Chiral auxiliary

A chiral auxiliary is a substance temporarily attached to a molecule to control its 3D shape during a chemical reaction. It guides the reaction to produce a specific mirror-image form (enantiomer), which is important in creating pharmaceuticals and materials with particular properties. After the reaction, the auxiliary is removed, leaving behind the desired product with the correct stereochemistry. Essentially, it acts like a template or a steering tool, ensuring the reaction proceeds in a way that yields the precise spatial arrangement needed.