Science News from research organizations A lab mistake at Cambridge reveals a powerful new way to modify drug molecules A surprising lab discovery reveals a light-powered shortcut for redesigning drug molecules faster and more cleanly. Date: March 14, 2026 Source: St. John's College, University of Cambridge Summary: Cambridge scientists have discovered a light-powered chemical reaction that lets researchers modify complex drug molecules at the final stages of development. Unlike traditional methods that rely on toxic chemicals and harsh conditions, the new approach uses an LED lamp to create essential carbon–carbon bonds under mild conditions. This could make drug discovery faster and more environmentally friendly. The breakthrough was uncovered unexpectedly during a failed laboratory experiment. Share: Facebook Twitter Pinterest LinkedIN Email FULL STORY The chemistry is powered by an LED lamp that triggers a self-sustaining chain reaction, forging new carbon–carbon bonds under mild conditions without toxic or expensive chemicals. Credit: Nordin Ćatić / St John’s College, Cambridge Researchers at the University of Cambridge have created a new technique that uses light instead of toxic chemicals to change complex drug molecules. The discovery could speed up drug development and make the process of designing medicines more efficient. The study, published on March 12 in Nature Synthesis , introduces what the team calls an "anti-Friedel-Crafts" reaction. Traditional Friedel-Crafts chemistry requires powerful chemicals or metal catalysts and harsh laboratory conditions. Because of these requirements, the reaction normally takes place early in drug manufacturing and is followed by many additional chemical steps to produce the final medicine. The new Cambridge method turns that process around by allowing researchers to make changes to drug molecules much later in development. LED Powered Reaction Forms Key Chemical Bonds Instead of relying on heavy metal catalysts, the reaction is activated by an LED lamp at ambient temperature. When the light triggers the reaction, it sets off a self sustaining chain process that forms carbon-carbon bonds under mild conditions without toxic or costly reagents. In practical terms, this approach lets chemists adjust complex molecules near the end of the drug development process rather than dismantling them and rebuilding them piece by piece -- something that can otherwise take months. "We've found a new way to make precise changes to complex drug molecules, particularly ones that have been exceptionally difficult to modify in the past," said David Vahey, first author and a PhD researcher at St John's College, Cambridge. "Scientists can spend months rebuilding large parts of a molecule just to test one small change. Now, instead of doing a multistep process for hundreds of molecules, scientists can start with their hit and make small modifications later on." "This reaction lets scientists make precise adjustments much later in the process, under mild conditions and without relying on toxic or expensive reagents. That opens chemical space that has been hard to access before and gives medicinal chemists a cleaner, more efficient tool for exploring new versions of a drug." Faster Drug Discovery With Less Waste Reducing the number of synthesis steps lowers chemical use, cuts energy consumption and shrinks the environmental footprint of drug development. It also saves researchers valuable time. The reaction is highly selective, allowing chemists to change one specific part of a molecule without disturbing other sensitive areas. This precision is important because even small structural changes can influence how a medicine works in the body, how it behaves biologically or whether it produces side effects. At its core, the breakthrough addresses a fundamental chemical challenge: forming carbon-carbon bonds. These bonds create the backbone of countless substances including fuels, plastics and complex biological molecules. The technique also shows what chemists describe as "high functional-group tolerance." That means it can modify one region of a molecule while leaving other functional groups untouched. This makes the reaction particularly useful for late-stage optimization, a stage of drug discovery where scientists fine tune molecules to improve how medicines perform. Because the approach avoids heavy metals, harsh reaction conditions and lengthy synthesis pathways, it could also reduce toxic waste and energy consumption in pharmaceutical manufacturing. These environmental benefits are increasingly important as the chemical industry works to reduce its environmental impact. Inspired by Sustainable Chemistry Research Vahey works in the research group led by Professor Erwin Reisner at Cambridge. Reisner's team is known for developing chemical systems inspired by photosynthesis. Their research explores ways to use sunlight to convert waste ma