Synthesis helps scientists create sufficient amounts of these polyphenols for biological studies

Resveratrol—made famous by its presence in red wine—has been touted for its health benefits. Oligomers of the compound may have even more promising medicinal properties, as they exhibit anti-inflammatory, immunomodulatory, and cytotoxic activities in cell studies. But getting enough of these complex polyphenols to study their mechanisms of action has been challenging. Chemists led by the University of Michigan’s Corey Stephenson and the University of Ottawa’s Derek Pratt now report a stereoconvergent synthesis of the resveratrol tetramers nepalensinol B and vateriaphenol C in 13 steps (Science 2016, DOI: 10.1126/science.aaj1597). Their strategy makes use of a persistent radical (shown) that’s derived from the resveratrol dimer, ε-viniferin. “Persistent free radicals have become indispensable in the synthesis of organic materials through living radical polymerization,” the chemists point out in the report. “However, examples of their use in the synthesis of small molecules are rare.” Stephenson and Pratt note that thermodynamic stereocontrol in the dimerization of persistent free radicals plays a critical role in their strategy.