Modifications to five-substituted 3,3-diethyl-4,5-dihydro-2(3H)-furanones en route to novel muscarinic receptor ligands

Lead lactone-based ligands with modest affinity for muscarinic receptors were modified based on structure-activity relationship data in the literature to provide a new series of 5-substituted 4,5-dihydro-2(3H)-furanones. The modifications included the addition of various nitrogen-containing heterocycles attached to substituted and unsubstituted aromatic rings. The target compounds were synthesized in modest yields and evaluated in preliminary muscarinic binding assays. A lactone-based ligand containing a diphenylmethylpiperazine moiety was identified as a nonselective muscarinic ligand with IC(50) of 340 nM. The design of future ligands will be based, in part, on structure-activity data reported herein.