Photocatalytic 1,2-Dicarboxylation of Unactivated Alkynes with CO₂

Abstract

The carboxylation of widely available raw materials with CO₂ represents a highly desirable transformation in synthetic chemistry, enabling the streamlined synthesis of valuable carboxylic acids. While the photocatalytic carboxylation of activated unsaturated compounds with CO₂ has emerged as a powerful strategy for accessing diverse carboxylated products, the direct carboxylation of unactivated alkynes with CO₂ remains a formidable challenge due to the intrinsic inertness of both aliphatic alkynes and CO₂. Herein, we report the first visible-light photocatalytic 1,2-dicarboxylation of unactivated alkynes with CO₂, providing a versatile platform for synthesizing structurally diverse succinic acid derivatives. This method exhibits good functional group tolerance and high chemoselectivity under mild reaction conditions. Mechanistic investigations indicated that the <i>in situ</i> generated carbon dioxide radical anion (CO₂^•-) might initiate the first hydrocarboxylation of unactivated alkynes to deliver a key acrylate intermediate, which could undergo a second hydrocarboxylation process to selectively yield succinic acid derivatives. The synthetic utility of this protocol is further demonstrated by constructing bioactive molecules and CO₂-based polyesters.