Potassium peroxymonosulfate (264 mg) was suspended in water (1 ml) and THF (1 ml), and then tert-butyl(4-{2-[2-(acetylamino)-5-({[4-(methylthio)benzyl]amino}carbonyl)-1,3-thiazol-4-yl]ethyl}phenyl)carbamate (155 mg) in THF (2 ml) was added dropwise to the suspension at 0° C. The reaction mixture was stirred at r.t. for an hour, and then water was added to the suspension. The solution was extracted with AcOEt (twice). The combined organic layer was washed with brine, dried over anhydrous MgSO4, and concentrated in vacuo to give tert-butyl (4-{2-[2-(acetylamino)-5-({[4-(methylsulfonyl)benzyl]amino}carbonyl)-1,3-thiazol-4-yl]ethyl}phenyl)carbamate (140.6 mg) as an off-white solid.
