O6C-20-nor-salvinorin A is a stable and potent KOR agonist.
Bioorganic & medicinal chemistry letters September 1, 2018 Shun Hirasawa, Min Cho, Tarsis F Brust et al.
Salvinorin A (SalA) is a potent and selective kappa-opioid receptor agonist, but its chemical instability has hindered medicinal chemistry. Weak bases cause C8 epimerization, which destroys receptor affinity and signaling. Replacing C20 with hydrogen and O6 with CH2 stabilizes the scaffold so completely that epimerization is suppressed. The resulting compound, O6C-20-nor-SalA, retains high potency for kappa-opioid receptor agonism.