Derivatives of 17-(2-methylallyl)-substituted noroxymorphone: variation of the delta address and its effects on affinity and selectivity for the delta opioid receptor

In an effort to establish the importance of the N-(2-methylallyl) substituent in the noroxymorphone series, several derivatives have been synthesized, retaining that N-substituent and modifying the δ address moiety. A few compounds showed moderate binding affinity and selectivity for the δ receptor; none displayed a pharmacological profile as exceptional as N-(2-methylallyl)noroxymorphindole. A second study showed that 3-O-methylation of all derivatives decreases binding affinity. The present results indicate that only a combination of the N-(2-methylallyl) group and an indole δ address provided high selectivity for the δ receptor.