Developments in CO surrogates for base-metal-catalyzed carbonylation

Transition-metal-catalyzed carbonylation, which introduces CO into organic molecules, is one of the most important tools to synthesize carbonyl derivatives. Despite the considerable synthetic utility of carbonylation reactions, their advancement remains hindered by several critical limitations, including the use of high-loading noble metal catalysts, such as Pd, Ru, and Rh, and use of toxic and environmentally unfriendly CO or metal carbonyl complexes. Taking safety and operability into account, the base-metal-catalyzed carbonylation utilizing various CO surrogates has been identified as an ideal alternative to overcome the above-mentioned challenges. In this research field, the development of small-molecule CO surrogates occupies a central position and has achieved remarkable progress. In this review, we systematically summarize the progress in the development of CO surrogates for base-metal-catalyzed carbonylation reactions. Moreover, this review provides forward-looking perspectives to guide chemists in designing low-cost, more efficient, and environmentally benign CO surrogates, thereby establishing a robust foundation for the wider application of carbonylation reactions in organic synthesis and chemical industry.