Achieving selective synthesis of N-benzylformamide via one-step electrocatalytic C-N coupling of CO2 and benzylamine

Abstract

The pressing demands of CO₂ emission reduction and organic amine pollutant treatment motivate the development of electrocatalytic C-N coupling toward resource recovery and green synthesis. The key challenge lies in co-activating both reactants while suppressing CO₂ excessive reduction. Herein, we report the first efficient one-step electrocatalytic synthesis of N‑benzylformamide from CO₂ and benzylamine under mild conditions over a bridging‑oxygen coordinated tin phthalocyanine catalyst (C-O-SnPc). At –3.8 V, it achieved a current density of 32 mA·cm^–2, a Faradaic efficiency of 33.4%, and a yield of 53 mmol·L^–1·h^–1. In situ experiments identified key intermediates *COOH and *PhCH₂NHCOOH, confirming a *COOH-mediated pathway. Theoretical calculations revealed oxygen coordination created a multifunctional electron-deficient Sn center. It polarized N-H bond and initiated an electron‑withdrawing chain that enhanced *COOH electrophilicity, facilitating the nucleophilic attack (C-N bonding). It also reduced the hydrogenation barrier from *PhCH₂NHCOOH to *PhCH₂NHCH₂O₂. This work provides a green strategy for resource recovery and upgrading CO₂ and amines into high-value amides.