3-(acetylthio)-2-(tert-butoxycarbonylamino)-3-methylbutanoic acid (693 mg, 2.38 mmol) was dissolved in DCM (10 ml). DMAP (73 mg, 0.59 mmol), EDC (342 mg, 1.79 mmol), and (S)-3,5-dichloro-4-(2-(3-(cyclopropylmethoxy)-4-(difluoromethoxy)phenyl)-2-hydroxyethyl)pyridine 1-oxide (500 mg, 1.19 mmol) were added, and the mixture stirred for 4 hours at RT. The reaction mixture was diluted with DCM and washed with NaHCO3 sat. sol. (10 ml), HCl 1N, brine, dried over Na2SO4 and evaporated under vacuum to give 1.06 g. Crude compound was used in the next step without further purification.
