title: A Novel Mechanistic Study on Ultrasound-Assisted, One-Pot Synthesis of Functionalized Benzimidazo[2,1-b]quinazolin-1(1H)-ones.
abstract: 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.
authors.affiliation: Department of Applied Chemistry, National Chiao-Tung University , 1001 Ta-Hseuh Road, Hsinchu 300-10, Taiwan.
authors.forename: Li-Hsun
authors.initials: LH
authors.lastname: Chen
authors.affiliation: Department of Applied Chemistry, National Chiao-Tung University , 1001 Ta-Hseuh Road, Hsinchu 300-10, Taiwan.
authors.forename: Tsai-Wen
authors.initials: TW
authors.lastname: Chung
authors.affiliation: Department of Applied Chemistry, National Chiao-Tung University , 1001 Ta-Hseuh Road, Hsinchu 300-10, Taiwan.
authors.forename: Bharat D
authors.initials: BD
authors.lastname: Narhe
authors.affiliation: Department of Applied Chemistry, National Chiao-Tung University , 1001 Ta-Hseuh Road, Hsinchu 300-10, Taiwan.|Department of Medicinal and Applied Chemistry, Kaohsiung Medical University , 100, Shih-Chuan first Road, Kaohsiung 807-08, Taiwan.
authors.forename: Chung-Ming
authors.initials: CM
authors.lastname: Sun
mesh_terms: D001562:Benzimidazoles / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D020650:Combinatorial Chemistry Techniques / Q000379:methods*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D010880:Piperidines / Q000138:chemical synthesis / Q000737:chemistry; D052999:Quinazolinones / Q000138:chemical synthesis* / Q000737:chemistry; D013010:Sonication / Q000379:methods
chemical_list: D001562:Benzimidazoles; D010880:Piperidines; D052999:Quinazolinones; C032727:piperidine; C027391:2-aminobenzimidazole
keywords: benzimidazo[2,1-b]quinazolin-1(1H)-ones; multicomponent reaction; ultrasonication