Substituted benzimidazoles. Part 2. Synthesis and properties of 2-aryl-hydroxy-5-(2-thenoyl)benzimidazole 3-oxides

A selected set of 2-aryl- and 2-hetaryl-1-hydroxy-5-(2-thenoyl)benzimidazol e 3-oxides (10a-m) was prepared for bioassay via condensation of the corres ponding aldehydes with 4-(2-thenoyl)-1,2-benzoquinone dioxime (8) as cataly zed by perchloric acid. The dioxime (8) was obtained by facile reduction of 5-(2-thenoyl)benzofuroxan (7a) with 1,2-diphenylhydrazine. The furoxans (7 a,b) are accessible by pyrolysis of the respective o-nitrophenyl azides (6a ,b). Compounds (10a-g) showed a comparable range of in vitro activity again st Escherichia coli and Candida albicans (MIC 62.5 - 125 mu g/mL).