Single-catalyst stereoenrichment

Sometimes, conformity is a good thing. Particularly when it comes to stereochemistry. While stereocenters arise in mirror-image enantiomer pairs when left to their own devices, enantiomers can have very different biological activity. So synthetic and medicinal chemists would prefer to make only one of them at a time. Researchers from the Shanghai Institute of Organic Chemistry, led by Zhiwei Zuo , have now added a new reaction to the stereoselective toolbox. They have devised a clever method for turning mixtures of alcohol isomers into an enantiomerically pure product using a single catalyst ( Science 2023, DOI: 10.1126/science.adj0040 ). Once a mixture of stereoisomers is created, it’s very difficult to amend it without separating the isomers from each other and throwing out the unwanted one. Mixtures have higher entropy, which the universe prefers. And something called the principle of microscopic reversibility says that any mechanistic step that flips an unwanted enantiomer