Discovery of a novel, CNS penetrant M4 PAM chemotype based on a 6-fluoro-4-(piperidin-1-yl)quinoline-3-carbonitrile core

Abstract

This Letter details the discovery and subsequent optimization of a novel M4 PAM scaffold based on an 6-fluoro-4-(piperidin-1-yl)quinoline-3-carbonitrile core, which represents a distinct departure from the classical M4 PAM chemotypes. Optimized compounds in this series demonstrated improved M4 PAM potency on both human and rat M4 (4 to 5-fold relative to HTS hit), and displayed attractive physicochemical and DMPK profiles, including good CNS penetration (rat brain:plasma Kp = 5.3, Kp,uu = 2.4; MDCK-MDR1 (P-gp) ER = 1.1).