A Novel [5.2.1]Bicyclic Amine Is A Potent Analgesic Without Mu Opioid Activity

We identified (5R)-6-methyl-5-phenyl-1,3,4,5,6,7-hexahydro-2,5-methano-2,6-benzodiazonine (DS21980956: 4(R)) as a novel [5.2.1]bicyclic basic compound. The scaffold was inspired by fentanyl or pethidine, which possess potent analgesic activities. DS21980956 had potent analgesic activity in the mouse acetic acid writhing test or tail flick test without agonistic activity at the mu opioid receptor (MOR). The mechanism of analgesic action of DS21980956 was considered to differ from a biased ligand, for example, TRV-130 (3, oliceridine).