To a stirred solution of 4-(N-tert-butyloxy-carbonyl-4-piperidinyloxy)-2-(2,2,2-trifluoroethoxy)phenylacetic acid from Step 8 of Example 1 and 1-(piperidin-4-yl)-3,4-dihydroquinolin-2(1H)-one prepared by the method of Ogawa, et al., J. Med. Chem. (1993), vol. 36, pp. 2011-2017) in DMF was added HOBT, EDC, and DIEA. The solution was stirred at ambient temperature for 14 h. The solvent was removed under reduced pressure and the residue was partitioned between EtOAc (100 mL) and 0.25 M aqueous citric acid (75 mL). The organic phase was separated and washed with H2O (25 mL), saturated aqueous NaHCO3 (75 mL), and brine (25 mL). The organic phase was dried (MgSO4), filtered, and the solvent was removed under reduced pressure. The residue was purified by pressurized silica gel column chromatography using EtOAc as eluant. The product-containing fractions were evaporated under reduced pressure to give 1-(1-(4-(N-tert-butyloxycarbonyl-4-piperidinyloxy)-2-(2,2,2-trifluoroethoxy)phenylacetyl)piperidin-4-yl)-3,4-dihydro-quinolin-2(1H)-one as an amorphous solid (HPLC retention time=10.8 min (method A); TLC Rf=0.7 (EtOAc)).
