Epoxides are among the most important building blocks in organic synthesis [
1]. Due to its intrinsic ring strain and electrophilicity, the functionalization of epoxides has attracted much attention to generate complicated heteroatom-containing products [
2]. On the other hand, CO
2 is an ideal one-carbon (C1) building block in chemical synthesis in light of environmental protection and resource utilization [
3–
13]. The catalytic coupling and polymerization of CO
2 and epoxides to yield cyclic carbonates or polycarbonates remain amongst the most successful examples for CO
2 utilization as carbon resource (
Scheme 1A) [
14–
24]. Traditionally, Lewis acid catalysts are required to activate epoxides to facilitate the ring-opening and following
O-centered carboxylation in these process. With the development of the photo/electrochemistry over the past few years [
25–
36], single electron activation emerges as an alternative strategy for the transformation of epoxide [
37–
39]. Although the ring strain of epoxides makes them sensitive to both acids and bases, regioselective cleavage of C—O bond of epoxides via single electron activation strategy could generate
C-centered radical for controllable functionalization rather than polymerization, isomerization and deoxygenation [
2]. In 2023, Zhang, Lu and Qiu independently reported novel electroreductive ring-opening carboxylation of epoxides with CO
2 in good chemoselectivity, providing valuable
β-hydroxy acids and relevant drug molecules (
Scheme 1B) [
40,
41]. However, these methods always need to use expensive platinum as cathode and magnesium as sacrificial anode, which might limit their applications. Recently, visible light photoredox catalysis has gained significant attention since it enables new chemical transformations under mild conditions. Motivated by the advancements in photocatalysis and our continuous interest in the carboxylation reactions with CO
2 [
42–
50], we would like to achieve the reductive
C-centered carboxylation of epoxides with CO
2 via visible-light photoredox catalysis, which could provide a new way for conversion of epoxides with CO
2. Herein, we report the first photocatalytic carboxylation of epoxides with CO
2 via sequential single electron transfer (SSET) process (
Scheme 1C) [
51,
52]. Many valuable
β-hydroxy acids can be synthesized in high regioselectivities and yields. Furthermore, more challenging substrates, such as oxetanes, tetrahydrofurans and tetrahydropyrans, could also undergo reductive ring-opening carboxylation reaction with CO
2, affording valuable
γ-,
δ-,
ε-hydroxy acids.