To a solution of sodium 3-(4-(trifluoromethoxy)phenyl)-1,2,4-oxadiazole-5-carboxylate (500 mg, 1.7 mmol) in DCM (15 mL), DIEA (436 mg, 3.4 mmol), EDC.HCl (496 mg, 2.6 mmol), HOBT (351 mg, 2.6 mmol) and 3-amino-1-(3-bromophenyl)butan-2-ol (500 mg, 2.0 mmol) were added in sequence. The mixture was stirred at RT for 2 h, heated at 40 overnight, cooled to RT, quenched by the addition of H2O (50 mL), and extracted with DCM (50 mL×3). The combined organic layers were washed with H2O (10 mL) and brine (10 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (Petroleum ether:EtOAc=5:1) to afford N-(4-(3-bromophenyl)-3-hydroxybutan-2-yl)-3-(4-(trifluoromethoxy)phenyl)-1,2,4-oxadiazole-5-carboxamide (350 mg, 41%) as a white solid. MS (ES+) C20H13BrF3N3O3 requires: 499, 501 found: 500 [M+H]+, 502 [M+2+H]+(1:1).
