Intra-molecular hydrogen bonding was introduced to the quinazoline motif to form a pseudo ring (intra-molecular H-bond scaffold, iMHBS) to mimic our previous published core structures, pyrido [2.3-D] pyrimidin-7-one and pteridinone, as PI3K/mTOR dual inhibitors. This design results in potent PI3K/mTOR dual inhibitors and the purposed intra-molecular hydrogen bonding structure is well supported by co-crystal structure in PI3Kγ enzyme. In ...