1H-Pyrrolo[2,3-b]pyridine, 4-chloro-2-iodo-

1312581-05-7

940948-29-8

Step a) Synthesis of 4-chloro-2-iodo-1H-pyrrolo[2,3-b]pyridine: 4-chloro-2-iodo-1-methoxymethyl-1H-pyrrolo[2,3-b]pyridine (20 g, 62 mmol, 1 eq.) was dissolved in anhydrous dichloromethane (300 mL) under ice-bath cooling, and bromo catecholborane (16.06 g, 200 mL. 80 mmol, 1.3 equiv) to the solution. The reaction mixture initially showed a bright yellow color and rapidly changed to a thick suspension. After 1.5 hours of reaction, the solvent was removed by evaporation under reduced pressure. Potassium acetate (182 g, 1863 mmol, 30 eq.) and ethanol (400 mL) were added to the residue and the suspension was stirred at room temperature for 24 hours. Subsequently, ethanol was removed by evaporation under reduced pressure and the crude product was ground with water (400 mL) for 24 hours and washed with saturated sodium bicarbonate solution. The solid was collected by filtration and dried under vacuum to give 4-chloro-2-iodo-1H-pyrrolo[2,3-b]pyridine white solid (14.1 g, 82% yield). The product can be used directly in the subsequent reaction without further purification.