New method for the annelation of a pyridine ring on derivatives of imidazole and benzimidazole

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• 作者：L. M. Potikha ; A. R. Turelyk ; V. A. Kovtunenko and A. V. Turov
• 关键词：γ ; bromodypnone ; imidazo[1 ; 2 ; a]pyridine ; pyrido[1 ; 2 ; a]benzimidazole ; cyclization of azolium ylides
• 刊名：Chemistry of Heterocyclic Compounds
• 出版年：2010
• 出版时间：May, 2010
• 年：2010
• 卷：46
• 期：1
• 页码：82-95
• 全文大小：536.3 KB

文摘

The interaction of (Z)-1,3-diaryl-4-bromo-2-buten-1-ones with 1-substituted (benz)imidazoles in benzene gave (Z)-1-R-3-(2,4-diaryl-4-oxo-2-butenyl)-1H-imidazolium bromides and (Z)-1-R-3-(2,4-diaryl-4-oxo-2-butenyl)-1H-benzimidazolium bromides which readily cyclize in the presence of base to form derivatives of 7,9-diarylpyrido[1,2-a]benzimidazole and 6,8-diarylpyrimidazo[1,2-a]pyridine. The effects of the nature of substituents in the benzene ring of the diarylbutenones and the substituent at N(1) in the (benz)imidazoles on the alkylation and cyclization reactions has been studied. The optimum conditions for the synthesis of the 5-R-4-hydroxy-2,4-diphenyl-4,5-dihydro-1H-pyrido[1,2-a]benz-imidazol-10-ium, 5-R-2,4-diaryl-4-hydroxy-4,5-dihydro-3H-pyrido[1,2-a]benzimidazol-10-ium, and 5-R-2,4-diaryl-5H-pyrido[1,2-a]benzimidazol-10-ium have been found.