Some spiro analogs of the potent analgesic ketobemidone

Some spiro analogs of the potent analgesic ketobemidone N-(2-Cyanoethyl) derivatives of meperidine, ketobemidone, and a potent 6,7-benzomorphan C-Alkylated spiro[benzofuran-3(2H),4′-1′-methyl-piperidine-7-ols] as potent opioids: A conformation-activity study The xanthene-9-spiro-4'-piperidine nucleus as a probe for opiate activity Synthesis of spiro[tetralin-2,2'-pyrrolidine] and spiro[indan-2,2'-pyrrolidine] derivatives as potential analgesics 5-Aryl-3-azabicyclo[3.2.0]heptan-5-one ketals, compounds with morphine-like analgesic activity 5,11-Dimethyl-2,9-bis(phenylacetyl)-5,11-diazatetracyclo[6.2.2.02,7.04,9]dodecane, a potent, novel analgesic Selective reversible and irreversible ligands for the .kappa. opioid receptor Analgesic activity of novel spiro heterocycles. 2-Amino-7-oxa-3-thia-1-azaspiro[5.5]undec-1-enes and related compounds Synthesis and analgesic activity of some spiro[dibenz[b,f]oxepin-10,4'-piperidine] derivatives