Research Article
Sulfonic Acid Functionalized Nano-γ-Al2O3: A New, Efficient, and Reusable Catalyst for Synthesis of 3-Substituted-2H-1,4-Benzothiazines
Table 3
Preparation of 3-substituted-2H-1,4-benzothiazinesa.
| Entry | R1 | R2 | Time/h | Product | Yield/%b |
| 1 | H | C6H5 | 3 | 3a | 96 | 2 | H | 4-Me-C6H4 | 2 | 3b | 97 | 3 | H | 4-MeO-C6H4 | 2 | 3c | 95 | 4 | H | 4-F-C6H4 | 4 | 3d | 93 | 5 | H | 4-Cl-C6H4 | 4 | 3e | 94 | 6 | H | 4-Br-C6H4 | 4 | 3f | 90 | 7 | H | 4-NO2-C6H4 | 6 | 3g | 89 | 8 | H | 2-MeO-C6H4 | 3 | 3h | 90 | 9 | H | 3-NO2-C6H4 | 6 | 3i | 88 | 10 | H | 3,4,5-(MeO)3-C6H2 | 6 | 3j | 86 | 11 | H | 2-Benzofuryl | 5 | 3k | 91 | 12 | Cl | CH3 | 10 | 3l | 78 | 13 | Cl | C6H5 | 3 | 3m | 93 | 14 | Cl | 4-Me-C6H4 | 3 | 3n | 95 | 15 | Cl | 4-MeO-C6H4 | 3 | 3o | 93 | 16 | Cl | 4-Cl-C6H4 | 4 | 3p | 90 | 17 | Cl | 4-Br-C6H4 | 4 | 3q | 87 | 18 | Cl | 2-Benzofuryl | 4 | 3r | 88 | 19 | CF3 | C6H5 | 4 | 3s | 86 | 20 | CF3 | 4-MeO-C6H4 | 4 | 3t | 89 |
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Reaction conditions: o-aminothiophenol (1 mmol), ω-bromoketones (1 mmol); sulfonic acid functionalized nano-γ-Al2O3 (50 mg); EtOH (10 mL); reflux. Isolated yield.
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