N-formylation and N-methylation of amines using metal-free N-heterocyclic carbene catalysts and CO2 as carbon source

This protocol describes the environmentally benign N -formylation and N -methylation of primary and secondary amines using carbon dioxide as the carbon source, hydrosilanes as reductants and N -heterocyclic carbenes as catalysts. N -formylation and N -methylation of amines are important reactions that are used to produce a wide range of key intermediates and compounds. This protocol describes the environmentally benign N -formylation and N -methylation of primary and secondary amines using carbon dioxide (CO 2 ) as the carbon source, hydrosilanes as reductants and N -heterocyclic carbenes (NHCs) as catalysts. Using CO 2 as a reagent has the advantage of low cost and negligible toxicity. However, the catalyst is air-sensitive and must be generated fresh before use; consequently, the techniques used to prepare and manipulate the catalyst are described. The synthetic approach described in this protocol does not use any toxic reagents; using the appropriate catalyst, N -formylated or N -methylated products can be obtained with high selectivity. The overall time for catalyst preparation and for conducting several catalytic reactions in parallel is 15–48 h, depending on the nature of the substrates.