ABSTRACT
The optimization for selectivity and central receptor occupancy for a series of spirocyclic azetidine-piperidine inverse agonists of the ghrelin receptor is described. Decreased mAChR muscarinic M2 binding was achieved by use of a chiral indane in place of a substituted benzylic group. Compounds with desirable balance of human in vitro clearance and ex vivo central receptor occupancy were discovered by incorporation of heterocycles. Specifically, heteroaryl rings with nitrogen(s) vicinal to the indane linkage provided the most attractive overall properties.
Subject(s)
Central Nervous System/drug effects , Receptors, Ghrelin/antagonists & inhibitors , Amino Acid Sequence , Animals , Binding Sites , Drug Inverse Agonism , Heterocyclic Compounds/chemistry , Heterocyclic Compounds/pharmacology , Humans , Indans/chemistry , Indans/pharmacology , Inhibitory Concentration 50 , Isomerism , Molecular Structure , Protein Binding/drug effects , Rats , Structure-Activity RelationshipABSTRACT
A series of GPR119 agonists based on a 2,6-diazatricyclo[3.3.1.1â¼3,7â¼]decane ring system is described. Also provided is a detailed account of the development of a multigram scale synthesis of the diazatricyclic ring system, which was achieved using a Hofmann-Löffler-Freytag reaction as the key step. The basis for the use of this complex framework lies in an attempt to constrain one end of the molecule in the "agonist conformation" as was previously described for 3-oxa-7-aza-bicyclo[3.3.1]nonanes. Optimization of carbamate analogues of the diazatricylic compounds led to the identification of 32i as a potent agonist of the GPR119 receptor with low unbound human liver microsomal clearance. The use of an agonist response weighted ligand lipophilic efficiency (LLE) termed AgLLE is discussed along with the issues of applying efficiency measures to agonist programs. Ultimately, solubility limited absorption and poor exposure reduced further interest in these molecules.
