2-Arylureidophenyl-4-(3-oxa-8-azabicyclo[3.2.1]octan-8-yl)triazines as highly potent and selective ATP competitive mTOR inhibitors: optimization of human microsomal stability.

Abstract Isosteric replacement of one of the 3,5-ethylene-bridged morpholines in 2-arylureidophenyl-4,6-di(3-oxa-8-azabicyclo[3.2.1]octan-8-yl)triazines led to significant improvements in human microsomal stability. 3- R -Me-morpholine and tetrahydropyran were identified as preferred isosteres for the bridged morpholine. Combination of tetrahydropyran substitution with an N -Me-piperazinophenylureido group led to 27 , that selectively suppressed mTOR biomarkers in vivo and possessed excellent efficacy in a murine xenograft model.