Sodium Carbonate → 4-Chloro-1H-pyrrolo[2,3-b]pyridine

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Reaction Steps

To cooled POCl3 (50 mL) in a dried round bottom flask, 1H-pyrrolo[2,3-b]pyridine 7-oxide (6.6 g, step A) was added in portions. The mixture was heated to reflux for 5 h. After cooling to RT, POCl3 was evaporated under high vacuum with gentle heating (40-50° C.) to obtain a black residue. Water (50 mL) was added slowly and the pH was adjusted to 8-9 with Na2CO3 (first with solid, then saturated aqueous solution). The resulting precipitate was collected by filtration, washed with cold H2O and dried in a vacuum oven (50° C.) to give 4-chloro-1H-pyrrolo[2,3-b]pyridine as a tan powder. This was a mixture of desired product and a regioisomer, which was used in the next step without further purification.

Provenance & Evidence