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

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Reaction Steps

1H-Pyrrolo[2,3-b]pyridine 7-oxide (1.86 g, 13.9 mmol, literature reference: J. Org. Chem. 45(20):4045-8 (1980)) was dissolved in 10 mL of phosphorus oxychloride. The reaction mixture was refluxed for 6 hours, cooled to room temperature and concentrated. The residue was extracted with ethyl acetate/water. The organic layer was washed with brine to pH 6, dried over anhydrous sodium sulfate, concentrated and dried in a vacuum oven overnight to give 0.88 g (42%) of 4-chloro-1H-pyrrolo[2,3-b]pyridine as a tan solid. 1H NMR (360 MHz, DMSO-d6) δ 11.99 (s, br, 1H, NH), 8.16 (d, J=5.15 Hz, 1H), 7.57 (t, br, J=3.38 Hz, 1H), 7.17 (d, J=5.15 Hz, 1H), 6.49 (dd, J=1.80, 3.38 Hz, 1H). MS m/e 153 [M+].

Provenance & Evidence