Visible-Light-Driven Catalytic Reductive Carboxylation with CO₂

Carbon dioxide (CO2) is an important C1 source for the generation of important carboxylic acids and derivatives. Stoichiometric and catalytic carboxylation of nucleophiles, including organometallic reagents, with CO2 has been widely investigated. Since many kinds of organometallic reagents are prepared from electrophiles, transition-metal-catalyzed direct carboxylation of diverse electrophiles with CO2 has attracted much attention with high step economy and user-friendly protocols. Although significant progress has been achieved, the use of stoichiometric metallic or pyrophoric reductants is common. The renaissance of photochemistry has seen numerous efforts devoted to light-driven carboxylation with CO2, which has become one of the most active directions in this field. In this Perspective, we summarize recent advances of visible-light-driven catalytic reductive carboxylation of diverse substrates, such as unsaturated hydrocarbons, organic (pseudo)halides, and imines, with CO2 in the presence of mild electron donors, including amines, Hantzsch esters, and formates. We highlight the mechanisms of such reactions, which can proceed in the presence or absence of a photoredox catalyst or a dual visible light photoredox/transition metal catalytic system. We also discuss the future of this field and offer some insight into the challenges that remain.