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0 °C

Ex-29A: 2-Hydroxy-4-methoxybenzaldehyde (6.0 g, 39 mmol) was dissolved in dichloromethane (50 mL) and cooled to 0° C. using an ice-water bath. Bromine (6.8 g, 43 mmol) in dichloromethane (2 mL) was added dropwise to the cooled solution and stirred for 2 h at 0° C. The mixture was warmed to room temperature and stirred for an additional 1 h and the resulting yellow precipitate was collected. Recrystallization (ethyl acetate/hexanes) yielded 7.1 g (80%) of 5-bromo-2-hydroxy-4-methoxybenzaldehyde as white needles, m.p. 63–64° C. 1H-NMR (300 MHz, CDCl3) δ 11.43 (s, 1H), 9.69 (s, 1H), 7.68 (s, 1H), 6.48 (s, 1H), 3.95 (s, 3H). Anal. Calcd. for C8H7BrO3: C, 41.59; H, 3.05. Found: C, 41.86; H, 3.05.

1. temperatureThe mixture was warmed to room temperature
2. stirringstirred for an additional 1 h
3. customthe resulting yellow precipitate was collected
4. customRecrystallization (ethyl acetate/hexanes)