59 mg (0.16 mmol) of the crude 3-(4-[1,2,4]triazol-1-ylmethylphenyl)-5-iso-butylthiophene-2-sulfonamide from step (c) above was mixed with butyl chloroformate (31 μL, 0.24 mmol) and 4-dimethylaminopyridine (2 mg, 16 μmol) in 5 mL of triethylamine at 0° C. The reaction mixture was stirred overnight and then diluted with ethyl acetate, washed with water and dried over K2CO3. The reaction mixture was then separated on a silica column (dichloromethane+15% methanol), circular chromatography (dichloromethane+10-15% methanol and preparative LC-MS to yield 7.0 mg of the title compound (9% isolated yield).
