Oxalyl chloride → 7-Chloro-2-(3-methyl-1,2,4-oxadiazol-5-yl)thieno[3,2-b]pyridine

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Reaction Steps

To a mixture of lithium 7-chlorothieno[3,2-b]pyridine-2-carboxylate (2.125 g, 9.7 mmol) and DMF (20 drops) in CH2Cl2(35 mL), oxalyl dichloride (1.3 ml, 15 mmol) was added dropwise. The mixture was stirred at RT for 2.5 h and then was concentrated to give a yellow solid. The resultant crude acid chloride and (Z)-N′-hydroxyacetamidine (1.4 g, 19 mmol) were heated at 140° C. in xylene/pyridine (6/1, 35 mL) for 1 h. The mixture was diluted with CH2Cl2, and then washed with water, then sat. NaHCO3 and brine. The crude product was purified via column chromatography on silica gel (RediSep 120 g column, gradient elution with 0-50% EtOAc in Hexane) to afford 7-chloro-2-(3-methyl-1,2,4-oxadiazol-5-yl)thieno[3,2-b]pyridine as a white solid.

Provenance & Evidence