The 2026 Nobel Prize in Chemistry Goes to Henri B. Kagan and Kenso Soai

The 2026 Nobel Prize in Chemistry was awarded to Henri B. Kagan and Kenso Soai for the “discovery of non-linear effects and autocatalysis in asymmetric organic synthesis.”

“Kagan and Soai led the way in dreaming and making new ways to control molecular handedness with remarkable precision,” says ACS President Rigoberto Hernandez. “Kagan helped establish the principles for producing one molecular form with extraordinary selectivity, while Soai revealed the remarkable phenomenon that such molecules can amplify their own handedness. Just like dancing partners must match, chemistry depends on molecules coming together in the right way. Their discoveries gave chemists unprecedented control over that process, enabling advances in medicines, materials, and so much more.”

Kagan has been an ACS member for 60 years, and Soai was an ACS member for 26 years and is a part of the ACS member community. The laureates' seminal papers were published in the Journal of the American Chemical Society and Accounts of Chemical Research.

The 2026 winners have each published extensively in ACS journals throughout the years. In recognition of their contributions to the advancement of science, ACS Publications is providing free-to-read access to the following articles from each laureate, along with related research published in ACS journals. The articles will be freely available via the links below through the end of the year.

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A Closer Look: Solving Chemistry’s Mirror-Image Mystery
Read ACS Journal Articles by Henri B. Kagan
Read ACS Journal Articles by Kenso Soai
Read Related ACS Journal Articles
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A Closer Look: Solving Chemistry’s Mirror-Image Mystery

Many molecules, like your hands, come in mirror-image forms that look alike but cannot be superimposed. The two forms are rarely interchangeable in living organisms, so chemists who make pharmaceuticals, flavors, and agrochemicals must often go to great lengths to obtain only one. This year’s Nobel Prize in Chemistry honors two discoveries that show how a slight excess of one mirror-image form can be amplified until it dominates.

In 1986, Henri B. Kagan reported in JACS that a catalyst made with a mixture of mirror-image ligands can deliver a product that is purer than the mixture used to make it. Chemists had assumed the two would track each other. Kagan realized that a metal can bind more than one ligand, so a mixed batch forms both matched and mismatched pairs. If the mismatched pairs are less active, the matched pairs do most of the work, and the product ends up purer than the ligand. Chemists now use these "non-linear effects" to understand how chiral catalysts amplify small imbalances.

Kenso Soai pushed amplification even further through autocatalysis, in which a reaction product catalyzes its own formation. Such asymmetric autocatalysis can, in principle, snowball a tiny imbalance into a dominant one, as physicist Frederick Charles Frank proposed in 1953. In 1995, Soai reported a reaction that does exactly this (his group later described the work in Accounts of Chemical Research). Each round's product catalyzes the next, and the ee grows with every cycle. In one version, a starting mixture with an ee of just 0.00005% reached more than 99.5% after three rounds. Left to chance, the autocatalytic reaction can even tip toward either mirror-image form, offering insight into how molecular handedness might arise from an almost perfectly balanced starting point.

Together these discoveries transformed chemists’ understanding of how molecular handedness can be amplified and controlled, while providing new insights into one of science’s enduring questions: how a tiny chiral imbalance can grow into dominant molecular preference.

Read ACS Journal Articles by Henri B. Kagan

Asymmetric catalytic reduction with transition metal complexes. I. Catalytic system of rhodium(I) with (-)-2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane, a new chiral diphosphine
Henri B. Kagan; Tuan-Phat Dang
Journal American Chemical Society (1972) 94 (18): 6429–6433.
DOI: 10.1021/ja00773a028

Asymmetric catalytic reduction with transition metal complexes. II. Asymmetric catalysis by a supported chiral rhodium complex
Willy. Dumont; Jean C. Poulin; Dang Tuan Phat; Henri B. Kagan
Journal American Chemical Society (1973) 95 (25): 8295–8299.
DOI: 10.1021/ja00806a015

An efficient asymmetric oxidation of sulfides to sulfoxides
P. Pitchen; E. Dunach; M. N. Deshmukh; H. B. Kagan
Journal American Chemical Society (1984) 106 (26): 8188–8193.
DOI: 10.1021/ja00338a030

Nonlinear effects in asymmetric synthesis. Examples in asymmetric oxidations and aldolization reactions
C. Puchot; O. Samuel; E. Dunach; S. Zhao; C. Agami; H. B. Kagan
Journal American Chemical Society (1986) 108 (9): 2353–2357.
DOI: 10.1021/ja00269a036

Enantiomeric enrichment of sulfoxides by preparative flash chromatography on an achiral phase
Patrick Diter; Stefan Taudien; Odile Samuel; Henri B. Kagan
Journal of Organic Chemistry (1994) 59 (2): 370–373.
DOI: 10.1021/jo00081a015

Nonlinear Effects in Asymmetric Catalysis
Denis Guillaneux; Shu-Hai Zhao; Odile Samuel; David Rainford; Henri B. Kagan
Journal American Chemical Society (1994) 116 (21): 9430–9439.
DOI: 10.1021/ja00100a004

Highly Enantioselective Oxidation of Sulfides Mediated by a Chiral Titanium Complex
Jean-Michel Brunel; Patrick Diter; Michael Duetsch; Henri B. Kagan
Journal of Organic Chemistry (1995) 60 (24): 8086–8088.
DOI: 10.1021/jo00129a060

Kinetic Resolution When the Chiral Auxiliary Is Not Enantiomerically Pure: Normal and Abnormal Behavior
Timo O. Luukas; Christian Girard; David R. Fenwick; Henri B. Kagan
Journal American Chemical Society (1999) 121 (40): 9299–9306.
DOI: 10.1021/ja990793t

Is It Possible To Estimate the Enantioselectivity of a Chiral Catalyst from Its Racemic Mixture?
Franz Lagasse; Masaki Tsukamoto; Christopher J. Welch; Henri B. Kagan
Journal American Chemical Society (2003) 125 (25): 7490–7491.
DOI: 10.1021/ja0300315

Asymmetric Amplification in Catalysis by trans-1,2-Diaminocyclohexane Bistriflamide
Tummanapalli Satyanarayana; Benoit Ferber; Henri B. Kagan
Org. Lett. (2007) 9 (2): 251–253.
DOI: 10.1021/ol062653b

Equilibrium of Homochiral Oligomerization of a Mixture of Enantiomers. Its Relevance to Nonlinear Effects in Asymmetric Catalysis
Masaki Tsukamoto; Kovuru Gopalaiah; Henri B. Kagan
J. Phys. Chem. B (2008) 112 (48): 15361–15368.
DOI: 10.1021/jp8058917

Read ACS Journal Articles by Kenso Soai

Highly Enantioselective Catalytic Asymmetric Automultiplication of Chiral Pyrimidyl Alcohol
Takanori Shibata; Hiroshi Morioka; Tadakatsu Hayase; Kaori Choji; Kenso Soai
Journal American Chemical Society (1996) 118 (2): 471–472.
DOI: 10.1021/ja953066g

Amplification of a Slight Enantiomeric Imbalance in Molecules Based on Asymmetric Autocatalysis: The First Correlation between High Enantiomeric Enrichment in a Chiral Molecule and Circularly Polarized Light
Takanori Shibata; Jun Yamamoto; Naoko Matsumoto; Shigeru Yonekubo; Shunji Osanai; Kenso Soai
Journal American Chemical Society (1998) 120 (46): 12157–12158.
DOI: 10.1021/ja980815w

d- and l-Quartz-Promoted Highly Enantioselective Synthesis of a Chiral Organic Compound
Kenso Soai; Shunji Osanai; Kousuke Kadowaki; Shigeru Yonekubo; Takanori Shibata; Itaru Sato
Journal American Chemical Society (1999) 121 (48): 11235–11236.
DOI: 10.1021/ja993128t

Enantioselective Automultiplication of Chiral Molecules by Asymmetric Autocatalysis
Kenso Soai; Takanori Shibata; Itaru Sato
Acc. Chem. Res. (2000) 33 (6): 382–390.
DOI: 10.1021/ar9900820

Highly Enantioselective Synthesis Induced by Chiral Primary Alcohols Due to Deuterium Substitution
Itaru Sato; Daisuke Omiya; Takahiro Saito; Kenso Soai
Journal American Chemical Society (2000) 122 (47): 11739–11740.
DOI: 10.1021/ja002992e

Asymmetric Autocatalysis of a Pyrimidyl Alkanol Induced by Chiral Monosubstituted [2.2]Paracyclophanes
Shigehisa Tanji; Atsushi Ohno; Itaru Sato; Kenso Soai
Org. Lett. (2001) 3 (2): 287–289.
DOI: 10.1021/ol006921w

Enantioselective Synthesis of Near Enantiopure Compound by Asymmetric Autocatalysis Triggered by Asymmetric Photolysis with Circularly Polarized Light
Tsuneomi Kawasaki; Mirai Sato; Saori Ishiguro; Takahiro Saito; Yosuke Morishita; Itaru Sato; Hideo Nishino; Yoshihisa Inoue; Kenso Soai
Journal American Chemical Society (2005) 127 (10): 3274–3275.
DOI: 10.1021/ja0422108

Chiral Discrimination of Cryptochiral Saturated Quaternary and Tertiary Hydrocarbons by Asymmetric Autocatalysis
Tsuneomi Kawasaki; Hiroyuki Tanaka; Takashi Tsutsumi; Toshinari Kasahara; Itaru Sato; Kenso Soai
Journal American Chemical Society (2006) 128 (18): 6032–6033.
DOI: 10.1021/ja061429e

Mechanistic Insights in the Reversal of Enantioselectivity of Chiral Catalysts by Achiral Catalysts in Asymmetric Autocatalysis
François Lutz; Takashi Igarashi; Tomoyuki Kinoshita; Mai Asahina; Koichi Tsukiyama; Tsuneomi Kawasaki; Kenso Soai
Journal American Chemical Society (2008) 130 (10): 2956–2958.
DOI: 10.1021/ja077156k

Enantioselective Synthesis Utilizing Enantiomorphous Organic Crystal of Achiral Benzils as a Source of Chirality in Asymmetric Autocatalysis
Tsuneomi Kawasaki; Yuuki Harada; Kenta Suzuki; Takayuki Tobita; Nicola Florini; Gyula Pályi; Kenso Soai
Org. Lett. (2008) 10 (18): 4085–4088.
DOI: 10.1021/ol801600y

Generation of Absolute Controlled Crystal Chirality by the Removal of Crystal Water from Achiral Crystal of Nucleobase Cytosine
Tsuneomi Kawasaki; Yuko Hakoda; Hiroko Mineki; Kenta Suzuki; Kenso Soai
Journal American Chemical Society (2010) 132 (9): 2874–2875.
DOI: 10.1021/ja1000938

Enantioselective Synthesis Induced by Chiral Crystal Composed of dl-Serine in Conjunction with Asymmetric Autocatalysis
Tsuneomi Kawasaki; Taisuke Sasagawa; Kazuya Shiozawa; Mizuki Uchida; Kenta Suzuki; Kenso Soai
Org. Lett. (2011) 13 (9): 2361–2363.
DOI: 10.1021/ol200616t

Asymmetric Autocatalysis of Pyrimidyl Alkanol and Its Application to the Study on the Origin of Homochirality
Kenso Soai; Tsuneomi Kawasaki; Arimasa Matsumoto
Acc. Chem. Res. (2014) 47 (12): 3643–3654.
DOI: 10.1021/ar5003208

Asymmetric Autocatalysis Initiated by Finite Single-Wall Carbon Nanotube Molecules with Helical Chirality
Shunpei Hitosugi; Arimasa Matsumoto; Yoshiyasu Kaimori; Ryosuke Iizuka; Kenso Soai; Hiroyuki Isobe
Org. Lett. (2014) 16 (3): 645–647.
DOI: 10.1021/ol403384q

Read Related ACS Journal Articles

Asymmetric amplifying phenomena in enantioselective addition of diethylzinc to benzaldehyde
N. Oguni; Y. Matsuda; T. Kaneko
Journal American Chemical Society (1988) 110 (23): 7877–7878.
DOI: 10.1021/ja00231a049

Enantioselective addition of dialkylzincs to aldehydes promoted by chiral amino alcohols. Mechanism and nonlinear effect
M. Kitamura; S. Okada; S. Suga; R. Noyori
Journal American Chemical Society (1989) 111 (11): 4028–4036.
DOI: 10.1021/ja00193a040

The role of the product in asymmetric carbon-carbon bond formation: stoichiometric and catalytic enantioselective autoinduction
Albert H. Alberts; Hans Wynberg
Journal American Chemical Society (1989) 111 (18): 7265–7266.
DOI: 10.1021/ja00200a059

An efficient synthesis of LTD₄ antagonist L-699,392
A. O. King; E. G. Corley; R. K. Anderson; R. D. Larsen; T. R. Verhoeven; P. J. Reider; Y. B. Xiang; M. Belley; Y. Leblanc
Journal of Organic Chemistry (1993) 58 (14): 3731–3735.
DOI: 10.1021/jo00066a027

On the Mechanism of Asymmetric Nucleophilic Ring-Opening of Epoxides Catalyzed by (Salen)Cr^III Complexes
Karl B. Hansen; James L. Leighton; Eric N. Jacobsen
Journal American Chemical Society (1996) 118 (44): 10924–10925.
DOI: 10.1021/ja962600x

Mathematical Models of Nonlinear Effects in Asymmetric Catalysis: New Insights Based on the Role of Reaction Rate
Donna G. Blackmond
Journal American Chemical Society (1997) 119 (52): 12934–12939.
DOI: 10.1021/ja973049m

Origins of Asymmetric Amplification in Autocatalytic Alkylzinc Additions
Donna G. Blackmond; Christopher R. McMillan; Shailesh Ramdeehul; Andrea Schorm; John M. Brown
Journal American Chemical Society (2001) 123 (41): 10103–10104.
DOI: 10.1021/ja0165133

Enantioselective Synthesis without Discrete Optically Active Additives
Daniel A. Singleton; Loan K. Vo
Journal American Chemical Society (2002) 124 (34): 10010–10011.
DOI: 10.1021/ja027129o

A Few Molecules Can Control the Enantiomeric Outcome. Evidence Supporting Absolute Asymmetric Synthesis Using the Soai Asymmetric Autocatalysis
Daniel A. Singleton; Loan K. Vo
Org. Lett. (2003) 5 (23): 4337–4339.
DOI: 10.1021/ol035605p

Unusual Inverse Temperature Dependence on Reaction Rate in the Asymmetric Autocatalytic Alkylation of Pyrimidyl Aldehydes
Michela Quaranta; Timo Gehring; Barbara Odell; John M. Brown; Donna G. Blackmond
Journal American Chemical Society (2010) 132 (43): 15104–15107.
DOI: 10.1021/ja103204w

Structural Contributions to Autocatalysis and Asymmetric Amplification in the Soai Reaction
Soumitra V. Athavale; Adam Simon; K. N. Houk; Scott E. Denmark
Journal American Chemical Society (2020) 142 (43): 18387–18406.
DOI: 10.1021/jacs.0c05994

Nonlinear Effects in Asymmetric Catalysis by Design: Concept, Synthesis, and Applications
Lena C. Mayer; Simone Heitsch; Oliver Trapp
Acc. Chem. Res. (2022) 55 (23): 3345–3361.
DOI: 10.1021/acs.accounts.2c00557

A Radical Approach for Asymmetric α‑C–H Addition of N‑Sulfonyl Benzylamines to Aldehydes
Hui Hu; Zhaoxin Shi; Xiaochong Guo; Feng-Hua Zhang; Zhaobin Wang
Journal American Chemical Society (2024) 146 (8): 5316–5323.
DOI: 10.1021/jacs.3c12043

Nonclassical Nonlinear Effects (nc-NLEs) Provide Mechanistic Insights in Asymmetric Catalytic Cascade Reactions
Jinhan Yu; Donna G. Blackmond
ACS Catal. (2025) 15 (5): 3890–3897.
DOI: 10.1021/acscatal.5c00220

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