反应详情

To a cold (−78° C.) solution of di-tert-butyl [5-(2-methoxypyridin-3-yl)-1,2-benzoxazol-3-yl]imidodicarbonate (0.235 g, 0.53 mmol) in dichloromethane (10 mL) was added boron tribromide (0.40 mL, 4.24 mmol). The mixture was stirred at ambient temperature for 16 h. The reaction mixture was concentrated in vacuo and the resultant solid was suspended in acetic acid (3 mL), 48% w/w hydrobromic acid (1 mL) was added the mixture was stirred at ambient temperature 16 h, heated to 75° C., stirred for a further 6 h, allowed to cool to ambient temperature and concentrated in vacuo. The residue was taken up in water (100 mL) and extracted with ethyl acetate (3×50 mL). The organic layers were combined, washed with brine (25 mL), dried over magnesium sulfate, filtered and concentrated in vacuo to afford 3-(3-aminobenzo[d]isoxazol-5-yl)pyridin-2(1H)-one as a brownish-orange solid in 62% yield (0.08 g): 1H NMR (300 MHz, DMSO-d6) δ 11.87 (br s, 1H), 8.18 (d, J=1.2 Hz, 1H), 7.84 (dd, J=8.7, 1.8 Hz, 1H), 7.64 (dd, J=6.9, 2.1 Hz, 1H), 7.46-7.38 (m, 2H), 6.43 (br s, 2H), 6.32 (dd, J=6.7, 6.7 Hz, 1H); 13C NMR (75 MHz, DMSO-d6): 161.2, 161.1, 158.6, 138.6, 134.5, 130.9, 130.3, 129.6, 121.3, 116.7, 108.6, 105.4; MS (ES+) m/z 228.0 (M+1).

1. concentrationThe reaction mixture was concentrated in vacuo
2. addition48% w/w hydrobromic acid (1 mL) was added the mixture
3. stirringwas stirred at ambient temperature 16 h
4. temperatureheated to 75° C.
5. stirringstirred for a further 6 h
6. temperatureto cool to ambient temperature
7. concentrationconcentrated in vacuo
8. extractionextracted with ethyl acetate (3×50 mL)
9. washwashed with brine (25 mL)
10. dry with materialdried over magnesium sulfate
11. filtrationfiltered
12. concentrationconcentrated in vacuo