Selective C(8)–H Activation of Imidazopyridines Mediated by Cooperative Nickel–Aluminum Catalysis

Abstract

This work is dedicated to the victims of the recent Tainan earthquake. N N Ar N N R N N R N N Ar 5-substituted imidazopyridine 3-arylimidazopyridine IMes R 3 P ligands Ni-Al C-H activation at C828 examples 17-98% yield Ni(cod) 2 (5 mol%) ligand (5-20 mol%) 60-100 °C AlMe 3 (20-100 mol%) Abstract A catalytic paradigm is described featuring a synergistic interaction between nickel, aluminum and different ligands to impart a rather remote C-H alkenylation of imidazo[1,5-a]pyridines at the C-8 position without the necessity of installing a directing group. The scope of the direct C-H activation reactions of various 5-aryl-and 3-arylimidazopyridines is established using different sterically hindered alkynes.

C–H Functionalization of Arenes via NHC-Supported Ni/Al Bimetallic Catalysis

“…Besides, various C8-alkenylated products could be obtained when C5 position is blocked under almost identical conditions. 20 In 2021, C-H alkenylation at a less acidic C3 position of pyridine was realized via ligand-ligated anchoring catalysis by Ye, Yu and co-workers (Scheme 5). 21 The application of a bifunctional NHC ligand 11, which contains an aliphatic alcohol side arm, resulted in a proper geometry for remote C3functionalization.…”

“…Besides, various C8-alkenylated products were obtained when the C5-position was blocked under almost identical conditions. 21…”