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Communication | Regular issue | Vol 14, No. 11, 1980, pp.1725-1728
Published online, 1st January, 1970
DOI: 10.3987/R-1980-11-1725
Synthesis of 2-Aryl-benzimidazoles via Cyclic N-Diazonium Ions

Richaed Kreher* and Udo Bergmann

*Institut für Chemie, Medizinische Hochschule Lübeck, Ratzeburger Allee 160, D-2400, Germany


Condensation of 2-azido-aniline with aromatic aldehydes and protonation with tetrafluoroboric acid lead to phenylogous azidoiminium salts. Subsequent cyclisation to cyclic N-diazonium ions and N2-elimination give rise to the formation of 2-aryl-benzimidazoles. In the same manner 2-azido-N-methylaniline can be converted with aromatic aldehydes through a one step procedure into the corresponding 1-methyl-2-aryl-benzimidazoles. The common reaction principle is the intermediate formation of cyclic N-diazonium salts as precursors for 5-membered heterocycles.