To a stirred solution of 2-(4-bromo-2-nitrophenyl)propionic acid (0.800 g, 2.91 mmol) dissolved in a mixture of 50% H2SO4 (6.2 mL) and EtOH (8.5 mL), Zn powder (0.76 g, 11.6 mmol) was added. The reaction was carried out at 90 °C under nitrogen protection. Subsequently, the reaction mixture was treated according to a cyclization method similar to that described in Example 6 to afford 6-bromo-3-methyl-1,3-dihydroindol-2-one (0.61 g, 93% yield). Theoretical values of elemental analysis: C, 47.82; H, 3.57; N, 6.20. measured values: C, 47.80; H, 3.78; N, 5.83.
