N-heterocyclic carbenes as efficient organocatalysts for CO2 fixation reactions.

Getting a fix: N-heterocyclic carbenes (NHCs) and NHC-CO(2) adducts serve as potent organocatalysts for carbonate synthesis by the addition of a CO(2) unit to propargylic alcohols or epoxides under mild and solvent-free reaction conditions (see scheme). The enhanced Lewis basicity of imidazol-2-ylidenes bearing electron-donating alkyl groups on the nitrogen atoms leads to utilizing CO(2) as a nucleophilic fragment in the chemical fixation processes.