1. tBuOCl (20 mL, 176 mmol) is slowly added to a suspension of 3-hydroxybenzaldehyde (20.12 g, 160 mmol) in acetic acid (40 mL) under stirring conditions. The reaction solution became clarified and significantly exothermic. The reaction mixture was cooled and stirred continuously for 16 hours to produce a white precipitate. The solid product was collected by filtration, washed with water and dried to give 2-chloro-3-hydroxybenzaldehyde (13.77 g, 55% yield). gCMS (EI) m/z 156, 158 (M+).
2. 2-Chloro-3-hydroxybenzaldehyde (4.55 g, 29 mmol) was dissolved in DMF (30 mL), K2CO3 (4.8 g, 34.9 mmol) was added followed by iodomethane (2.7 mL, 43.6 mmol). The reaction mixture was stirred at room temperature for 16 hours. After completion of the reaction, the solvent was removed by concentration under reduced pressure, and the residue was dissolved in ethyl acetate, washed sequentially with water and brine, dried over Na2SO4 and concentrated. Purification by silica gel column chromatography using ethyl acetate/hexane (1:5) as eluent afforded 2-chloro-3-methoxybenzaldehyde (4.68 g, 94% yield) as a colorless oil, which solidified on standing. gCMS (EI) m/z 170, 172 (M+).
