Methanol → 4-(2-Thienyl)butanoic acid methyl ester

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Reaktionsschritte

A mixture of 4-(2-thienyl)butyric acid (4.25 g, 25.0 mmol) and 3 mL of concentrated sulfuric acid in 25 mL of methanol is heated at reflux for 2 hours. The reaction mixture is cooled to room temperature and partitioned between ethyl acetate and saturated aqueous sodium carbonate solution. The organic layer is separated and passed through a short pad of silica gel. The filtrate is concentrated and purified by flash column chromatography eluting with 1:5 ethyl acetate:hexane to provide 4.02 g of 4-thiophen-2-yl-butyric acid methyl ester as a yellow oil, 1H NMR (DMSO-d6) δ 1.85 (quintet, J=7 Hz, 2H), 2.35 (t, J=7 Hz, 2H), 2.81 (t, J=7 Hz, 2H), 3.59 (s, 3H), 6.84 (m, 1H), 6.95 (m, 1H), 7.32 (dd, J=5, 1 Hz, 1H); MS 185.0 (M+H)+.

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