Copper-Catalyzed Decarboxylative Alkynylation of Arylacetic Acids via an Electrophotochemical Approach

The decarboxylative transformation of carboxylic acids is a valuable tool for C-C and C-X bond construction owing to its ubiquitous nature and structural diversity. However, traditional two-electron decarboxylation strategies require harsh reaction conditions and suffer from a limited substrate scope, which severely hamper their application in organic synthesis. In contrast, by integrating with photocatalytic or electrocatalytic processes, a single electron transfer-induced decarboxylative strategy provides a mild and general platform, enabling a series of C-C and C-X cross-coupling reactions with bench-stable carboxylic acids. Herein, we report a copper-catalyzed direct decarboxylative alkynylation of arylacetic acids under electrophotochemical conditions in which the copper catalyst not only induced the decarboxylation via a ligand-to-metal charge-transfer (LMCT) process but also captured the alkyl radical and coupled it with an alkyne to access the alkynylation product. The introduction of electricity provides this mild and green protocol with a better functional group tolerance that makes it a good alternative strategy for carboxylic acid functionalization in organic synthesis and bioconjugation.