Syntheses of affinity reagents for opiate receptors based on the fentanyl, endo- ethenotetrahydrooripavine, and etonitazene carbon-nitrogen skeletons are described. The isothiocyanate, bromoacetamido, and methylfumaramido alkylating functions were employed in these compounds, some of which had previously been shown to be p specific (12, BIT) and 6 specific (8, FIT and 19, FAO) in vitro. Antinociceptive activity of the title ...