5-Chloro-1H-indole-2-carboxylic acid [(1S)-benzyl-2-(4-hydroxy-piperidin-1-yl)-2-oxo-ethyl]-amide (Example 46, 669 mg) was added in one portion at 0° C. to a mixture of 1-(3-dimethylaminopropyl)3-ethylcarbodiimide hydrochloride (DEC, 1.80 g, 9.4 mmol) and dichloroacetic acid (307 mg, 1.5 mmol) in anhydrous toluene (e mL) and anhydrous dimethylsulfoxide (e mL). The mixture was stirred at 0-20° C. for 2 h, diluted with ethyl acetate, the resulting solution washed twice with 1 N HCl, twice with saturated aqueous NaHCO3, dried, concentrated and the residue purified by chromatography on silica gel eluted with 25%, 50%, and 75% ethyl acetate-hexanes giving a foam (424 mg, 64%).
