Synthesis and In Silico Profile Modeling of 6-O-Fluoroalkyl-6-O-desmethyl-diprenorphine Analogs

We present the first preparation of novel 6-O-(fluoroalkyl)-6-O-desmethyl-diprenorphine analogs and 6-O-(tosyloxyalkyl)-6-O-desmethyl-3-O-trityl-diprenorphine-type precursors for the radiosynthesis of 6-O-([¹⁸F]fluoroalkyl)-6-O-desmethyl-diprenorphine radiotracers for molecular imaging by positron emission tomography (PET). The synthesis sequence to the new opioid receptor ligands consists of eleven steps starting from the poppy alkaloid thebaine. The precursor molecules were prepared in a three-step synthesis process from the «Luthra precursor» (TDDPN). We report the complete ¹H- and ¹³C-NMR assignment of the new 6-O-(substituted)-6-O-desmethyl-diprenorphine derivatives, as well as the results of docking studies in silico for diverse novel opioid receptor ligands, including a new series of 6-O-(fluoroalkyl)- and 6-O-(hydroxyalkyl)-6-O-desmethyl-diprenorphine derivatives.