Sodium Hydroxide → 2-(Methylthio)-6-phenylpyrimidine-4-carboxylic acid

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A mixture of 2,4-dioxo-4-phenylbutanoic acid (19.2 g, 100 mmol), 2-methylisothiourea sulfate (27.8 g, 100 mmol) and sodium ethoxide (37 mL, 21% wt. solution, 100 mmol) in ethanol (200 mL) was heated to reflux overnight. After removal of volatiles, water was added (200 mL) to give a suspension, which was adjusted to pH>9 with 10% NaOH. The mixture was extracted with diethyl ether (2×100 mL). The aqueous layer was taken to pH=2 with conc. HCI and extracted with diethyl ether (4×100 mL). The combined ethereal extracts were evaporated, and the residue was dried in vacuo overnight to afford 22.0 g of 2-methylsulfanyl-6-phenylpyrimidine-4-carboxylic acid as a yellow solid. 1H NMR (DMSO-d6, 300 MHz) δ 8.24 (dd, J=7.8, 1.8 Hz, 2H), 8.12 (s, 1H), 7.58 (m, 3H), 2.64 (s, 3H). 13C NMR (DMSO-d6, 75 MHz) δ 172.8, 165.7, 165.6, 157.9, 135.8, 132.5, 129.8, 128.0, 14.6. HPLC ret. time 1.95 min, 10-100% CH3CN, 5 min run. ESI-MS m/z 247.1 (M+H)+.

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