Phosphorus oxychloride → 3-Bromo-4-chlorothieno(3,2-c)pyridine

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Reaction Steps

A suspension of Example 1A (35.91 g, 0.156 mol) in POCl3 (80 mL) was heated to reflux for 2.5 hours, cooled to room temperature, poured onto 800 g of ice, and extracted repeatedly with dichloromethane. The combined extracts were washed with water and brine, dried (Na2SO4), filtered, and concentrated. The residue was purified by flash column chromatography on silica gel with 0 to 5% methanol/dichloromethane to provide 29.3 g of 3-bromo-4-chlorothieno[3,2-c]pyridine (mp 158–159° C.), which was diluted with dioxane (500 mL) and concentrated aqueous NH3 (500 mL), heated to 150° C. under pressure (260 psi) for 20 hours, and concentrated. The residue was triturated from MTBE then from methanol to provide 20.29 g of the desired product. m.p. 153–155° C.

Provenance & Evidence