P(Cl)(Cl)([Cl:3])=O.[CH3:6][C:7]1[C:11]2=[N:12][CH:13]=[CH:14][C:15](O)=[C:10]2[S:9][CH:8]=1>ClCCCl>[Cl:3][C:15]1[CH:14]=[CH:13][N:12]=[C:11]2[C:7]([CH3:6])=[CH:8][S:9][C:10]=12Phosphorous oxychloride (2.2 mL, 24 mmol) in 1,2-dichloroethane (12 mL) was charged with 3-methylthieno[3,2-b]pyridin-7-ol (2.0 g, 12 mmol). The reaction stirred overnight at reflux under nitrogen. The mixture was the cooled and concentrated. Saturated NaHCO3 solution was carefully added to neutralize the residue. The biphasic mixture was extracted with dichloromethane, dried, and concentrated. Flash chromatography (15% EtOAc/hexanes) gave the title compound (1.23 g, 55%).
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