Ethyl 2-hydroxy-5-[[4-[(3-methyl-2-pyridinylamino)sulfonyl]phenyl]ethynyl]benzoate (15.5 g, 35 mmol) was refluxed in potassium hydroxide (10 g, 0.15 mol) in water (100 ml) for 1 h. After cooling to ca 70° C., ethyl acetate (50 ml) was added and hydrochloric acid was added to reach pH 7-8. Cooling during stirring and then filration gave a solid that was disolved in acetone (100 ml) and water (100 ml). The solution was acidified at ca 50° C. and cooled, filtered and washed with water. Yield 8.0 g (56%).
