A type of MCM-41 supported dicationic imidazolium ionic liquid nanocatalyst has been synthesized and found to be competent for the synthesis of 2-oxazolidinones through the sustainable chemical conversion of CO₂ with aziridines. It was shown that the highest efficiency was achieved in the cycloaddition of a series of aziridines and CO₂ in the presence of a catalytic amount of the solid catalyst MCM-41@ILLaCl₄ under mild conditions. Merits of this meticulously designed protocol are the use of a novel supported ionic liquid catalyst, the easy work-up process, good to excellent yields, a short reaction time, and purification without column chromatography. Overall, the present protocol of synthesizing 2-oxazolidinones under cocatalyst- and solvent-free conditions using MCM-41@ILLaCl₄ is promising for industrial applications.

The conversion of CO₂ into 2-oxazolidinones through carboxylative cyclization with propargylic amines is considered an effective method for utilizing waste gas as a sustainable C1 resource and mitigating the greenhouse effect. In this context, a series of nano-SiO₂-supported ionic liquids have been prepared and developed as multifunctional heterogeneous catalysts in the carboxylative cyclization of propargylic amines with CO₂. The catalyst IL-SbF₆@nano-SiO₂ demonstrated a high compatibility with various propargylic amines, achieving excellent yields (90~98%) for the desired 2-oxazolidinones under mild conditions. Additionally, IL-SbF₆@nano-SiO₂ can be easily separated from the reaction mixture and reused for up to six cycles without any significant activity loss. This is important for sustainable chemistry, as it reduces waste and potentially lowers costs. This study offers novel insights into the development and design of green and efficient catalysts for the synthesis of 2-oxazolidinones from carbon dioxide.

Chemical fixation of CO₂ into 2-oxazolidinones is of significance because of the important application in the chemical synthesis. In this study, a series of ionic liquid functionalized SiO₂ nanocomposites were synthesized and developed as heterogeneous catalysts for the CO₂ cyclization reaction. The resulting SiO₂-MILZrCl₅ behaved as high-efficiency heterogeneous catalyst for solvent-additive-free CO₂ cyclization at 70 °C and 0.1 MPa CO₂. A high yield of 93% with selectivity of 99.4% over 5-methyl-3-phenyloxazolidin-2-one was attained. Furthermore, a wide range of epoxides were transformed with high yields and excellent selectivities under atmospheric pressure. Additionally, SiO₂-MILZrCl₅ could serve as a durable and recoverable heterogeneous catalyst for the reaction, which could be used for five cycles without significant loss of catalytic activity. This study offers novel insights for the development of green catalysts for the efficient CO₂ fixation. Graphical Abstract

The development of sustainable and multifunctional catalytic systems is of paramount importance in advancing green synthetic methodologies. In this study, a type of novel functional ionic liquids functionalized silica nanocomposites, based on a pyrazolium core, were strategically designed and synthesized. The catalytic efficacy of these nanocomposites was systematically investigated in the one‐pot three-component reaction of aldehydes and malononitrile with 1,3-cyclohexanedione or ethyl acetoacetate, targeting the synthesis of 4H-pyrans. Among the evaluated systems, SiO ₂ @PILAlO ₂ exhibited superior catalytic activity, affording 89–98% isolated product yields under optimized green conditions using water as the reaction medium. Notably, the catalyst SiO ₂ @PILAlO ₂ exhibited excellent recyclability, retaining catalytic performance over six successive cycles without observable loss in activity. Compared to conventional catalysts, this method offers significantly shorter reaction times, higher yields, operation at room temperature, and facile recovery with reusability up to six cycles. Thus, this approach provides a practical and eco-friendly for the synthesis of 4H-pyran derivatives. Graphical Abstract

Carbon dioxide (CO ₂ ) as a C1 building block to synthesize 2-oxazolidinones is an environmental and sustainable approach. In this work, we present the synthesis and characterization of novel heterogeneous catalysts by immobilizing homogeneous phosphonium ionic liquids (ILs) onto magnetic Fe ₃ O ₄ @SiO ₂ , which could realize the cycloaddition of CO ₂ and a range of aziridines into 2-oxazolidinones under mild conditions of 90°C and 1 atm CO ₂ pressure. The immobilized IL Fe ₃ O ₄ @SiO ₂ @PILCeCl ₄ demonstrated remarkable catalytic activity in the CO ₂ transformation, leading to high to excellent yields (87–95%) as well as excellent selectivities (98–99.2%) in the absence of solvent at reaction times of 8–10 h, from alkyl- or aryl-substituted and N -alkyl-substituted aziridines. The heterogeneous and magnetic nature of the catalyst facilitated effortless recovery and efficient reusability, which could be easily separated and reused up to five consecutive cycles without considerable decrease in catalytic activity. This protocol provides a novel and efficient strategy for producing 2-oxazolidinones, with potential applications in chemical transformation of CO ₂ into value-added chemicals.