title: Comparison of azabicyclic esters and oxadiazoles as ligands for the muscarinic receptor.
abstract: The link between the cognitive deficit associated with Alzheimer type dementia and the loss of cholinergic function in the disease provides a basis for examining muscarinic agonists as potential therapeutic agents. This paper describes the design and synthesis of novel azabicyclic methyl esters as ligands for the muscarinic receptor. Replacement of the methyl ester by a 3-methyl-1,2,4-oxadiazole ring produces potent metabolically more stable muscarinic agonists capable of penetrating the central nervous system. These compounds generally show improved affinity relative to the corresponding methyl esters. 3-Methyl-1,2,4-oxadiazole 7b has an affinity 4 times that of acetylcholine. Receptor affinity is discussed in relation to the size and geometry of the azabicyclic ring and the electronic properties of the heteroaromatic ring.
authors.affiliation: SmithKline Beecham Pharmaceuticals, Medicinal Research Centre, Harlow, Essex, England.
authors.forename: B S
authors.initials: BS
authors.lastname: Orlek
authors.forename: F E
authors.initials: FE
authors.lastname: Blaney
authors.forename: F
authors.initials: F
authors.lastname: Brown
authors.forename: M S
authors.initials: MS
authors.lastname: Clark
authors.forename: M S
authors.initials: MS
authors.lastname: Hadley
authors.forename: J
authors.initials: J
authors.lastname: Hatcher
authors.forename: G J
authors.initials: GJ
authors.lastname: Riley
authors.forename: H E
authors.initials: HE
authors.lastname: Rosenberg
authors.forename: H J
authors.initials: HJ
authors.lastname: Wadsworth
authors.forename: P
authors.initials: P
authors.lastname: Wyman
mesh_terms: D000634:Aminoquinolines / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D001372:Aza Compounds / Q000378:metabolism*; D001643:Bridged Bicyclo Compounds / Q000378:metabolism*; D002540:Cerebral Cortex / Q000378:metabolism; D008024:Ligands; D008297:Male; D051379:Mice; D010069:Oxadiazoles / Q000378:metabolism*; D051381:Rats; D011976:Receptors, Muscarinic / Q000378:metabolism*; D013844:Thiazoles / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000634:Aminoquinolines; D001372:Aza Compounds; D001643:Bridged Bicyclo Compounds; D008024:Ligands; D010069:Oxadiazoles; D011976:Receptors, Muscarinic; D013844:Thiazoles; C070943:6-propyl-4,5,5a,6,7,8-hexahydrothiazolo(4,5-f)quinolin-2-amine