Abstract A series of N-7-methyl-imidazolopyrimidine inhibitors of the mTOR kinase have been designed and prepared, based on the hypothesis that the N-7-methyl substituent on imidazolopyrimidine would impart selectivity for mTOR over the related PI3Kα and δ kinases. The corresponding N-Me substituted pyrrolo [3, 2-d] pyrimidines and pyrazolo [4, 3-d] pyrimidines also show potent mTOR inhibition with selectivity toward both PI3α and δ ...