Reaction Steps
To a solution of 3-(5-(3-(5-(4-tert-butylphenyl)-1,3,4-oxadiazol-2-yl)phenyl)-1,3,4-oxadiazol-2-yl)phenol (0.92 g, 2.10 mmol) and bicyclo[2,2,1]hept-5-en-2-ylmethyl 4-methylbenzenesulfonate (1.6 g, 5.75 mmol) in DMF (45.0 ml), was added Cs2CO3 (4.5 g, 13.81 mmol) at room temperature under nitrogen. The reaction was carried out at 100° C. for 2 hours. After cooling down to room temperature, water (100.0 ml) was added into the reaction mixture. A brown solid precipitate was collected by filtration and washed with methanol and then dried under vacuum. The crude product was purified by a silica gel column using dichloromethane/ethyl acetate, ratio (9.3:0.7), as the eluent. After removal of the solvents, a pure white solid product was obtained in 0.97 g (85.1%) yield by recrystallization from dichloromethane/methanol. 1H NMR (400 MHz, CDCl3) δ: 8.86 (m, 1H), 8.34 (dd, 2H, J1=8.0 Hz, J2=1.6 Hz), 8.11 (d, 2H, J=8.4 Hz), 7.73 (m, 2H), 7.67 (m, 1H), 7.58 (d, 2H, J=8.4 Hz), 7.45 (m, 1H), 7.12 (m, 1H), 6.22-5.99 (m, 2H, C═C—H, endo and exo), 4.17-3.64 (m, 2H, OCH2, endo and exo), 3.09 (s, br), 2.91 (m, br), 2.61 (m, br), 1.95 (m), 1.52 (m), 1.39 (s, 9H, 3×CH3), 1.40-1.23 (m), 0.68 (m) ppm. 13C NMR (100 MHz, CDCl3) δ: 165.14, 163.65, 163.38, 159.57, 155.67, 137.68, 136.90, 136.38, 132.29, 130.26, 129.99, 129.77, 129.71, 126.92, 126.13, 125.13, 124.98, 124.94, 124.61, 120.73, 119.31, 119.22, 118.90, 112.29, 72.57, 71.78, 49.42, 45.06, 43.87, 43.69, 42.23, 41.60, 38.54, 38.32, 35.12, 31.10, 29.62, 28.99 ppm. MS (m/z): [M+1]+ calcd for C34H32N4O3 545.3. found 545.2. Anal. Calcd for C34H32N4O3: C, 74.98; H, 5.92; N, 10.29. Found: C, 74.77; H, 6.02; N, 10.27.
