Novel M positive allosteric modulators derived from questioning the role and impact of a presumed intramolecular hydrogen-bonding motif in β-amino carboxamide-harboring ligands.

Poslusney MS, Salovich JM, Wood MR, Melancon BJ, Bollinger KA, Luscombe VB, Rodriguez AL, Engers DW, Bridges TM, Niswender CM, Conn PJ, Lindsley CW
Bioorg Med Chem Lett. 2019 29 (3): 362-366

PMID: 30580918 · PMCID: PMC6690489 · DOI:10.1016/j.bmcl.2018.12.039

This letter describes a focused exercise to explore the role of the β-amino carboxamide moiety found in all of the first generation M PAMs and question if the NH group served solely to stabilize an intramolecular hydrogen bond (IMHB) and enforce planarity. To address this issue (and to potentially find a substitute for the β-amino carboxamide that engendered P-gp and contributed to solubility liabilities), we removed the NH, generating des-amino congeners and surveyed other functional groups in the β-position. These modifications led to weak M PAMs with poor DMPK properties. Cyclization of the β-amino carboxamide moiety by virtue of a pyrazole ring re-enforced the IMHB, led to potent (and patented) M PAMs, many as potent as the classical bicyclic β-amino carboxamide analogs, but with significant CYP1A2 inhibition. Overall, this exercise indicated that the β-amino carboxamide moiety most likely facilitates an IMHB, and is essential for M PAM activity within classical bicyclic M PAM scaffolds.

Copyright © 2018 Elsevier Ltd. All rights reserved.

MeSH Terms (9)

Allosteric Regulation Amides Dose-Response Relationship, Drug Humans Hydrogen Bonding Ligands Molecular Structure Receptor, Muscarinic M4 Structure-Activity Relationship

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