MOST people do their best to avoid the manchineel tree. Even sheltering under it during a rain shower could give you a nasty surprise. Its sap is toxic and water-soluble, so any drips bouncing off the trunk and on to your skin will yield blisters. And don’t even think about eating its small round fruit – in central America, where it grows, it is sometimes known as the “little apple of death”. Phil Baran isn’t like most people. For him, the toxin the tree secretes, called phorbol, is an intriguing curiosity. It exemplifies the elaborate chemical structures and interesting effects that naturally produced molecules can have. Give phorbol a few tweaks and it morphs from a toxin into a potential anticancer agent. Other natural products might be the basis of the next great pill, perfume, plastic or pigment. To study them we must first make and manipulate these natural products in the lab. And that’s where synthetic chemists such as Baran run up against a gnarly problem. Natural chemicals put up a barrier in the form of a particular atomic bond, one that crops up in all of them and is incredibly tough to break. Until now, that is: Baran and a few others think they have a way to break the unbreakable and usher in a new era of chemical alchemy. Synthetic chemistry is all about breaking old bonds and making new ones: it is responsible for most of the human-made stuff we see around us. And the bonds we most want to make are between one carbon atom and another. That’s because