Transition-metal-catalyzed direct functionalization of C−H bonds is important for new compound synthesis, but usually needs special reagents and harsh conditions. With the aid of an azo directing group, the palladium-catalyzed ortho-sp² C−H bond activation of azoarenes with hydrazines has been explored. In the reaction, the Pd catalyst reacts with azobenzene to form a palladacyclic intermediate, which reacts with a phenyl radical generated from phenylhydrazine under heating and oxygen to produce a Pd^IV or Pd^III intermediate. This finally undergoes reductive elimination to give the ortho-arylated products with the release of the Pd^II catalyst. This reaction provides a novel access to ortho-aryl azoarenes under mild conditions in high yield.

Resveratrol polymer has better effects than monomer in some aspects as reported, but most of synthetic methods acquire severe conditions and no analgesic effects are investigated. A novel method is found to synthesize resveratrol polymer by excitation of photosensitizer pheophorbide at red light of 630 nm. The polymer was analyzed by fluorescence spectra and HPLC, further isolated by preparative liquid chromatography and identified as a resveratrol dimer by MS and NMR. Analgesic effects were measured by acetic acid writhing and hot-plate test in mice. The resveratrol dimer has the stronger analgesic effects than monomer, and drug combination of the dimer and cobra neurotoxin enhances and prolongs analgesic effects, suggesting the synergistic action. Simulation of molecular interaction reveals that the dimer spontaneously binds to cobra neurotoxin and makes a complex substance. The dimer can interact with cyclooxygenase-2, μ receptor and nicotine receptor, the synergistic analgesic effects of the complex are attributed to its multiple targets role. The combination of resveratrol dimer and cobra neurotoxin may make up for their deficiencies in analgesic effects, and has prospects in clinical use.