Imidazolium-Based Ionic Liquids Catalyzed Formylation of Amines Using Carbon Dioxide and Phenylsilane at Room Temperature

The CO₂-involved synthesis of chemicals is of significance. In this work, we found that 1-alkyl-3-methylimidazolium ionic liquids (ILs) had high efficiency for catalyzing the formylation of amines using CO₂ and phenylsilane at room temperature, producing the corresponding formylated products in excellent yields under the metal-free condition. The ILs acted as bifunctional catalysts, which activated the Si-H bond of phenylsilane to react with CO₂ to form the formoxysilane intermediate and simultaneously activated the amine substrate through the hydrogen bond. Moreover, the imidazolium cation and the anions of the ILs showed an excellent synergistic effect on catalyzing the formylation of amines.