Step 2: Preparation of 4-acetamido-2-hydroxyacetophenone
N-(4-acetyl-3-hydroxyphenyl)acetamide was prepared based on the improved method of Elliott, J.M. et al. (J. Med. Chem., 1992, 35, 3973-3976): over 20 min, aluminum chloride (27 g, 206 mmol) was added batchwise to mechanically stirred 3'-methoxyacetanilide (10 g, 60.5 mmol), acetyl chloride (12.5 mL, 175.6 mmol) and dichloromethane (25 mL) mixture. Upon completion of the reaction, all dichloromethane was removed by distillation and the resulting viscous mixture was left to heat at 80°C for 3.5 hours. Subsequently, chlorobenzene (60 mL) was added and the mixture was heated to reflux (132°C) and stirred under reflux conditions for 1 hour. The reaction mixture was cooled to 0°C and crushed ice was slowly added while stirring. The resulting solid product was collected by filtration and purified by silica gel column chromatography to afford N-(4-acetyl-3-hydroxyphenyl)acetamide 7.34 g (63% yield).
1H NMR (400 MHz, DMSO-d6): δ 12.31 (s, 1H), 10.26 (s, 1H), 7.83 (d, J = 8.8 Hz, 1H), 7.34 (d, J = 1.8 Hz, 1H), 7.05 (dd, J = 8.8, 1.8 Hz, 1H), 2.56 (s, 3H), 2.08 (s, 3H) .
MS-APCI (m/z +): 194 (M + 1).
