Can CO2 be a catalyst? Yes, CO2-catalyzed N-formylation of aliphatic amines with DMF

Carbon dioxide (CO 2 ) was found to serve as a novel and green catalyst for the first time in N -formylation of amines with N, N -dimethylformamide (DMF), wherein only the aliphatic amines were applicable to afford the formamides in the yield of 71∼95%. The isotope labeling experiment with DMF- d 7 indicated that the N -formyl group in the formylated product was originated from DMF rather than CO 2 . The control experiments and the in situ high-pressure FT-IR spectra demonstrated that the formation of the carbamate salt of cyclohexylammonium cyclohexylcarbamate ( A ) derived from the reaction of CO 2 with cyclohexylamine was the driving force for this reaction. Accordingly, the mechanism of CO 2 -catalyed N -formylation of aliphatic amines with DMF was proposed, involving the formation of carbamate salt intermediate with enhanced nucleophilicity in anion in favor of the attack on carbonyl-group of DMF.