The 2026 Nobel Prize in Chemistry “is about making chemistry choose a mirror image.” With those words, members of the Nobel committee announced that they had awarded the 2026 prize to Henri B. Kagan, PhD, professor emeritus at Université Paris-Sud, and Kenso Soai, PhD, professor emeritus at Tokyo University of Science, for complementary breakthroughs related to the emergence of homochirality. Kagan received the award for his discovery of nonlinear effects in asymmetric organic synthesis, and Soai for the development of autocatalysis in asymmetric organic synthesis.

The year’s prize recognized foundational discoveries that helped explain a chemical asymmetry observed in living organisms.  Small molecules like amino acids exist as two variants that are mirror images, yet living organisms contain only one of these images while the other is rarely found in nature. Kagan and Soai’s work provided the answer to the question of how homochirality can emerge. Their discoveries have enabled chemists to drive chemical reactions that lead to homochirality, and have been beneficial to scientists that design reactions used in manufacturing to develop new drugs, flavors, scents, and other materials. 

Their combined efforts “have provided a solution to a chemical mystery that is over a century old,” said Heiner Linke, PhD, chair of the Nobel Committee for Chemistry. “The chemical reactions they have developed are spectacular.”

How homochirality emerges is “probably the most fundamental question in life,” explained Peter Somfai, PhD, a professor of organic chemistry at Lund University and a member of the Nobel committee for Chemistry, in an interview. Scientists have long wondered how it happened billions of years ago. “Now we mimicked it in a lab today, not the way it happened four billion years ago, it’s important to stress, but we have for the first time mimicked it.”

The core scientific question

Though chiral molecules exist as non-identical mirror images with potential biological effects, life is homochiral and built exclusively from left-handed amino acids and right-handed sugars. And different enantiomers can have dramatically different properties. “Many molecules occur in two different versions, like my hands. They are one another’s mirror image. They look alike, but they’re not identical,” Linke said. 

When scientists began experimenting with chemical reactions that can form two mirrored molecules, they typically obtained equal proportions of both. But attempts to produce only one of the mirror images, in the context of pharmaceutical development, for example, proved challenging. Some of the earliest discoveries about chirality can be traced back to the mid-19^th century to Louis Pasteur and his efforts to investigate the behavior of tartaric acid. The field also owes some insights to the work of the chemist Willy Marckwald, who carried out the first successful asymmetric reaction in the early 1900s. He succeeded by using a chiral catalyst which boosted the formation of one mirror image over the other. 

In their respective laboratories, Kagan and Soai made their contributions to the question of how homochirality emerges spontaneously. In 1986, Kagan discovered a new way of manipulating chemical reactions that made it possible to create a larger quantity of one of the images than had previously been thought possible. 

At the time, he and other chemists were working to refine asymmetric reactions with an eye towards producing pure enantiomers. Building on the work done by Marckwald and others, as well as mathematical contributions from Charles Frank, PhD, a theoretical physicist at the University of Bristol, scientists typically used catalysts comprising a metal atom and a chiral substance. They typically used an enantiomer that was as pure as possible the catalyst assuming that combining two mirrored enantiomers would result in a product with equivalent proportions of mirror images. 

Kagan questioned this belief that mixing left- and right-handed catalysts would produce a linear relationship in product chirality, explained Somfai in his remarks during the announcement. “For a long time, it was believed that if we mix a left and right-handed catalyst, the proportion of an ancillary in the product would correlate linearly to that in the catalyst.”

Kagan’s question led him to test driving a reaction with different combinations of enantiomers in the catalyst. Ultimately, he realized that the relationship to the proportions of enantiomers in the product was not linear as previously thought. One form of the catalyst, the left-right catalyst, drove the chemical reaction in a different way than the two other forms of the catalyst — the right-right or left-left forms. This meant that he had found a way to enhance the formation of one enantiomer over the other. In 1986, he described at least three different asymmetric reactions that displayed what chemists call non-linear effects. 

Other scientists were keen to build on Kagan’s discovery, including Soai. While studying an asymmetrical chemical reaction with a non-linear effect, he discovered similarities between the structure of the reaction’s catalyst and the products. That discovery suggested that it may be possible to design a reaction in which the catalyst formed itself in an autocatalytic process. After experimenting with different molecules, Soai published a paper in 1995, where he described finding a chiral substance that could create itself although it did not achieve 100 percent enantiomeric purity. 

Eight years later, in 2003, he was finally able to present a chemical reaction, dubbed the Soai reaction,  in which only one of the two possible mirror images was formed. Specifically, the chemical reaction results in an excess of an enantiomer which then forms copies of itself, marking the first time a scientist successfully generated chirality from achiral or racemic conditions outside of nature.  As Somfai put it in his remarks “this is probably the coolest experiment in organic chemistry.”

Following the award announcement, Soai took questions from the press during which stated that he was out shopping near his home in Hiroshima, Japan when he got the call from the committee letting him know he and Kagan would share this year’s prize. “There are many excellent researchers in this field, so I’m very especially glad to receive this prize” and “to share the prize with Professor Henri Kagan, such a famous organic chemist,” he said. 

Basic research with a broad impact

Though this award recognizes basic organic chemistry research, Kagan and Soai’s work has been hugely impactful in both industrial and pharmaceutical manufacturing. Many active drug molecules are also chiral with only one compound having a desired therapeutic effect. The other might have no therapeutic effect or even be harmful. Given these risks, “we need methods to selectively prepare them, and in developing such methods, the findings of this year’s Nobel laureates are important. They provided powerful tools for this,” Somfai said.