Alkylative/arylative carboxylation of unsaturated hydrocarbons utilizing CO2 as C1 synthon: An update

The difunctionalization of unsaturated hydrocarbons, the incorporation of two functional groups onto an unsaturated carbon-carbon bonds, is one of the most active and popular topics in modern organic chemistry due to its significance in the rapid and highly atom economical synthesis of complex molecules from simple starting materials within a single click. Among various difunctionalization reactions, difunctionalizing carboxylations utilizing CO2 as a renewable and environmental friendly C1 feedstock has attracted more and more attention in recent years. In this regard, several interesting strategies have been developed in the last two decades for the preparation of branched carboxylic acids and their derivatives through the alkylative/arylative carboxylation of the corresponding unsaturated hydrocarbons using CO2 as a carboxyl source. Thus, it is an appropriate time to summarize those advances. The purpose of this Mini-Review is to focus on the most important advances and developments on the attractive research field with particular emphasis on the mechanistic features of the reaction pathways. Notably, we have organized this review based on the type of bond where the CO2 insertion occurs.