Phosphorus oxychloride → 4-Chloropyrido[2,3-d]pyrimidine

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Reaction Steps

The Pyrido[2,3-d]pyrimidin-4-ol (3 g) in POCl3 (45 mL) was stirred at reflux for 3 hours. The excess POCl3 was removed. The residue was added 10 mL of cold water and extracted with EtOAc (2×30 mL). The combined organic layer was washed with brine and dried over sodium sulfate. After removal of solvent, it gave 4-chloropyrido[2,3-d]pyrimidine as yellow solid (0.3 g, 7.6%). 1H NMR (CDCl3, 400 MHz) δ 9.38 (br, 1H), 9.31 (s, 1H), 8.62 (d, 1H), 7.75 (m, 1H).

Provenance & Evidence