Isonicotinic Acid → 3-(3,4-Diethoxyphenyl)-5-pyridin-4-yl-1,2,4-oxadiazole

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In a microwave vial, a stirring solution of isonicotinic acid (200 mg, 1.62 mmol) in DMF was treated with HOBt (319 mg, 2.43 mmol) and EDCI (467 mg, 2.43 mmol) at room temperature. The reaction was stirred for 20 min followed by addition, in a single portion, of (Z)-3,4-diethoxy-N-hydroxybenzimidamide (436 mg, 1.94 mmol). The reaction was stirred for additional 30 min at room temperature and then heated to 130° C. for 35 min in the initiator. The reaction was diluted using a saturated solution of NaHCO3 and extracted with EtOAc (80 ml×3). The organic phase was dried over Na2SO4 anhydrous and concentrated under reduced pressure. The product was purified by column chromatography using CH2Cl2:MeOH (95:5) to offer the product in 26% yield (131 mg) as pale brown solid. 1H NMR (300 MHz, CDCl3): δ 8.85 (d, J=5.4 Hz, 2H), 8.02 (d, J=6.0 Hz, 2H), 7.71 (dd, J1=1.8 Hz, J2=8.1 Hz, 1H), 7.62 (d, J=2.1 Hz, 1H), 6.95 (d, J=8.4 Hz, 1H), 4.19 (q, J=6.9 Hz, 2H), 4.14 (q, J=6.9 Hz, 2H), 1.50 (t, J=3.0 Hz, 3H), 1.46 (t, J=3.3 Hz, 3H); 13C NMR (75 MHz, CDCl3): δ 173.54, 16928, 151.64, 151.07, 148.91, 131.37, 121.48, 121.15, 118.75, 112.74, 111.82, 64.78, 64.59, 14.87, 14.81. MS (EI) m/z: 312 (M+), HRMS (EI) for C17H17N3O3 (M+): calcd 312.1343. found 312.1348.

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