CO₂ as a C1 Source: B(C₆F₅)₃‑Catalyzed Cyclization of o‑Phenylene-diamines To Construct Benzimidazoles in the Presence of Hydrosilane

The catalytic construction of benzimidazoles using CO₂ as a carbon source represents a facile and sustainable approach to obtaining these valuable compounds. Herein, we describe the B­(C₆F₅)₃-catalyzed synthesis of benzimidazoles via cyclization of o-phenylenediamines with CO₂ and PhSiH₃. This metal-free catalytic route achieves the desired products in high yield under convenient reaction conditions and is applicable to a broad substrate scope. A plausible mechanism for the reaction involving a frustrated Lewis pair pathway is proposed based on spectroscopic characterization (e.g., ¹³C NMR) of the reaction intermediates.