Synthesis and Evaluation of Three Structurally Related¹⁸F-Labeled Orvinols of Different Intrinsic Activities: 6-O-[¹⁸F]Fluoroethyl-diprenorphine ([¹⁸F]FDPN), 6-O-[¹⁸F]Fluoroethyl-buprenorphine ([¹⁸F]FBPN), and 6-O-[¹⁸F]Fluoroethyl-phenethyl-orvinol ([¹⁸F]FPEO)

We report the synthesis and biological evaluation of a triplet of 6-O-(18)F-fluoroethylated derivatives of structurally related orvinols that span across the full range of intrinsic activities, the antagonist diprenorphine, the partial agonist buprenorphine, and the full agonist phenethyl-orvinol. [(18)F]fluoroethyl-diprenorphine, [(18)F]fluoroethyl-buprenorphine, and [(18)F]fluoroethyl-phenethyl-orvinol were prepared in high yields and quality from their 6-O-desmethyl-precursors. The results indicate suitable properties of the three 6-O-(18)F-fluoroethylated derivatives as functional analogues to the native carbon-11 labeled versions with similar pharmacological properties.