Magnetically recyclable Fe 3 O 4 @SiO 2 supported phosphonium ionic liquids for efficient and sustainable transformation of CO 2 into oxazolidinones

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.