Phosphorus oxychloride → 6-Chloro-1,3-diphenylpyrimidine-2,4-dione

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Reaction Steps

To 1,3-diphenyl-pyrimidine-2,4,6-trione 19 (78.0 g) obtained in Step 1 was added water (16 ml). Phosphorus oxychloride (422 ml) was added dropwise under stirring at room temperature over 50 min. After the completion of the dropwise addition, the mixture was stirred under heating at 110° C. for 3 hrs. After allowing to cool to room temperature, the reaction mixture was added to ice water by small portions and the mixture was stirred at room temperature and extracted with ethyl acetate. The organic layer was washed with brine and saturated aqueous sodium hydrogen carbonate, and dried over anhydrous sodium sulfate. Anhydrous sodium sulfate was filtered off and the filtrate was concentrated under reduced pressure. The residue was purified by column chromatography (hexane:ethyl acetate=2:1→3:2) to give 6-chloro-1,3-diphenyl-1H-pyrimidine-2,4-dione 20 (61.5 g, yield 74%) as pale-yellow crystals.

Provenance & Evidence