Homogeneous catalysts generally show higher catalytic activities, while heterogeneous catalysts are more easily separated from products. To combine the advantages of heterogeneous and homogeneous catalysts has been of great interest for many years. Here, we report a kind of facilely prepared cross-linked poly­(ionic liquid)­s (PILs) with swelling property to increase catalytic activities of heterogeneous catalysts. The swelling ability of PILs was greatly affected by cross-linking density and chain length of substituents on imidazolium, and the unique swelling property prompted the nonporous PILs to contact with substrates sufficiently, enhancing their catalytic activities similar to homogeneous ionic liquid monomers.

An intermolecular synergistic catalytic combination of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) and a DBU‐derived bromide ionic liquid has been developed for the conversion of CO2, epoxides, and amines under metal‐ and solvent‐free conditions. Various 3‐aryl‐2‐oxazolidinones are produced in moderate to excellent yields within a short reaction time. NMR spectroscopy and DFT calculations demonstrate that DBU as a hydrogen bond acceptor and the ionic liquid as a hydrogen bond donor activate the substrates cooperatively by inducing hydrogen bonds to promote the reaction effectively. Based on these results, a possible reaction mechanism on the synergistic catalysis of DBU and the ionic liquid is proposed. In addition, the reaction of CS2, ethylene oxide, and aniline catalyzed by the combination of DBU and the DBU‐derived ionic liquid also proceeds smoothly, which opens a hitherto unreported route to [1,3]dithiolan‐2‐ylidenephenylamine in a straightforward way.

The exchange of bulky salicylate and its dimers/clusters in PILs by other smaller anions increased specific surface area and fabricated a hierarchical porous structure.

We have investigated the reactions of cyclic carbonates/trithiocarbonate and aromatic amines in the presence of a basic ionic liquid, 1butyl-3-methylimidazolium acetate (BmimOAc), which produced various cyclic carbamates/dithiocarbonimidates in fairly good to excellent yields. The use of BmimOAc as catalyst here not only offers an effective approach to the synthesis of the target compounds, but also avoids the use of conventional toxic materials. By means of the reactions of cyclic carbonates and aromatic amines, 3-aryloxazolidin-2-ones, 3,3'-aryldioxazolidin-2-ones and 3-arylA C H T U N G T R E N N U N G [1,3]oxazinan-2-ones could be synthesized. NMR spectroscopy and DFT calculations revealed that both the cation and the anion of BmimOAc activate cooperatively the substrates in these reactions by means of inducing hydrogen bonding. In addition, condensation reactions of ethylene trithiocarbonate and aromatic amines also proceeded very well in the presence of the BmimOAc catalyst, which opened a hitherto unreported route to [1,3]dithiolan-2-ylidene-arylamine derivatives in a straightforward way.