4-Chloro-2-(methylthio)pyrimidine-5-carboxylic acid ethyl ester → Ethyl 4-methoxy-2-(methylthio)-pyrimidine-5-carboxylate

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A mixture of ethyl 4-chloro-2-(methylthio)pyrimidine-5-carboxylate (2.5 g, 10.74 mmol) and sodium methoxide (2.50 mL, 13.11 mmol) in methanol (107 mL) was stirred at room temperature under nitrogen for 4 h, quenched with acetic acid (5 mL), and concentrated. The oily residue was purified by flash chromatography on silica gel using 0-40% ethyl acetate in hexanes to give methyl 4-methoxy-2-(methylthio)pyrimidine-5-carboxylate as a white solid (0.52 g, 23%) and ethyl 4-methoxy-2-(methylthio)pyrimidine-5-carboxylate as a colorless oil (0.61 g, 25%). Methyl 4-methoxy-2-(methylthio)pyrimidine-5-carboxylate: 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 8.83 (s, 1H), 4.11 (s, 3H), 3.90 (s, 3H), 2.60 (s, 3H). LCMS: R.T.=0.92; [M+H]+=229.1. Ethyl 4-methoxy-2-(methylthio)pyrimidine-5-carboxylate: 1H NMR (400 MHz, CHLOROFORM-d) δ 8.82 (s, 1H), 4.36 (q, J=7.0 Hz, 2H), 4.11 (s, 3H), 2.60 (s, 3H), 1.38 (t, J=7.2 Hz, 3H). LCMS: R.T.=0.92; [M+H]+=229.1.

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