We report on the design of benzodiazepinones as peptidomimetics at the carboxy terminus of hydroxyamides. Structure–activity relationships of diazepinones were investigated and orally active γ-secretase inhibitors were synthesized. Active metabolites contributing to Aβ reduction were identified by analysis of plasma samples from Tg2576 mice. In particular,(S)- 2-((S)-2-(3, 5-difluorophenyl)-2-hydroxyacetamido)-N-((S, Z)-3-methyl-4-oxo-4, 5-dihydro- ...