| 1. |
- Hallman, K., et al.
(author)
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Palladium(II)-catalyzed oxidation of alcohols with air as reoxidant
- 2001
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In: Advanced Synthesis and Catalysis. - 1615-4150 .- 1615-4169. ; 343:3, s. 260-263
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Journal article (peer-reviewed)abstract
- Oxidation of primary and secondary aliphatic and secondary benzylic alcohols into their corresponding aldehydes and ketones was achieved in good yields with palladium catalysts using air as the reoxidant of palladium. The use of palladacycle 1 resulted in higher yields and a faster reaction than the use of Pd(OAc)(2) as the palladium source.
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| 2. |
- Afewerki, Samson, et al.
(author)
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Off-Cycle Catalyst Cooperativity in Amine/Transition Metal Combined Catalysis : Bicyclo[3.2.0]heptanes as Key Species in Co-Catalytic Enantioselective Carbocyclizations
- 2022
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In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 364:8, s. 1394-1401
-
Journal article (peer-reviewed)abstract
- The existence of off-cycle catalyst cooperativity in amine/metal combined catalysis is disclosed. The experimental and density functional theory study of the amine/metal co-catalyzed enantioselective Michael/carbocyclization cascade reaction between allenes and α,β-unsaturated aldehydes reveals that the dual catalysts can perform off-cycle cooperativity that gives access to stable bicyclo[3.2.0]heptane species that limits the carbocycle product formation. Insight into this mode of co-catalyst cooperativity sheds new light on the chiral amine/metal co-catalyzed reactions of to date and gives deeper understanding for improved future design of this type of enantioselective reactions.
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| 3. |
- Agasti, Soumitra, et al.
(author)
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Palladium-Catalyzed Synthesis of 2,3-Disubstituted Benzofurans : An Approach Towards the Synthesis of Deuterium Labeled Compounds
- 2015
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 357:10, s. 2331-2338
-
Journal article (peer-reviewed)abstract
- Palladium-catalyzed oxidative annulations between phenols and alkenylcarboxylic acids produced a library of benzofuran compounds. Depending on the nature of the substitution of the phenol precursor, either 2,3-dialkylbenzofurans or 2-alkyl-3-methylene-2,3-dihydrobenzofurans can be synthesized with excellent regioselectivity. Reactions between conjugated 5-phenylpenta-2,4-dienoic acids and phenol gave 3-alkylidenedihydrobenzofuran alkaloid motifs while biologically active 7-arylbenzofuran derivatives were prepared by starting from 2-phenylphenols. More interestingly, selective incorporation of deuterium from D2O has been discovered, which offers an attractive one-step method to access deuterated compounds.
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| 4. |
- Ahlsten, Nanna, 1982-, et al.
(author)
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Rhodium-catalysed coupling of allylic, homoallylic, and bishomoallylic alcohols with aldehydes and N-tosylimines : insights into the mechanism
- 2009
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 351:16, s. 2657-2666
-
Journal article (peer-reviewed)abstract
- The isomerisation of alkenols followed by reaction with aldehydes or N-tosylimines catalysed by rhodium complexes has been studied. The catalytically active rhodium complex is formed in situ from commercially available (cyclooctadiene)rhodium(l) chloride dimer [Rh(COD)Cl](2). The tandem process affords aldol and Mannich-type products in excellent yields. The key to the success of the coupling reaction is the activation of the catalysts by reaction with postassium tert-butoxide (t-BuOK), which promotes a catalytic cycle via alkoxides rather than rhodium hydrides. This mechanism minimises the formation of unwanted by-products. The mechanism has been studied by (1)H NMR spectroscopy and deuterium labelling experiments.
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| 5. |
- Anderson, Mattias, et al.
(author)
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Total Synthesis of Capsaicin Analogues from Lignin-Derived Compounds by Combined Heterogeneous Metal, Organocatalytic and Enzymatic Cascades in One Pot
- 2014
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 356:9, s. 2113-2118
-
Journal article (peer-reviewed)abstract
- The total synthesis of capsaicin analogues was performed in one pot, starting from compounds that can be derived from lignin. Heterogeneous palladium nanoparticles were used to oxidise alcohols to aldehydes, which were further converted to amines by an enzyme cascade system, including an amine transaminase. It was shown that the palladium catalyst and the enzyme cascade system could be successfully combined in the same pot for conversion of alcohols to amines without any purification of intermediates. The intermediate vanillyl-amine, prepared with the enzyme cascade system, could be further converted to capsaicin analogues without any purification using either fatty acids and a lipase, or Schotten-Baumann conditions, in the same pot. An aldol compound (a simple lignin model) could also be used as starting material for the synthesis of capsaicin analogues. Using l-alanine as organocatalyst, vanillin could be obtained by a retro-aldol reaction. This could be combined with the enzyme cascade system to convert the aldol compound to vanillylamine in a one-step one-pot reaction.
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| 6. |
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| 7. |
- Bah, Juho, et al.
(author)
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Carbocations as Lewis Acid Catalysts : Reactivity and Scope
- 2015
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 357:1, s. 148-158
-
Journal article (peer-reviewed)abstract
- One class of potential Lewis acids that has received negligible attention as a catalyst is the carbocation. Here we show the potential of triarylmethylium ions as highly powerful Lewis acid catalysts for organic reactions. The Lewis acidity of the triarylmethylium ion can be easily tuned by variation of the electronic properties of the aromatic rings and the catalytic activity of the carbocation is shown to correlate directly to the level of stabilization of the empty p(C)-orbital at the cationic carbon. The versatility of triarylmethylium ions as efficient Lewis acid catalysts for organic reactions is demonstrated in Diels-Alder, aza-Diels-Alder, conjugate addition, halogenation, epoxide rearrangement and intramolecular hetro-ene reactions.
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| 8. |
- Bielawski, Marcin, et al.
(author)
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Efficient and General One-Pot Synthesis of Diaryliodonium Triflates : Optimization, Scope and Limitations
- 2007
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 349:17-18, s. 2610-2618
-
Journal article (peer-reviewed)abstract
- Symmetrical and unsymmetrical diaryliodonium triflates have been synthesized from both electron-deficient and electron-rich arenes and aryl iodides with mCPBA and triflic acid. A thorough investigation of the optimization, scope and limitations has resulted in an improved one-pot protocol that is fast, high-yielding, and operationally simple. The reaction has been extended to the direct synthesis of symmetrical iodonium salts from iodine and arenes, conveniently circumventing the need for aryl iodides.
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| 9. |
- Borg, Tessie, et al.
(author)
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Diastereoselective Nucleophilic Addition to Aldehydes with Polar alpha- and alpha,beta-Substituents
- 2011
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 353:11-12, s. 2022-2036
-
Journal article (peer-reviewed)abstract
- The stereoselectivities obtained in Lewis acid-promoted Mukaiyama aldol additions and Sakurai allylations of mono-, and syn- and anti-disubstituted aldehydes possessing various polar alpha- and beta-substituents under non-chelating conditions are presented. The stereochemical outcome in the nucleophilic addition to alpha-substituted aldehydes containing an alpha-benzyloxy, alpha-fluoro or alpha-sulfonamide substituent are accurately predicted by current stereoinduction models. In contrast, the selectivitites obtained from addition of sterically demanding nucleophiles to alpha-chloro-substituted aldehydes cannot be rationalized by the same models and an alternative is discussed. The stereochemichal outcome in the additions to alpha, beta-disubstituted aldehydes is more complex and cannot be predicted using current models.
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| 10. |
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| 11. |
- Buitrago, Elina, et al.
(author)
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Efficient and Selective Hydrosilylation of Carbonyls Catalyzed by Iron Acetate and N-Hydroxyethylimidazolium Salts
- 2012
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 354:1, s. 217-222
-
Journal article (peer-reviewed)abstract
- Aromatic aldehydes, along with aryl alkyl, heteroaryl alkyl, and dialkyl ketones were efficiently reduced to their corresponding primary and secondary alcohols, respectively, in high yields, using the commercially available and inexpensive polymeric silane, polymethylhydrosiloxane (PMHS), as reducing agent. The reaction is catalyzed by in situ generated iron complexes containing hydroxyethyl-functionalized NHC ligands. Turnover frequencies up to 600 h−1 were obtained
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| 12. |
- Byrne, Liam, et al.
(author)
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Enantioselective Synthesis of Atropisomeric Biaryls using Biaryl 2,5-Diphenylphospholanes as Ligands for Palladium-Catalysed Suzuki-Miyaura Reactions
- 2021
-
In: Advanced Synthesis and Catalysis. - : John Wiley & Sons. - 1615-4150 .- 1615-4169. ; 363:1, s. 259-267
-
Journal article (peer-reviewed)abstract
- Here we describe the development of biaryl 2,5-diphenylphospholanes as a new class of C-2-symmetric, monodentate ligands for asymmetric Suzuki-Miyaura (ASM) reactions. Screening of a series of exemplary phospholanes led to the identification of two ligands that were used to prepare a range of atropisomeric biaryl and heterobiaryl products with good to excellent levels of enantioselectivity (up to 97:3 e.r.) under mild conditions. DFT studies suggest that the formation of a constraining ligand pocket and coordination of one of the biaryl methoxy groups in the optimised ligands to the metal centre is crucial for restricting conformational freedom in the bond-forming step.
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| 13. |
- Číhalová, Sylva, et al.
(author)
-
Asymmetric Aza-Morita–Baylis–Hillman-type reactions : The highly enantioselective reaction between unmodified α,β-unsaturated aldehydes and N-acylimines by organo-co-catal
- 2011
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 353:7, s. 1096-1108
-
Journal article (peer-reviewed)abstract
- The highly enantioselective organo-co-catalytic aza-Morita–Baylis–Hillman (MBH)-type reaction between N-carbamate-protected imines and α,β-unsaturated aldehydes has been developed. The organic co-catalytic system of proline and 1,4-diazabicyclo[2.2.2]octane (DABCO) enables the asymmetric synthesis of the corresponding N-Boc- and N-Cbz-protected β-amino-α-alkylidene-aldehydes in good to high yields and up to 99% ee. In the case of aza-MBH-type addition of enals to phenylprop-2-ene-1-imines, the co-catalytic reaction exhibits excellent 1,2-selectivity. The organo-co-catalytic aza-MBH-type reaction can also be performed by the direct highly enantioselective addition of α,β-unsaturated aldehydes to bench-stableN-carbamate-protected α-amidosulfones to give the corresponding β-amino-α-alkylidene-aldehydes with up to 99% ee.The organo-co-catalytic aza-MBH-type reaction is also an expeditious entry to nearly enantiomerically pure β-amino-α-alkylidene-amino acids and β-amino-α-alkylidene-lactams (99% ee). The mechanism and stereochemistry of the chiral amine and DABCO co-catalyzed aza-MBH-type reaction arealso discussed.
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| 14. |
- Coll, Mercedes, et al.
(author)
-
Modular Furanoside Pseudodipeptides and Thioamides, Readily Available Ligand Libraries for Metal-Catalyzed Transfer Hydrogenation Reactions : Scope and Limitations
- 2012
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 354:2-3, s. 415-427
-
Journal article (peer-reviewed)abstract
- Two new highly modular carbohydrate-based, pseudodipeptide and thioamide ligand libraries have been synthesized for the rhodium- and ruthenium-catalyzed asymmetric transfer hydrogenation (ATH) of prochiral ketones. These series of ligands can be prepared efficiently from easily accessible D-xylose and D-glucose. The ligand libraries contain two main ligand structures (pseudodipeptide and thioamide) that have been designed by making systematic modifications to one of the most successful ligand families developed for the ATH. As well as studying the effect of these two ligand structures on the catalytic performance, we also evaluated the effect of modifying several of the ligand parameters. We found that the effectiveness of the ligands at transferring the chiral information in the product can be tuned by correctly choosing the ligand components (ligand structure and ligand parameters). Excellent enantioselectivities (ees up to 99%) were therefore obtained in both enantiomers of the alcohol products using a wide range of substrates.
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| 15. |
- Cordova, Armando, et al.
(author)
-
Concise catalytic asymmetric total synthesis of biologically active tropane alkaloids
- 2012
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 354:7, s. 1363-1372
-
Journal article (peer-reviewed)abstract
- A general strategy for the total asymmetric synthesis of valuable tropane alkaloids by catalytic stereoselective transformations is disclosed. The power of this approach is exemplified by the concise catalytic enantioselective total syntheses of (+)-methylecgonine, (-)-cocaine and (+)-cocaine as well as the first catalytic asymmetric total syntheses of a cocaine C-1 derivative and (+)-ferruginine starting from 5-oxo-protected-a,beta-unsaturated enals using only two and three column chromatographic purification steps, respectively.
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| 16. |
- Deiana, Luca, 1982-, et al.
(author)
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Enantioselective Heterogeneous Synergistic Catalysis for Asymmetric Cascade Transformations
- 2014
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 356:11-12, s. 2485-2492
-
Journal article (peer-reviewed)abstract
- A modular design for a novel heterogeneous synergistic catalytic system, which simultaneously activates the electrophile and nucleophile by the combined activation modes of a separate metal and non-metal catalyst, for asymmetric cascade transformations on a solid surface is disclosed. This modular catalysis strategy generates carbocycles (up to 97.5: 2.5 er) as well as spirocyclic oxindoles (97.5: 2.5 to > 99: 0.5 er), containing all-carbon quaternary centers, in a highly enantioselective fashion via a one-pot dynamic relay process.
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| 17. |
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| 18. |
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| 19. |
- Di Francesco, Davide, et al.
(author)
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Ductile Pd-Catalysed Hydrodearomatization of Phenol-Containing Bio-Oils Into Either Ketones or Alcohols using PMHS and H2O as Hydrogen Source
- 2018
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 360:20, s. 3924-3929
-
Journal article (peer-reviewed)abstract
- A series of phenolic bio-oil components were selectively hydrodearomatized by palladium on carbon into the corresponding ketones or alcohols in excellent yields using polymethylhydrosiloxane and water as reducing agent. The selectivity of the reaction was governed by the water concentration where selectivity to alcohol was favoured at higher water concentrations. As phenolic bio-oil examples cardanol and beech wood tar creosote were studied as substrate to the developed reaction conditions. Cardanol was hydrodearomatized into 3-pentadecylcyclohexanone in excellent yield. From beech wood tar creosote, a mixture of cyclohexanols was produced. No hydrodeoxygenation occurred, suggesting the applicability of the reported method for the production of ketone-alcohol oil from biomass.
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| 20. |
- Ekström, Jesper, et al.
(author)
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A Simple and Efficient Catalytic Method for the Reduction of Ketones
- 2007
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 349:10, s. 1609-1613
-
Journal article (peer-reviewed)abstract
- A range of ketones was efficiently reduced in the presence of catalytic amounts of lithium isopropoxide in 2-propanol under microwave heating, with alcohol products being formed in yields up to 99 %.
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| 21. |
- Engman, Mattias, et al.
(author)
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Highly Selective Iridium-Catalyzed Asymmetric Hydrogenation of Trifluoromethyl Olefins : A New Route to Trifluoromethyl-Bearing Stereocenters
- 2009
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 351:3, s. 375-378
-
Journal article (peer-reviewed)abstract
- Fluorine-containing compounds are useful in many applications ranging from pharmaceuticals to ferroelectric crystals. We have developed a new, highly enantioselective synthetic route to trifluoromethyl-bearing stereocenters in up to 96% ee via asymmetric hydrogenation using N,P-ligated iridium catalysts. We also hydrogenated an isomeric mixture of olefins; this reaction gave the hydrogenation product highly enantioselectively (87% ee), and only the E isomer was present after the reaction had reached 56% conversion.
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| 22. |
- Fardost, Ashkan, et al.
(author)
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Palladium(II)-Catalyzed Decarboxylative Heck Arylations of Acyclic Electron-Rich Olefins with Internal Selectivity
- 2014
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 356:4, s. 870-878
-
Journal article (peer-reviewed)abstract
- Despite the recent emergence of decarboxylative CC bond forming reactions, methodologies providing internally arylated electron-rich olefins are still lacking. We herein report on palladium(II)-catalyzed decarboxylative Heck arylations of linear electron-rich olefins with excellent selectivity for the internal position. The method allows a variety of electron-rich linear olefins to undergo arylation with ortho-functionalized aromatic carboxylic acids, including heterocycles. The reaction mechanism has been explored with ESI-MS studies to confirm previous findings, and to reveal the formation of a highly stable palladium complex as a result of the Heck product reacting with the catalyst.
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| 23. |
- Fiorati, Andrea, et al.
(author)
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Application of Transaminases in a Disperse System for the Bioamination of Hydrophobic Substrates
- 2020
-
In: Advanced Synthesis and Catalysis. - : Wiley-VCH Verlagsgesellschaft. - 1615-4150 .- 1615-4169. ; 362:5, s. 1156-1166
-
Journal article (peer-reviewed)abstract
- Abstract The challenging bioamination of hydrophobic substrates has been attained through the employment of a disperse system consisting of a combination of a low polarity solvent (e. g. isooctane or methyl-tert-butylether), a non-ionic surfactant and a minimal amount of water. In these conditions, amine transaminases (ATA) were shown to efficiently carry out the reductive amination of variously substituted cyclohexanones, providing good conversions often coupled with a superior stereoselectivity if compared with the corresponding chemical reductive amination. An array of synthetically useful 4-substituted aminocyclohexanes was consequentially synthesized through biocatalysis, analyzed and stereochemically characterized.
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| 24. |
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| 25. |
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| 26. |
- Gerdin, Martin, 1976-, et al.
(author)
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Enantioselective Platinum-Catalyzed Silicon-Boron Addition to 1,3-Cyclohexadiene
- 2005
-
In: Advanced Synthesis and Catalysis. - Weinheim : Wiley-VCH. - 1615-4150 .- 1615-4169. ; 347:6, s. 749-753
-
Journal article (peer-reviewed)abstract
- Silaboration of 1,3-cyclohexadiene in the presence of Pt(acac)(2), DIBALH, and a phosphoramidite prepared from (S)-1,1'-bi-2-naphthol and diisopropylamine led to (1R,4S)-1-(dimethylphenylsilyl)4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2-cyclohexene with 70% ee. Chiral catalysts based on Ni gave no or essentially racemic product, whereas complexes containing Pd were inactive.
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| 27. |
- Gerdin, Martin, et al.
(author)
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Regioselective Preparation of Functionalized exo-Methylene-cyclopentanes and exo-Methylenepyrrolidines via Silaborative Carbocyclization of 1,6-Enynes
- 2010
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 352:14-15, s. 2559-2570
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Journal article (peer-reviewed)abstract
- Silaborative carbocyclization of 1,6-enynes catalyzed by Pd-PEPPSI-IPr {PEPPSI=pyridine-enhanced precatalyst preparation stabilization and initiation; IPr=N,N-bis[2,6-(diisopropyl)phenyl] imidazolium} employing either (dimethylphenylsilyl) pinacolborane or (chlorodimethylsilyl)pinacolborane provides access to densely functionalized five-membered rings as single diastereomers in excellent yields. The vinylboronate functions were employed in palladium-catalyzed Suzuki cross-coupling reactions with a range of aryl bromides, containing electron-with-drawing as well as electron-donating substituents, furnishing arylated exo-methylenecyclopentanes or exo-methylenepyrrolidines in good yields. Subsequent oxidation of the isopropoxydimethylsilyl function generated via addition of (chlorodimethylsilyl)-pinacolborane provided access to hydroxymethyl derivatives of the arylated compounds. Use of a chiral ester, bismenthyl (2-propenyl)(2-propynyl)malonate, afforded two diastereomeric products which could be separated, thereby giving access to the cyclized compounds as single isomers, with opposite absolute configurations at the newly formed stereocenter.
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| 28. |
- Grutters, Michiel M. P., et al.
(author)
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Highly Selective Cobalt-Catalyzed Hydrovinylation of Styrene
- 2009
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In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 351:13, s. 2199-2208
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Journal article (peer-reviewed)abstract
- Phosphine complexes of cobalt halide salts activated by diethylaluminum chloride are shown to yield highly active catalysts in the hydrovinylation of styrene, with unprecedented high selectivity to the desired product 3-phenyl-1-butene (3P1B). Double-bond isomerization, a common problem in codimerization reactions, only occurs after full conversion with these catalyst systems, even at elevated temperature. The most active catalysts are based on cobalt halide species combined with either C-1- or C-2-bridged diphosphines, heterodonor P,N or P,O ligands, flexible bidentate phosphine ligands or monodentate phosphine ligands. Kinetic investigations show an order > 1 in catalyst, which indicates either the involvement of dinuclear species in the catalytic cycle or partial catalyst decomposition via a bimolecular pathway.
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| 29. |
- Hammar, Peter, et al.
(author)
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Density Functional Theory Study of the Cinchona Thiourea-Catalyzed Henry reaction : Mechanism and Enantioselectivity
- 2007
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 349:17-18, s. 2537-2548
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Journal article (peer-reviewed)abstract
- We report a density functional theory investigation of the enantioselective Cinchona thiourea-catalyzed Henry reaction of aromatic aldehydes with nitromethane. We show that two pathways (differing in the binding modes of the reactants to the catalyst) are possible for the formation of the C-C bond, and that they have comparable reaction barriers. The enantioselectivity is investigated, and our results are in agreement with the experimentally observed solvent dependence of the reaction.
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| 30. |
- Hedberg, Christian, et al.
(author)
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Catalytic Asymmetric Total Synthesis of Muscarinic Receptor Antagonist (R)-Tolterodine
- 2005
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In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 347:5, s. 662-666
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Journal article (peer-reviewed)abstract
- A convenient and high yielding method for the preparation of (R)-tolterodine, utilizing a catalytic asymmetric Me-CBS reduction was developed. Highly enantioenriched (R)-6-methyl-4-phenyl-3,4-dihydrochromen-2-one (94% ee) was recrystallized to yield practically enantiopure material (ee >99%) and converted to (R)-tolterodine in a four-step procedure. The configuration of the crucial stereocenter was preserved during the synthesis and the obtained product was identified by chiral HPLC to be the (R)-tolterodine enantiomer.
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| 31. |
- Hojabri, Leila, et al.
(author)
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A new Imidazole-Containing Imidazolidinone Catalyst for Organocatalyzed Asymmetric Conjugate Addition of Nitroalkanes to Aldehydes
- 2007
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 349:4-5, s. 740-748
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Journal article (peer-reviewed)abstract
- Herein we report a new organocatalyst for the asymmetric Michael addition of nitroalkanes to α,β-unsaturated aldehydes. This catalyst incorporates a basic imidazole group in addition to the secondary amine responsible for activation of the α,β-unsaturated carbonyl compounds via iminium ion formation. The new organocatalyst is capable of catalyzing the enantioselective carbon-carbon bond formation with a high degree of enantiocontrol providing products in enantiomeric excesses of up to 92% and yields of up to to 91 %. These results constitute the best results so far reported for organocatalyzed Michael additions of nitroalkanes to α,β-unsaturated aldehydes, and provide proof of principle that organocatalysts incorporating two internal basic moieties may find broad application in organocatalyzed Michael additions.
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| 32. |
- Ibrahem, Ismail, et al.
(author)
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Enantioselective Conjugate Silyl Additions to alpha,beta-Unsaturated Aldehydes Catalyzed by Combination of Transition Metal and Chiral Amine Catalysts
- 2011
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 353:2-3, s. 245-252
-
Journal article (peer-reviewed)abstract
- We report that transition metal-catalyzed nucleophilic activation can be combined with chiral amine-catalyzed iminium activation as exemplified by the unprecedented enantioselective conjugate addition of a dimethylsilanyl group to alpha,beta-unsaturated aldehydes. These reactions proceed with excellent 1,4-selectivity to afford the corresponding beta-silyl aldehyde products 3 in high yields and up to 97:3 er using inexpensive bench stable copper salts and simple chiral amine catalysts. The reaction can also generate a quaternary stereocenter with good enantioselectivity. Density functional calculations are performed to elucidate the reaction mechanism and the origin of enantioselectivity.
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| 33. |
- Ibrahem, Ismail, et al.
(author)
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Enantioselective conjugate silyl additions to α,β-unsaturated aldehydes catalyzed by combination of transition metal and chiral amine catalysts
- 2011
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 353:2+3, s. 245-252
-
Journal article (peer-reviewed)abstract
- We report that transition metal-catalyzed nucleophilic activation can be combined with chiral amine-catalyzed iminium activation as exemplified by the unprecedented enantioselective conjugate addition of a dimethylsilanyl group to α,β-unsaturated aldehydes. These reactions proceed with excellent 1,4-selectivity to afford the corresponding β-silyl aldehyde products 3 in high yields and up to 97:3 er using inexpensive bench stable copper salts and simple chiral amine catalysts. The reaction canalso generate a quaternary stereocenter with goodenantioselectivity. Density functional calculations are performed to elucidate the reaction mechanism and the origin of enantioselectivity.
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| 34. |
- Ibrahem, Ismail, et al.
(author)
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Organocatalytic asymmetric hydrophosphination of alpha,beta-unsaturated aldehydes : Development, mechanism and DFT calculations
- 2008
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 350:11-12, s. 1875-1884
-
Research review (peer-reviewed)abstract
- The development and mechanism of the highly chemo- and enantioselective organocatalytic hydrophosphination reaction of alpha,beta-unsaturated aldehydes is presented. The reactions are catalyzed by protected chiral diarylprolinol derivatives and give access to optically active phosphine derivatives in high yields with up to 99% ee. The organocatalytic addition of other phosphorus nucleophiles was also investigated. The origin of the high enantioselectivity for the reaction with diphenylphosphine as the nucleophile is investigated by density functional theory calculations.
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| 35. |
- Johansson, Mikael, et al.
(author)
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Aerobic Oxidations Catalyzed by Zeolite-Encapsulated Cobalt Salophen
- 2008
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 350:11-12, s. 1807-1815
-
Journal article (peer-reviewed)abstract
- Cobalt salophen was encapsulated in a series of zeolites with a wide variation of the silicon-to-aluminium atomic ratio and with different cations. The zeolite-cobalt salophen catalysts were prepared using the “ship-in-a-bottle technique” where the complex was synthesized in the super cage of the zeolite and therefore locked into the pocket. The encapsulated catalysts were then tested in the aerobic oxidation of hydroquinone to p-benzoquinone; the best encapsulated catalyst was shown to be an efficient electron-transfer mediator in a palladium-catalyzed aerobic oxidative carbocyclization.
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| 36. |
- Jurberg, Igor D., et al.
(author)
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Visible Light-Enhanced C-H Amination of Cyclic Ethers with Iminoiodinanes
- 2022
-
In: Advanced Synthesis and Catalysis. - : John Wiley & Sons. - 1615-4150 .- 1615-4169. ; 364:23, s. 4061-4068
-
Journal article (peer-reviewed)abstract
- A two-step protocol allowing the C-H amination of cyclic ethers with iminoiodinanes, followed by the reduction of the resulting intermediate has been developed for the preparation of amino alcohols. The initial C-H functionalization is accelerated by visible light, improving the reactivity compared to the thermal process performed in the dark. The effect of different substituents on the photochemical reactivity of iminoiodinanes has been studied both experimentally and computationally. Photophysical measurements and DFT calculations were performed to better understand the observed reactivities and corroborate the proposed mechanistic proposal.
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| 37. |
- Kalek, Marcin, 1983-, et al.
(author)
-
Novel, stereoselective and stereospecific synthesis of allenylphosphonates and related compounds via palladium-catalyzed propargylic substitution
- 2011
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 353:10, s. 1741-1755
-
Journal article (peer-reviewed)abstract
- We have developed a novel method for the synthesis of allenylphosphonates and related compounds based on a palladium(0)-catalyzed reaction of propargylic derivatives with H-phosphonate,H-phosphonothioate, H-phosphonoselenoate, and H-phosphinateesters. The reaction is stereoselective and stereospecific, and provides a convenient entry to a vast array of allenylphosphonates and their analogues with diverse substitution patterns in the allenic moiety and at the phosphorus center. Some mechanistic aspects of this new reaction were also investigated.
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| 38. |
- Kalek, Marcin, et al.
(author)
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Preparation of arylphosphonates by palladium(0)-catalyzed cross-coupling in the presence of acetate additives : Synthetic and mechanistic studies
- 2009
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 351:18, s. 3207-3216
-
Journal article (peer-reviewed)abstract
- An efficient protocol for the synthesis of arylphosphonate diesters via a palladium-catalyzed cross-coupling of H-phosphonate diesters with aryl electrophiles, promoted by acetate ions, was developed. A significant shortening of the cross-coupling time in the presence of the added acetate ions was achieved for bidentate and monodentate supporting ligands, and for different aryl electrophiles (iodo, bromo and triflate derivatives). The reaction conditions were optimized in terms of amount of the catalyst, supporting ligands, and source of the acetate ion used. Various arylphosphonates, including those of potential biological significance, were synthesized using this newly developed protocol. Some mechanistic aspects of the investigated reactions are also discussed.
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| 39. |
- Kaukoranta, Päivi, et al.
(author)
-
Iridium Catalysts with Chiral Imidazole-Phosphine Ligands for Asymmetric Hydrogenation of Vinyl Fluorides and other Olefins
- 2008
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 350:7-8, s. 1168-1176
-
Journal article (peer-reviewed)abstract
- New chiral bidentate imidazole-phosphine ligands have been prepared and evaluated for the iridium-catalysed asymmetric hydrogenation of olefins. The imidazole-phosphine-ligated iridium catalysts hydrogenated trisubstituted olefins with the same sense of enantiodiscrimination as known iridium catalysts possessing oxazole and thiazole as N-donors. The imidazole-based catalysts were shown to hydrogenate vinyl fluorides, in some cases with the highest ee values published to date.
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| 40. |
- Kaukoranta, Päivi, et al.
(author)
-
Microwave-Assisted Asymmetric Intermolecular Heck Reaction using Phosphine-Thiazole Ligands
- 2007
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 349:7-18, s. 2595-2602
-
Journal article (peer-reviewed)abstract
- A series of new phosphine-thiazole compounds has been synthesized and used as efficient ligands in the palladium-catalyzed asymmetric intermolecular Heck coupling of 2,3-dihydrofuran with aryl triflates and cyclohexenyl triflate. Microwave heating was used to accelerate the reactions and gave complete conversions in as little as one hour. Products were obtained with good to excellent enantioselectivities.
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| 41. |
- Kohls, Hannes, et al.
(author)
-
Selective Access to All Four Diastereomers of a 1,3-Amino Alcohol by Combination of a Keto Reductase- and an Amine Transaminase-Catalysed Reaction
- 2015
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 357:8, s. 1808-1814
-
Journal article (peer-reviewed)abstract
- The biocatalytic synthesis of chiral amines has become a valuable addition to the chemists' tool-box. However, the efficient asymmetric synthesis of functionalised amines bearing more than one stereocentre, such as 1,3-amino alcohols, remains challenging. By employing a keto reductase (KRED) and two enantiocomplementary amine transaminases (ATA), we developed a biocatalytic route towards all four diastereomers of 4-amino-1-phenylpentane-2-ol as a representative molecule bearing the 1,3-amino alcohol functionality. Starting from a racemic hydroxy ketone, a kinetic resolution using an (S)-selective KRED provided optically active hydroxy ketone (86% ee) and the corresponding diketone. Further transamination of the hydroxy ketone was performed by either an (R)- or an (S)-selective ATA, yielding the (2R,4R)- and (2R,4S)-1,3-amino alcohol diastereomers. The remaining two diastereomers were accessible in two subsequent asymmetric steps: the diketone was reduced regio- and enantioselectively by the same KRED, which yielded the (S)-configured hydroxy ketone. Eventually, the subsequent transamination of the crude product with (R)- and (S)-selective ATAs yielded the remaining (2S,4R)and (2S,4S)-diastereomers, respectively.
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| 42. |
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| 43. |
- Land, Henrik, et al.
(author)
-
Engineering the Active Site of an (S)-Selective Amine Transaminase for Acceptance of Doubly Bulky Primary Amines
- 2020
-
In: Advanced Synthesis and Catalysis. - : Wiley-VCH Verlagsgesellschaft. - 1615-4150 .- 1615-4169. ; 362:4, s. 812-821
-
Journal article (peer-reviewed)abstract
- A protein engineering approach for expanding the substrate scope of the (S)-selective Chromobacterium violaceum amine transaminase is presented. Amino acid residues in the small binding pocket of the active site were targeted in order to increase the pocket size for acceptance of primary amines bearing two bulky groups. A highly sensitive fluorescence assay was then used to evaluate the generated enzyme variants for their activity towards propyl- and benzyl-substituted screening substrates. The best variant, L59A/F88A, was successfully applied in the kinetic resolution of 1,2-diphenylethylamine using different conditions and substrate loadings. The variant L59A/F88A generated enantiomerically pure (R)-1,2-diphenylethylamine with ee >99 % under all tested conditions. The variant also holds great promise for synthesis of hydrophobic compounds as it shows optimum activity when 20 % (v/v) DMSO is applied as cosolvent. The variant L59A/F88A provides a great addition to the available catalyst toolbox for synthesis of chiral amines, as it is the first published (S)-selective amine transaminase showing activity towards benzyl-substituted primary amines.
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| 44. |
- Lihammar, Richard, et al.
(author)
-
An Efficient Dynamic Kinetic Resolution of N-Heterocyclic 1,2-Amino Alcohols
- 2011
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 353:13, s. 2321-2327
-
Journal article (peer-reviewed)abstract
- A chemoenzymatic dynamic kinetic resolution (DKR) of N-heterocyclic amino alcohols is described. Various lipases were studied as biocatalysts for the kinetic resolution of N-heterocyclic 1,2-amino alcohols. The influence of the support of the enzymes on the enantioselectivity in the resolution of different substrates is highlighted. Various 3-acetoxypyrrolidines and -piperidines were obtained in high yield and high enantiomeric excess in efficient DKR reactions.
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| 45. |
- Linde, Erika, 1992-, et al.
(author)
-
Advancements in the Synthesis of Diaryliodonium Salts : Updated Protocols
- 2023
-
In: Advanced Synthesis and Catalysis. - 1615-4150 .- 1615-4169. ; 365:16, s. 2751-2756
-
Journal article (peer-reviewed)abstract
- Our group has reported several one-pot protocols for the synthesis of diaryliodonium salts, which have been recognized as attractive multi-purpose reagents in areas ranging from organic synthesis to materials chemistry. Over the years, we have identified limitations in the published protocols concerning synthesis of mixed electron-rich and electron-poor, as well as highly electron-poor diaryliodonium salts, as the corresponding starting materials are either too reactive or too unreactive. In this update, we discuss the underlying limitations concerning the stability and reactivity of the involved reagents and provide strategies to overcome these challenges through updated synthetic protocols.
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| 46. |
- Lundgren, Stina, et al.
(author)
-
Lewis acid-Lewis base-catalysed enantioselective addition of alpha-ketonitriles to aldehydes
- 2007
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 349:3, s. 364-372
-
Journal article (peer-reviewed)abstract
- Additions of structurally diverse alpha-ketonitriles to aromatic and aliphatic prochiral aldehydes yielding highly enantioenriched acylated cyanohydrins were achieved using a combination of a titanium salen dimer and an achiral or chiral Lewis base. In most cases high yields and high enantioselectivities were observed. The ee was moderate in the initial part of the reaction but increased over time. This could be avoided, and higher ees obtained, by keeping the titanium complex, in the presence or absence of aldehyde and ketonitrile, at -40 degrees C prior to the addition of the Lewis base. A mechanism initiated by nucleophilic attack of the tertiary amine at the carbonyl carbon atom of the ketonitile is supported by C-13 labelling experiments.
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| 47. |
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| 48. |
- Ma, Guangning, et al.
(author)
-
Highly enantioselective co-catalytic direct aldol reactions by combination of hydrogen-bond donating and acyclic amino acid catalysts
- 2011
-
In: Advanced Synthesis and Catalysis. - : Wiley-VCH Verlagsgesellschaft. - 1615-4150 .- 1615-4169. ; 353:17, s. 3114-3122
-
Journal article (peer-reviewed)abstract
- Highly enantioselective co-catalytic direct aldol reactions by a combination of simple hydrophobic acyclic amino acid and hydrogen-bond donating catalysts are presented. The corresponding aldol products are formed in high yields with high regio-, diastereo- (anti or syn) and enantioselectivity (up to 99.5:0.5 er). The catalyst loadings can be decreased to as little as 2 mol%.
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| 49. |
- Marcelli, Tommaso, et al.
(author)
-
Origin of Enantioselectivity in the Organocatalytic Reductive Amination of α-Branched Aldehydes
- 2009
-
In: Advanced Synthesis and Catalysis. - Weinheim : Wiley-VCH Verlag GmbH&Co. KGaA. - 1615-4150 .- 1615-4169. ; 351:4, s. 525-529
-
Journal article (peer-reviewed)abstract
- The reason for enantioselectivity in thereductive amination of α-branched aldehydes wasinvestigated. The relative energies of all the diastereomeric transition states for hydride transfer of a suitable computational model were calculated at the B3LYP/6-311+(2d,2p) level of theory. Our calculations successfully reproduce and rationalize the experimentally observed stereochemical outcome of the reaction.
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| 50. |
- Margalef, Jessica, et al.
(author)
-
Third-Generation Amino Acid Furanoside-Based Ligands from d-Mannose for the Asymmetric Transfer Hydrogenation of Ketones : Catalysts with an Exceptionally Wide Substrate Scope
- 2016
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 358:24, s. 4006-4018
-
Journal article (peer-reviewed)abstract
- A modular ligand library of -amino acid hydroxyamides and thioamides was prepared from 10 different N-tert-butyloxycarbonyl-protected -amino acids and three different amino alcohols derived from 2,3-O-isopropylidene--d-mannofuranoside. The ligand library was evaluated in the half-sandwich ruthenium- and rhodium-catalyzed asymmetric transfer hydrogenation of a wide array of ketone substrates, including simple as well as sterically demanding aryl alkyl ketones, aryl fluoroalkyl ketones, heteroaromatic alkyl ketones, aliphatic, conjugated and propargylic ketones. Under the optimized reaction conditions, secondary alcohols were obtained in high yields and in enantioselectivities up to >99%. The choice of ligand/catalyst allowed for the generation of both enantiomers of the secondary alcohols, where the ruthenium-hydroxyamide and the rhodium-thioamide catalysts act complementarily towards each other. The catalytic systems were also evaluated in the tandem isomerization/asymmetric transfer hydrogenation of racemic allylic alcohols to yield enantiomerically enriched saturated secondary alcohols in up to 98% ee. Furthermore, the catalytic tandem -alkylation/asymmetric transfer hydrogenation of acetophenones and 3-acetylpyridine with primary alcohols as alkylating and reducing agents was studied. Secondary alcohols containing an elongated alkyl chain were obtained in up to 92% ee.
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