A bifunctional [Ch][Triz] ionic liquid catalyst for CO2 transformation into quinazoline-2,4(1H,3H)-diones under mild conditions†

The utilization and transformation of CO₂ under mild conditions, particularly at ambient pressure and moderate temperature, remain challenging and attract widespread attention. Ionic liquids are considered to be green and designable solvents, and have high efficiency for CO₂ conversion. Here, a novel aprotic ionic liquid, [Ch][Triz], was discovered as a dual-functional catalyst capable of simultaneously activating CO₂ and the substrates, and exhibited outstanding performance in catalyzing the cyclization of CO₂ and 2-aminobenzonitriles under solvent-free and mild conditions (such as 0.1 MPa, 30–50 °C), affording a range of quinazoline-2,4(1H,3H)-diones in high yields. Furthermore, [Ch][Triz] IL could be easily recovered and reused up to five recycle runs without obvious activity loss. This work proposes a sustainable approach to CO₂ conversion, and holds great potential for quinazoline-2,4(1H,3H)-dione preparation under mild conditions.