Electrogenerated Sm(II)-Catalyzed CO₂ Activation for Carboxylation of Benzyl Halides

Abstract

Sm(II)-catalyzed carboxylation of benzyl halides is reported through the electrochemical reduction of CO 2 . The transformation proceeds under mild reaction conditions to afford the corresponding phenylacetic acids in good to excellent yields. This user-friendly and operationally simple protocol represents an alternative to traditional strategies, which usually proceeds through C(sp 3 )-halide activation pathway.Currently, carbon dioxide (CO 2 ) represents one of the major contributors to the greenhouse effect in the atmosphere. Thus, in the past decade, scientists, notably organic chemists, have dedicated substantial research efforts to find ways to fix CO 2 and to convert it into valuable chemicals. [1][2][3] The difficulty is that, due to the thermodynamic stability of its CO bond, the insertion of CO 2 into an organic moiety remains challenging, especially if we aim at high reactivities and functional group tolerance. Nucleophiles such as Grignard and organolithium reagents are typically required for direct activation of CO 2 . 2,3 Recent advances in catalysis and electrochemistry have independently provided efficient solutions for the chemical transformation of CO 2 (Scheme 1). 3,4 ASSOCIATED CONTENT Supporting InformationThe Supporting Information is available free of charge on the ACS Publications. Experimental procedures, compounds data, and spectra.

Electrocatalytic Reactions for Converting CO2 to Value‐Added Products

“…Sacrificial anode method is also a useful means to activate CO 2 and organic halides. [78,79] Mellah and coworkers reported carboxylation of benzyl halides to phenylacetic acids using samarium sacrificial anode (Figure 8b). [78] The Sm(II) units produced by the precatalysis process bound with CO 2 to form Sm III -O bonds.…”

Electrochemical Approaches to Carbonylative Coupling Reactions

“…And the reaction started from the reductive activation of carbon dioxide (Scheme 19 Mellah). [88,89] Starting from the anode to find an excellent electrocatalyst is a pioneering work, which provides a new way for catalyst optimization. In 2019, the Guirado Group synthesized naproxen in ionic liquids and achieved a conversion rate of 90%, while the yield was close to the conversion rate, using CO 2 as the C1 source (Scheme 19 Guirado).…”

Development in SmI2 Catalyzed Reactions

“…Mellah further used this catalytic procedure to perform carboxylation of a series of benzyl halides (Scheme 15). [17c] They proposed the reaction mechanism as transfer of an electron from SmI 2 to CO 2 to form an anionic intermediate in coordination to Sm 3+ . This anionic intermediate was trapped with benzyl halides to produce the corresponding acid.…”