“…However, this reaction cannot take place spontaneously, and suitable catalysts are generally required for the efficient conversion of CO 2 . Over the past decades, various catalysts have been successfully developed to catalyze the cycloaddition reaction, including organocatalysts (e.g., quaternary ammonium salts, ionic liquids, and organoboron catalysts), ,− metal complexes catalysts (e.g., salen–metal complexes and metalloporphyrin-based complexes), ,− and heterogeneous catalysts (e.g., porous organic polymers and metal organic frameworks). − Typically, these active catalytic systems involve a Lewis acidic metal center for the activation of the C–O bond of the epoxide and a nucleophilic site (such as halogen anion, Br – or I – ) for the epoxide ring-opening step . Thus, a simple nucleophilic reagent such as tetrabutyl ammonium bromide (TBAB) is widely used in binary catalytic systems together with metal complexes.…”