A CO2-induced ROCO2Na/ROCO2H buffer solution promoted the carboxylative cyclization of propargyl alcohol to synthesize cyclic carbonates

Abstract

A CO₂-induced ROCO₂Na/ROCO₂H buffer solution is developed and employed in the carboxylative cyclization of propargyl alcohol to generate α-alkylene cyclic carbonates. The introduction of CO₂ into the propargyl alcohol/sodium tertiary pentoxide system can provide the ROCO₂Na/ROCO₂H buffer solution with both basic and acidic species. The basic and acidic species can simultaneously promote the generation of a carbonate anion intermediate and the interaction between the alkyne moieties of propargyl alcohol and protons (H⁺), facilitating carboxylative cyclization. Furthermore, the bulky (n-C₄H₉)₄N⁺ cation of tetrabutylammonium bromide as an additive plays a crucial role in enhancing the nucleophilicity of the carbonate anion intermediate. Various α-alkylene cyclic carbonates are obtained in this catalytic system with relatively good yields at 80 °C.