Benzimidazole誘導体の合成研究 (第3報)

2-Methyl-5 (or 6)-alkyl (or aryl) carbamoylbenzimidazole類の合成

抄録

Copeland synthesized about 10 kinds of 2-N-substituted carbamoylbenzimidazoles (I) as a compound of physiological interest but compounds with alkyl- or aryl-carbamoyl substituted in 5- or 6-position have not been reported. In order to prepare this compound reductive cyclization of 2′-nitro-4′-alkyl (or aryl) carbamoyl-acetanilide (III or IV) (Table I) with sodium dithionite was carried out and 2-methyl-5 (or 6)-alkyl (or aryl) carbamoylbenzimidazole (V or VI) (Table II) was obtained in a good yield. Isolation procedure was quite simple and a good result was obtained. (III) and (IV) are obtained by the application of amines to 3-nitro-4-acetamidobenzoyl chloride. Both (III) and (IV), and compounds derived from them, (V) and (VI), are new substances. The amines used in the foregoing reaction were primary amines, R-NH₂ with R=CH₃, C₂H₅, n-C₃H₇, iso-C₃H₇, n-C₄H₉, iso-C₄H₉, tert-C₄H₉, n-C₅H₁₁, n-C₆H₁₃, CH₃(CH₂)₃CH(C₂H₅)CH₂, n-C₁₂H₂₅, n-C₁₈H₃₇, C₆H₅, CH₂(CH₂)₄CH, and C₆H₅CH₂, and secondary amines, R₂NH with R=CH₃, C₂H₅, n-C₃H₇, iso-C₃H₇, n-C₄H₉, iso-C₄H₉, C₆H₅, CH₂(CH₂)₄CH, C₆H₅CH, morpholine, and piperidine.