80477-73-2Relevant academic research and scientific papers
ACIDIC PROPERTIES OF BENZIMIDAZOLES AND SUBSTITUENT EFFECTS. V. PROTECTION OF BENZIMIDAZOLES BY N-ALKYL BOND FORMATION USING VINYLPYRIDINES
Ichikawa, Masataka,Yamamoto, Chiyuki,Hisano, Takuzo
, p. 3042 - 3047 (2007/10/02)
Vinylpyridines were utilized for protection of the benzimidazole N-H bond to give 1-(2-pyridylethyl)-benzimidazoles.The reaction was found to progress smoothly when glacial acetic acid was used as a catalyst.In the alkylation of 5- or 7-substituted-2-arylbenzimidazoles with vinylpyridines, the yield decreased with increasing electron-attracting effect of the substituent groups in the benzimidazole ring.On the other hand, the removal of pyridylethyl groups by the use of aluminum chloride as a catalyst was kinetically examined; a large excess of sodium hydroxide was used for decomposition of the intermediate adduct of aluminum chloride.The rate increased somewhat when electron-releasing substituent groups were present in the benzimidazole ring. 1--2-arylbenzimidazoles were resistant to removal of their (2-pyridyl)ethyl groups. 4-Vinylpyridine can be used more efficiently as a protecting agent.Keywords: 2-pyridylbenzimidazoles; protection with vinylpyridines for imidazole; 1-(2-pyridylethyl)-benzimidazoles; substituent effect on N-alkylation of benzimidazoles; rate of removal of pyridylethyl groups by aluminum chloride catalyst
