Methane → Lesinurad

Sodium hydroxide solution (2M aqueous, 33.7 mL, 67 mmol, 2 eq) was added to a suspension of 2-(5-bromo-4-(4-cyclopropylnaphthalen-1-yl)-4H-1,2,4-triazol-3-ylthio)-N-(2-chloro-4-sulfamoylphenyl)acetamide (prepared by previously published procedures; 20 g, 34 mmol) in ethanol (200 mL) and the mixture heated at reflux for 4 hours. Charcoal (10 g) was added, the mixture stirred at room temperature for 12 hours and the charcoal removed by filtration. The charcoal was washed several times with ethanol and the filtrate then concentrated. Water (200 mL) was added and then concentrated to approx. one third volume, to remove all ethanol. Water (200 mL) and ethyl acetate (250 mL) were added, the mixture stirred vigorously for 15 mins and the organic layer removed. The aqueous layer was cooled to 0° C. and acidified by treatment with HCl (IN) resulting in the formation of a cloudy oily precipitate. The mixture was extracted with ethyl acetate (3×) and the combined organic extracts dried over sodium sulfate and concentrated to give 2-(5-bromo-4-(4-cyclopropylnaphthalen-1-yl)-4H-1,2,4-triazol-3-ylthio)acetic acid as an off white solid (11.2 g, 82%).