Sodium Hydroxide → 6-(2-Methoxyphenyl)-2-(methylthio)pyrimidine-4-carboxylic acid

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A mixture of 2,4-dioxo-4-(2-methoxyphenyl)butyric acid (15.6 g, 70 mmol), 2-methyl-isothiourea sulfate (10.4 g, 73.5 mmol) and sodium ethoxide (26 mL, 21% by wt. in ethanol, 70 mmol) in ethanol (200 mL) was heated to reflux overnight. The resulting solution was reduced to approximately 50 mL using a rotary evaporator, water (200 mL) was added to give a suspension, which was adjusted to pH >9 with 10% NaOH. The mixture was extracted with diethyl ether (100 mL). The aqueous layer was taken to pH=3 with conc. HCI solution to give a suspension, which was heated to 90° C. for 10 minutes. Upon cooling in an ice bath for 1 h, a precipitate formed, which was filtered, washed with water (20 mL), and dried overnight under vacuum to give 6-(2-methoxyphenyl)-2-(methylthio)pyrimidine-4-carboxylic acid. 1H NMR (300 MHz, CDCl3) δ 8.45 (s, 1H), 8.10 (dd, J=7.5, 1.8 Hz, 1H), 7.48 (m, 1H), 7.09 (t, J=6.9 Hz, 1H), 7.02 (d, J=8.7 Hz, 1H), 3.94 (s, 3H), 2.67 (s, 3H). HPLC ret. time 2.02 min, 10-100% CH3CN, 5 min gradient; ESI-MS m/z 277.1 (M+H)+.

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