2-Alkylbenzimidazoles have been obtained from o-nitroaniline and aliphatic carboxylic acids by reductive cyclization.Interaction of the former with arenesulfonyl chlorides led to the synthesis of 2-alkyl-1-arylsulfonylbenzimidazoles, the yield of which depended on the structure of the substituent in position 2.The high biological activity and broad spectrum of action of benzimidazole derivatives [2-8] has caused increased interest in them. Among 2-substituted benzimidazoles are found substances possessing antitumor, hypotensive, spasmolytic, neuroleptic, and antibacterial action [2-6], and also herbicidal, fungicidal, and growth stimulating activity [7,8].Communications have appeared recently on the synthesis of 2-cycloalkyl(aralkyl)benzimidazoles and sulfonylation of the latter with methane-and benzenesulfonyl chlorides [9]. Similar reactions for 2-alkylbenzimidazoles have not been studied. Continuing our investigations on the synthesis and conversion of benzazoles [1], in this work we have synthesized 2-alkylbenzimidazoles 2a-e and have studied their interaction with arene sulfonyl chlorides.2-Alkylbenzimidazoles were obtained previously from o-phenylenediamine and the appropriate acids [10]. Compounds 2a-e were synthesized by us from o-nitroaniline (1) and aliphatic acids by reductive cyclization using iron powder and hydrochloric acid. The interaction of products 2a-e with arene sulfonyl chlorides in the presence of triethylamine at room temperature led to 2-alkyl-1-arylsulfonyl benzimidazoles 3a-e and 8a-e (Table 1).It should be noted that with the lengthening of the substituent R the yields of compounds 3a-e and 8a-e were reduced. This is probably explained by the action of steric factors. Substitution in Ar did not have a significant influence on the course of the reaction.

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