Described herein are pyrrolo{2,3-d}pyrimidine derivatives, their use as Janus Kinase (JAK) inhibitors, pharmaceutical compositions containing them, and therapeutic uses thereof.本文說明吡咯并[2,3-d]嘧啶衍生物,彼等作為詹納斯氏激酶(Janus Kinase,JAK)抑制劑之用途,含彼等之藥學組成物、及彼等之醫療用途。