Carboxylation of Alkenes and Alkynes Using CO2 as a Reagent: An Overview

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CO₂ fixation reactions are of paramount interest both from economical and environmental perspectives. As an abundant, non-toxic, and renewable C1 feedstock, CO₂ can be utilized for the synthesis of fuels and commodity chemicals under elevated reaction conditions. The major challenge in the CO₂ utilization reactions is its chemical inertness due to high thermodynamic stability and kinetic barrier. The carboxylation of unsaturated hydrocarbons with CO₂ is an important transformation as it forms high-value reaction products having industrial as well as medicinal importance. This mini-review is mainly focused on the recent developments in the homogeneously and heterogeneously catalyzed carboxylation of alkenes and alkynes by using carbon dioxide as a reagent. We have highlighted various types of carboxylation reactions of alkenes and alkynes involving different catalytic systems, which comprise mainly C-H bond activation, hydrocarboxylation, carbocarboxylation, heterocarboxylation, and ring-closing carboxylation, including visible-light assisted synthesis processes. The mechanistic pathways of these carboxylation reactions have been described. Moreover, challenges and future perspectives of these carboxylation reactions are discussed.