{ "id": "ephwycg1bq", "slug": "asymmetric-reduction", "title": "Asymmetric reduction", "updated": "2026-10-15", "topic_path": [ { "id": "physical", "label": "Physical world and mathematics", "api_url": "https://www.edgepedia.org/api/v1/topics/physical" }, { "id": "physical.chemistry", "label": "Chemistry", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry" }, { "id": "physical.chemistry.methods", "label": "Chemical principles and methods", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.methods" }, { "id": "physical.chemistry.methods.chemical-synthesis", "label": "Chemical synthesis", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.methods.chemical-synthesis" }, { "id": "physical.chemistry.methods.chemical-synthesis.asymmetric-synthesis", "label": "Asymmetric synthesis", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.methods.chemical-synthesis.asymmetric-synthesis" } ], "geo": [ { "id": "geo.nongeo.t1800.physical.chemistry.methods.chemical-synthesis", "label": "Non-geographic · 1800 to 1945: Chemical synthesis", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1800.physical.chemistry.methods.chemical-synthesis", "path": [ { "id": "geo.nongeo", "label": "Non-geographic", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo" }, { "id": "geo.nongeo.t1800", "label": "Non-geographic · 1800 to 1945", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1800" }, { "id": "geo.nongeo.t1800.physical", "label": "Physical world and mathematics", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1800.physical" }, { "id": "geo.nongeo.t1800.physical.chemistry", "label": "Chemistry", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1800.physical.chemistry" }, { "id": "geo.nongeo.t1800.physical.chemistry.methods", "label": "Chemical principles and methods", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1800.physical.chemistry.methods" }, { "id": "geo.nongeo.t1800.physical.chemistry.methods.chemical-synthesis", "label": "Chemical synthesis", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1800.physical.chemistry.methods.chemical-synthesis" } ] }, { "id": "geo.nongeo.t1946.physical.chemistry.methods.chemical-synthesis", "label": "Non-geographic · 1946 to 2000: Chemical synthesis", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.physical.chemistry.methods.chemical-synthesis", "path": [ { "id": "geo.nongeo", "label": "Non-geographic", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo" }, { "id": "geo.nongeo.t1946", "label": "Non-geographic · 1946 to 2000", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946" }, { "id": "geo.nongeo.t1946.physical", "label": "Physical world and mathematics", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.physical" }, { "id": "geo.nongeo.t1946.physical.chemistry", "label": "Chemistry", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.physical.chemistry" }, { "id": "geo.nongeo.t1946.physical.chemistry.methods", "label": "Chemical principles and methods", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.physical.chemistry.methods" }, { "id": "geo.nongeo.t1946.physical.chemistry.methods.chemical-synthesis", "label": "Chemical synthesis", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.physical.chemistry.methods.chemical-synthesis" } ] } ], "excerpt": "Asymmetric reduction converts a prochiral carbonyl, imine, or alkene into a single-enantiomer product using a chiral metal catalyst, an enzyme, or a stoichiometric chiral reagent.", "snippet": "Asymmetric reduction converts a prochiral carbonyl, imine, or alkene into a single-enantiomer product using a chiral metal catalyst, an enzyme, or a stoichiometric chiral reagent.", "node": "physical.chemistry.methods.chemical-synthesis.asymmetric-synthesis", "markdown": "# Asymmetric reduction\n\nAsymmetric reduction converts a prochiral carbonyl, imine, or alkene into a single-enantiomer product using a chiral metal catalyst, an enzyme, or a stoichiometric chiral reagent. The product quality metric is enantiomeric excess (ee).[1](https://www.nature.com/articles/s41467-023-39375-8) [Transfer hydrogenation](https://www.edgepedia.org/transfer-hydrogenation), borane reagents, and enzyme cofactors supply hydrogen in other forms. The main practical platforms are chiral ruthenium, iridium, and manganese complexes, oxazaborolidine-catalyzed borane reduction (CBS), and engineered ketoreductases (KREDs).\n\n| Key fact | Value |\n|---|---|\n| CBS reduction conditions | 0.6 equiv BH·THF, 5–10 mol% oxazaborolidine, THF, minutes at 23 °C; 83–97% ee across ten ketones [2](https://www.york.ac.uk/res/pac/teaching/ja00259a075.pdf) |\n| ATH of acetophenone (Ru–TsDPEN, generated in situ) | (S)-1-phenylethanol, 97% ee, 95% yield [3](https://pmc.ncbi.nlm.nih.gov/articles/PMC6264677/) |\n| Ru–BINAP hydrogenation of a ketoester | ~1500 psi H₂, 90% yield, 91% ee by chiral HPLC [4](https://synarchive.com/named-reactions/noyori-asymmetric-hydrogenation) |\n| KRED atorvastatin intermediate (industrial) | 96% isolated yield, >99.9% ee, glucose as stoichiometric reductant [5](https://pubs.rsc.org/en/content/articlepdf/2023/cc/d3cc01474f?page=search) |\n| Record turnover number | Ir/f-phamidol catalyst, 13,425,000 TON, 224 s⁻¹ TOF, 99% ee (acetophenone, 100 bar H₂, 30 days) [1](https://www.nature.com/articles/s41467-023-39375-8) |\n| Chiral nicotine production | 40 tons at 99% ee, substrate/catalyst ratio 100,000 [1](https://www.nature.com/articles/s41467-023-39375-8) |\n| ee standard of the field | 95% ee was once called excellent; >99.9% is now the benchmark [5](https://pubs.rsc.org/en/content/articlepdf/2023/cc/d3cc01474f?page=search) |\n\n## How it works\n\nEnantioselectivity comes from a chiral catalyst environment that reduces one enantioface of a planar prochiral group faster than the other. In the CBS reduction, the oxazaborolidine organizes the ketone and borane so that hydride transfer from boron to carbon is face-specific; the observed absolute configuration of ten reduced ketones matched this mechanistic model.[2](https://www.york.ac.uk/res/pac/teaching/ja00259a075.pdf)\n\nNoyori–Ikariya-type [(arene)RuCl(TsDPEN)] catalysts reduce C=O and C=N bonds through a ruthenium–hydride intermediate that sets the product stereochemistry, typically giving >90% ee.[6](https://pubs.acs.org/accacs/article/11/21/13649/459496/Does-the-Configuration-at-the-Metal-Matter-in) In the outer-sphere mechanism, both hydrogen atoms move simultaneously through a six-membered pericyclic transition state requiring a syn-coplanar H–Ru–N–H arrangement.[6](https://pubs.acs.org/accacs/article/11/21/13649/459496/Does-the-Configuration-at-the-Metal-Matter-in) Metal charge itself can direct the face: with a fixed enantiomer of an amido-ene(amido)diphosphine ligand, the charge on the amino(hydrido) intermediate determined product configuration across Fe, Co, and Ni catalysts, with ee correlating linearly with Hirshfeld charge.[7](https://doi.org/10.1016/j.chempr.2023.09.004) KREDs deliver hydride from active-site NAD(P)H to the carbonyl.[8](https://comptes-rendus.academie-sciences.fr/chimie/item/10.5802/crchim.408.pdf)\n\n## How it is done\n\n**CBS borane reduction.** Use 0.6 equiv of borane per mol ketone and 0.05–0.1 mol catalyst per mol ketone in THF; reactions complete within minutes at 23 °C, and the secondary alcohol is the only detectable product by capillary GC.[2](https://www.york.ac.uk/res/pac/teaching/ja00259a075.pdf) The B-methylated catalyst can be stored and weighed in air, unlike the air- and moisture-sensitive parent.[2](https://www.york.ac.uk/res/pac/teaching/ja00259a075.pdf)\n\n**Direct hydrogenation.** A representative Ru–[BINAP](https://www.edgepedia.org/binap) procedure generates the catalyst from [Ru(η⁶-C₆H₆)Cl₂]₂ and (R)-BINAP in DMF at 110 °C, then hydrogenates a ketoester under roughly 1500–1575 psi H₂, giving 90% yield at 91% ee.[4](https://synarchive.com/named-reactions/noyori-asymmetric-hydrogenation)\n\n**Asymmetric transfer hydrogenation (ATH).** Catalysts form in situ from [RuCl₂(η⁶-arene)]₂ dimers and TsDPEN; heating [RuCl₂(η⁶-mesitylene)]₂ with (S,S)-TsDPEN at 80 °C for 20 min gave a system reducing acetophenone to (S)-1-phenylethanol in 97% ee and 95% yield.[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC6264677/) Hydrogen donors are isopropanol (ketones) or formic acid–triethylamine, avoiding gaseous hydrogen and pressure reactors.[9](https://mdpi-res.com/d_attachment/molecules/molecules-18-06804/article_deploy/molecules-18-06804.pdf?version=1403114807)\n\n**Biocatalytic KRED reduction.** Cofactor recycling uses a large excess of isopropanol, or glucose/glucose dehydrogenase (GDH), or formate/formate dehydrogenase (FDH) when the enzyme does not accept isopropanol.[5](https://pubs.rsc.org/en/content/articlepdf/2023/cc/d3cc01474f?page=search)\n\n**ee measurement.** Products are analyzed by chiral GC-MS or chiral LC; amines can alternatively be derivatized with (−)-(1R)-menthyl chloroformate to diastereomeric carbamates resolved on an achiral GC column [9](https://mdpi-res.com/d_attachment/molecules/molecules-18-06804/article_deploy/molecules-18-06804.pdf?version=1403114807), and chiral HPLC is standard for ketoester products.[4](https://synarchive.com/named-reactions/noyori-asymmetric-hydrogenation)\n\n## Origin\n\nA precursor to the CBS catalyst appeared when Akira Hirao and colleagues reported asymmetric reduction of aromatic ketones with chiral alkoxy-amine-borane complexes in the Journal of the Chemical Society Chemical Communications in 1981.[10](https://doi.org/10.1039/c39810000315) E. J. Corey, Raman K. Bakshi, and Saizo Shibata then reported the oxazaborolidine-catalyzed borane reduction of ketones in the [Journal of the American Chemical Society](https://www.edgepedia.org/journal-of-the-american-chemical-society) in 1987 [11](https://doi.org/10.1021/ja00252a056), and E. J. Corey and colleagues reported the stable, easily prepared B-methyl catalyst the same year.[12](https://doi.org/10.1021/ja00259a075)\n\nAlso in 1987, [Ryoji Noyori](https://www.edgepedia.org/ryoji-noyori) and colleagues reported Ru–BINAP asymmetric hydrogenation of β-keto esters as a practical route to β-hydroxy esters in high enantiomeric purity [13](https://doi.org/10.1021/ja00253a051), and Tetsuo Ohta and colleagues extended BINAP–ruthenium(II) hydrogenation to unsaturated carboxylic acids.[14](https://doi.org/10.1021/jo00390a043) Earlier background includes chiral phosphine ligands such as DIOP and CAMP used with rhodium for hydrogenation of unsaturated carboxylic acids [3](https://pmc.ncbi.nlm.nih.gov/articles/PMC6264677/), and heterogeneous asymmetric hydrogenation over modified [Raney nickel](https://www.edgepedia.org/raney-nickel) or palladium, which gave only moderate enantioselectivity.[15](https://api.intechopen.com/chapter/pdf-download/39727.pdf) In biocatalysis, whole-cell systems such as [Baker's yeast](https://www.edgepedia.org/bakers-yeast) preceded isolated KREDs; recombinant DNA technology and cofactor regeneration shifted practice to isolated enzymes, which replaced platinum-group-metal asymmetric hydrogenation as the method of choice for chiral alcohols.[5](https://pubs.rsc.org/en/content/articlepdf/2023/cc/d3cc01474f?page=search) Asymmetric hydrogenation was recognized with the 2001 Nobel Prize in Chemistry.[16](https://pubs.rsc.org/en/content/articlehtml/2025/sc/d5sc02606g) More recently, Yunfei He and colleagues reported engineered nonheme iron enzymes enabling asymmetric hydrogenation of alkenes in the Journal of the American Chemical Society in 2026.[17](https://doi.org/10.1021/jacs.6c08443)\n\n## Variants\n\n**ATH versus direct hydrogenation.** ATH uses isopropanol or formic acid as hydrogen donor; with formic acid/triethylamine the reaction is irreversible, whereas isopropanol/base gives a reversible reaction detrimental to yield and ee.[18](https://www.ingentaconnect.com/contentone/matthey/pmr/2005/00000049/00000004/art00001?crawler=true&mimetype=application%2Fpdf)\n\n**DKR-coupled reduction.** [Dynamic kinetic resolution](https://www.edgepedia.org/dynamic-kinetic-resolution) racemizes the substrate while one enantiomer is reduced selectively. Efficient DKR requires Curtin–Hammett conditions, racemization faster than the asymmetric transformation, and an irreversible product-forming step, giving 100% theoretical yield from racemic substrate.[19](https://d-nb.info/1183139845/34) KRED kinetic resolution alone is capped below 50% yield, which motivates DKR with spontaneous, organocatalytic, or photoredox racemization.[20](https://pmc.ncbi.nlm.nih.gov/articles/PMC9280296/)\n\n**Photoredox-coupled biocatalysis.** Combining photoredox catalysis, organocatalysis, and biocatalysis gave stereoconvergent 3-substituted cyclohexanols and cyclohexylamines in 68–92% yield with >98% ee [21](https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2024.1398397/full); related photoredox/enzyme DKR of β-substituted ketones gave 68–82% yield, up to >20:1 dr and >99:1 er.[20](https://pmc.ncbi.nlm.nih.gov/articles/PMC9280296/)\n\n**Artificial metalloenzymes and base metals.** Mn(I) complexes anchored in streptavidin through biotinylated ligands gave the first base-metal artificial transfer hydrogenases, reducing aryl ketones with nearly quantitative yield and up to 98% ee.[22](https://onlinelibrary.wiley.com/doi/10.1002/anie.202311896) Mn(I)–cinchona systems hydrogenate ketones, β-ketoesters, and γ-amino ketones with ee up to 99% using molecular hydrogen as sole reductant.[16](https://pubs.rsc.org/en/content/articlehtml/2025/sc/d5sc02606g) Changing the metal's oxidation state with one chiral ligand reverses product configuration: Co(I) gave (R)-1-phenylethanol (80% ee) while Co(II) and Co(III) gave (S) at 76% and 79% ee.[7](https://doi.org/10.1016/j.chempr.2023.09.004)\n\n## Applications\n\n**Pharmaceutical hydrogenation.** Pfizer's sitagliptin process hydrogenates an unprotected α-(amino)acrylamide with a Rh/trichickenfootphos catalyst at 17 bar H₂ in methanol at 50 °C, giving 98% yield, 95% ee (>99.9% after recrystallization), and turnover numbers above 27,000.[23](https://myers.faculty.chemistry.harvard.edu/sites/g/files/omnuum7271/files/myers/files/18-noyori_asymmetric_hydrogenation_reaction.pdf) A trans-Ru–xylbinap–diapen catalyst enables a chromatography-free synthesis of (R)-fluoxetine [23](https://myers.faculty.chemistry.harvard.edu/sites/g/files/omnuum7271/files/myers/files/18-noyori_asymmetric_hydrogenation_reaction.pdf), and BINAP–Ru DKR of β-keto esters is applied industrially by Takasago for carbapenem intermediates.[15](https://api.intechopen.com/chapter/pdf-download/39727.pdf)\n\n**Biocatalytic processes.** The Codexis atorvastatin route produces the R-hydroxy ester in 96% yield and >99.9% ee with glucose as reductant.[5](https://pubs.rsc.org/en/content/articlepdf/2023/cc/d3cc01474f?page=search) A montelukast intermediate was made from 230 kg of ketone in propan-2-ol/toluene/triethanolamine buffer in 97% yield, with crystallization driving conversion.[8](https://comptes-rendus.academie-sciences.fr/chimie/item/10.5802/crchim.408.pdf) An iridium-catalyzed route to chiral nicotine has produced 40 tons at 99% ee.[1](https://www.nature.com/articles/s41467-023-39375-8)\n\n## Limitations and alternatives\n\n**Substrate-class limits.** Aliphatic ketones are reduced only with moderate selectivity in Ru systems [18](https://www.ingentaconnect.com/contentone/matthey/pmr/2005/00000049/00000004/art00001?crawler=true&mimetype=application%2Fpdf), give poor-to-moderate ee with Mn–cinchona catalysts [16](https://pubs.rsc.org/en/content/articlehtml/2025/sc/d5sc02606g), and gave at most 50% ee with the Mn artificial transfer hydrogenase [22](https://onlinelibrary.wiley.com/doi/10.1002/anie.202311896); aliphatic ketone reduction remains underdeveloped across Mn chemistry, where 1–5 mol% loadings are typical.[24](https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10.1002/cctc.202301567)\n\n**Process limits.** With isopropanol/base, ATH reversibility erodes yield and ee; formic acid systems avoid this, and CO₂ outgassing suppresses the reverse reaction.[18](https://www.ingentaconnect.com/contentone/matthey/pmr/2005/00000049/00000004/art00001?crawler=true&mimetype=application%2Fpdf) • [6](https://pubs.acs.org/accacs/article/11/21/13649/459496/Does-the-Configuration-at-the-Metal-Matter-in) Raising temperature accelerates ATH but lowers enantioselectivity, and higher catalyst loading slightly lowers ee.[9](https://mdpi-res.com/d_attachment/molecules/molecules-18-06804/article_deploy/molecules-18-06804.pdf?version=1403114807) Enzymes depend on NAD(P)H cofactor recycling.[8](https://comptes-rendus.academie-sciences.fr/chimie/item/10.5802/crchim.408.pdf)\n\n**Alternatives.** Classical kinetic resolution discards half the material, capped below 50% theoretical yield, which DKR-coupled reduction avoids [20](https://pmc.ncbi.nlm.nih.gov/articles/PMC9280296/).\n\n## References\n\n1. [A 13-million turnover-number anionic Ir-catalyst for a selective industrial route to chiral nicotine | Nature Communications](https://www.nature.com/articles/s41467-023-39375-8)\n2. [(RIR2CH-0)2BH - A Stable and Easily Prepared Catalyst for the Enantioselective Reduction of Ketones. Applications to Multistep Syntheses](https://www.york.ac.uk/res/pac/teaching/ja00259a075.pdf)\n3. [Opportunities Offered by Chiral η6-Arene/N-Arylsulfonyl-diamine-RuII Catalysts in the Asymmetric Transfer Hydrogenation of Ketones and Imines](https://pmc.ncbi.nlm.nih.gov/articles/PMC6264677/)\n4. [Noyori Asymmetric Hydrogenation](https://synarchive.com/named-reactions/noyori-asymmetric-hydrogenation)\n5. [The use of engineered ketoreductases (KREDS) in the highly enantiospecific reduction of prochiral ketones (Chem. Commun. 2023 review)](https://pubs.rsc.org/en/content/articlepdf/2023/cc/d3cc01474f?page=search)\n6. [Does the Configuration at the Metal Matter in Noyori–Ikariya Type Asymmetric Transfer Hydrogenation Catalysts?](https://pubs.acs.org/accacs/article/11/21/13649/459496/Does-the-Configuration-at-the-Metal-Matter-in)\n7. [Metal charge-directed enantiodivergent asymmetric transfer hydrogenation of ketones (Chem, 2024)](https://doi.org/10.1016/j.chempr.2023.09.004)\n8. [Practical examples of biocatalysis in industry (C. R. Chimie, 2025)](https://comptes-rendus.academie-sciences.fr/chimie/item/10.5802/crchim.408.pdf)\n9. [Practical Aspects and Mechanism of Asymmetric Hydrogenation with Chiral Half-Sandwich Complexes (Molecules 2013, 18, 6804)](https://mdpi-res.com/d_attachment/molecules/molecules-18-06804/article_deploy/molecules-18-06804.pdf?version=1403114807)\n10. [Akira Hirao and colleagues (1981). Asymmetric reduction of aromatic ketones with chiral alkoxy-amineborane complexes. Journal of the Chemical Society Chemical Communications.](https://doi.org/10.1039/c39810000315)\n11. [E. J. Corey, Raman K. Bakshi, Saizo Shibata (1987). Highly enantioselective borane reduction of ketones catalyzed by chiral oxazaborolidines. Mechanism and synthetic implications. Journal of the American Chemical Society.](https://doi.org/10.1021/ja00252a056)\n12. [E. J. Corey and colleagues (1987). A stable and easily prepared catalyst for the enantioselective reduction of ketones. Applications to multistep syntheses. Journal of the American Chemical Society.](https://doi.org/10.1021/ja00259a075)\n13. [Ryoji Noyori and colleagues (1987). Asymmetric hydrogenation of .beta.-keto carboxylic esters. A practical, purely chemical access to .beta.-hydroxy esters in high enantiomeric purity. Journal of the American Chemical Society.](https://doi.org/10.1021/ja00253a051)\n14. [Tetsuo Ohta and colleagues (1987). Asymmetric hydrogenation of unsaturated carboxylic acids catalyzed by BINAP-ruthenium(II) complexes. The Journal of Organic Chemistry.](https://doi.org/10.1021/jo00390a043)\n15. [Asymmetric Hydrogenation (book chapter)](https://api.intechopen.com/chapter/pdf-download/39727.pdf)\n16. [A priori Design of [Mn(I)-Cinchona] catalyst for Asymmetric Hydrogenation of Ketones and β-Keto carbonyl Derivatives](https://pubs.rsc.org/en/content/articlehtml/2025/sc/d5sc02606g)\n17. [Yunfei He and colleagues (2026). Engineered Nonheme Iron Enzymes Enable Asymmetric Hydrogenation of Alkenes. Journal of the American Chemical Society.](https://doi.org/10.1021/jacs.6c08443)\n18. [Asymmetric Reduction of Ketones (Platinum Metals Review, 2005)](https://www.ingentaconnect.com/contentone/matthey/pmr/2005/00000049/00000004/art00001?crawler=true&mimetype=application%2Fpdf)\n19. [Recent developments in asymmetric hydrogenation and transfer hydrogenation of ketones and imines through dynamic kinetic resolution (review)](https://d-nb.info/1183139845/34)\n20. [Ketoreductase Catalyzed (Dynamic) Kinetic Resolution for Biomanufacturing of Chiral Chemicals](https://pmc.ncbi.nlm.nih.gov/articles/PMC9280296/)\n21. [Recent advances in catalytic asymmetric synthesis (Frontiers in Chemistry, 2024)](https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2024.1398397/full)\n22. [Manganese Transfer Hydrogenases Based on the Biotin-Streptavidin Technology](https://onlinelibrary.wiley.com/doi/10.1002/anie.202311896)\n23. [Myers, The Noyori Asymmetric Hydrogenation Reaction (Chem 115 lecture notes)](https://myers.faculty.chemistry.harvard.edu/sites/g/files/omnuum7271/files/myers/files/18-noyori_asymmetric_hydrogenation_reaction.pdf)\n24. [Organometallic Mn(I) Complexes in Asymmetric Catalytic (Transfer) Hydrogenation and Related Transformations](https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10.1002/cctc.202301567)\n\n---\n*Topic: Encyclopedia › Physical world and mathematics › Chemistry › Chemical principles and methods › Chemical synthesis › Asymmetric synthesis*\n\n*Initially written Sep 29, 2026 · Edited: Oct 15, 2026*\n\n*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*\n\nLicense: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license\n", "same_as": [], "url": "https://www.edgepedia.org/asymmetric-reduction", "markdown_url": "https://www.edgepedia.org/asymmetric-reduction.md", "license": { "name": "Edgepedia Community License 1.0", "url": "https://www.edgepedia.org/edgepedia/license", "summary": "Free with credit, commercial use included. AI training is open to everyone. For other uses, organizations over USD 100M in revenue or 100M monthly users license separately.", "spdx": "LicenseRef-Edgepedia-Community-1.0" }, "credit": "\"Asymmetric reduction\", Edgepedia (EdgeChat), https://www.edgepedia.org/asymmetric-reduction. Edgepedia Community License 1.0.", "credit_md": "\"[Asymmetric reduction](https://www.edgepedia.org/asymmetric-reduction)\", Edgepedia (EdgeChat), [https://www.edgepedia.org/asymmetric-reduction](https://www.edgepedia.org/asymmetric-reduction). [Edgepedia Community License 1.0](https://www.edgepedia.org/edgepedia/license).", "credit_html": "\"Asymmetric reduction\", Edgepedia (EdgeChat), https://www.edgepedia.org/asymmetric-reduction. Edgepedia Community License 1.0.", "speakable": "Asymmetric reduction converts a prochiral carbonyl, imine, or alkene into a single-enantiomer product using a chiral metal catalyst, an enzyme, or a stoichiometric chiral reagent." }