Unsupported Nanoporous Palladium Catalyst for N-Formylation of Amines Using CO2 as a Sustainable C1 Source

An efficient heterogeneous catalytic system for the N-formylation of amines using CO2 as a sustainable C1 source was developed using unsupported nanoporous palladium (PdNPore). The PdNPore-catalyzed N-formylation of amines and CO2 with hydrosilane proceeded smoothly under mild reaction conditions to yield formamides in satisfactory to excellent yields. Various synthetically useful functional groups, such as halogen, hydroxyl, allyl, and cyano groups, remained intact during the N-formylation of amines. No palladium leached from PdNPore during the hydrogenation reaction. Moreover, the catalyst was easily recovered and reused without any loss of catalytic activity. This study is the first to demonstrate that PdNPore catalyzed CO2 conversion to form C-N bond, which enriches the reaction types of CO2 conversion catalyzed by PdNPore catalyst.