γ-secretase modulators(Merck)

Herein, we disclose three structurally differentiated γ-secretase modulators (GSMs) based on an oxadiazine scaffold. The analogues from series I potently inhibit the generation of Aβ₄₂ in vitro when the substituents at 3 and 4 positions of the oxadiazine moiety adopt an α orientation (cf. 11). To address the concern around potential reactivity of the exocyclic double bond present in series I toward nucleophilic attack, compounds containing either an endocyclic double bond, such as 20 (series II), or devoid of an olefinic moiety, such as 27 (series III), were designed and validated as novel GSMs. Compound 11 and azepine 20 exhibit robust lowering of CSF Aβ₄₂ in rats treated with a 30 mg/kg oral dose.