GENERAL METHOD: (2-Amino-3-chlorophenyl)methanol (1.2 g, 7.61 mmol) was dissolved in dichloromethane (20 mL) and manganese dioxide (2.6 g, 30.1 mmol) was added. The reaction mixture was stirred at room temperature for 23 hours under argon protection. After completion of the reaction, the solid catalyst was removed by filtration and the filtrate was concentrated under reduced pressure. The residue was recrystallized by ethyl acetate to give 2-amino-3-chlorobenzaldehyde (1.0 g, 85% yield) as yellow needle-like crystals.
