2-Ethyl-5-methyl-2H-pyrazole-3-carboxylic acid [3-(2-oxo-2,3-dihydro-1H-indole-5-carbonyl)-phenyl]-amide (1.12 g, 2.89 mmol) and ethyl formate (0.700 mL, 8.67 mmol) were dissolved in anhydrous ethanol (5.78 mL). The resulting solution was treated in dropwise fashion with a 21 wt % solution of sodium ethoxide in ethanol (5.40 mL, 14.50 mmol). This reaction mixture was heated at 78° C. for 1 h, producing a black oil. Subsequently, the reaction mixture was cooled to room temperature, and then the reaction pH was adjusted to pH 1 with dropwise addition of 1M HCl(aq) causing the formation of a pale orange precipitate. The suspension was filtered yielding an orange solid as the pure product (0.609 g, 1.47 mmol, 57%).
