One-Pot, Borax-mediated synthesis of structurally diverse N, S-heterocycles in water

• Published in: Tetrahedron letters Vol. 74; p. 153159
• Main Authors: Rao, Mugada Sugunakara, Hussain, Sahid
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 22-06-2021
• Subjects: 1-Dioxide; Benzothiadiazine 1; Benzothioazole; Borax; Quinazolin-4(3H)-one; ααα-Trihalotoluene; Quinazolin-4(3H)-one; ααα-Trihalotoluene; Borax; Benzothioazole; Benzothiadiazine 1; 1-Dioxide
• ISSN: 0040-4039; 1873-3581
• DOI: 10.1016/j.tetlet.2021.153159

[Display omitted]
•One-Pot, synthesis of structurally diverse N,S-heterocycles.•Borax providing hydroxyl anion (Brønsted base) and boric acid (Lewis acid)•Reactions preceded in water.•Broad substrate scope.
Herein, a borax–mediated convenient and efficient strategy for the synthesis of prominent structurally diverse N, S-heterocycles such as quinazolin-4(3H)-one, benzothiadiazine 1,1-dioxide, benzothioazole, and benzoxazoles from readily available 2-aminobenzamide/2-aminobenzenesulfonamide/2-aminothiophenol/2-aminophenol with α,α,α-trihalotoluenes at 100 ℃ in water is elaborated. Upon using aldehydes instead of α,α,α-trihalotoluenes, the reactions proceed through domino fashion under the catalytic effect borax to yield 2,3-dihydroquinazolin-4(1H)-one, 3,4-dihydrothiadiazine 1,1-dioxide, and benzothiazoles in one-pot at 60 ℃. The advantages of this protocol are practical simplicity, large substrate scope, moderate to excellent yields, and the use of water as the solvent.