N-Heterocyclic carbene-based porous polymer macroligand for the Ni-catalyzed C–H arylation of benzothiophenes

Abstract

A porous organic polymer (POP) with imidazolium functionality (IM-POP) has been synthesized through radical polymerization. N-Heterocyclic carbene (NHC) has been generated from an imidazolium moiety via base treatment followed by coordination of nickel salt, giving access to a single-site Ni–NHC catalyst inside the polymeric network. The NiCl₂@NHC-POP was found to heterogeneously catalyze the direct selective C2–H arylation of (benzo)thiophenes using various aryl electrophiles with a turnover number (TON) up to 75, reaching cumulative TON of ca. 400 after recycling for six consecutive runs.