C?N and N?H Bond Metathesis Reactions Mediated by Carbon Dioxide

Graphical CO 2 -mediated reactions: CO 2 -mediated metathesis reactions between amines and DMF to synthesize formamides are described. The N -formylation of amines to formamides is achieved by activating amines, not DMF, via a C  N and N  H bond metathesis reaction. Using this method, primary, secondary, aromatic, and heterocyclic amines as well as diamines can be obtained with good to excellent formamide yields. Herein, we report CO 2 -mediated metathesis reactions between amines and DMF to synthesize formamides. More than 20 amines, including primary, secondary, aromatic, and heterocyclic amines, diamines, and amino acids, are converted to the corresponding formamides with good-to-excellent conversions and selectivities under mild conditions. This strategy employs CO 2 as a mediator to activate the amine under metal-free conditions. The experimental data and in situ NMR and attenuated total reflectance IR spectroscopy measurements support the formation of the N -carbamic acid as an intermediate through the weak acid–base interaction between CO 2 and the amine. The metathesis reaction is driven by the formation of a stable carbamate, and a reaction mechanism is proposed.