Hydrochloric Acid → 4-[3E-(2,4-Dimethoxy-5-thien-2-yl-phenyl)acryloyl]-N-(5-methylisoxazol-3-yl)benzenesulfonamide

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Reaction Steps

4-Acetyl-N-(5-methylisoxazole-3-yl)benzenesulfonamide (Ex-1B, 2.50 g, 8.9 mmol) and 2,4-dimethoxy-5-thien-2-ylbenzaldehyde (Ex-1A, 2.20 g, 8.9 mmol) were dissolved in a dimethylformamide-methanol solution (55 mL, 7:3). After complete dissolution, lithium methoxide (1.35 g, 35.6 mmol) was added and the resulting orange slurry was stirred in the dark at room temperature for 1 h. Upon completion, as determined by HPLC, the mixture was diluted with water (80 mL), acidified with a 1 N hydrochloric acid solution, and extracted with ethyl acetate (3×40 mL). The combined organic extracts were dried over sodium sulfate and evaporated to dryness. The crude oil was taken up in ethanol (20 mL) and warmed to 60° C. to obtain complete dissolution and allowed to cool to room temperature. The resulting precipitate was collected on filter paper and dried in vacuo to yield 3.78 g (83%) of the title compound as an orange solid, mp 202–203° C. 1H-NMR (300 MHz, DMSO-d6) 8.31 (d, 2H, J=8.1 Hz), 8.27 (s, 1H), 8.08 (d, 1H, J=15.9 Hz), 8.01 (d, 2H, J=8.1 Hz), 7.88 (d, 1H, J=15.9 Hz), 7.66 (d, 1H, J=3.3 Hz), 7.53 (d, 1H, J=5.1 Hz), 7.13 (dd, 1H, J=5.1, 3.3 Hz), 6.84 (s, 1H), 6.18 (s, 1H), 4.02 (s, 3H), 4.00 (s, 3H), 2.31 (s, 3H). Anal. Calcd. for C25H22N2O6S2: C, 58.81; H, 4.34; N, 5.49; S, 12.56; Found: C, 58.68; H, 4.40; N, 5.61; S, 12.62. HRMS (EI) Calcd. for C25H22N2O6S2: 511.0997 (M+); Found: 511.0983.

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