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 tBuOK baseenabled Ni-Al bimetallic catalyst prove critical to the endo selectivity.

Automated summary

Compared with exo-selective C-H cyclization, the endo-selective C-H cyclization of benzimidazoles with alkenes has been a challenge. Previous methods relied on substrate-controlled approaches, limiting the complexity of the products. This study reports a catalyst-controlled method using a bulky N-heterocyclic carbene ligand and tBuOK baseenabled Ni-Al bimetallic catalyst to facilitate endo-cyclization.