Azole‐Anion‐Based Aprotic Ionic Liquids: Functional Solvents for Atmospheric CO 2 Transformation into Various Heterocyclic Compounds

The chemical transformation of atmospheric CO 2 is of great significance yet still poses a great challenge. Herein, azole‐anion‐based aprotic ionic liquids (ILs) were synthesized by the deprotonation of weak proton donors (e.g., 2‐methylimidazole, 4‐methylimidazole, and 2,4‐dimethylimidazole) with tetrabutylphosphonium hydroxide, [Bu 4 P][OH]. We found that these ILs, such as [Bu 4 P][2‐MIm], could activate atmospheric CO 2 through the formation of carbamates. The resultant carbamate intermediates could further react with various types of substrate, including propargylic alcohols, 2‐aminobenzonitriles, ortho ‐phenylenediamines, and 2‐aminothiophenol, thereby producing α ‐alkylidene cyclic carbonates, quinazoline‐2,4(1 H,3 H)‐diones, benzimidazolones, and benzothiazoline, respectively, in moderate‐to‐good yields. Thus, we have achieved the transformation of CO 2 at atmospheric pressure, and we expect this method to open up new routes for the synthesis of various oxygen‐containing heterocyclic compounds under metal‐free conditions.