To a solution of 2-cyclopentyl-6-methoxy-isonicotinic acid hydrazide (870 mg, 3.70 mmol), 4-benzyloxy-3-ethyl-5-methyl-benzoic acid (1.00 g, 3.70 mmol) and DIPEA (1.44 g, 11.1 mmol) in DCM (30 mL), TBTU (1.43 g, 4.44 mmol) is added. The mixture is stirred at rt for 1 h before diluted with EA (150 mL) and water (50 mL). The org. phase is separated, washed with sat. aq. NaHCO3 solution (50 mL) followed by brine (50 mL), dried over MgSO4, filtered and concentrated. The remaining pale yellow oil is dissolved in THF (50 mL) and Burgess reagent (1.23 g, 5.18 mmol) is added. The mixture is stirred at 110° C. for 15 min under microwave irradiation before it is diluted with EA (200 mL) and washed twice with water (50 mL). The org. extract is dried over MgSO4, filtered and concentrated and the crude product is purified by CC on silica gel eluting with heptane:EA 1:9 to give 4-[5-(4-benzyloxy-3-ethyl-5-methyl-phenyl)-[1,3,4]oxadiazol-2-yl]-2-cyclopentyl-6-methoxy-pyridine (750 mg) as a pale yellow oil; LC-MS**: tR=1.06 min, [M+H]+=470.21.
