These essential building blocks are found in medicines and commonly used insecticides, but they are also difficult to synthesise: alkylidenecyclopropanes. In Nature, an international team presents a new method that makes producing these ring-shaped carbon structures much more efficient.

These small, triangular carbon rings are necessary for the production of certain medicines and insecticides. They occur as enantiomers — mirror-image versions of the same molecule — each with different properties. While one enantiomer is the active ingredient in a drug, the other has no effect or can even be harmful. The enantioselective synthesis of these carbon rings has long presented a challenge to organic chemists, and production has been inefficient until now.