4-Chloro-7-tosyl-7H-pyrrolo[2,3-d]pyrimidine

4-Chloro-7-tosyl-7H-pyrrolo[2,3-d]pyrimidine is a reagent in the synthesis of (+)-tofacitinib, a selective Janus kinase 3 inhibitor (JAK3) and an immunosuppressant drug.

4-Chloro-7H-pyrrolo[2,3-d]pyrimidine (2kg, 12.96mol) and dichloromethane (40L) were added to the reaction flask at room temperature, stirred and dissolved. Triethylamine (3.88 kg, 38.4 mol) and 4-dimethylamino pyridine (157.6 g, 1.28 mol) were added in that order, and after stirring and dissolved, p-toluenesulfonyl chloride (2.6 kg, 13.6 mol) was added dropwise at 0 °C. The chloromethane (30 L) solution was added dropwise, and the mixture was stirred at room temperature for 30 min. After the TLC was applied, the mixture was washed with water (16L×3). 4-Chloro-7-tosyl-7H-pyrrolo[2,3-d]pyrimidine (3.9 kg, yield 97.7%) was obtained after drying under reduced pressure.