Design, Synthesis, and Biological Evaluation of Macrocyclic 2-Amino-4-phenylaminopyrimidine Derivatives as Potent JAK2 Inhibitors

Janus kinase 2 with the activating mutation V617F is a potential target for the treatment of myeloproliferative neoplasms. Current JAK2 inhibitors often suffer from multiple pharmacological limitations such as limited selectivity and rapid metabolic clearance. In this study, we describe the design, synthesis, and biological evaluation of a series of macrocyclic 2-amino-4-phenylaminopyrimidine derivatives as JAK2 inhibitors. Among them, compound 11 showed potent inhibitory activity against JAK2 kinase (IC₅₀ = 54.70 nM), as well as JAK2-dependent HEL and SET-2 cells, with IC₅₀ values of 0.57 μM and 1.07 μM, respectively. Besides, compound 11 downregulated the expression of p-STAT3 and p-STAT5 in HEL cells. Importantly, compound 11 also exhibited good bioavailability (F = 54.8%) and potent inhibition of rhEPO-induced extramedullary erythropoiesis and polycythemia vera in vivo. In summary, the macrocyclic design introduces structural innovation and provides a more efficient and selective strategy for JAK2 inhibition.