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

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Reaction Steps

A solution of 3H-thieno[3,2-d]pyrimid-4-one (3, 2.7 g, 18 mmol) in phosphorus oxychloride (18 mL) under N2 was heated at reflux for 1 hour. The resulting solution was allowed to cool to room temperature and then poured into a saturated aqueous solution of sodium bicarbonate to neutralize. The aqueous mixture was extracted with diethyl ether. The organic layer was washed with water followed by saturated aqueous sodium chloride, dried over anhydrous magnesium sulfate and the solvent evaporated under reduced pressure to yield 4-chlorothieno[3,2-d]pyrimidine (2.9 g, 97% yield) as a white solid.

Provenance & Evidence