Olefins are important components in many organic compounds, such as fragrances, natural products, and drugs. And while chemists have many ways of introducing double bonds into molecules, most rely on chemistry developed more than 30 years ago. Researchers led by Phil S. Baran of Scripps Research Institute California have now come up with a new way to introduce olefins into organic compounds (Nature 2017, DOI: 10.1038/nature22307). The reaction—known as decarboxylative alkenylation—starts with ubiquitous alkyl carboxylic acids. The chemists first transform the carboxylic acid into a redox-active ester, which then undergoes nucleophilic attack from an alkenyl zinc reagent in the presence of a nickel or iron catalyst. The whole process takes place in a single pot and can be used to make mono-, di-, tri-, and tetrasubstituted olefins. The reaction also allows exquisite control of olefin geometry because it is established by the geometry of the alkenyl zinc reagent rather than the C–C bond-forming event, as is the case in olefin metathesis. The chemists used the new reaction to prepare more than 60 different olefins, including the prostaglandin (+)-PFG2α (shown; red bonds made via decarboxylative alkenylation).