(3S,4R)-Tofacitinib (Tofacitinib Impurity B) is a less active isomer/enantiomer of Tofacitinib (CP-690550; tasocitinib; Xeljanz), which is an inhibitor of JAK3 (Janus-Associated kinase, IC50 = 1 nM) and an FDA approved drug for the treatment of rheumatoid arthritis (RA), psoriatic arthritis, and ulcerative colitis.

纯度：≥98%

CAS：1092578-48-7