Visible-Light-Driven Catalytic Reductive Carboxylation with CO2

Abstract

Carbon dioxide (CO 2 ) is an important C1 source for the generation of important carboxylic acids and derivatives. Stoichiometric and catalytic carboxylation of nucleophiles, including organometallic reagents, with CO 2 has been widely investigated. Since many kinds of organometallic reagents are prepared from electrophiles, transition-metal-catalyzed direct carboxylation of diverse electrophiles with CO 2 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 CO 2, 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 CO 2 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.