Borane‐Modulated 2‐Aminopyridine Catalysis: Switchable <i>N</i> ‐Methylation and <i>N</i> ‐Formylation of Amines with CO ₂

Abstract Herein, we address the longstanding challenge of selective N ‐methylation and N ‐formylation coupling between CO 2 and amines by developing tunable 2‐aminopyridine–HBcat (catecholborane)/ HBpin (pincolborane) catalytic systems. This metal‐free, solvent‐free approach achieves remarkable chemo‐switchable selectivity, enabling the divergent synthesis of various N ‐methylamines and N ‐formamides. Mechanistic investigations reveal that the observed high selectivity might be governed by both the structure of borane and its Lewis acidity.