title: Ionic liquid-supported synthesis of dihydroquinazolines and tetrahydroquinazolines under microwave irradiation.
abstract: An efficient microwave-assisted and water-soluble ionic liquid (IL)-supported synthesis of medicinally important dihydro- and tetrahydroquinazolines has been developed. The protocol involves the S(N)2 substitution reaction of IL-bound 4-bromomethyl-3-nitrobenzoic acid with various primary amines to provide IL-bound 4-((alkylamino) methyl)-3-nitrobenzoate under microwave irradiation. Further elaboration followed by sequential cyclization with various isothiocyanates and aldehydes furnished IL-bound target compounds. Cleavage of the IL support by methanolysis gave dihydro- and tetrahydroquinazolines with high purity and excellent yields. The new protocol has the advantages of shorter reaction time, easy workup process, excellent yields, reduced environmental impact, wide substrate scope, and convenient procedure.
authors.affiliation: Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan.
authors.forename: Hai-Yuan
authors.initials: HY
authors.lastname: Hsu
authors.forename: Chih-Chun
authors.initials: CC
authors.lastname: Tseng
authors.forename: Banrali
authors.initials: B
authors.lastname: Matii
authors.forename: Chung-Ming
authors.initials: CM
authors.lastname: Sun
mesh_terms: D002264:Carboxylic Acids / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry*; D008872:Microwaves; D009579:Nitrobenzoates / Q000737:chemistry; D011799:Quinazolines / Q000138:chemical synthesis*
chemical_list: D002264:Carboxylic Acids; D052578:Ionic Liquids; D009579:Nitrobenzoates; D011799:Quinazolines; C075153:4-bromomethyl-3-nitrobenzoic acid