Hydrochloric Acid → 4-{3E-[2-(1-Carboxy-1-methyl-ethoxy)-4-methoxy-5-thiophen-2-yl-phenyl]-acryloyl}-benzoic acid

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2-(2-Formyl-5-methoxy-4-thiophen-2-yl-phenoxy)-2-methyl-propionic acid (Ex-59B, 0.12 g, 0.39 mmol) and 4-acetylbenzoic acid (0.064 g, 0.39 mmol) were dissolved in a dimethylformamide-methanol solution (2.7 mL, 7:3). After complete dissolution, lithium methoxide (0.060 g, 1.6 mmol) was added and the resulting bright orange slurry was stirred in the dark at room temperature for 2 h. Upon completion, as determined by HPLC, the mixture was diluted with water (15 mL), acidified with a 1 N hydrochloric acid solution, and extracted with ethyl acetate (3×15 mL). The combined organic extracts were dried over sodium sulfate and evaporated to dryness. The crude oil was taken up in ethyl alcohol (5 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 0.15 g (85%) of the title compound as a dark yellow solid, mp 223–225° C. 1H-NMR (300 MHz, DMSO-d6) δ 8.31 (s, 1H), 8.23 (d, 2H, J=8.1 Hz), 8.10 (d, 2H, J=8.1 Hz), 8.06 (s, 1H), 7.95 (d, 1H, J=16.2 Hz), 7.69 (d, 1H, J=3.0 Hz), 7.55 (d, 1H, J=5.1 Hz), 7.14 (dd, 1H, J=5.1, 3.0 Hz), 6.58 (s, 1H), 3.88 (s, 3H), 1.66 (s, 6H). MS (ESI) m/z=467 ([M+H]+, 100%). Anal. Calcd. for C25H22O7S.⅓H2O: C, 63.55; H, 4.84; S, 6.79. Found: C, 63.39; H, 5.02; S, 6.53.

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