- Person
- Henri B. Kagan
- Lived
- b. 1930
- Field
- Organic chemistry
- From
- French
The story
Many drug molecules exist in two mirror-image forms, like a left and a right hand. In the body, usually only one fits the protein it is meant to act on; the other may be useless or harmful. The thalidomide disaster of the early 1960s, which caused birth defects in thousands of children, showed how much this can matter. Yet ordinary chemical reactions produce equal amounts of both forms, which must then be separated at great cost.
Henri Kagan, born in 1930 near Paris to a Jewish family that survived the Nazi occupation by hiding in a southern French village under assumed names, spent his career at the University of Paris-Sud in Orsay finding ways to make chemistry choose one hand. In 1971 he introduced DIOP, one of the first highly effective one-handed ligands for metal catalysts, whose design inspired many later catalysts. In 1984 his group, and independently Giorgio Modena’s in Italy, adapted a titanium-tartrate catalyst to make one mirror image of sulphur-containing compounds called sulfoxides. Patent literature records that the Kagan protocol was applied to making esomeprazole, the single-mirror-image form of the widely used acid-reflux drug omeprazole.
In 1986 Kagan made the discovery that won him the 2026 Nobel Prize in Chemistry, shared with Kenso Soai. Chemists had assumed that a catalyst containing a mixture of both mirror images would make an equally mixed product. Kagan showed that this need not be true: because mixed catalyst pairs react more slowly, the product can come out purer than the catalyst. This non-linear effect gave chemists a new way to understand and improve catalysts, and, together with Soai’s work, explained how life’s chemistry could have become one-handed.
The Nobel committee said the discoveries have been decisive for chemists who design reactions for the manufacture of pharmaceuticals, and called Kagan’s work revolutionary for making medicines, flavours, scents and new materials.
Why it matters
Kagan’s methods help industry make purer single-mirror-image medicines more efficiently, reducing waste and avoiding the inactive or harmful twin.
About Henri B. Kagan
French chemist, a hidden child during the Nazi occupation, whose methods help chemists make the single mirror-image form of a drug molecule, safer and more effective. Nobel Prize 2026.
Henri B. Kagan in the news
Sources
- Press release: The Nobel Prize in Chemistry 2026 NobelPrize.org
- Popular information: The Nobel Prize in Chemistry 2026 NobelPrize.org
- US Patent 8889873: Process for the preparation of enantiomerically enriched proton pump inhibitors Google Patents
- French Holocaust survivor wins 2026 Nobel Prize in Chemistry The Algemeiner
Another act of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.