Giannella_1994_Chem.Pharm.Bull.(Tokyo)_42_1286

To acquire more information about the so-called "muscarinic subsite", compound 4 was synthesized and tested. The results show that in comparison with deoxamuscarine (23) the muscarinic potency of 4 on M2 and M3 subtypes is not significantly altered by the presence of an epoxidic function, which confirms the donor-acceptor hydrogen bonding character of this receptive site. Conversely, there is a negative influence on the transduction processes. In addition, a second hydroxylic function bound on the carbon carrying the terminal methyl of the fourth substituent on the nitrogen dramatically affects the muscarinic behavior; the resulting compounds (11-14) lack any agonist or antagonist activity.