HCOONa can completely shift N-alkylation to the 5a side by significantly reducing activation energy from 55.3 to 46.8 kJ mol−1 in the 4a-to-5a transfer-hydrogenation stage, which leads to a 15-fold increase in the rate constant for 4a hydrogenation at 140 °C. This research study highlights a kinetic understanding of N-alkylation for the construction of biomass-based amines.