“…The pyridopyrimidine skeletons appear in the literature including pyrido[2,3- d ]pyrimidine, pyrido[3,2- d ]pyrimidine, pyrido[3,4- d ]pyrimidine, and pyrido[4,3- d ]pyrimidine (Figure ). Pyrido[2,3- d ]pyrimidine is commonly used in the kinase inhibitors of AKT, ARK5, CDK4, CDK6, c-Met, c-Src, DYRK1A, DYRK1B, eEF2K, EGFR, EGFR T790M , ERK1/2, FGFR1, FGFR3, MEK, PDGFR, PI3K/mTOR, and RAF . Other types of pyridopyrimidines are rarely used in the kinase inhibitor design.…”