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Compound 98 (33.0 g, 0.14 mol) was treated with sulfuric acid (13.7 mL) and was refluxed in EtOH (550 mL) for 0.5 hours, followed by addition of NaNO2 (23.8 g, 0.35 mol). The resulting mixture was refluxed for additional 1 hour and the volatile was evaporated. The residue was taken up with ethyl acetate and water. The layers were separated and the organic layer was washed with water, saturated sodium bicarbonate, and brine. After removal of solvent, the residue was purified by column chromatography on silica gel to afford the title compound (26 g, 85%); 1H NMR (500 MHz, CD3OD): δ 5.00 (brs, 1H), 7.58 (dd, 1H, J=1.7, 2.3 Hz), 7.47 (t, 1H, J=2.1 Hz), 7.69 (t, 1H, J=1.9 Hz); 13C NMR (125 MHz, CD3OD): δ 110.5, 118.1, 123.7, 125.6, 151.0, 160.5; HRMS (FAB) calcd for C6H4BrNO3(M+) 216.9375. found 216.9374.

1. temperatureThe resulting mixture was refluxed for additional 1 hour
2. customthe volatile was evaporated
3. customThe layers were separated
4. washthe organic layer was washed with water, saturated sodium bicarbonate, and brine
5. customAfter removal of solvent
6. customthe residue was purified by column chromatography on silica gel