Methanol → 2-(4-Formyl-5-methoxy-2-thiophen-2-yl-phenoxy)-2-methyl-propionic acid

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Ex-47D: To a solution of 2-(4-formyl-5-methoxy-2-thiophen-2-yl-phenoxy)-2-methyl-propionic acid ethyl ester (0.29 g, 0.83 mmol) in a mixture of tetrahydrofuran, water and methanol (9 mL, 4:1:1) was added lithium hydroxide (0.10 g, 2.49 mmol) and the resulting yellow slurry was stirred at rt for 5 h. The mixture was diluted with water (5 mL) and extracted with ethyl acetate (1×5 mL). The aqueous layer was acidified with a 1 N HCl solution and extracted with ethyl acetate (3×15 mL). The combined organic layers was dried over sodium sulfate and concentrated to afford 0.13 g (87%) of 2-(4-formyl-5-methoxy-2-thiophen-2-yl-phenoxy)-2-methyl-propionic acid as a pale green solid, mp 183–184° C. 1H-NMR (300 MHz, CDCl3) δ 10.32 (s, 1H), 8.12 (s, 1H), 7.40 (d, 1H, J=3.6 Hz), 7.32 (d, 1H, J=4.8 Hz), 7.08 (dd, 1H, J=4.8, 3.6 Hz), 6.47 (s, 1H), 3.86 (s, 3H), 1.78 (s, 6H). MS (EI) m/z=320 ([M]+, 100%). Anal. Calcd. for C16H16O5S: C, 59.99; H, 5.03; S, 10.01. Found: C, 60.04; H, 5.26; S, 9.70.

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