Issue 87, 2019

The dilemma between acid and base catalysis in the synthesis of benzimidazole from o-phenylenediamine and carbon dioxide

Abstract

The tandem synthesis of benzimidazole and other azoles can be achived by the N-formylation of ortho-substituted anilines followed by a cyclization reaction. However, CO2-based N-formylations with hydrosilane reducing agents are base catalyzed whereas the cyclization reaction is acid catalyzed. The mismatch in catalytic conditions means that only one of the steps can be catalyzed in a single pot reaction. While the N-formylation reaction is frequently the target of catalyst development, the cyclization reaction requires comparably much harsher reaction conditions. Identification of these difficulties lead us to the development of a one-pot, two-step synthesis of benzimidazole under mild reaction conditions employing acid catalysts.

Graphical abstract: The dilemma between acid and base catalysis in the synthesis of benzimidazole from o-phenylenediamine and carbon dioxide

Supplementary files

Article information

Article type
Communication
Submitted
08 Aug. 2019
Accepted
08 Okt. 2019
First published
08 Okt. 2019

Chem. Commun., 2019,55, 13089-13092

The dilemma between acid and base catalysis in the synthesis of benzimidazole from o-phenylenediamine and carbon dioxide

M. Hulla, S. Nussbaum, A. R. Bonnin and P. J. Dyson, Chem. Commun., 2019, 55, 13089 DOI: 10.1039/C9CC06156H

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