Henri B. Kagan and Kenso Soai won the 2026 Nobel Prize in Chemistry on October 7 for showing how chemical reactions can amplify one “handed” form of a molecule until it dominates its mirror image.
The Royal Swedish Academy of Sciences honored the French and Japanese chemists for discovering nonlinear effects and autocatalysis in asymmetric organic synthesis. Their work addresses a century-old question known as homochirality: why living systems generally use only one of two molecular versions that are mirror images of each other. Kagan made a crucial advance in 1986 by finding a way to produce a significant excess of one molecular form.
Soai later developed a reaction in which a product helps promote the formation of more of its own molecular “hand,” a feedback process that can magnify a small initial imbalance. In 2003, Soai demonstrated a reaction that produced only one of the two possible mirror-image forms. The discovery is important to drug development because mirror-image versions of the same compound can have very different biological effects, including unwanted or harmful side effects.
The laureates’ findings therefore gave chemists powerful methods for designing medicines and other compounds with precisely controlled structures.