O-tert-butylhydroxylamine hydrochloride (127 mg, 1.01 mmol), 1-(3-dimethylaminopropyl)-3-ethylcaibodiimide hydrochloride (129 mg, 0.67 mmol), N,N-dimethylaminopyridine (41 mg, 0.34 mmol), and N-methylmorpholine (0.15 ml, 1.3 mmol) were added to a solution of 1-[4-(4-chlorobenzoyl)piperidine-1-sulfonyl]piperidine-2-(R)-carboxylic acid (140 mg, 0.34 mmol), [prepared by proceeding as described in Example 9, but replacing D-valine and 4-(4chlorophenoxy)piperidinesulfamoyl chloride with D-pipecolinic acid and 4-(4-chlorobenzoylpiperidinesulfamoyl chloride, respectively], in methylene chloride (2 ml). After stirring overnight, the reaction mixture was diluted with ethyl acetate, washed with 1M HCl, and brine, and dried over MgSO4. The organics were evaporated in vacuo and the residue was chromatographed (PTLC, SiO2, 40% ethyl acetate/hexane) to give N-tert-butoxy-1-[4-(4-chlorobenzoyl)piperidine-1-sulfonyl]piperidine-2-(R)-carboxamide as a white solid (65%).
