General method: Compound 22 (15.8 mmol) or Compound 23 (15.8 mmol) was dissolved in methanol, 10 μl of 10% Pd-C catalyst was added and hydrogen was passed through. The reaction mixture was stirred for 5 hours. After completion of the reaction, the catalyst was removed by filtration and the filtrate was concentrated. The residue obtained was purified by recrystallization from methanol to give methyl 4-carboxylate dihydroindol-2-one.
