An Orally Available BACE1 Inhibitor That Affords Robust CNS Aβ Reduction without Cardiovascular Liabilities

BACE1 inhibition to prevent Aβ peptide formation is considered to be a potential route to a disease-modifying treatment for Alzheimer’s disease. Previous efforts in our laboratory using a combined structure- and property-based approach have resulted in the identification of aminooxazoline xanthenes as potent BACE1 inhibitors. Herein, we report further optimization leading to the discovery of inhibitor <b>15</b> as an orally available and highly efficacious BACE1 inhibitor that robustly reduces CSF and brain Aβ levels in both rats and nonhuman primates. In addition, compound <b>15</b> exhibited low activity on the hERG ion channel and was well tolerated in an integrated cardiovascular safety model

Design and Synthesis of Potent, Orally Efficacious Hydroxyethylamine Derived β-Site Amyloid Precursor Protein Cleaving Enzyme (BACE1) Inhibitors

We have previously shown that hydroxyethylamines can be potent inhibitors of the BACE1 enzyme and that the generation of BACE1 inhibitors with CYP 3A4 inhibitory activities in this scaffold affords compounds (e.g., <b>1</b>) with sufficient bioavailability and pharmacokinetic profiles to reduce central amyloid-β peptide (Aβ) levels in wild-type rats following oral dosing. In this article, we describe further modifications of the P1-phenyl ring of the hydroxyethylamine series to afford potent, dual BACE1/CYP 3A4 inhibitors which demonstrate improved penetration into the CNS. Several of these compounds caused robust reduction of Aβ levels in rat CSF and brain following oral dosing, and compound <b>37</b> exhibited an improved cardiovascular safety profile relative to <b>1</b>