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    2353 results match your criteria Beilstein Journal of Organic Chemistry [Journal]

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    One-pot sequential synthesis of tetrasubstituted thiophenes via sulfur ylide-like intermediates.
    Beilstein J Org Chem 2018 26;14:243-252. Epub 2018 Jan 26.
    Research Center for Medicinal Chemistry, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, Korea.
    Herein, we describe a novel approach for the practical synthesis of tetrasubstituted thiophenes. The developed method was particularly used for the facile preparation of thienyl heterocycles. The mechanism for this reaction is based on the formation of a sulfur ylide-like intermediate. Read More

    5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines.
    Beilstein J Org Chem 2018 25;14:203-242. Epub 2018 Jan 25.
    Department of Chemistry, Kurukshetra University, Kurukshetra-136119, Haryana, India.
    The condensation of 5-aminopyrazole with various bielectrophilic moieties results in the formation of pyrazoloazines, an interesting array of fused heterocyclic systems. The development of new synthetic routes towards pyrazoloazines for their biological and medicinal exploration is an attractive area for researchers throughout the world. The present review focuses on various synthetic methods developed in the last decade for the synthesis of differently substituted pyrazoloazines by a broad range of organic reactions by means of 5-aminopyrazole as a precursor. Read More

    Transition-metal-free [3 + 3] annulation of indol-2-ylmethyl carbanions to nitroarenes. A novel synthesis of indolo[3,2-]quinolines (quindolines).
    Beilstein J Org Chem 2018 23;14:194-202. Epub 2018 Jan 23.
    Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
    Indol-2-ylmethyl carbanions stabilized by alkoxycarbonyl, cyano or benzenesulfonyl groups react with nitroarenes to form σ-adducts, which in the presence of base (triethylamine or DBU) and trimethylchlorosilane transform into indolo[3,2-]quinoline derivatives in moderate to good yields. Read More

    Synthesis and spectroscopic properties of β-directly linked porphyrin-corrole hybrid compounds.
    Beilstein J Org Chem 2018 22;14:187-193. Epub 2018 Jan 22.
    Hacettepe University, Department of Chemistry, Beytepe Campus, 06800, Ankara, Turkey.
    The preparation of β-directly linked porphyrin-corrole hybrids was realized for the first time via an InCl-catalyzed condensation reaction of 2-formyl-5,10,15,20-tetraphenylporphyrins with-substituted dipyrromethanes. Hybrid compounds have been characterized byH NMR,C NMR, 2D NMR, UV-vis absorption and fluorescence spectroscopy. Read More

    Nucleophilic fluoroalkylation/cyclization route to fluorinated phthalides.
    Beilstein J Org Chem 2018 19;14:182-186. Epub 2018 Jan 19.
    Division of Molecular Science, Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma, 376-8515, Japan.
    Discribed in this article is a versatile and practical method for the synthesis of C3-perfluoroalkyl-substituted phthalides in a one-pot manner. Upon treatment of KF or triethylamine, 2-cyanobenzaldehyde reacted with (perfluoroalkyl)trimethylsilanes via nucleophilic addition and subsequent intramolecular cyclization to give perfluoroalkylphthalides in good yields. Read More

    Progress in copper-catalyzed trifluoromethylation.
    Beilstein J Org Chem 2018 17;14:155-181. Epub 2018 Jan 17.
    Department of chemistry, Shandong University, 27 Shanda South Road, Jinan 250100, PR China.
    The introduction of trifluoromethyl groups into organic molecules has attracted great attention in the past five years. In this review, we describe the recent efforts in the development of trifluoromethylation via copper catalysis using nucleophilic, electrophilic or radical trifluoromethylation reagents. Read More

    Gram-scale preparation of negative-type liquid crystals with a CFCF-carbocycle unit via an improved short-step synthetic protocol.
    Beilstein J Org Chem 2018 15;14:148-154. Epub 2018 Jan 15.
    Faculty of Molecular Chemistry and Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
    Herein, we demonstrate an improved short-step protocol for the synthesis of multicyclic molecules having a CFCF-containing cyclohexadiene or cyclohexane framework in a mesogenic structure. These molecules are promising candidates for vertical alignment (VA)-mode liquid crystal (LC) display devices owing to their large negative dielectric constant. The tetrafluorinated multicyclic molecules were successfully obtained in only five or six reaction steps without the need for special handling techniques, as is generally required for thermally unstable organometallic species, representing a reduction of three reaction steps. Read More

    Volatiles from the tropical ascomycete(Hypoxylaceae, Xylariales).
    Beilstein J Org Chem 2018 12;14:135-147. Epub 2018 Jan 12.
    Kekulé-Institut für Organische Chemie, Universität Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany.
    The volatiles from the funguswere collected by use of a closed-loop stripping apparatus and analysed by GC-MS. A few compounds were readily identified by comparison of measured to library mass spectra and of retention indices to published data, while for other compounds a synthesis of references was required. For one of the main compounds, 5-hydroxy-4,6-dimethyloctan-3-one, the relative and absolute configuration was determined by synthesis of all eight stereoisomers and gas chromatographic analysis using a homochiral stationary phase. Read More

    Aminomethylation/hydrogenolysis as an alternative to direct methylation of metalated isoquinolines - a novel total synthesis of the alkaloid 7-hydroxy-6-methoxy-1-methylisoquinoline.
    Beilstein J Org Chem 2018 11;14:130-134. Epub 2018 Jan 11.
    Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians University of Munich, Butenandtstr. 5-13, D-81377 Munich, Germany.
    Highly-substituted isoquinolines are important scaffolds in syntheses of natural products and in drug development and hence, effective synthetic approaches are required. Here we present a novel method for the introduction of a methyl group at C1 of isoquinolines. This is exemplified by a new total synthesis of the alkaloid 7-hydroxy-6-methoxy-1-methylisoquinoline. Read More

    Fluorescent nucleobase analogues for base-base FRET in nucleic acids: synthesis, photophysics and applications.
    Beilstein J Org Chem 2018 10;14:114-129. Epub 2018 Jan 10.
    Department of Chemistry and Chemical Engineering, Chemistry and Biochemistry, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Förster resonance energy transfer (FRET) between a donor nucleobase analogue and an acceptor nucleobase analogue, base-base FRET, works as a spectroscopic ruler and protractor. With their firm stacking and ability to replace the natural nucleic acid bases inside the base-stack, base analogue donor and acceptor molecules complement external fluorophores like the Cy-, Alexa- and ATTO-dyes and enable detailed investigations of structure and dynamics of nucleic acid containing systems. The first base-base FRET pair, tC-tC, has recently been complemented with among others the adenine analogue FRET pair, qAN1-qA, increasing the flexibility of the methodology. Read More

    Stereochemical outcomes of C-F activation reactions of benzyl fluoride.
    Beilstein J Org Chem 2018 9;14:106-113. Epub 2018 Jan 9.
    School of Chemistry, Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, United Kingdom.
    In recent years, the highly polar C-F bond has been utilised in activation chemistry despite its low reactivity to traditional nucleophiles, when compared to other C-X halogen bonds. Paquin's group has reported extensive studies on the C-F activation of benzylic fluorides for nucleophilic substitutions and Friedel-Crafts reactions, using a range of hydrogen bond donors such as water, triols or hexafluoroisopropanol (HFIP) as the activators. This study examines the stereointegrity of the C-F activation reaction through the use of an enantiopure isotopomer of benzyl fluoride to identify whether the reaction conditions favour a dissociative (S1) or associative (S2) pathway. Read More

    Polarization spectroscopy methods in the determination of interactions of small molecules with nucleic acids - tutorial.
    Beilstein J Org Chem 2018 8;14:84-105. Epub 2018 Jan 8.
    Department of Chemistry, University of Pisa, via Moruzzi 13, Pisa, Italy.
    The structural characterization of non-covalent complexes between nucleic acids and small molecules (ligands) is of a paramount significance to bioorganic research. Highly informative methods about nucleic acid/ligand complexes such as single crystal X-ray diffraction or NMR spectroscopy cannot be performed under biologically compatible conditions and are extensively time consuming. Therefore, in search for faster methods which can be applied to conditions that are at least similar to the naturally occurring ones, a set of polarization spectroscopy methods has shown highly promising results. Read More

    Photocatalytic formation of carbon-sulfur bonds.
    Beilstein J Org Chem 2018 5;14:54-83. Epub 2018 Jan 5.
    Department of Chemistry and Pharmacy, Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany.
    This review summarizes recent developments in photocatalyzed carbon-sulfur bond formation. General concepts, synthetic strategies and the substrate scope of reactions yielding thiols, disulfides, sulfoxides, sulfones and other organosulfur compounds are discussed together with the proposed mechanistic pathways. Read More

    Aminosugar-based immunomodulator lipid A: synthetic approaches.
    Beilstein J Org Chem 2018 4;14:25-53. Epub 2018 Jan 4.
    Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria.
    The immediate immune response to infection by Gram-negative bacteria depends on the structure of a lipopolysaccharide (LPS, also known as endotoxin), a complex glycolipid constituting the outer leaflet of the bacterial outer membrane. Recognition of picomolar quantities of pathogenic LPS by the germ-line encoded Toll-like Receptor 4 (TLR4) complex triggers the intracellular pro-inflammatory signaling cascade leading to the expression of cytokines, chemokines, prostaglandins and reactive oxygen species which manifest an acute inflammatory response to infection. The "endotoxic principle" of LPS resides in its amphiphilic membrane-bound fragment glycophospholipid lipid A which directly binds to the TLR4·MD-2 receptor complex. Read More

    Recent applications of click chemistry for the functionalization of gold nanoparticles and their conversion to glyco-gold nanoparticles.
    Beilstein J Org Chem 2018 3;14:11-24. Epub 2018 Jan 3.
    Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch, 8140, New Zealand.
    Glycoscience, despite its myriad of challenges, promises to unravel the causes of, potential new detection methods for, and novel therapeutic strategies against, many disease states. In the last two decades, glyco-gold nanoparticles have emerged as one of several potential new tools for glycoscientists. Glyco-gold nanoparticles consist of the unique structural combination of a gold nanoparticle core and an outer-shell comprising multivalent presentation of carbohydrates. Read More

    From dipivaloylketene to tetraoxaadamantanes.
    Beilstein J Org Chem 2018 2;14:1-10. Epub 2018 Jan 2.
    School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia.
    Dipivaloylketene () is obtained by flash vacuum pyrolysis of furan-2,3-dioneand dimerizes to 1,3-dioxin-4-one, which is a stable but reactive ketene. The transannular addition and rearrangement of enols formed by the addition of nucleophiles to the ketene function ingenerates axially chiral 2,6,9-trioxabicyclo[3.3. Read More

    Electrophilic trifluoromethylselenolation of terminal alkynes with-(trifluoromethyl) 4-methylbenzenesulfonoselenoate.
    Beilstein J Org Chem 2017 7;13:2626-2630. Epub 2017 Dec 7.
    Institute of Chemistry and Biochemistry, Univ Lyon, Université Lyon 1, CNRS, 43 Bd du 11 novembre 1918, F-69622 Villeurbanne, France.
    Herein the nucleophilic addition of-(trifluoromethyl) 4-methylbenzenesulfonoselenoate, a stable and easy-to-handle reagent, to alkynes is described. This reaction provides trifluoromethylselenylated vinyl sulfones with good results and the method was extended also to higher fluorinated homologs. The obtained compounds are valuable building blocks for further syntheses of fluoroalkylselenolated molecules. Read More

    Regioselective decarboxylative addition of malonic acid and its mono(thio)esters to 4-trifluoromethylpyrimidin-2(1)-ones.
    Beilstein J Org Chem 2017 7;13:2617-2625. Epub 2017 Dec 7.
    Institute of Organic Chemistry, National Academy of Sciences of Ukraine, 5 Murmanska str., Kyiv 02660, Ukraine.
    Due to the high reactivity towards various C-nucleophiles, trifluoromethylketimines are known to be useful reagents for the synthesis of α-trifluoromethylated amine derivatives. However, decarboxylative reactions with malonic acid and its mono(thio)esters have been poorly investigated so far despite the potential to become a convenient route to β-trifluoromethyl-β-amino acid derivatives and to their partially saturated heterocyclic analogues.In this paper we show that 4-trifluoromethylpyrimidin-2(1)-ones, unique heterocyclic ketimines, react with malonic acid under organic base catalysis to regioselectively provide either Michael- or Mannich-type decarboxylative addition products depending on solvent polarity. Read More

    Palladium-catalyzed Heck-type reaction of secondary trifluoromethylated alkyl bromides.
    Beilstein J Org Chem 2017 6;13:2610-2616. Epub 2017 Dec 6.
    Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
    An efficient palladium-catalyzed Heck-type reaction of secondary trifluoromethylated alkyl bromides has been developed. The reaction proceeds under mild reaction conditions with high efficiency and excellent functional group tolerance, even towards formyl and hydroxy groups. Preliminary mechanistic studies reveal that a secondary trifluoromethylated alkyl radical is involved in the reaction. Read More

    A semisynthesis of 3'--ethyl-5,6-dihydrospinosyn J based on the spinosyn A aglycone.
    Beilstein J Org Chem 2017 6;13:2603-2609. Epub 2017 Dec 6.
    Institute of Grassland Research of CAAS, No. 120 Wulanchabu East Street, Saihan District, Hohhot, China.
    Spinetoram, a mixture of 3'--ethyl-5,6-dihydrospinosyn J (XDE-175-J, major component) and 3'--ethylspinosyn L (XDE-175-L, minor component), is a novel kind of green and efficient insecticide with a broad range of action against various insects. Nowadays, spinetoram is widely used in agriculture and food storage. This work reports a 7-step semisynthesis of 3'--ethyl-5,6-dihydrospinosyn J from spinosyn A aglycone. Read More

    Consecutive hydrazino-Ugi-azide reactions: synthesis of acylhydrazines bearing 1,5-disubstituted tetrazoles.
    Beilstein J Org Chem 2017 5;13:2596-2602. Epub 2017 Dec 5.
    Laboratório de Química Metodológica e Orgânica Sintética, Instituto de Química, Universidade de Brasília, 70910-970, Brasília-DF, Brazil.
    Isocyanide-based multicomponent reactions (IMCRs) allow the construction of relatively complex molecules through a one-pot synthesis. The combination of IMCRs in a consecutive or sequential fashion further extends the complexity of the molecules obtained. Herein, we report the efficient application of this approach to the synthesis of acylhydrazines bearing 1,5-disubstituted tetrazoles. Read More

    What contributes to an effective mannose recognition domain?
    Beilstein J Org Chem 2017 4;13:2584-2595. Epub 2017 Dec 4.
    Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, CH-4056 Basel, Switzerland.
    In general, carbohydrate-lectin interactions are characterized by high specificity but also low affinity. The main reason for the low affinities are desolvation costs, due to the numerous hydroxy groups present on the ligand, together with the typically polar surface of the binding sites. Nonetheless, nature has evolved strategies to overcome this hurdle, most prominently in relation to carbohydrate-lectin interactions of the innate immune system but also in bacterial adhesion, a process key for the bacterium's survival. Read More

    Synthesis of 1,3--disubstituted sterically encumbered imidazolidinone organocatalysts.
    Beilstein J Org Chem 2017 1;13:2577-2583. Epub 2017 Dec 1.
    Institut für Organische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany.
    A variety of novel imidazolidinone-based organocatalysts with bulky substituents were synthesized under mild reaction conditions starting from easily accessible substrates. Different natural and unnatural amino acid methyl amides were cyclized with aromatic carbaldehydes to yield two diastereomeric MacMillan-type catalysts. Special emphasis was put on bulky residues such as mesityl and pyrene moieties. Read More

    Rh(II)-mediated domino [4 + 1]-annulation of α-cyanothioacetamides using diazoesters: A new entry for the synthesis of multisubstituted thiophenes.
    Beilstein J Org Chem 2017 30;13:2569-2576. Epub 2017 Nov 30.
    Department of Organic Chemistry, St-Petersburg State University, 26 University pr., 198504, Saint-Petersburg, Russia.
    A new approach towards the synthesis of multisubstituted thiophenes is elaborated based on Rh(II)-catalyzed domino reactions of acyclic diazoesters with α-cyanothioacetamides. It provides a way for the preparation of 5-amino-3-(alkoxycarbonylamino)thiophene-2-carboxylates, 2-(5-amino-2-methoxycarbonylthiophene-3-yl)aminomalonates and (2-cyano-5-aminothiophene-3-yl)carbamates with the preparative yields of up to 67%. It was also shown that α-cyanothioacetamides easily interact with dirhodium carboxylates to give rather stable 2:1 complexes, resulting in an evident decrease in the efficiency of the catalytic process at moderate temperatures (20-30 °C). Read More

    A novel synthetic approach to hydroimidazo[1,5-]pyridazines by the recyclization of itaconimides and HPLC-HRMS monitoring of the reaction pathway.
    Beilstein J Org Chem 2017 30;13:2561-2568. Epub 2017 Nov 30.
    Faculty of Physics and Mathematics and Natural Sciences, RUDN University, Miklukho-Maklaya St., 6, Moscow 117198, Russian Federation.
    The novel cascade two-stage reaction between itaconimides and 1,2-diamino-4-phenylimidazole proceeds regio- and chemoselectively to form tetrahydroimidazo[1,5-]pyridazines and includes nucleophilic C-addition by the activated C=C double bond and subsequent intramolecular recyclization of the intermediate with the amino group involved. Read More

    A concise flow synthesis of indole-3-carboxylic ester and its derivatisation to an auxin mimic.
    Beilstein J Org Chem 2017 29;13:2549-2560. Epub 2017 Nov 29.
    Department of Chemistry, University of Durham, South Road, Durham, Durham, DH1 3LE, UK.
    An assembled suite of flow-based transformations have been used to rapidly scale-up the production of a novel auxin mimic-based herbicide which was required for preliminary field trials. The overall synthetic approach and optimisation studies are described along with a full description of the final reactor configurations employed for the synthesis as well as the downstream processing of the reaction streams. Read More

    N-Labelling and structure determination of adamantylated azolo-azines in solution.
    Beilstein J Org Chem 2017 29;13:2535-2548. Epub 2017 Nov 29.
    Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, 117997 Moscow, Russia.
    Determining the accurate chemical structures of synthesized compounds is essential for biomedical studies and computer-assisted drug design. The unequivocal determination of N-adamantylation or N-arylation site(s) in nitrogen-rich heterocycles, characterized by a low density of hydrogen atoms, using NMR methods at natural isotopic abundance is difficult. In these compounds, the heterocyclic moiety is covalently attached to the carbon atom of the substituent group that has no bound hydrogen atoms, and the connection between the two moieties of the compound cannot always be established via conventionalH-H andH-C NMR correlation experiments (COSY and HMBC, respectively) or nuclear Overhauser effect spectroscopy (NOESY or ROESY). Read More

    Pyrene-nucleobase conjugates: synthesis, oligonucleotide binding and confocal bioimaging studies.
    Beilstein J Org Chem 2017 28;13:2521-2534. Epub 2017 Nov 28.
    Faculty of Chemistry, Department of Organic Chemistry, University of Łódź, Tamka 12, PL-91403 Łódź, Poland.
    Fluorescent pyrene-linker-nucleobase (nucleobase = thymine, adenine) conjugates with carbonyl and hydroxy functionalities in the linker were synthesized and characterized. X-ray single-crystal structure analysis performed for the pyrene-C(O)CHCH-thymine () conjugate reveals dimers of moleculesstabilized by hydrogen bonds between the thymine moieties. The photochemical characterization showed structure-dependent fluorescence properties of the investigated compounds. Read More

    Synthesis and supramolecular properties of regioisomers of mononaphthylallyl derivatives of γ-cyclodextrin.
    Beilstein J Org Chem 2017 27;13:2509-2520. Epub 2017 Nov 27.
    Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43 Prague 2, Czech Republic.
    Monosubstituted derivatives of γ-cyclodextrin (γ-CD) are suitable building blocks for supramolecular polymers, and can also serve as precursors for the synthesis of other regioselectively monosubstituted γ-CD derivatives. We prepared a set of monosubstituted 2--, 3--, and 6--(3-(naphthalen-2-yl)prop-2-en-1-yl) derivatives of γ-CD using two different methods. A key step of the first synthetic procedure is a cross-metathesis between previously described regioisomers of mono--allyl derivatives of γ-CD and 2-vinylnaphthalene which gives yields of about 16-25% (2-5% starting from γ-CD). Read More

    One-pot three-component route for the synthesis of-trifluoromethyl dithiocarbamates using Togni's reagent.
    Beilstein J Org Chem 2017 24;13:2502-2508. Epub 2017 Nov 24.
    The Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo namestí 2, 166 10 Prague 6, Czech Republic.
    A one-pot three-component route for the synthesis of-trifluoromethyl dithiocarbamates by the reaction of secondary amines, carbon disulfide and Togni's reagent is described. The reactions proceed in moderate to good yields. A similar reaction using a primary aliphatic amine afforded the corresponding isothiocyanate in high yield. Read More

    Syntheses, structures, and stabilities of aliphatic and aromatic fluorous iodine(I) and iodine(III) compounds: the role of iodine Lewis basicity.
    Beilstein J Org Chem 2017 23;13:2486-2501. Epub 2017 Nov 23.
    Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas, 77842-3012, USA.
    The title molecules are sought in connection with various synthetic applications. The aliphatic fluorous alcohols RCHOH (R= CF(CF);= 11, 13, 15) are converted to the triflates RCHOTf (TfO, pyridine; 22-61%) and then to RCHI (NaI, acetone; 58-69%). Subsequent reactions with NaOCl/HCl give iodine(III) dichlorides RCHICl(= 11, 13; 33-81%), which slowly evolve Cl. Read More

    A permutation approach to the assignment of the configuration to diastereomeric tetrads by comparison of experimental and ab initio calculated differences in NMR data.
    Beilstein J Org Chem 2017 22;13:2478-2485. Epub 2017 Nov 22.
    Department of Organic Chemistry, Wrocław University of Technology, Wyspiańskiego 27, 50-370 Wrocław, Poland.
    Scoring permutations of experimental chemical shift deviations and DFT/GIAO calculated deviations of isotropic shieldings for sets of four diastereomers can help to assign their relative configurations. This method was exercised on a set of diastereomericalkaloid derivatives, whereC NMR data always identified the proper configuration. The presented approach is also an attempt to quantify the assignment by exclusion. Read More

    Diastereoselective Mannich reactions of pseudo--symmetric glutarimide with activated imines.
    Beilstein J Org Chem 2017 21;13:2473-2477. Epub 2017 Nov 21.
    Division of Applied Chemistry, Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei 184-8588, Japan.
    As an extension of the boron enolate-based aldol reactions, the oxazolidinone-installed bisimidefrom 3-(trifluoromethyl)glutaric acid was employed for Mannich reactions with tosylated iminesas electrophiles to successfully obtain the corresponding adducts in a stereoselective manner. Read More

    Synthesis of naturally-derived macromolecules through simplified electrochemically mediated ATRP.
    Beilstein J Org Chem 2017 20;13:2466-2472. Epub 2017 Nov 20.
    Department of Physical Chemistry, Faculty of Chemistry, Rzeszów University of Technology, Al. Powstańców Warszawy 6, 35-959 Rzeszów, Poland.
    The flavonoid-based macroinitiator was received for the first time by the transesterification reaction of quercetin with 2-bromoisobutyryl bromide. In accordance with the "grafting from" strategy, a naturally-occurring star-like polymer with a polar 3,3',4',5,6-pentahydroxyflavone core and hydrophobic poly(-butyl acrylate) (PBA) side arms was synthesized via a simplified electrochemically mediated ATRP (ATRP), utilizing only 78 ppm by weight (wt) of a catalytic Cucomplex. To demonstrate the possibility of temporal control,ATRP was carried out utilizing a multiple-step potential electrolysis. Read More

    Herpetopanone, a diterpene fromdiscovered by isotope labeling.
    Beilstein J Org Chem 2017 17;13:2458-2465. Epub 2017 Nov 17.
    Department of Biochemical and Chemical Engineering, Technical Biology, Technical University Dortmund, Emil-Figge-Strasse 66, 44227 Dortmund, Germany.
    The genome of the predatory bacterium114-95harbors a number of biosynthesis genes, including four terpene cyclase genes. To identify the terpenes biosynthesized from114-95, we fed the strain withC-labeled glucose and, subsequently, searched for characteristic mass shifts in its metabolome. This approach led to the discovery of a new natural product, of which the isotope pattern is indicative for a diterpene originating from the methylerythritol phosphate pathway. Read More

    Hydrolysis, polarity, and conformational impact of C-terminal partially fluorinated ethyl esters in peptide models.
    Beilstein J Org Chem 2017 16;13:2442-2457. Epub 2017 Nov 16.
    Biocatalysis group, Institute of Chemistry, Technical University of Berlin, Müller-Breslau-Strasse 10, Berlin 10623, Germany.
    Fluorinated moieties are highly valuable to chemists due to the sensitive NMR detectability of theF nucleus. Fluorination of molecular scaffolds can also selectively influence a molecule's polarity, conformational preferences and chemical reactivity, properties that can be exploited for various chemical applications. A powerful route for incorporating fluorine atoms in biomolecules is last-stage fluorination of peptide scaffolds. Read More

    Asymmetric synthesis of propargylamines as amino acid surrogates in peptidomimetics.
    Beilstein J Org Chem 2017 15;13:2428-2441. Epub 2017 Nov 15.
    Organic and Bioorganic Chemistry, Department of Chemistry, Bielefeld University, Universitätsstraße 25, D-33615 Bielefeld, Germany.
    The amide moiety of peptides can be replaced for example by a triazole moiety, which is considered to be bioisosteric. Therefore, the carbonyl moiety of an amino acid has to be replaced by an alkyne in order to provide a precursor of such peptidomimetics. As most amino acids have a chiral center at C, such amide bond surrogates need a chiral moiety. Read More

    Exploring mechanochemistry to turn organic bio-relevant molecules into metal-organic frameworks: a short review.
    Beilstein J Org Chem 2017 14;13:2416-2427. Epub 2017 Nov 14.
    Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal.
    Mechanochemistry is a powerful and environmentally friendly synthetic technique successfully employed in different fields of synthetic chemistry. Application spans from organic to inorganic chemistry including the synthesis of coordination compounds. Metal-organic frameworks (MOFs) are a class of compounds with numerous applications, from which we highlight herein their application in the pharmaceutical field (BioMOFs), whose importance has been growing and is now assuming a relevant and promising domain. Read More

    Sulfation and amidinohydrolysis in the biosynthesis of giant linear polyenes.
    Beilstein J Org Chem 2017 13;13:2408-2415. Epub 2017 Nov 13.
    Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK.
    Clethramycin fromDSM4137, and mediomycins (produced together with clethramycin from), are near-identical giant linear polyenes apparently constructed from, respectively, a 4-guanidinobutanoate or 4-aminobutanoate starter unit and 27 polyketide extender units, and bearing a specific-sulfonate modification at the C-29 hydroxy group. We show here that mediomycins are actually biosynthesised not by use of a different starter unit but by direct late-stage deamidination of (desulfo)clethramycin. A gene () encoding a candidate sulfotransferase has been located in both gene clusters. Read More

    Synthesis, effect of substituents on the regiochemistry and equilibrium studies of tetrazolo[1,5-]pyrimidine/2-azidopyrimidines.
    Beilstein J Org Chem 2017 10;13:2396-2407. Epub 2017 Nov 10.
    Núcleo de Química de Heterociclos (NUQUIMHE), Department of Chemistry, Federal University of Santa Maria (UFSM), 97105-900, Santa Maria, RS, Brazil.
    An efficient synthesis methodology for a series of tetrazolo[1,5-]pyrimidines substituted at the 5- and 7-positions from the cyclocondensation reaction [CCC + NCN] was developed. The NCN corresponds to 5-aminotetrazole and CCC to β-enaminone. Two distinct products were observed in accordance with the β-enaminone substituent. Read More

    Electron-deficient pyridinium salts/thiourea cooperative catalyzed-glycosylation via activation of-glycosyl trichloroacetimidate donors.
    Beilstein J Org Chem 2017 9;13:2385-2395. Epub 2017 Nov 9.
    Department of Chemistry, Indian Institute of Technology Patna, Bihta 801106, Bihar, India.
    The glycosylation of-glycosyl trichloroacetimidate donors using a synergistic catalytic system of electron-deficient pyridinium salts/aryl thiourea derivatives at room temperature is demonstrated. The acidity of the adduct formed by the 1,2-addition of alcohol to the electron-deficient pyridinium salt is increased in the presence of an aryl thiourea derivative as an hydrogen-bonding cocatalyst. This transformation occurs under mild reaction conditions with a wide range of-glycosyl trichloroacetimidate donors and glycosyl acceptors to afford the corresponding-glycosides in moderate to good yields with predictable selectivity. Read More

    Structure-property relationships and third-order nonlinearities in diketopyrrolopyrrole based D-π-A-π-D molecules.
    Beilstein J Org Chem 2017 8;13:2374-2384. Epub 2017 Nov 8.
    Institute of Organic Chemistry and Technology, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice, 53210, Czech Republic.
    Nine new quadrupolar chromophores based on diketopyrrolopyrrole were designed and prepared by cross-coupling reactions. The property tuning has been achieved by structural variation of the peripheral substituents (donor) and enlargement of the π-system. Fundamental properties of target molecules were studied by differential scanning calorimetry, electrochemistry, and absorption and emission spectra. Read More

    Fluorination of some highly functionalized cycloalkanes: chemoselectivity and substrate dependence.
    Beilstein J Org Chem 2017 6;13:2364-2371. Epub 2017 Nov 6.
    Institute of Pharmaceutical Chemistry, University of Szeged, H-6720 Szeged, Eötvös u. 6, Hungary.
    A study exploring the chemical behavior of some dihydroxylated β-amino ester stereo- and regioisomers, derived from unsaturated cyclic β-amino acids is described. The nucleophilic fluorinations involving hydroxy-fluorine exchange of some highly functionalized alicyclic diol derivatives have been carried out in view of selective fluorination, investigating substrate dependence, neighboring group assistance and chemodifferentiation. Read More

    Solvent-free copper-catalyzed click chemistry for the synthesis of-heterocyclic hybrids based on quinoline and 1,2,3-triazole.
    Beilstein J Org Chem 2017 6;13:2352-2363. Epub 2017 Nov 6.
    Laboratory for Green Synthesis, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia.
    Copper-catalyzed mechanochemical click reactions using Cu(II), Cu(I) and Cu(0) catalysts have been successfully implemented to provide novel 6-phenyl-2-(trifluoromethyl)quinolines with a phenyl-1,2,3-triazole moiety at O-4 of the quinoline core. Milling procedures proved to be significantly more efficient than the corresponding solution reactions, with up to a 15-fold gain in yield. Efficiency of both solution and milling procedures depended on the-substituent in the azide reactant, resulting in H < Cl < Br < I reactivity bias. Read More

    One-pot syntheses of blue-luminescent 4-aryl-1-benzo[]isoindole-1,3(2)-diones by T3Pactivation of 3-arylpropiolic acids.
    Beilstein J Org Chem 2017 3;13:2340-2351. Epub 2017 Nov 3.
    Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany.
    In situ activation of 3-arylpropiolic acids with T3P(-propylphosphonic acid anhydride) initiates a domino reaction furnishing 4-arylnaphtho[2,3-]furan-1,3-diones in excellent yields. Upon employing these anhydrides as reactive intermediates blue-luminescent 4-aryl-1-benzo[]isoindole-1,3(2)-diones are formed by consecutive pseudo three-component syntheses in a one-pot fashion. The Stokes shifts correlate excellently with the Hammett-Taft σparameter indicating an extended degree of resonance stabilization in the vibrationally relaxed excited singlet state. Read More

    Is the tungsten(IV) complex (NEt)[WO(mnt)] a functional analogue of acetylene hydratase?
    Beilstein J Org Chem 2017 2;13:2332-2339. Epub 2017 Nov 2.
    Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85748 Garching bei München, Germany.
    The tungsten(IV) complex (EtN)[W(O)(mnt)] (; mnt = maleonitriledithiolate) was proposed (Sarkar et al.,,, 4315) to be a functional analogue of the active center of the enzyme acetylene hydratase from, which hydrates acetylene (ethyne;) to acetaldehyde (ethanal;). In the absence of a satisfactory mechanistic proposal for the hydration reaction, we considered the possibility of a metal-vinylidene type activation mode, as it is well established for ruthenium-based alkyne hydration catalysts with anti-Markovnikov regioselectivity. Read More

    Synthesis of ergostane-type brassinosteroids with modifications in ring A.
    Beilstein J Org Chem 2017 2;13:2326-2331. Epub 2017 Nov 2.
    Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, Kuprevich st., 5/2, 220141 Minsk, Belarus.
    Herein, we present a new strategy for the preparation of a broad range of brassinosteroid biosynthetic precursors/metabolites differing by the ring A fragment. The protocol is based on the use of readily available phytohormones of this class bearing a 2α,3α-diol moiety (epibrassinolide or epicastasterone) as starting materials. The required functionalities (Δ-, 2α,3α- and 2β,3β-epoxy-, 2α,3β-, 2β,3α-, and 2β,3β-dihydroxy-, 3-keto-, 3α- and 3β-hydroxy-, 2α-hydroxy-3-keto-) were synthesized from 2α,3α-diols in a few simple steps (Corey-Winter reaction, epoxidation, oxidation, hydride reduction, etc. Read More

    Homologated amino acids with three vicinal fluorines positioned along the backbone: development of a stereoselective synthesis.
    Beilstein J Org Chem 2017 1;13:2316-2325. Epub 2017 Nov 1.
    School of Chemistry, The University of New South Wales, Sydney NSW 2052, Australia.
    Backbone-extended amino acids have a variety of potential applications in peptide and protein science, particularly if the geometry of the amino acid is controllable. Here we describe the synthesis of δ-amino acids that contain three vicinal C-F bonds positioned along the backbone. The ultimately successful synthetic approach emerged through the investigation of several methods based on both electrophilic and nucleophilic fluorination chemistry. Read More

    Diosgenyl 2-amino-2-deoxy-β-D-galactopyranoside: synthesis, derivatives and antimicrobial activity.
    Beilstein J Org Chem 2017 1;13:2310-2315. Epub 2017 Nov 1.
    Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland.
    The synthesis of diosgenyl 2-amino-2-deoxy-β-D-galactopyranoside is presented for the first time. This synthetic saponin was transformed into its hydrochloride as well as-acyl, 2-ureido,-alkyl, and,-dialkyl derivatives. Antifungal and antibacterial studies show that some of the obtained compounds are active against Gram-positive bacteria andtype fungi. Read More

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