Nobel Prize in Chemistry Honors Kagan and Soai for Discoveries That Help Make Better Medicines

The 2026 Nobel Prize in Chemistry has been awarded jointly to French chemist Henri B. Kagan and Japanese chemist Kenso Soai "for the discovery of non-linear effects and autocatalysis in asymmetric organic synthesis."

Left hands and right hands

Many molecules come in two mirror-image forms, like a left and a right hand. In medicine the difference can be everything: one form of a drug may heal while its mirror image does nothing, or causes harm. Making only the right form is one of chemistry's most important jobs.

What they discovered

• Kagan, in 1986, found that a catalyst with only a modest preference for one form, say 75:25, could produce a product closer to 90:10. Reactions could amplify a small bias.
• Soai discovered asymmetric autocatalysis, where a product helps make more of itself. In 1995 he reported the first case where the product ended up more lopsided than the starting catalyst. By 2003, a tiny initial imbalance had grown into a product that was about 99.75% one form.

Why it matters

The work helps chemists design cleaner, more precise routes to medicines and other useful compounds. It also offers a clue to one of science's oldest puzzles: why life on Earth uses only one mirror-image form of key molecules such as amino acids and sugars.

Kagan is emeritus professor at Université Paris-Saclay. Soai is professor emeritus at the Tokyo University of Science.