Cycloaddition of tertiary aziridines and carbon dioxide using a recyclable organocatalyst, 1,3-di-tert-butylimidazolium-2-carboxylate: straightforward access to 3-substituted 2-oxazolidones

Imidazolium-2-carboxylates derived from N-heterocyclic carbenes (NHCs) and CO2 serve as efficient catalysts for CO2-carboxylation of tertiary aziridines bearing various substituents such as halogens, ether, olefin, ester, acetal, and nitro groups on the aziridine ring in 2-propanol, leading to 3-substituted-2-oxazolidones in good to excellent yields and with high selectivity. The NHC-CO2 adducts facilitate nucleophilic attack of the CO2 moiety on the aziridines, in which the substituents are intact during the carboxylation. The catalyst is successfully recycled up to five times with no apparent loss in activity.