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

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Reaction Steps

The solution of 4-hydroxypyrido[2,3-d]pyrimidine (2.00 g, 13.6 mmol) in POCl3 (40 mL) was refluxed for 2 hours. After cooling, the excess POCl3 was removed under vacuum. The residue was quenched with saturated NaHCO3 and extracted with ethyl acetate (3×100 mL). The organic phase was dried and concentrated. The residue was subject to column chromatography, eluted by hexane/ethyl acetate (1:1) to give 4-chloropyrido[2,3-d]pyrimidine (0.72 g, 32%). 1H NMR (CDCl3, 400 MHz) δ 9.35 (m, 1H), 9.30 (s, 1H), 8.66 (m, 1H), 7.73 (m, 1H). MS (APCI+) [M+H]+166.

Provenance & Evidence