Chem. Pharm. Bull., 52(5),570-576, May 2004

Regular Articles

Product Analyses of Ozone Mediated Nitration of Benzimidazole Derivatives with Nitrogen Dioxide: Formation of 1-Nitrobenzimidazoles and Conversion to Benzotriazoles

Toyo KAIYA, Kei NAKAMURA, Masaru TANAKA, Naoki MIYATA, and Kohfuku KOHDA^*

Graduate School of Pharmaceutical Sciences, Nagoya City University; Tanabedori, Mizuho-ku, Nagoya 467-8603, Japan. * To whom correspondence should be addressed. e-mail: kohda@phar.nagoya-cu.ac.jp

Several benzimidazole derivatives having electron-withdrawing or -donating substituent(s) at the benzene moiety were used as models of the imidazole moiety of purine bases and their nitration with nitrogen dioxide and ozone (so-called Kyodai nitration) were examined. Products were extracted from the reaction mixture with AcOEt and their structures were analyzed. 1-Nitrobenzimidazole derivatives and unexpected 1-nitrobenzotriazole derivatives were identified. Although the yields of 1-nitrobenzimidazole derivatives were quite low, these were all new compounds that could be obtained only by Kyodai nitration. It was speculated that benzotriazoles were formed via 1-nitrobenzimidazoles and subsequent nitration toward benzotriazoles resulted in the formation of 1-nitrobenzotriazoles.

Key words nitration; nitrogen dioxide; benzimidazole; N-nitration; conversion; benzotriazole