Benzimidazole誘導体の合成研究(第5報) : 1-置換-2-methyl-5-acetylbenzimidazole類の合成

概要

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Syntheses of the subject compound were carried out and two kinds of compounds (V : R=CH_3 and C_6H_5CH_2) having a substituent in 1-position were obtained by the route shown in Chart 1. In the reaction of 3-nitro-4-chloroacetophenone (I) and amines, by-product formation was observed besides the main product, the ketone compound (II : R=CH_3 and C_6H_5CH_2), as follows : (1) In the case of methylamine, the imino compound (III : R=CH_3) was produced and this was found to be related to the amount of the amine used (Table I). (2) In the case of benzylamine, 2,6-bis (4-benzylamino-3-nitrophenyl)-4-phenylpyridine (VIII) formed as a by-product (Chart 2). In order to obtain V by the reductive cyclization with sodium dithionite, acetylation and benzoylation of II were attempted but neither materialized. Therefore, II was reduced to the diamine compound (IV) and was obtained by the Phillips method. Ultraviolet absorption spectra of II and V (Fig. 1 and 2) showed that the maximum absorption of V has become extremely broad and this was considered to be due to the presence of a carbonyl group in 5-position.
公益社団法人日本薬学会の論文
1967-06-25