Visible-Light Photoredox-Catalyzed Carboxylation of Activated C(sp 3 )─O Bonds with CO 2

The photocatalytic carboxylation with CO 2 has emerged as an efficient way to afford valuable aliphatic carboxylic acids. However, the difficultly available starting materials, limited substrate scope, and/or the use of high loading of transition-metal catalysts hamper their wide application. In contrast, alcohols and derivatives, which are environmentally benign and readily available in nature and industry, have rarely been investigated in such a process. Herein, we report a visible-light photoredox-catalyzed carboxylation of activated C(sp 3 )─O bonds with CO 2 under mild and transition-metal-free conditions. A variety of benzyl alcohols and derivatives, bearing primary, secondary, and more challenging tertiary C(sp 3 )─O bonds, undergo carboxylation with CO 2, generating valuable aryl acetic acids, such as ibuprofen, naproxen, fenoprofen, and flurbiprofen, with broad substrate scope and good functional group tolerance. Moreover, this strategy is also applicable to other carboxylates of α-hydroxyl amides, esters, and nitriles, as well as allyl alcohols, representing a practical method for aliphatic carboxylic acid synthesis.