Synthesis and opioid receptor activity of indolopropellanes

A series of skeletal rearranged indolomorphinans 7a–d were obtained by N-demethylation of 3-methoxy-N-methyl-14-hydroxymorphinan-6-one 12 followed by N-realkylation, reduction and Fischer indole cyclization. The structure of the novel skeleton was confirmed by X-ray analysis. These new indoles displayed moderate binding affinity and selectivity at the μ receptor, with compound 7b showing the highest affinity at this receptor with a Ki value of 40 nM, and 6- and 25-fold selectivity against δ and κ receptors, respectively. Function assays showed that indolopropellanes 7b and 7c possessed full agonistic activity at all the opioid receptors indicating a different interaction model existed.

Graphical abstractA series of skeletal rearranged indolomorphinans 7a–d was synthesized, and their binding affinity and functional activity for opioid receptors were evaluated.Figure optionsDownload full-size imageDownload as PowerPoint slide