Selective mono-methylation of primary alcohols and amines with methanol catalyzed by two-dimensional NHC–Ir coordination assemblies

Methanol, as a low-cost, abundant, and sustainable C 1 feedstock, has garnered considerable attention for methylation reactions via the borrowing hydrogen (BH) process. Herein, we designed and synthesized two-dimensional (2D) N -heterocyclic carbene–iridium (NHC–Ir) coordination assemblies, which act as self-supporting solid molecular catalysts and exhibit excellent activity and exclusive chemoselectivity in two methylation reactions, including β -methylation of primary alcohols and selective mono- N -methylation of arylamines. The protocol delivers up to 98% yield with quantitative mono-selectivity and a turnover number (TON) up to 4940 under mildly basic conditions. A wide range of structurally diverse primary alcohols and anilines is well tolerated, highlighting the capability of this methodology for late-stage methylation of pharmaceutical molecules bearing methyl groups. Moreover, the solid catalyst demonstrates exceptional stability and recyclability; no obvious loss in activity and selectivity was observed even after seven consecutive runs.