反应详情

4-brombenzenesulfonyl chloride (solid) was added, in five portions, to a solution of 3-methyl-5-aminoisoxazole (3.82 g, 40 mmol) in dry pyridine (30 ml). This was stirred at room temperature for 3 h and the pyridine was removed under reduced pressure. The residue was dissolved in THF (300 ml) and a 5% NaOH solution (100 ml) was added. Stirring continued for 1 h at room temperature. The THF was removed under reduced pressure and the resultant residue was neutralized to pH 2 using concentrated hydrochloric acid. This was extracted with ethyl acetate (3×200 ml) and the combined organic layer was dried over MgSO4 and concentrated. The crude product was recrystallized using hexane/ethyl acetate giving N-(3-methyl-5-isoxazolyl)-4-bromobenzenesulfonamide (9.2 g, 72% yield).

1. customthe pyridine was removed under reduced pressure
2. dissolutionThe residue was dissolved in THF (300 ml)
3. additiona 5% NaOH solution (100 ml) was added
4. stirringStirring
5. waitcontinued for 1 h at room temperature
6. customThe THF was removed under reduced pressure
7. extractionThis was extracted with ethyl acetate (3×200 ml)
8. dry with materialthe combined organic layer was dried over MgSO4
9. concentrationconcentrated
10. customThe crude product was recrystallized