryl acetic acids, including several pharmaceutical molecules and drug precursors, in moderate to high yields. Moreover, this reaction features mild reaction conditions (one atmospheric pressure of CO2 and room temperature), broad substrate scope, good functional group tolerance, easy scalability, and low catalyst loading, thus providing an efficient approach for the assembly of aryl acetic acids.