7,765 results match your criteria chiral acids


Catalytic Asymmetric Hydroalkoxylation of C-C Multiple Bonds.

Chem Rev 2021 Dec 3. Epub 2021 Dec 3.

Max-Planck-Institut für Kohlenforschung, Kaiser Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.

Asymmetric hydroalkoxylation of alkenes constitutes a redox-neutral and 100% atom-economical strategy toward enantioenriched oxygenated building blocks from readily available starting materials. Despite their great potential, catalytic enantioselective additions of alcohols across a C-C multiple bond are particularly underdeveloped, especially compared to other hydrofunctionalization methods such as hydroamination. However, driven by some recent innovations, e. Read More

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December 2021

Catalytic asymmetric synthesis of α-stereogenic carboxylic acids: recent advances.

Org Biomol Chem 2021 Dec 2. Epub 2021 Dec 2.

Shaanxi Key Laboratory of Chemical Reaction Engineering, College of Chemistry and Chemical Engineering, Yan'an University, Yan'an 716000, China.

Chiral carboxylic acids bearing an α-stereogenic center constitute the backbone of many natural products and therapeutic reagents as well as privileged chiral ligands and catalysts. Hence, it is not surprising that a large number of elegant catalytic asymmetric strategies have been developed toward the efficient synthesis of α-chiral carboxylic acids, such as α-hydroxy acids and α-amino acids. In this review, the recent advances in asymmetric synthesis of α-stereogenic free carboxylic acids organocatalysis and transition metal catalysis are summarized (mainly from 2010 to 2020). Read More

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December 2021

Remote Amino Acid Recognition Enables Effective Hydrogen Peroxide Activation at a Manganese Oxidation Catalys.

Angew Chem Int Ed Engl 2021 Dec 1. Epub 2021 Dec 1.

Universitat de Girona, Institut de Química Computacional i Catàlisi, SPAIN.

Precise delivery of a proton plays a key role in O 2 activation at iron oxygenases, enabling the crucial O-O cleavage step that generates the oxidizing high valent metal-oxo species. Such proton is delivered by acidic residues that may either directly bind the iron center or lie in its second coordination sphere. Herein, a supramolecular strategy for enzyme-like H 2 O 2 activation at a biologically inspired manganese catalyst, with nearly stoichiometric amount (1-1. Read More

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December 2021

Artificial Biomolecular Channels: Enantioselective Transmembrane Transport of Amino Acids Mediated by Homochiral Zirconium Metal-Organic Cages.

J Am Chem Soc 2021 Dec 1. Epub 2021 Dec 1.

School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China.

Natural transport channels (or carriers), such as aquaporins, are a distinct type of biomacromolecule capable of highly effective transmembrane transport of water or ions. Such behavior is routine for biology but has proved difficult to achieve in synthetic systems. Perhaps most significantly, the enantioselective transmembrane transport of biomolecules is an especially challenging problem both for chemists and for natural systems. Read More

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December 2021

Construction of an enzyme-based all-fiber SPR biosensor for detection of enantiomers.

Biosens Bioelectron 2021 Nov 25;198:113836. Epub 2021 Nov 25.

College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China. Electronic address:

Chiral analysis of amino acids (AAs) is of great importance in medical science due to the distinctive effect of AA isomers on human health. Although various chiral recognition techniques have been developed, the quantitative chiral recognition of low-level AA isomers remains challenging. Here, we combined the fiber optic SPR with an enzyme-substrate recognition mechanism to construct a direct-assay-type chiral AA biosensor. Read More

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November 2021

Optical Detection of Stereoselective Interactions with DNA-Wrapped Single-Wall Carbon Nanotubes.

J Am Chem Soc 2021 Nov 29. Epub 2021 Nov 29.

Materials Science and Engineering Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States.

DNA-wrapped carbon nanotubes have been explored increasingly as sensitive near-infrared fluorescence probes for biomolecules. However, notably missing in previous studies is an inquiry on stereoselective interactions between DNA-wrapped carbon nanotubes and biomolecules. Here, enantiopure (+) and (-)(6,5), and (-)(8,3) as well as achiral (11,0) carbon nanotubes wrapped with specific resolving DNA sequences are used to demonstrate their stereoselective detection of amino acid enantiomers. Read More

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November 2021

D-Amino Acids and D-Amino Acid-Containing Peptides: Potential Disease Biomarkers and Therapeutic Targets?

Biomolecules 2021 Nov 18;11(11). Epub 2021 Nov 18.

Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing 210009, China.

In nature, amino acids are found in two forms, L and D enantiomers, except for glycine which does not have a chiral center. The change of one form to the other will lead to a change in the primary structure of proteins and hence may affect the function and biological activity of proteins. Indeed, several D-amino acid-containing peptides (DAACPs) were isolated from patients with cataracts, Alzheimer's and other diseases. Read More

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November 2021

Selenocystine and Photo-Irradiation Directed Growth of Helically Grooved Gold Nanoarrows.

Small 2021 Nov 25:e2104301. Epub 2021 Nov 25.

CAS Key Laboratory of Colloid Interface and Chemical Thermodynamics Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.

The fabrication of discrete nanostructures with both plasmonic circular dichroism (PCD) and chiral features is still a challenge. Here, gold nanoarrows (GNAs) with both chiroptical responses and chiral morphologies are achieved by using L-selenocystine (L-SeCys ) as a chiral inducer. While L-SeCys generates GNAs with a weak PCD signal, the irradiated L-SeCys (irr-L-SeCys ) leads to GNAs with featured helical grooves (HeliGNAs) accompanying with a strong PCD signal. Read More

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November 2021

Chiral Phosphoric Acids as Versatile Tools for Organocatalytic Asymmetric Transfer Hydrogenations.

European J Org Chem 2021 Oct;2021(38):5367-5381

Institute of Applied Synthetic Chemistry TU Wien Getreidemarkt Vienna, 9/163 1060 Wien Austria.

Herein, recent developments in the field of organocatalytic asymmetric transfer hydrogenation (ATH) of C=N, C=O and C=C double bonds using chiral phosphoric acid catalysis are reviewed. This still rapidly growing area of asymmetric catalysis relies on metal-free catalysts in combination with biomimetic hydrogen sources. Chiral phosphoric acids have proven to be extremely versatile tools in this area, providing highly active and enantioselective alternatives for the asymmetric reduction of α,β-unsaturated carbonyl compounds, imines and various heterocycles. Read More

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October 2021

Impact of chiral tebuconazole on the flavor components and color attributes of Merlot and Cabernet Sauvignon wines at the enantiomeric level.

Food Chem 2021 Nov 9:131577. Epub 2021 Nov 9.

State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, PR China. Electronic address:

The impact of chiral tebuconazole on the flavor and appearance of Merlot and Cabernet Sauvignon wines were systematically studied. Gas chromatography-ion mobility spectrometry and headspace-solid phase microextraction coupled with gas chromatography mass spectrometry qualitatively and quantitatively identified the flavor components, and a photographic colorimeter was used for color attribute analysis. Tebuconazole enantiomers had different effects on the flavor and appearance of young wines, especially R-tebuconazole. Read More

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November 2021

Nickel-Catalyzed Asymmetric Hydrogenation for the Synthesis of Key Sitagliptin Intermediate.

Chem Asian J 2021 Nov 24. Epub 2021 Nov 24.

National Chemical Laboratory CSIR, Chemical Engineering Division, Dr. Homi Bhabha Road, 411008, Pune, INDIA.

Nickel-catalyzed enantioselective hydrogenation of enamines leading to the efficient synthesis of 3- R -Boc-amino-4-(2,4,5-trifluorophenyl)butyric esters, the key intermediate of the blockbuster antidiabetic drug ( R )-SITAGLIPTIN, is described. The sitagliptin motifs were isolated in more than 99% yield and with 75-92% ee using the earth-abundant nickel catalyst. Upon chiral resolution with ( R )- and ( S )-1-phenylethylamines, the partially enantioenriched ( R )- and ( S )-Boc-3-amino-4-(2,4,5-trifluorophenyl)butanoic acids provided > 99. Read More

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November 2021

Enantioselective recognition of chiral acids by supramolecular interactions with chiral AIEgens.

Chem Commun (Camb) 2021 Nov 23. Epub 2021 Nov 23.

Shenzhen Institute of Aggregate Science and Technology, School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China.

Novel chiral AIEgens bearing optically pure amino groups were synthesized and showed excellent discrimination for a series of chiral acidic compounds and amino acids. Interestingly, after supramolecular assembly with 4-sulfocalix[4]arene, the obtained complexes showed enhanced enantioselectivity for chiral acids. Read More

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November 2021

Orthogonal Catalysis for an Enantioselective Domino Inverse-Electron Demand Diels-Alder / Substitution Reaction.

Chemistry 2021 Nov 23. Epub 2021 Nov 23.

Justus-Liebig Universität, Institut für Organische Chemie, Heinrich-Buff-Ring 17, 35392, Giessen, GERMANY.

An enantioselective domino process for the synthesis of substituted 1,2-dihydronaphthalenes has been developed, by the combination of chiral amines and a bidentate Lewis acid in an orthogonal catalysis. This new method is based on an inverse electron-demand Diels-Alder and a subsequent group exchange reaction. An enamine is generated in situ from an aldehyde and a chiral secondary amine catalyst which reacts with phthalazine, activated by the coordination to a bidentate Lewis acid catalyst. Read More

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November 2021

Anionic Chiral Co(III) Complexes Mediated Asymmetric Halocyclization─Synthesis of 5-Halomethyl Pyrazolines and Isoxazolines.

Org Lett 2021 Dec 23;23(23):9134-9139. Epub 2021 Nov 23.

Department of Applied Chemistry, Anhui Agricultural University, Hefei 230036, China.

An asymmetric synthesis of 5-halomethyl pyrazolines and isoxazolines which bear a tertiary stereocenter by catalytic halocyclization of β,γ-unsaturated hydrazones and ketoximes is described. By using Brønsted acids of anionic chiral Co(III) complexes as catalysts, a variety of chiral 5-halomethyl pyrazolines and isoxazolines were obtained in good yields with high enantioselectivities (up to 99% yield, 97:3 er). Preliminary bioassay results indicated that several isoxazoline derivatives exhibited significant antifungal activities. Read More

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December 2021

Cooperative Hydrogen-Bond-Donor Catalysis with Hydrogen Chloride Enables Highly Enantioselective Prins Cyclization Reactions.

J Am Chem Soc 2021 Nov 23. Epub 2021 Nov 23.

Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States.

Cooperative asymmetric catalysis with hydrogen chloride (HCl) and chiral dual-hydrogen-bond donors (HBDs) is applied successfully to highly enantioselective Prins cyclization reactions of a wide variety of simple alkenyl aldehydes. The optimal chiral catalysts were designed to withstand the strongly acidic reaction conditions and were found to induce rate accelerations of 2 orders of magnitude over reactions catalyzed by HCl alone. We propose that the combination of strong mineral acids and chiral hydrogen-bond-donor catalysts may represent a general strategy for inducing enantioselectivity in reactions that require highly acidic conditions. Read More

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November 2021

Amino acid-derived bisphenolate palladium complexes as C-C coupling catalysts.

Dalton Trans 2021 Nov 22. Epub 2021 Nov 22.

Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.

A series of amine bisphenol (ABP) pro-ligands featuring amino acid ester pendant arms were prepared. Optimisation of the synthetic method allowed the facile incorporation of naturally occurring, chiral amino acids into the ABP scaffold with minimal racemisation. Reaction of the pro-ligands (LH) with Pd(OAc), in the presence of amines, led to the formation of complexes with an unprecedented pincer-like O,N,O coordination mode around the Pd centre. Read More

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November 2021

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues.

Beilstein J Org Chem 2021 4;17:2680-2715. Epub 2021 Nov 4.

Department of Pharmaceutical Chemistry, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal-576104, Karnataka, India.

Sugar-modified nucleosides have gained considerable attention in the scientific community, either for use as molecular probes or as therapeutic agents. When the methylene group of the ribose ring is replaced with a sulfur atom at the 3'-position, these compounds have proved to be structurally potent nucleoside analogues, and the best example is BCH-189. The majority of methods traditionally involves the chemical modification of nucleoside structures. Read More

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November 2021

Plasmonic Nanosensors with Extraordinary Sensitivity to Molecularly Enantioselective Recognition at Nanoscale Interfaces.

ACS Nano 2021 Nov 19. Epub 2021 Nov 19.

School of Physics, Beijing Institute of Technology, Beijing 100081, China.

Molecular chirality recognition plays a pivotal role in chiral generation and transfer in living systems and makes important contribution to the development of diverse applications spanning from chiral separation to soft nanorobots. To detect chirality recognition, most of the molecular sensors described to date are based on the design and preparation of the host-guest complexation with chromophore or fluorophore at the reporter unit. Nevertheless, the involved tedious procedures and complicated chemical syntheses hamper their practical applications. Read More

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November 2021

Asymmetric radical carboesterification of dienes.

Nat Commun 2021 Nov 18;12(1):6670. Epub 2021 Nov 18.

State Key Laboratory of Structural Chemistry, Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, 155 Yangqiao Road West, Fuzhou, Fujian, 350002, P. R. of China.

The straightforward strategy of building a chiral C-O bond directly on a general carbon radical center is challenging and stereocontrol of the reactions of open-chain hydrocarbon radicals remains a largely unsolved problem. Advance in this elementary step will spur the development of asymmetric radical C-O bond construction. Herein, we report a copper-catalyzed regioselective and enantioselective carboesterification of substituted dienes using alkyl diacyl peroxides as the source of both the carbon and oxygen substituents. Read More

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November 2021

Pd-Catalyzed C(sp)-H olefination: synthesis of -alkylated isoindolinone scaffolds from aryl amides of amino acid esters.

Org Biomol Chem 2021 Dec 1;19(46):10097-10104. Epub 2021 Dec 1.

School of Chemical Sciences, National Institute of Science Education and Research (NISER)-Bhubaneswar, Jatni campus, Bhubaneswar-752050, Odisha, India.

Isoindolinone is a constituent of various natural products and synthetic biologically active compounds. The classical multi-step synthetic methods used to prepare various indolinone derivatives are tedious and challenging. One-pot synthetic methods are attractive and economical. Read More

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December 2021

Unusual Pseudopeptides: Syntheses and Structural Analyses of Ethylenediprolyl Peptides and Their Metal Complexes with Cu(II) Ion.

J Org Chem 2021 Dec 16;86(23):16327-16336. Epub 2021 Nov 16.

National Institute of Science Education and Research (NISER)-Bhubaneswar, Jatni Campus, Bhubaneswar 752050, India.

The synthetic unnatural amino acids and their peptides as peptidomimetics have shown remarkable structural and functional properties. In the repertoire of synthetic peptides, pseudopeptides have emerged as attractive small peptidomimetics that are capable of forming the characteristic secondary structures in the solid/solution phase, as in natural peptides. This report describes the synthesis and structural analyses of novel pseudopeptides as ethylenediprolyl () tetra/hexapeptides, comprising a chiral diaminedicarboxylate scaffold. Read More

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December 2021

A General Method for α-Oxyacylation of Vinyl Ketones Using Koser's Reagent.

J Org Chem 2021 Dec 16;86(23):17318-17327. Epub 2021 Nov 16.

Division of Molecular Synthesis & Drug Discovery, Centre of Biomedical Research, SGPGIMS Campus, Raebareli Road, Lucknow 226014, India.

A direct general method for the preparation of α-oxyacylated vinyl ketones using Koser's hypervalent iodine reagent is reported. A variety of acyloxy groups from long-chain aliphatic, aromatic, α,β-unsaturated carboxylic acids have been installed efficiently for the first time. The oxyacylated adducts were used for the preparation of densely functionalized chiral δ-lactones and cyclopentenes using carbene organocatalysis. Read More

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December 2021

Comparison of cyclofructan-, cyclodextrin-, and polysaccharide-based chiral stationary phases for the separation of pharmaceuticals.

Anal Bioanal Chem 2021 Nov 15. Epub 2021 Nov 15.

Department of Chemistry, University of Cyprus, 1678, Nicosia, Cyprus.

In this study, cyclofructan (CF)-, cyclodextrin (CD)-, and polysaccharide-based chiral stationary phases (CSPs) were exploited in high-performance liquid chromatography (HPLC) for the chiral separations of different clinically and pharmaceutically important compounds. In particular, R-naphthylethyl carbamate CF6 (RN-CF6), 3,5-dimethylphenyl carbamate CF7 (DMP-CF7), neutral beta cyclodextrin (β-CD), 3,5-dimethylphenyl carbamate β-CD (DMP-β-CD), and cellulose tris-(3,5-dimethylphenylcarbamate) (Cellulose-Tris DMP) columns were utilized under isocratic elution. The performance of these CSPs as chiral separation media was evaluated by use of nine analytes: acidic, basic, and amphiprotic. Read More

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November 2021

Enhanced carboxypeptidase efficacies and differentiation of peptide epimers.

Anal Biochem 2021 Nov 10:114451. Epub 2021 Nov 10.

Department of Chemistry and Biochemistry, University of Texas at Arlington, 700 Planetarium Place, Arlington, TX, 76019, USA. Electronic address:

Carboxypeptidases enzymatically cleaves the peptide bond of C-terminal amino acids within peptides. In humans, it is involved in enzymatic synthesis and maturation of proteins and peptides. Carboxypeptidases A and Y have difficulty hydrolyzing the peptide bond of dipeptides and some other amino acid sequences. Read More

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November 2021

Synthesis of Novel Crown Ether-Squaramides and Their Application as Phase-Transfer Catalysts.

Molecules 2021 Oct 29;26(21). Epub 2021 Oct 29.

Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, Szent Gellért tér 4, H-1111 Budapest, Hungary.

This work presents the synthesis of six new phase-transfer organocatalysts in which the squaramide unit is directly linked to the nitrogen atom of an aza-crown ether. Four chiral skeletons, namely hydroquinine, quinine, cinchonine (cinchonas), and α-d-glucopyranoside were responsible for the asymmetric construction of an all-carbon quaternary stereogenic center in α-alkylation and Michael addition reactions of malonic esters. We investigated the effects of these different chiral units and that of crown ethers with different sizes on catalytic activity and enantioselectivity. Read More

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October 2021

Enantioselective Synthesis of 2-Functionalized Tetrahydroquinolines through Biomimetic Reduction.

Org Lett 2021 Dec 12;23(23):9112-9117. Epub 2021 Nov 12.

State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China.

Biomimetic asymmetric reduction of 2-functionalized quinolines has been successfully developed with the chiral and regenerable NAD(P)H model CYNAM in the presence of transfer catalyst simple achiral phosphoric acids, providing the chiral 2-functionalized tetrahydroquinolines with up to 99% ee. Using this methodology as a key step, a chiral and potent opioid analgesic containing a 1,2,3,4-tetrahydroquinoline motif was synthesized with high overall yield. Read More

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December 2021

Construction of Thioamide Peptide via Sulfur-Involved Amino Acids/Amino Aldehydes Coupling.

Org Lett 2021 Nov 11;23(22):8862-8866. Epub 2021 Nov 11.

Shanghai Key Laboratory of Green Chemistry and Chemical Process, School of Chemistry and Molecular Engineering, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, P. R. China.

A sulfur-involved ligation for thioamide quasi-peptides was developed via amino acids and amino aldehydes coupling. The key to the transformation was the chelation of copper with imines for chiral activation and fixation. In this environment, linear polysulfur decreased the alkalinity of single sulfur anions to prevent racemization caused by the interaction between sulfur and sodium sulfide. Read More

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November 2021

Enantioselective palladaelectro-catalyzed C-H olefinations and allylations for N-C axial chirality.

Chem Sci 2021 Nov 13;12(42):14182-14188. Epub 2021 Oct 13.

Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen Tammannstraße 2 37077 Göttingen Germany

Enantioselective palladaelectro-catalyzed C-H alkenylations and allylations were achieved with easily-accessible amino acids as transient directing groups. This strategy provided access to highly enantiomerically-enriched N-C axially chiral scaffolds under exceedingly mild conditions. The synthetic utility of our strategy was demonstrated by a variety of alkenes, while the versatility of our approach was reflected by atroposelective C-H allylations. Read More

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November 2021

Enantioselective metabolomics by liquid chromatography-mass spectrometry.

J Pharm Biomed Anal 2022 Jan 16;207:114430. Epub 2021 Oct 16.

Institute of Pharmaceutical Sciences, Pharmaceutical (Bio-)Analysis, University of Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany. Electronic address:

Metabolomics strives to capture the entirety of the metabolites in a biological system by comprehensive analysis, often by liquid chromatography hyphenated to mass spectrometry. A particular challenge thereby is the differentiation of structural isomers. Common achiral targeted and untargeted assays do not distinguish between enantiomers. Read More

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January 2022

β-Keto acids in asymmetric metal catalysis and organocatalysis.

Org Biomol Chem 2021 Dec 1;19(46):10030-10046. Epub 2021 Dec 1.

School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212100, China.

β-Keto acids, ideal surrogates of inactive ketones, play an important role in organic synthesis. The asymmetric decarboxylative reaction using β-keto acids is the one which is being studied the most. Herein we present a comprehensive review on this research topic, which is generally classified according to different catalytic systems and chiral induction modes. Read More

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December 2021