Phosphorus oxychloride → 4-chloro-6-ethylthieno[2,3-d]pyrimidine

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Reaction Steps

Phosphoryl trichloride (2.3 mL, 3.00 equiv) was added to a solution of 6-ethylthieno[2,3-d]pyrimidin-4-ol (1.5 g, 8.32 mmol, 1.00 equiv) in dioxane (15 mL) dropwise with stirring at room temperature. The resulting solution was stirred overnight at 110° C. in an oil bath. The resulting solution was cooled and quenched by the addition of 100 mL of water and ice mixture. The resulting solution was extracted with 3×100 mL of ethyl acetate and the organic layers combined. The resulting mixture was washed with 3×200 mL of brine. The mixture was dried over anhydrous sodium sulfate and concentrated under vacuum. The residue was applied onto a silica gel column with ethyl acetate/petroleum ether (1/10) to yield 700 mg (42%) of 4-chloro-6-ethylthieno[2,3-d]pyrimidine as a yellow solid. MS: m/z 199 (M+H)+.

Provenance & Evidence