French and Japanese chemists win 2026 Nobel for amplifying molecular handedness

French chemist Henri B. Kagan and Japanese chemist Kenso Soai have been awarded the 2026 Nobel Prize in Chemistry for revealing how tiny initial imbalances in chiral reactions can become large through nonlinear amplification and self‑catalysis. The Royal Swedish Academy of Sciences said the duo earned the prize for uncovering these effects in asymmetric organic synthesis and will share the honour equally. Kagan is professor emeritus at the former Université Paris‑Sud, while Soai holds emeritus status at Tokyo University of Science. Their research centers on chiral molecules, which exist as left‑handed and right‑handed versions called enantiomers. Because biological systems use one handedness preferentially, the two forms can behave very differently in drugs, enzymes and receptors. In 1986 Kagan’s group showed that the chiral parts of a catalyst can pair up; opposite‑handed pairs react poorly and are removed, leaving the catalyst enriched in one handedness and producing a disproportionately one‑handed product. Building on this, Soai demonstrated in 1995 that a chiral molecule can speed up the creation of more molecules with the same handedness. In the Soai reaction, an excess of just 0.00005% of right‑handed molecules grew to 99.75% right‑handed after three cycles. Today, Kagan’s findings help chemists design processes that yield single‑enantiomer drugs, agrochemicals and fragrances, while Soai’s work supports theories that a minute early imbalance could explain the uniform handedness of life’s building blocks. ## Context The story highlights how fundamental research on molecular symmetry can drive practical advances in medicine and deepen our understanding of the origins of biological chirality.