SAR STUDIES ON THE POTENT AND SELECTIVE MUSCARINIC ANTAGONIST 2-ETHYLTHIO-2,2-DIPHENYLACETIC ACID N,N-DIETHYLAMINOETHYL ESTER

Molecular modification of the potent and selective muscarinic antagoni st 2-thylthio-2,2-diphenylacetic acid N,N-diethylaminoethyl ester was performed in order to identify M-2 selective antagonists able to cross the blood brain barrier and potentially useful in the treatment of Al zheimer's disease. Modifications included substitution or hydrogenatio n of one of the phenyl rings as well as their incorporation in a tricy clic system. In general the changes introduced were detrimental for bo th affinity and selectivity. Only a modest M-2 selectivity is present in some compounds that, on the other hand, carry a quaternary ammonium group which precludes their penetration into the brain.