Enhancing C-N bond formation in amine carbonylation through dual hydrogen bonding catalysis under mild reaction conditions

The carbonylation of amines offers a promising route for synthesizing N-substituted carbamates with high atom economy. However, conventional catalysts exhibit limited catalytic efficiency, and the underlying proton transfer mechanism remains elusive. Herein, we reported a metal-free, room-temperature strategy utilizing 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as a dual hydrogen bond catalyst to synergistically activate propylamine (PA) and dimethyl carbonate (DMC). This green catalytic system achieves a 10-fold acceleration in reaction rate compared to other hydrogen bonding catalysts under mild conditions. This is enabled by dual hydrogen bonding of TBD with PA and DMC, which facilitates rapid proton transfer and stabilizes tetrahedral intermediates. Theoretical calculations confirm that the dual hydrogen bond system significantly lowers activation energy compared to single hydrogen bond analogs. Furthermore, it was revealed that the hydrogen bonding network within the product is the primary factor responsible for the sluggish reaction rate. This study demonstrates the effectiveness of a dual hydrogen bond system in accelerating the carbonylation of amines and provides a green route to access carbamates.