790 results match your criteria directly alkynes

π-conjugated Materials Derived From Boron-chalcogenophene Combination. A Brief Description of Synthetic Routes and Optoelectronic Applications.

Chem Rec 2021 Apr 12. Epub 2021 Apr 12.

Catalysis and Fine Chemicals Department, CSIR-Indian Institute of Chemical Technology, Hyderabad, Uppal Road, Tarnaka, Hyderabad,, 500007, Telangana, India.

Functional materials composed of Boron-chalcogenophene conjugates have emerged as promising ensemble featuring commendable optoelectronic properties. This review describes the categories, synthetic routes and optoelectronic applications of a range of boron-chalcogenophene conjugates. Conjugation and linking of different types of tri- and tetra-coordinated boron moieties with chalcogenophenes have remained an important strategy for constructing a range of functional materials. Read More

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Rhodium-Catalyzed C-H Alkenylation/Electrocyclization Cascade Provides Dihydropyridines That Serve as Versatile Intermediates to Diverse Nitrogen Heterocycles.

Acc Chem Res 2021 04 19;54(7):1766-1778. Epub 2021 Mar 19.

Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States.

Nitrogen heterocycles are present in approximately 60% of drugs, with nonplanar heterocycles incorporating stereogenic centers being of considerable interest to the fields of medicinal chemistry, chemical biology, and synthetic methods development. Over the past several years, our laboratory has developed synthetic strategies to access highly functionalized nitrogen heterocycles with multiple stereogenic centers. This approach centers on the efficient preparation of diverse 1,2-dihydropyridines by a Rh-catalyzed C-H bond alkenylation/electrocyclization cascade from readily available α,β-unsaturated imines and alkynes. Read More

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Reactivity of ynamides in catalytic intermolecular annulations.

Chem Soc Rev 2021 Mar;50(4):2582-2625

Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China.

Ynamides are unique alkynes with a carbon-carbon triple bond directly attached to the nitrogen atom bearing an electron-withdrawing group. The alkyne is strongly polarized by the electron-donating nitrogen atom, but its high reactivity can be finely tempered by the electron-withdrawing group. Accordingly, ynamides are endowed with both nucleophilic and electrophilic properties and their chemistry has been an active research field. Read More

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In-tube solid-phase microextraction directly coupled to tandem mass spectrometry for anandamide and 2-arachidonoylglycerol determination in rat brain samples from an animal model of Parkinson's disease.

J Chromatogr A 2021 Jan 5;1636:461766. Epub 2020 Dec 5.

Universidade de São Paulo (USP), Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Departamento de Química, Avenida Bandeirantes, 3900, CEP 14040-901. Electronic address:

To evaluate the endocannabinoid system in an animal model of Parkinson's disease, in-tube solid-phase microextraction (in-tube SPME) was directly coupled to a tandem mass spectrometry (MS/MS) system for determination of the endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG) in rat brain samples. In-tube SPME-which consisted of a microtube of restricted access material (RAM) with a hydrophilic diol external surface and a hydrophobic octyl inner surface-efficiently excluded (up to 95%) macromolecules from the biological samples and selectively pre-concentrated the analytes. In-tube SPME parameters, such as sample volume, mobile phases, flow rate, and pre-concentration time, were evaluated to improve the extraction efficiency and throughput performance. Read More

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January 2021

Therapeutic Approach against 2019-nCoV by Inhibition of ACE-2 Receptor.

Drug Res (Stuttg) 2021 Apr 12;71(4):213-218. Epub 2020 Nov 12.

Department of Chemistry, Deen Dayal Upadhyaya Gorakhpur University, Gorakhpur, Uttar Pradesh, India.

The continued spread of 2019-nCoV has prompted widespread concern around the world. WHO formally named COVID-19 and International Committee on Taxonomy called it Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). Due to this viral attack, the whole world is in lockdown. Read More

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Oxidize Amines to Nitrile Oxides: One Type of Amine Oxidation and Its Application to Directly Construct Isoxazoles and Isoxazolines.

J Org Chem 2020 12 11;85(23):15726-15735. Epub 2020 Nov 11.

National Engineering Research Center for Carbohydrate Synthesis, Jiangxi Normal University, 99 Ziyang Road, Nanchang, Jiangxi 330022, China.

A facile oxidative heterocyclization of commercially available amines and -butyl nitrite with alkynes or alkenes leading to isoxazoles or isoxazolines is described. The unprecedented strategy of the oxidation of an amine directly to a nitrile oxide was used in this cyclization process. This reaction is highly efficient, regiospecific, operationally simple, mild, and tolerant of a variety of functional groups. Read More

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December 2020

Intermolecular cyclotrimerization of haloketoalkynes and internal alkynes: facile access to arenes and phthalides.

Chem Commun (Camb) 2020 Nov 9;56(87):13417-13420. Epub 2020 Oct 9.

Department of Chemistry, Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.

A highly chemo- and regioselective cyclo(co)trimerization between 3-halopropiolamides and symmetrical internal alkynes is reported. The reaction is catalyzed by CpRuCl(COD) and proceeds under air at ambient temperature in ethanol with no additional precautions. Iodo-, bromo-, and chloropropiolamides, esters, and ketones are viable coupling partners and, in a 2 : 1 stoichiometry relative to internal alkyne, yield fully-substituted arenes in a single step. Read More

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November 2020

Ring-Closing Metathesis Approaches towards the Total Synthesis of Rhizoxins.

Molecules 2020 Oct 2;25(19). Epub 2020 Oct 2.

ETH Zürich, Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, 8093 Zürich, Switzerland.

Efforts are described towards the total synthesis of the bacterial macrolide rhizoxin F, which is a potent tubulin assembly and cancer cell growth inhibitor. A significant amount of work was expanded on the construction of the rhizoxin core macrocycle by ring-closing olefin metathesis (RCM) between C(9) and C(10), either directly or by using relay substrates, but in no case was ring-closure achieved. Macrocycle formation was possible by ring-closing alkyne metathesis (RCAM) at the C(9)/C(10) site. Read More

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October 2020

Stereoselective Formal Hydroamidation of Si-Substituted Arylacetylenes with DIBAL-H and Isocyanates: Synthesis of ()- and ()-α-Silyl-α,β-unsaturated Amides.

J Org Chem 2020 Oct 16;85(19):12024-12035. Epub 2020 Sep 16.

Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea.

An efficient and stereoselective method for the synthesis of ()- and ()-α-silyl-α,β-unsaturated amides and its synthetic applications are presented herein. The solvent-controlled hydroaluminations of Si-substituted alkynes with DIBAL-H generate diastereomerically enriched alkenylaluminum reagents that are directly reacted with isocyanates at ambient temperature to afford α-silyl-α,β-unsaturated amides in high yields with retained stereoselectivity. In particular, this process enables the synthesis of a broad range of ()-α-silyl-α,β-unsaturated amides, which are the less studied isomers. Read More

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October 2020

Transition Metal-Catalyzed Tandem Reactions of Ynamides for Divergent N-Heterocycle Synthesis.

Acc Chem Res 2020 Sep 1;53(9):2003-2019. Epub 2020 Sep 1.

State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory of Chemical Biology of Fujian Province, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.

ConspectusYnamides are electron-rich heteroatom-substituted alkynes with a C-C triple bond directly attached to the amide group. Importantly, this amide group is able to impose an electronic bias, thus resulting in the highly regioselective attack of this polarized alkyne by a large variety of nucleophiles. Over the past two decades, catalytic reactions of ynamides have experienced dramatic developments, especially those catalyzed by transition metals. Read More

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September 2020

Regio- and Enantioselective Allylic Alkylation of Terminal Alkynes by Synergistic Rh/Cu Catalysis.

J Am Chem Soc 2020 09 26;142(36):15276-15281. Epub 2020 Aug 26.

Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.

A highly branch- and enantioselective 1,4-enynes synthesis from readily available terminal alkynes and racemic allylic carbonates by Sonogashira type synergistic Rh and Cu catalysis under neutral conditions has been developed. Aliphatic and aromatic terminal alkynes with various functional groups could be used directly. An inner-sphere reductive elimination C(sp)-C(sp) bond formation mechanism is supported by the stoichiometric reaction. Read More

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September 2020

Carrier-Induced Modification of Palladium Nanoparticles on Porous Boron Nitride for Alkyne Semi-Hydrogenation.

Angew Chem Int Ed Engl 2020 Oct 13;59(44):19639-19644. Epub 2020 Aug 13.

Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1, 8093, Zürich, Switzerland.

Chemical modifiers enhance the efficiency of metal catalysts in numerous applications, but their introduction often involves toxic or expensive precursors and complicates the synthesis. Here, we show that a porous boron nitride carrier can directly modify supported palladium nanoparticles, originating unparalleled performance in the continuous semi-hydrogenation of alkynes. Analysis of the impact of various structural parameters reveals that using a defective high surface area boron nitride and ensuring a palladium particle size of 4-5 nm is critical for maximizing the specific rate. Read More

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October 2020

Nitrogen Fixation in Pozol, a Traditional Fermented Beverage.

Appl Environ Microbiol 2020 08 3;86(16). Epub 2020 Aug 3.

Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico

Traditional fermentations have been widely studied from the microbiological point of view, but little is known from the functional perspective. In this work, nitrogen fixation by free-living nitrogen-fixing bacteria was conclusively demonstrated in pozol, a traditional Mayan beverage prepared with nixtamalized and fermented maize dough. Three aspects of nitrogen fixation were investigated to ensure that fixation actually happens in the dough: (i) the detection of acetylene reduction activity directly in the substrate, (ii) the presence of potential diazotrophs, and (iii) an increase in acetylene reduction by inoculation with one of the microorganisms isolated from the dough. Read More

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Phenalenannulations: Three-Point Double Annulation Reactions that Convert Benzenes into Pyrenes.

Angew Chem Int Ed Engl 2020 Aug 15;59(34):14352-14357. Epub 2020 Jul 15.

Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, 32306-4390, USA.

3-Point annulations, or phenalenannulations, transform a benzene ring directly into a substituted pyrene by "wrapping" two new cycles around the perimeter of the central ring at three consecutive carbon atoms. This efficient, modular, and general method for π-extension opens access to non-symmetric pyrenes and their expanded analogues. Potentially, this approach can convert any aromatic ring bearing a -CH Br or a -CHO group into a pyrene moiety. Read More

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Disease-Specific Derangement of Circulating Endocannabinoids and -Acylethanolamines in Myeloproliferative Neoplasms.

Int J Mol Sci 2020 May 11;21(9). Epub 2020 May 11.

Institute of Hematology "L. e A. Seràgnoli", Department of Experimental, Diagnostic and Specialty Medicine (DIMES), School of Medicine, University of Bologna, 40138 Bologna, Italy.

Growing evidence highlights the endocannabinoid (EC) system involvement in cancer progression. Lipid mediators of this system are secreted by hematopoietic cells, including the ECs 2-arachidonoyl-glycerol (2AG) and arachidonoyl-ethanolamide (AEA), the 2AG metabolite 1AG, and members of N-acylethanolamine (NAE) family-palmitoyl-ethanolamide (PEA) and oleoyl-ethanolamide (OEA). However, the relevance of the EC system in myeloproliferative neoplasms (MPN) was never investigated. Read More

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Natural product piperine alleviates experimental allergic encephalomyelitis in mice by targeting dihydroorotate dehydrogenase.

Biochem Pharmacol 2020 07 28;177:114000. Epub 2020 Apr 28.

Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, China. Electronic address:

Multiple sclerosis (MS) is the most popular chronic and debilitating inflammatory disease of the central nervous system (CNS) that remains incurable. Dihydroorotate dehydrogenase (DHODH) is critical to the activity of T lymphocytes and represents a potential therapeutic target for MS. Here we identify piperine, a bioactive constituent of black pepper, as a potent inhibitor of DHODH with an IC value of 0. Read More

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Visible-Light-Induced Radical Carbo-Cyclization/-Diborylation through Triplet Energy Transfer between a Gold Catalyst and Aryl Iodides.

J Am Chem Soc 2020 06 27;142(23):10485-10493. Epub 2020 May 27.

Organisch-Chemisches Institut, Heidelberg University, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.

Geminal diboronates have attracted significant attention because of their unique structures and reactivity. However, benzofuran-, indole-, and benzothiophene-based benzylic -diboronates, building blocks for biologically relevant compounds, are unknown. A promising protocol using visible light and aryl iodides for constructing valuable building blocks, including benzofuran-, indole-, and benzothiophene-based benzylic -diboronates, via radical carbo-cyclization/-diborylation of alkynes with a high functional group tolerance is presented. Read More

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Sterically Shielded Heptamethine Cyanine Dyes for Bioconjugation and High Performance Near-Infrared Fluorescence Imaging.

Angew Chem Int Ed Engl 2020 07 11;59(29):12154-12161. Epub 2020 May 11.

Department of Chemistry and Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, IN, 46556, USA.

The near-infrared window of fluorescent heptamethine cyanine dyes greatly facilitates biological imaging because there is deep penetration of the light and negligible background fluorescence. However, dye instability, aggregation, and poor pharmacokinetics are current drawbacks that limit performance and the scope of possible applications. All these limitations are simultaneously overcome with a new molecular design strategy that produces a charge balanced and sterically shielded fluorochrome. Read More

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Excimer-FRET Cascade in Dual DNA Probes: Open Access to Large Stokes Shift, Enhanced Acceptor Light up, and Robust RNA Sensing.

Anal Chem 2020 05 5;92(10):7028-7036. Epub 2020 May 5.

Skolkovo Institute of Science and Technology, 143026 Skolkovo, Russia.

The efficacy of fluorescent hybridization assays is often limited by the low signal-to-background ratio of the probes that can be partially overcome by sophisticated signal amplification methods. Deep understanding of the mechanisms of fluorescence quenching and energy transfer in complex DNA probes and the choice of optimal donor/acceptor pairs along with rational design can significantly enhance the performance of DNA probes. Here, we proposed and studied novel Förster resonance energy transfer (FRET) dual DNA probes with the excimer-forming pyrene pair as a donor and sulfo-Cy3 dye as an acceptor, which demonstrated remarkable 75-fold enhancement of sulfo-Cy3 fluorescence upon target capturing. Read More

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Light-induced Ligation of -Quinodimethanes with Gated Fluorescence Self-reporting.

J Am Chem Soc 2020 04 21;142(17):7744-7748. Epub 2020 Apr 21.

Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany.

We introduce a highly efficient photoligation system, affording a pro-fluorescent Diels-Alder product that, on demand, converts into an intensively fluorescent naphthalene via E1 elimination in the presence of catalytic amounts of acid. The Diels-Alder reaction of the photocaged diene (-quinodimethane ether or thioether) with electron-deficient alkynes is induced by UV or visible light. In contrast to previously reported ligation techniques directly leading to fluorescent products, the fluorescence is turned on after the photoligation. Read More

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Ethynylation of Cysteine Residues: From Peptides to Proteins in Vitro and in Living Cells.

Angew Chem Int Ed Engl 2020 06 11;59(27):10961-10970. Epub 2020 May 11.

Laboratory of Catalysis and Organic Synthesis, Ecole Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCSO, BCH 4306, 1015, Lausanne, Switzerland.

Current approaches to introduce terminal alkynes for bioorthogonal reactions into biomolecules still present limitations in terms of either reactivity, selectivity, or adduct stability. We present a method for the ethynylation of cysteine residues based on the use of ethynylbenziodoxolone (EBX) reagents. The acetylene group is directly introduced onto the thiol group of cysteine and can be used for copper-catalyzed alkyne-azide cycloaddition (CuAAC) without further processing. Read More

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Oxidation of Alkynyl Boronates to Carboxylic Acids, Esters, and Amides.

Angew Chem Int Ed Engl 2020 06 7;59(27):10913-10917. Epub 2020 May 7.

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan, 410082, P. R. China.

A general efficient protocol was developed for the synthesis of carboxylic acids, esters, and amides through oxidation of alkynyl boronates, generated directly from terminal alkynes. This protocol represents the first example of C(sp)-B bond oxidation. This approach displays a broad substrate scope, including aryl and alkyl alkynes, and exhibits excellent functional group tolerance. Read More

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Zirconium-Catalyzed Synthesis of Alkenylaminoboranes: From a Reliable Preparation of Alkenylboronates to a Direct Stereodivergent Access to Alkenyl Bromides.

Org Lett 2020 04 24;22(7):2838-2843. Epub 2020 Mar 24.

Institut des Sciences Moléculaires, UMR 5255, CNRS, Université de Bordeaux, 351 Cours de la libération, 33405 Talence, France.

A simple procedure has been optimized for the preparation of alkenylaminoborane from alkynes using diisopropylaminoborane and HZrCpCl. Coupled with a magnesium-catalyzed dehydrogenation, it allowed for the use of air- and moisture-stable diisopropylamine. This synthesis has been extended to a one-pot sequence leading directly to bromoalkenes with controlled stereochemistry. Read More

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Supersensitive Multifluorophore RNA-FISH for Early Virus Detection and Flow-FISH by Using Click Chemistry.

Chembiochem 2020 08 20;21(15):2214-2218. Epub 2020 Apr 20.

Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstraße 5-13, 81377, Munich, Germany.

The reliable detection of transcription events through the quantification of the corresponding mRNA is of paramount importance for the diagnostics of infections and diseases. The quantification and localization analysis of the transcripts of a particular gene allows disease states to be characterized more directly compared to an analysis on the transcriptome wide level. This is particularly needed for the early detection of virus infections as now required for emergent viral diseases, e. Read More

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Combining site-directed spin labeling in vivo and in-cell EPR distance determination.

Phys Chem Chem Phys 2020 Mar 19;22(9):4875-4879. Epub 2020 Feb 19.

Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Konstanz, Germany.

Structural studies on proteins directly in their native environment are required for a comprehensive understanding of their function. Electron paramagnetic resonance (EPR) spectroscopy and in particular double electron-electron resonance (DEER) distance determination are suited to investigate spin-labeled proteins directly in the cell. The combination of intracellular bioorthogonal labeling with in-cell DEER measurements does not require additional purification or delivery steps of spin-labeled protein to the cells. Read More

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Dehydrative Cross-Coupling of Allylic Alcohols with Alkynes.

Org Lett 2020 02 30;22(4):1599-1604. Epub 2020 Jan 30.

School of Chemistry and Molecular Engineering, Institute of Advanced Synthesis , Nanjing Tech University , Nanjing 211816 , P. R. China.

A highly efficient Pd/Ca catalytic system for the directly dehydrative cross-coupling of allylic alcohols with terminal alkynes was developed. This calcium salt cocatalyst facilitates the oxidative addition of the palladium catalyst (1 mol %) to the C-OH bond. Then, the in situ-generated hydroxide ion deprotonates the terminal alkynes to promote the formation of the allylalkynylpalladium intermediate, liberating water as the only byproduct. Read More

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February 2020

Ultra-fast and universal detection of Gram-negative bacteria in complex samples based on colistin derivatives.

Biomater Sci 2020 Apr;8(8):2111-2119

Graduate School of Nanoscience and Technology, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea. and Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea.

Gram-negative bacteria are a significant cause of infections acquired in both hospital and community settings, resulting in a high mortality rate worldwide. Currently, a Gram-negative infection is diagnosed by symptom evaluation and is treated with empiric antibiotics which target both Gram-negative and Gram-positive bacteria. A rapid and simple diagnostic method would enable immediate and targeted treatment, while dramatically reducing antibiotic overuse. Read More

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Color-Tunable Light-up Bioorthogonal Probes for In Vivo Two-Photon Fluorescence Imaging.

Chemistry 2020 Apr 17;26(20):4576-4582. Epub 2020 Mar 17.

College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, P. R. China.

Light-up bioorthogonal probes have attracted increasing attention recently due to their capability to directly image diverse biomolecules in living cells without washing steps. The development of bioorthogonal probes with excellent fluorescent properties suitable for in vivo imaging, such as long excitation/emission wavelength, high fluorescence turn-on ratio, and deep penetration, has been rarely reported. Herein, a series of azide-based light-up bioorthogonal probes with tunable colors based on a weak fluorescent 8-aminoquinoline (AQ) scaffold were designed and synthesized. Read More

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Tunable Heteroaromatic Sulfones Enhance in-Cell Cysteine Profiling.

J Am Chem Soc 2020 01 13;142(4):1801-1810. Epub 2020 Jan 13.

Department of Medicinal Chemistry, College of Pharmacy , University of Michigan , 428 Church Street , Ann Arbor , Michigan 48109 , United States.

Heteroaromatic sulfones react with cysteine via nucleophilic aromatic substitution, providing a mechanistically selective and irreversible scaffold for cysteine conjugation. Here we evaluate a library of heteroaromatic sulfides with different oxidation states, heteroatom substitutions, and a series of electron-donating and electron-withdrawing substituents. Select substitutions profoundly influence reactivity and stability compared to conventional cysteine conjugation reagents, increasing the reaction rate by >3 orders of magnitude. Read More

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January 2020

Base-Promoted Nitrile-Alkyne Domino-Type Cyclization: A General Method to Trisubstituted Imidazoles.

Org Lett 2019 Dec 10;21(24):9874-9877. Epub 2019 Dec 10.

State Key Laboratory of Applied Organic Chemistry , Lanzhou University , Lanzhou 730000 , P.R. China.

An efficient base promoted nitrile-alkyne domino-type cyclization for multicomponent assembly of imidazoles from alkynes, nitriles, and tBuOK has been developed, which could run even in the absence of solvent on a gram scale with complete atom economy. This method contributes directly to reaching the synthesis of valuable imidazole derivatives from readily available raw materials. Read More

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December 2019