Decarboxylative Cross-Coupling Reactions in Deep Eutectic Solvents

Decarboxylative cross-coupling reactions have emerged as sustainable and versatile platforms for carbon–carbon bond formation, enabling the direct use of abundant, inexpensive, and structurally diverse carboxylic acids as coupling partners. By exploiting decarboxylation as a traceless activation strategy, these methodologies eliminate the need for pre-functionalized organometallic reagents and significantly reduce the environmental burden associated with traditional cross-coupling protocols.[1] In this work, we investigate decarboxylative cross-coupling reactions in deep eutectic solvents (DESs)–reaction media that have remained largely unexplored in this context to date. DESs represent a highly promising class of environmentally benign solvents, featuring negligible vapor pressure, tunable physicochemical properties, and straightforward preparation from inexpensive, readily available, and often biodegradable components.[2] Our study systematically evaluates a range of DES formulations to assess their compatibility with different catalytic systems and to elucidate their influence on key mechanistic aspects, including decarboxylation efficiency, catalyst stability, and reaction selectivity. Particular attention is devoted to solvent–catalyst and solvent– substrate interactions, which may enable reactivity patterns and mechanistic pathways inaccessible in conventional organic solvents (Figure 1).[3]