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CO2 as a C1 Source: B(C6F5)3‑Catalyzed Cyclization of o‑Phenylene-diamines To Construct Benzimidazoles in the Presence of Hydrosilane
journal contribution
posted on 2016-12-02, 21:05 authored by Zhenbei Zhang, Qiangsheng Sun, Chungu Xia, Wei SunThe 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.