Catalyst-Controlled Nickel-Catalyzed Intramolecular endo -Selective C-H Cyclization of Benzimidazoles with Alkenes.

Compared with the widely explored exo -selective C-H cyclization, transition metal-catalyzed endo -selective C-H cyclization of benzimidazoles with alkenes has been a formidable challenge. Previous efforts mainly rely on substrate-controlled methods, rendering the product complexity restricted. Herein we report a catalyst-controlled method to facilitate endo -cyclization, in which a bulky N -heterocyclic carbene ligand and t BuOK base-enabled Ni-Al bimetallic catalyst prove critical to the endo selectivity.