Description：4-Chloro-7H-pyrrolo[2,3-d]pyrimidine is a white to off-white powder. It is an important pharmaceutical intermediate and is used as an API for the treatment of adult patients with moderate to severe rheumatoid arthritis who have insufficient response or intolerance to methotrexate. Intermediates of tofacitinib. 4-Chloro-7H-pyrrolo[2,3-d]pyrimidine is also an important raw material for the development of many antibacterial, antitumor, antivertebral worm and other drugs.