Synthesis and structure-activity relationship studies of 1,5-isomers of triazole-pyrrolopyrimidine as selective Janus kinase 1 (JAK1) inhibitors

JAK inhibitors have been considered as useful targets for the treatment of related diseases. However, first-generation JAK inhibitors have side effects such as anemia, thrombocytopenia, neutropenia and headaches which have been suggested to result from high JAK2 inhibition. Second-generation JAK inhibitors with more specific JAK isozyme inhibition have been studied to eliminate these adverse effects. In this study, novel 4-(1,5- or 2,5-triazole)-pyrrolopyrimidine derivatives with aromatic moieties were synthesized as JAK1 inhibitors, and an in vitro Enzyme assay was used to evaluate the JAK inhibitory effects. Among these JAK1 inhibitors, the compound 23a showed an IC₅₀ level of 72 nM, as well as being selective against other JAKs by 12 times or more: the results of molecular docking studies suggested that the high JAK1 selectivity resulted from a key interaction between the iodine atom of compound 23a and His-885 of hJAK1.