反应详情

Compound 20 (0.265 g, 1.32 mmol) was diluted in anhydrous benzene (10 mL). N-Bromosuccinimide (0.247 g, 1.39 mmol) and a catalytic amount (0.020 g) of benzoyl peroxide were added, and the mixture was heated to reflux under argon until an orange tint was no longer visible in the solution refluxing in the condenser (typically 4 h). The mixture was cooled, concentrated, and purified by flash column chromatography (SiO2), eluting with a gradient of 7% to 14% EtOAc in CH2Cl2, to yield the product (0.236 g, 64%) as a flocculent yellow solid. 1H NMR chemical shifts for this compound are consistent with those reported in the literature for the 7-isomer. 1H-NMR (500 MHz; CDCl3): δ 8.43-8.41 (m, 2 H), 8.16 (d, J=8.9 Hz, 1 H), 7.79-7.77 (m, 2 H), 7.49 (dd, J=8.4, 1.7 Hz, 1 H), 4.65 (s, 2 H), 2.27 (s, 3 H).

1. temperaturethe mixture was heated
2. temperatureto reflux under argon until an orange tint
3. temperaturerefluxing in the condenser (typically 4 h)
4. temperatureThe mixture was cooled
5. concentrationconcentrated
6. custompurified by flash column chromatography (SiO2)
7. washeluting with a gradient of 7% to 14% EtOAc in CH2Cl2