Phosphorus oxychloride → 4-Chloro-2,3-dimethyl-1H-pyrrolo[3,2-c]pyridine

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Reaction Steps

2,3-dimethyl-1,5-dihydro-pyrrolo[3,2-c]pyridin-4-one (6.0 g, 37.0 mmol) prepared in Step 3 was added to phosphorus oxychloride (230 ml). The reaction mixture was refluxed under stirring for 6 hours, cooled to room temperature, and then concentrated under reduced pressure. The resulting residue was dissolved in methanol (200 ml). The obtained solution was alkalized with a saturated ammonia solution in methanol and concentrated under reduced pressure. The resulting residue was purified with silica gel column chromatography (ethyl acetate) and recrystallized with ether to give the titled compound as a pale yellow solid. (Yield: 43.0%)

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