To methyl N-(4-{4-[4-(tert-butoxycarbonyl)piperazin-1-yl]phenyl}-3-methylisoxazol-5-yl)leucinate (450 mg, 0.926 mmol) in MeOH (15 mL) was added an aqueous solution of LiOH (2.0 M, 2.3 mL, 4.6 mmol) and the reaction mixture was stirred overnight. The reaction was acidified (pH=4–5) with aqueous 10% HCl, the product extracted with EtOAc (3×), dried over Na2SO4, concentrated in vacuo and purified by flash chromatography over silica gel (AcOH(EtOAc/Hex, 1/29/70) to afford N-(4-{4-[4-(tert-butoxycarbonyl)piperazin-1-yl]phenyl}-3-methylisoxazol-5-yl)leucine.
