A Novel Mechanistic Study on Ultrasound-Assisted, One-Pot Synthesis of Functionalized Benzimidazo[2,1-b]quinazolin-1(1H)-ones

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• 作者：Li-Hsun Chen ; Tsai-Wen Chung ; Bharat D. Narhe ; Chung-Ming Sun
• 刊名：ACS Combinatorial Science
• 出版年：2016
• 出版时间：March 14, 2016
• 年：2016
• 卷：18
• 期：3
• 页码：162-169
• 全文大小：609K
• ISSN：2156-8944

文摘

Ultrasound-assisted synthesis of benzimidazo[2,1-b]quinazolin-1(1H)-ones was achieved via piperidine-catalyzed three-component reaction of 2-aminobenzimidazoles, an aromatic aldehyde, and 1,3-dione in aqueous isopropanol. This mechanism was first suspected following our identification of unusual reaction intermediates in a one-pot reaction. An unprecedented coupling reaction, it involved a nucleophilic attack by 2-aminobenzimidazole on in situ generated Michael adduct, followed by electrocyclic ring formation reaction. In contrast to the commonly accepted mechanism, that the direct reaction of 2-amino benzimidazole with a Knoevenagel adduct cannot deliver target compounds.