Benzo[4,5]imidazo[2,1-b]quinazolin-12-ones and benzo[4,5]imidazo[1,2-a]pyrido[2,3-d]pyrimidin-5-ones by a sequential N-acylation-S_NAr reaction

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• 作者：Krishna Kumar Gnanasekaran ; Nagendra Prasad Muddala ; Richard A. Bunce ; ^{rab@okstate.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Benzimidazoquinazolinones ; Acylation&ndash ; SNAr reaction ; Sequential reactions ; Tautomerism ; Heterocycles
• 刊名：Tetrahedron Letters
• 出版年：2015
• 出版时间：30 December 2015
• 年：2015
• 卷：56
• 期：52
• 页码：7180-7183
• 全文大小：719 K

文摘

An efficient synthesis of benzo[4.5]imidazo[2,1-b]quinazolin-12-ones and benzo[4,5]imidazo[1,2-a]pyrido[2,3-d]pyrimidin-5-ones is reported from the reaction of 2-aminobenzimidazole with 2-haloaroyl chlorides. The reaction takes advantage of the 1,3-disposition of nucleophilic centers in 2-aminobenzimidazole and the similar arrangement of electrophilic sites in the acid chloride to assemble the central six-membered ring. Initial treatment of 2-aminobenzimidazole (1.2 equiv) with the acid chloride (1 equiv) in the presence of NaHCO₃ (2 equiv) in DMF at −10 °C gives acylation at the saturated benzimidazole nitrogen. Subsequent heating to 75 °C, in the same reaction vessel, then completes the synthesis via an S_NAr ring closure by the C2 amino group. The reaction has broad scope, and gives 76–98% yields for the two-step sequence. The final products exist in a tautomeric equilibrium, which can be blocked by acylation at N6.