Muscarinic acetylcholine receptors as effector sites for present and future therapeutic applications: focus on non-neural cholinergic systems

Synthesis, affinity profile and functional activity of potent chiral muscarinic antagonists with a pyrrolidinylfuran structure

Starting from the structure of previously studied muscarinic agonists, characterized by a pyrrolidinylfuran scaffold, a new series of muscarinic antagonists was synthesized by substituting the 5-position of the furane cycle with bulky hydrophobic groups. Both tertiary amines and the corresponding iodomethyl derivatives were obtained and studied. All the new compounds show high affinity toward cloned human muscarinic M(1)-M(5) receptors expressed in Chinese hamster ovary (CHO) cells and behave as competitive antagonists on classical models of muscarinic receptors. The diastereoisomeric mixture of the highest affinity compound of the series was resolved into the four optical isomers by chiral HPLC. The relative and absolute configuration of the obtained compounds was established by means of a combined strategy based on X-ray crystallography and chiroptical techniques. Although generally fairly potent, the compounds showed only modest subtype selectivity, with the exception of 2a and 6a, which in functional assays presented clear-cut selectivity for the muscarinic receptors present in rabbit vas deferens.

Muscarinic antagonists with multiple stereocenters: Synthesis, affinity profile and functional activity of isomeric 1-methyl-2-(2,2-alkylaryl-1,3-oxathiolan-5-yl)pyrrolidine sulfoxide derivatives

Completing a long-lasting research on 1,3-oxathiolane muscarinic ligands, we have synthesized a set of isomeric 1-methyl-2-(2,2-alkylaryl-1,3-oxathiolan-5-yl)pyrrolidine 3-sulfoxide derivatives, containing three or four stereogenic centers. In general the compounds are very potent antagonists even if, unlike the corresponding agonists, they show modest subtype selectivity.