Phosphorus oxychloride → 7-Chloro-5-(4-fluorophenyl)thieno[3,2-b]pyridine

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Reaction Steps

A solution of 5-(4-fluorophenyl)-thieno[3,2-b]pyridin-7-ol (1.6 g) in phosphorus oxychloride (50 mL) is refluxed for 3 hours. After the excess phosphorus oxychloride is removed under vacuum, the residue is treated with ethyl acetate (20 mL), and NaOH (2N, 20 mL). The mixture is extracted with ethyl acetate (3×20 mL) and the combined organic layers are washed with brine and dried over MgSO4. Evaporation of the solvent gives 7-chloro-5-(4-fluorophenyl)thieno[3,2-b]pyridine (1.5 g, 88% yield) as a white solid, m.p. 119-121° C.

Provenance & Evidence