To develop novel analgesics with no side effects or less side effects than traditional opioids is highly demanded to treat opioid receptor mediated pain and addiction issues. Recently, κ-opioid receptor (KOR) has been established as an attractive target, although its selective agonists could bear heterogeneous pharmacological activities. In this study, we designed and synthesized two new series of nepenthone derivatives by inserting a spacer (carbonyl) between 6α,14α-endo-ethenylthebaine and the 7α-phenyl substitution of the skeleton and by substituting the 17-N-methyl group with a cyclopropylmethyl group. We performed in vitro tests (binding and functional assays) and molecular docking operations on our newly designed compounds. The results of wet-experimental measures and modeled binding structures demonstrate that these new compounds are selective KOR agonists with nanomolar level affinities. Compound 4 from these new derivatives showed the highest affinity (K = 0.4 ± 0.1 nM) and the highest selectivity (μ/κ = 339, δ/κ = 2034) toward KOR. The in vivo tests revealed that compound 4 is able to induce stronger (ED = 2.1 mg/kg) and much longer antinociceptive effect than that of the typical KOR agonist U50488H (ED = 4.4 mg/kg). Therefore, compound 4 can be used as a perfect lead compound for future design of potent analgesics acting through KOR.

An efficient tandem route to the synthesis of 3H-1,2a(1),3-triazaacenaphthylene derivatives of the cyclazine family has been developed. Target compounds were obtained in moderate to good yields by a Yb(OTf)(3)/Ag(2)CO(3)-catalyzed, three-component domino reaction. This in turn will set the stage for a wide application of this useful reaction for the synthesis of structurally diverse polyheterocyclic skeletons containing the imidazo[1,2-a]pyridine privileged structure.

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Silver-catalyzed on-water intramolecular cyclization of acetylenic free amines is reported, which affords 7-azaindoles in good to excellent yields. Neither strong base/acid catalysts nor N-substituted substrates are required to achieve this cycloisomerization. Hydrogen bonds between water medium and the substrates play an important role in improving chemical reactivity and regioselectivity. Furthermore, the on-water reaction is extendable to acetylenic amides for isoquinolone synthesis.

A Convenient Aqueous Copper-Catalyzed Synthesis of Quinazolinones. -A simple and efficient method for the coupling of 2-halobenzoic acids with amidines or guanidines is developed. The green reaction is catalyzed by an aqueous micellar surfactant which is recycled and reused in five additional catalytic cycles without loss of its activity. -(XU, Y.; XIE, Q.; LI, W.; SUN, H.; WANG, Y.; SHAO*, L.; Tetrahedron 71 (2015) 29, 4853-4858, http://dx.