To a suspension of 4-chloro-7H-pyrrolo[2,3-d]pyrimidine-5-carbaldehyde oxime (865 mg, 4.40 mmol, 1.0 eq.) in dichloromethane (20 mL) was slowly added thionyl chloride (3.1 mL, 43.7 mmol, 10.0 eq.). The reaction mixture was stirred at room temperature overnight. Upon completion of the reaction, the mixture was concentrated under reduced pressure to remove the solvent. The residue was suspended in water (60 mL) and the pH was adjusted slowly to 4 by addition of saturated aqueous sodium bicarbonate.The precipitated solid was collected by diafiltration and washed sequentially with water and ethyl acetate to give the first products. Subsequently, the filtrate was extracted with ethyl acetate (50 mL x 3). The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and the resulting residue was combined with the aforementioned solid. The crude product was recrystallized in a mixed solvent of ethyl acetate/hexane (1:1, v/v) and dried under reduced pressure to give 4-chloro-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile (763 mg, 97% yield).ESI-MS m/z: 178.8 [M + H]+, 176.8 [M - H]+.
![4-Chloro-7H-pyrrolo[2,3-d]pyrimidine-5-carbaldehyde oxime](/CAS/20200119/GIF/908287-23-0.gif)
![4-Chloro-7H-pyrrolo[2,3-d]pyrimidine-5-carbonitrile](/CAS/GIF/24391-41-1.gif)