Au catalyzed synthesis of benzimidazoles from 2-nitroanilines and CO2/H2

Au catalyzed synthesis of benzimidazoles from 2-nitroanilines and CO2/H2

http://pubs.rsc.org/en/Content/ArticleLanding/2014/GC/C4GC00153B?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

Green Chem., 2014, Advance Article
DOI: 10.1039/C4GC00153B, Paper

Leiduan Hao, Yanfei Zhao, Bo Yu, Hongye Zhang, Huanjun Xu, Zhimin Liu
The gold-catalyzed synthesis of benzimidazoles from 2-nitroanilines and CO₂ in the presence of H₂ was reported, and a series of benzimidazoles were obtained under relatively mild conditions.

The gold-catalyzed synthesis of benzimidazoles from 2-nitroanilines and CO₂ in the presence of

 H₂ was reported, and a series of benzimidazoles were obtained under relatively mild conditions. 

Several supported Au catalysts including Au/TiO₂, Au/Al₂O₃, Au/ZnO, Au/polyurea and Au/hydrotalcite

 were examined for the synthesis of benzimidazole from the reaction of 2-nitroaniline with CO₂ and H₂, 

among which Au/TiO₂ displayed the best performance. The reaction mechanism was investigated, 

and it was found that the production of benzimidazole underwent the formation of o-phenylenediamine 

via the hydrogenation of 2-nitroaniline, followed by the cyclization of o-phenylenediamine with CO₂ and H₂. 

This work provides a CO₂-involved route for the synthesis of benzimidazoles, 

which may widen the applications of CO₂ in the chemical synthesis.