2,437 results match your criteria Beilstein Journal of Organic Chemistry [Journal]


Mechanochemistry of nucleosides, nucleotides and related materials.

Beilstein J Org Chem 2018 27;14:955-970. Epub 2018 Apr 27.

School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, UK.

The application of mechanical force to induce the formation and cleavage of covalent bonds is a rapidly developing field within organic chemistry which has particular value in reducing or eliminating solvent usage, enhancing reaction rates and also in enabling the preparation of products which are otherwise inaccessible under solution-phase conditions. Mechanochemistry has also found recent attention in materials chemistry and API formulation during which rearrangement of non-covalent interactions give rise to functional products. However, this has been known to nucleic acids science almost since its inception in the late nineteenth century when Miescher exploited grinding to facilitate disaggregation of DNA from tightly bound proteins through selective denaturation of the latter. Read More

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On the design principles of peptide-drug conjugates for targeted drug delivery to the malignant tumor site.

Beilstein J Org Chem 2018 26;14:930-954. Epub 2018 Apr 26.

University of Ioannina, Department of Chemistry, Section of Organic Chemistry and Biochemistry, Ioannina, GR-45110, Greece.

Cancer is the second leading cause of death affecting nearly one in two people, and the appearance of new cases is projected to rise by >70% by 2030. To effectively combat the menace of cancer, a variety of strategies have been exploited. Among them, the development of peptide-drug conjugates (PDCs) is considered as an inextricable part of this armamentarium and is continuously explored as a viable approach to target malignant tumors. Read More

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Local energy decomposition analysis of hydrogen-bonded dimers within a domain-based pair natural orbital coupled cluster study.

Beilstein J Org Chem 2018 25;14:919-929. Epub 2018 Apr 25.

Max Planck Institute for Chemical Energy Conversion, Stifstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.

The local energy decomposition (LED) analysis allows for a decomposition of the accurate domain-based local pair natural orbital CCSD(T) [DLPNO-CCSD(T)] energy into physically meaningful contributions including geometric and electronic preparation, electrostatic interaction, interfragment exchange, dynamic charge polarization, and London dispersion terms. Herein, this technique is employed in the study of hydrogen-bonding interactions in a series of conformers of water and hydrogen fluoride dimers. Initially, DLPNO-CCSD(T) dissociation energies for the most stable conformers are computed and compared with available experimental data. Read More

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Development of novel cyclic NGR peptide-daunomycin conjugates with dual targeting property.

Beilstein J Org Chem 2018 25;14:911-918. Epub 2018 Apr 25.

Eötvös Loránd University, Faculty of Science, Institute of Chemistry, Pázmány P. stny. 1/A, H-1117 Budapest, Hungary.

Cyclic NGR peptides as homing devices are good candidates for the development of drug conjugates for targeted tumor therapy. In our previous study we reported that the Dau=Aoa-GFLGK(c[KNGRE]-GG-)-NH conjugate has a significant antitumor activity against both CD13+ HT-1080 human fibrosarcoma and CD13- but integrin positive HT-29 human colon adenocarcinoma cells. However, it seems that the free ε-amino group of Lys in the cycle is not necessary for the biological activity. Read More

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Volatiles from three genome sequenced fungi from the genus .

Beilstein J Org Chem 2018 24;14:900-910. Epub 2018 Apr 24.

Institute of Organic Chemistry, TU Braunschweig, Hagenring 30, 38106 Braunschweig, Germany (former address).

The volatiles emitted by agar plate cultures of three genome sequenced fungal strains from the genus were analysed by GC-MS. All three strains produced terpenes for which a biosynthetic relationship is discussed. The obtained data were also correlated to genetic information about the encoded terpene synthases for each strain. Read More

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Electrochemically modified Corey-Fuchs reaction for the synthesis of arylalkynes. The case of 2-(2,2-dibromovinyl)naphthalene.

Beilstein J Org Chem 2018 23;14:891-899. Epub 2018 Apr 23.

Deptartment of Fundamental and Applied Sciences for Engineering (SBAI), Sapienza University of Rome, via Castro Laurenziano, 7, 00161, Rome, Italy.

The electrochemical reduction of 2-(2,2-dibromovinyl)naphthalene in a DMF solution (Pt cathode) yields selectively 2-ethynylnaphthalene or 2-(bromoethynyl)naphthalene in high yields, depending on the electrolysis conditions. In particular, by simply changing the working potential and the supporting electrolyte, the reaction can be directed towards the synthesis of the terminal alkyne (EtNBF) or the bromoalkyne (NaClO). This study allowed to establish that 2-(bromoethynyl)naphthalene can be converted into 2-ethynylnaphthalene by cathodic reduction. Read More

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An efficient and facile access to highly functionalized pyrrole derivatives.

Beilstein J Org Chem 2018 20;14:884-890. Epub 2018 Apr 20.

State Key Laboratory of Bioactive Substance and Function of Natural Medicines & Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, 1 Xian Nong Tan Street, Beijing 100050, China.

A straightforward and one-pot synthesis of pyrrolo[3,4-]pyrrole-1,3-diones via Ag(I)-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with -alkyl maleimide, followed by readily complete oxidation with DDQ, has been successfully developed. Further transformation with alkylamine/sodium alkoxide alcohol solution conveniently afforded novel polysubstituted pyrroles in good to excellent yields. This methodology for highly functionalized pyrroles performed well over a broad scope of substrates. Read More

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Methyl isocyanide as a convertible functional group for the synthesis of spirocyclic oxindole γ-lactams via post-Ugi-4CR/transamidation/cyclization in a one-pot, three-step sequence.

Beilstein J Org Chem 2018 18;14:875-883. Epub 2018 Apr 18.

Department of Chemistry and Biochemistry and School of Green Chemistry and Engineering, University of Toledo, 2801 W. Bancroft Street, Toledo, OH 43606, USA.

The synthesis of spiro[indoline-3,2'-pyrrole]-2,5'(1')-diones and spiro[indoline-3,2'-pyrrolidine]-2,5'-diones, via a post-Ugi-domino transamidation/cyclization sequential process, has been achieved in three sequential steps utilizing a one-pot reaction protocol. The variation in carboxylic acid substrates allows for the generation of new chiral racemic quaternary carbon centers under basic conditions providing molecular diversity and a small library of spirocyclic oxindoles. Read More

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Two novel blue phosphorescent host materials containing phenothiazine-5,5-dioxide structure derivatives.

Beilstein J Org Chem 2018 17;14:869-874. Epub 2018 Apr 17.

College of Chemistry, Biology and Material Engineering, Suzhou University of Science and Technology, Suzhou, Jiangsu 215009, P.R. China.

Two novel D-A bipolar blue phosphorescent host materials based on phenothiazine-5,5-dioxide: 3-(9-carbazol-9-yl)-10-ethyl-10-phenothiazine-5,5-dioxide (CEPDO) and 10-butyl-3-(9-carbazol-9-yl)-10-phenothiazine-5,5-dioxide (CBPDO) were synthesized and characterized. The photophysical, electrochemical and thermal properties were systematically investigated. CEPDO and CBPDO not only have a high triplet energy but also show a bipolar behavior. Read More

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Anodic oxidation of bisamides from diaminoalkanes by constant current electrolysis.

Beilstein J Org Chem 2018 16;14:861-868. Epub 2018 Apr 16.

Department of Chemistry, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel.

In general, bisamides derived from diamines and involving 3 and 4 methylene groups as spacers between the two amide functionalities behave similar to monoamides upon anodic oxidation in methanol/LiClO because both types undergo majorly mono- and dimethoxylations at the α-position to the N atom. However, in cases where the spacer contains two methylene groups only the anodic process leads mostly to CH-CH bond cleavage to afford products of type RCONHCHOCH. Moreover, upon replacing LiClO with EtNBF an additional fragmentation type of product was generated from the latter amides, namely RCONHCHO. Read More

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A stereoselective and flexible synthesis to access both enantiomers of -acetylgalactosamine and peracetylated -acetylidosamine.

Beilstein J Org Chem 2018 13;14:856-860. Epub 2018 Apr 13.

University of Vienna, Institute of Organic Chemistry, Währinger Straße 38, A-1090 Vienna, Austria.

Synthetic approaches towards -acetylgalactosamine (GalNAc) have been attracting considerable interest since this compound is known for its pivotal role in cell-cell interaction and receptor induced cell signaling. Herein, we present a synthetic route in which two of the four stereogenic centers present in the target compound are derived from enantiopure tartaric acid being selectively converted to epoxy alcohols. The key step is the Pd-catalyzed, stereo- and regioselective epoxide opening and subsequent nucleophilic substitution of an azide functionality. Read More

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One-pot synthesis of diaryliodonium salts from arenes and aryl iodides with Oxone-sulfuric acid.

Beilstein J Org Chem 2018 12;14:849-855. Epub 2018 Apr 12.

The Tomsk Polytechnic University, 634050 Tomsk, Russia.

A facile synthesis of diaryliodonium salts utilizing Oxone as versatile and cheap oxidant has been developed. This method shows wide applicability and can be used for the preparation of iodonium salts containing electron-donating or electron-withdrawing groups in good yields. In addition, this procedure can be applied to the preparation of symmetric iodonium salts directly from arenes via a one-pot iodination-oxidation sequence. Read More

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April 2018
1 Read

Crystal structure of the inclusion complex of cholesterol in β-cyclodextrin and molecular dynamics studies.

Beilstein J Org Chem 2018 11;14:838-848. Epub 2018 Apr 11.

Department of Biotechnology, Agricultural University of Athens, 75 Iera Odos, Athens 11855, Greece.

The role of beta-cyclodextrin (β-CD) in cholesterol removal primarily from mammalian cells and secondly from dairy products has been studied thoroughly in recent years. Although the physicochemical characterization of the inclusion compound of cholesterol in β-CD has been achieved by various methods, no crystal structure has been determined so far. We report here the crystal structure of the inclusion compound of cholesterol in β-CD. Read More

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April 2018
2 Reads

Phosphodiester models for cleavage of nucleic acids.

Beilstein J Org Chem 2018 10;14:803-837. Epub 2018 Apr 10.

Department of Chemistry, University of Turku, FIN-20014 Turku, Finland.

Nucleic acids that store and transfer biological information are polymeric diesters of phosphoric acid. Cleavage of the phosphodiester linkages by protein enzymes, nucleases, is one of the underlying biological processes. The remarkable catalytic efficiency of nucleases, together with the ability of ribonucleic acids to serve sometimes as nucleases, has made the cleavage of phosphodiesters a subject of intensive mechanistic studies. Read More

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Chlorination of phenylallene derivatives with 1-chloro-1,2-benziodoxol-3-one: synthesis of -dichlorides and chlorodienes.

Beilstein J Org Chem 2018 9;14:796-802. Epub 2018 Apr 9.

Department of Chemistry, University of Waterloo, 200 University Ave. W., Waterloo, N2L3G1, ON, Canada.

Allyl and vinyl chlorides represent important structural motifs in organic chemistry. Herein is described the chemoselective and regioselective reaction of aryl- and α-substituted phenylallenes with the hypervalent iodine (HVI) reagent 1-chloro-1,2-benziodoxol-3-one. The reaction typically results in dichlorides, except with proton-containing α-alkyl substituents, which instead give chlorinated dienes as the major product. Read More

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Bromide-assisted chemoselective Heck reaction of 3-bromoindazoles under high-speed ball-milling conditions: synthesis of axitinib.

Beilstein J Org Chem 2018 6;14:786-795. Epub 2018 Apr 6.

Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology, Hangzhou 310014, PR China.

A mechanically-activated chemoselective Heck coupling for the synthesis of 3-vinylindazoles has been developed with the aid of catalytic amounts of TBAB and NaBr as both dehalogenation restrainer and grinding auxiliary. After tuning of the chemical conditions and mechanical parameters, a series of non-activated 3-bromoindazoles and a broad scope of olefins worked well to give the corresponding coupling products in good to excellent yields. A further application of this protocol was performed in a two-step mechanochemical Heck/Migita cross coupling, which provided a highly efficient route for the synthesis of axitinib. Read More

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April 2018
2 Reads

Recent advances in synthetic approaches for medicinal chemistry of C-nucleosides.

Beilstein J Org Chem 2018 5;14:772-785. Epub 2018 Apr 5.

Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, United States.

C-nucleosides have intrigued biologists and medicinal chemists since their discovery in 1950's. In that regard, C-nucleosides and their synthetic analogues have resulted in promising leads in drug design. Concurrently, advances in chemical syntheses have contributed to structural diversity and drug discovery efforts. Read More

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Synthesis and in vitro biochemical evaluation of oxime bond-linked daunorubicin-GnRH-III conjugates developed for targeted drug delivery.

Beilstein J Org Chem 2018 4;14:756-771. Epub 2018 Apr 4.

MTA-ELTE Research Group of Peptide Chemistry, Hungarian Academy of Sciences, Eötvös L. University, 1117 Budapest, Hungary.

Gonadotropin releasing hormone-III (GnRH-III), a native isoform of the human GnRH isolated from sea lamprey, specifically binds to GnRH receptors on cancer cells enabling its application as targeting moieties for anticancer drugs. Recently, we reported on the identification of a novel daunorubicin-GnRH-III conjugate (GnRH-III-[Lys(Bu), Lys(Dau=Aoa)] with efficient in vitro and in vivo antitumor activity. To get a deeper insight into the mechanism of action of our lead compound, the cellular uptake was followed by confocal laser scanning microscopy. Read More

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An uracil-linked hydroxyflavone probe for the recognition of ATP.

Beilstein J Org Chem 2018 3;14:747-755. Epub 2018 Apr 3.

Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, 1521 Budapest, Hungary.

Nucleotides are essential molecules in living systems due to their paramount importance in various physiological processes. In the past years, numerous attempts were made to selectively recognize and detect these analytes, especially ATP using small-molecule fluorescent chemosensors. Despite the various solutions, the selective detection of ATP is still challenging due to the structural similarity of various nucleotides. Read More

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April 2018
1 Read

Volatiles from the xylarialean fungus .

Beilstein J Org Chem 2018 29;14:734-746. Epub 2018 Mar 29.

Abteilung Mikrobielle Wirkstoffe, Helmholtz-Zentrum für Infektionsforschung, Inhoffenstraße 7, 38124 Braunschweig, Germany.

The volatiles emitted by agar plate cultures of the xylarialean fungus were investigated by use of a closed loop stripping apparatus in combination with GC-MS. Several aromatic compounds were found that could only be identified by comparison to all possible constitutional isomers with different ring substitution patterns. For the set of identified compounds a plausible biosynthetic scheme was suggested that gives further support for the assigned structures. Read More

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Nanoreactors for green catalysis.

Beilstein J Org Chem 2018 29;14:716-733. Epub 2018 Mar 29.

Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.

Sustainable and environmentally benign production are key drivers for developments in the chemical industrial sector, as protecting our planet has become a significant element that should be considered for every industrial breakthrough or technological advancement. As a result, the concept of green chemistry has been recently defined to guide chemists towards minimizing any harmful outcome of chemical processes in either industry or research. Towards greener reactions, scientists have developed various approaches in order to decrease environmental risks while attaining chemical sustainability and elegancy. Read More

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March 2018
1 Read

Cobalt-catalyzed directed C-H alkenylation of pivalophenone N-H imine with alkenyl phosphates.

Beilstein J Org Chem 2018 28;14:709-715. Epub 2018 Mar 28.

Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.

A cobalt-N-heterocyclic carbene (NHC) catalyst efficiently promotes an C-H alkenylation reaction of pivalophenone N-H imine with an alkenyl phosphate. The reaction tolerates various substituted pivalophenone N-H imines as well as cyclic and acyclic alkenyl phosphates. Read More

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Stepwise radical cation Diels-Alder reaction via multiple pathways.

Beilstein J Org Chem 2018 27;14:704-708. Epub 2018 Mar 27.

Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan.

Herein we disclose the radical cation Diels-Alder reaction of aryl vinyl ethers by electrocatalysis, which is triggered by an oxidative SET process. The reaction clearly proceeds in a stepwise fashion, which is a rare mechanism in this class. We also found that two distinctive pathways, including "direct" and "indirect", are possible to construct the Diels-Alder adduct. Read More

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Biocatalytic synthesis of the Green Note -2-hexenal in a continuous-flow microreactor.

Beilstein J Org Chem 2018 26;14:697-703. Epub 2018 Mar 26.

Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands.

The biocatalytic preparation of -hex-2-enal from -hex-2-enol using a novel aryl alcohol oxidase from (AAOx) is reported. As O-dependent enzyme AAOx-dependent reactions are generally plagued by the poor solubility of O in aqueous media and mass transfer limitations resulting in poor reaction rates. These limitations were efficiently overcome by conducting the reaction in a flow-reactor setup reaching unpreceded catalytic activities for the enzyme in terms of turnover frequency (up to 38 s) and turnover numbers (more than 300000) pointing towards preparative usefulness of the proposed reaction scheme. Read More

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Liquid-assisted grinding and ion pairing regulates percentage conversion and diastereoselectivity of the Wittig reaction under mechanochemical conditions.

Beilstein J Org Chem 2018 23;14:688-696. Epub 2018 Mar 23.

Department of Chemistry, University of Cincinnati, PO Box 210172, Cincinnati, OH 45221-0172, USA.

Mechanochemistry is maturing as a discipline and continuing to grow, so it is important to continue understanding the rules governing the system. In a mechanochemical reaction, the reactants are added into a vessel along with one or more grinding balls and the vessel is shaken at high speeds to facilitate a chemical reaction. The dielectric constant of the solvent used in liquid-assisted grinding (LAG) and properly chosen counter-ion pairing increases the percentage conversion of stilbenes in a mechanochemical Wittig reaction. Read More

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March 2018
3 Reads

AuBr-catalyzed azidation of per--acetylated and per--benzoylated sugars.

Beilstein J Org Chem 2018 22;14:682-687. Epub 2018 Mar 22.

Department of Chemistry, Indian Institute of Science Education and Research, Pune 411 008, India.

Herein we report, for the first time, the successful anomeric azidation of per--acetylated and per--benzoylated sugars by catalytic amounts of oxophilic AuBr in good to excellent yields. The method is applicable to a wide range of easily accessible per--acetylated and per--benzoylated sugars. While reaction with per--acetylated and per--benzoylated monosaccharides was complete within 1-3 h at room temperature, the per--benzoylated disaccharides needed 2-3 h of heating at 55 °C. Read More

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March 2018
8 Reads

D-A-D-type orange-light emitting thermally activated delayed fluorescence (TADF) materials based on a fluorenone unit: simulation, photoluminescence and electroluminescence studies.

Beilstein J Org Chem 2018 22;14:672-681. Epub 2018 Mar 22.

State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Wushan Road 381, Tianhe District, Guangzhou 510640, Guangdong Province, P. R. China.

The design of orange-light emitting, thermally activated, delayed fluorescence (TADF) materials is necessary and important for the development and application of organic light-emitting diodes (OLEDs). Herein, two donor-acceptor-donor (D-A-D)-type orange TADF materials based on fluorenone and acridine, namely 2,7-bis(9,9-dimethylacridin-10(9)-yl)-9-fluoren-9-one (27DACRFT, ) and 3,6-bis(9,9-dimethylacridin-10(9)-yl)-9-fluoren-9-one (36DACRFT, ), were successfully synthetized and characterized. The studies on their structure-property relationship show that the different configurations have a serious effect on the photoluminescence and electroluminescence performance according to the change in singlet-triplet splitting energy (Δ) and excited state geometry. Read More

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March 2018
7 Reads

Enhanced quantum yields by sterically demanding aryl-substituted β-diketonate ancillary ligands.

Beilstein J Org Chem 2018 21;14:664-671. Epub 2018 Mar 21.

Physical Organic Chemistry, Technische Universität Dresden, Bergstraße, 01069 Dresden, Germany.

Luminescent organometallic platinum(II) compounds are of interest as phosphors for organic light emitting devices. Their emissive properties can be tuned by variation of the ligands or by specific electron-withdrawing or electron-donating substituents. Different ancillary ligands can have a profound impact on the emission color and emission efficiency of these complexes. Read More

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March 2018
1 Read

Enantioselective dioxytosylation of styrenes using lactate-based chiral hypervalent iodine(III).

Beilstein J Org Chem 2018 20;14:659-663. Epub 2018 Mar 20.

Graduate School of Material Science, University of Hyogo, Kohto, Kamigori, Hyogo 678-1297, Japan.

A series of optically active hypervalent iodine(III) reagents prepared from the corresponding ()-2-(2-iodophenoxy)propanoate derivative was employed for the asymmetric dioxytosylation of styrene and its derivatives. The electrophilic addition of the hypervalent iodine(III) compound toward styrene proceeded with high enantioface selectivity to give 1-aryl-1,2-di(tosyloxy)ethane with an enantiomeric excess of 70-96% of the ()-isomer. Read More

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March 2018
2 Reads

Heterogeneous Pd catalysts as emulsifiers in Pickering emulsions for integrated multistep synthesis in flow chemistry.

Beilstein J Org Chem 2018 19;14:648-658. Epub 2018 Mar 19.

Institute of Process and Particle Engineering, Graz University of Technology, Inffeldgasse 13/III, 8010 Graz, Austria.

Within the "compartmentalised smart factory" approach of the ONE-FLOW project the implementation of different catalysts in "compartments" provided by Pickering emulsions and their application in continuous flow is targeted. We present here the development of heterogeneous Pd catalysts that are ready to be used in combination with biocatalysts for catalytic cascade synthesis of active pharmaceutical ingredients (APIs). In particular, we focus on the application of the catalytic systems for Suzuki-Miyaura cross-coupling reactions, which is the key step in the synthesis of the targeted APIs valsartan and sacubitril. Read More

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March 2018
1 Read

Investigating radical cation chain processes in the electrocatalytic Diels-Alder reaction.

Beilstein J Org Chem 2018 16;14:642-647. Epub 2018 Mar 16.

Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan.

Single electron transfer (SET)-triggered radical ion-based reactions have proven to be powerful options in synthetic organic chemistry. Although unique chain processes have been proposed in various photo- and electrochemical radical ion-based transformations, the turnover number, also referred to as catalytic efficiency, remains unclear in most cases. Herein, we disclose our investigations of radical cation chain processes in the electrocatalytic Diels-Alder reaction, leading to a scalable synthesis. Read More

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March 2018
2 Reads

Synthesis of a sucrose-based macrocycle with unsymmetrical monosaccharides "arms".

Beilstein J Org Chem 2018 15;14:634-641. Epub 2018 Mar 15.

Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.

An efficient methodology for the selective substitution of both terminal positions (C6 and C6') in 1',2,3,3',4,4'-hexa--benzylsucrose with different unsaturated monosaccharide units is presented. Such a highly functionalized intermediate was cyclized under RCM conditions to afford a macrocyclic derivative containing a 31-membered ring in 26% yield. Read More

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March 2018
2 Reads

Sequential Ugi reaction/base-induced ring closing/IAAC protocol toward triazolobenzodiazepine-fused diketopiperazines and hydantoins.

Beilstein J Org Chem 2018 14;14:626-633. Epub 2018 Mar 14.

Molecular Design and Synthesis, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium.

A practical three-step protocol for the assembly of triazolobenzodiazepine-fused diketopiperazines and hydantoins has been developed. The synthesis of these tetracyclic ring systems was initiated by an Ugi reaction, which brought together all necessary functionalities for further transformations. The Ugi adducts were then subjected to a base-induced ring closing and an intramolecular azide-alkyne cycloaddition reaction in succession to obtain highly fused benzodiazepine frameworks. Read More

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March 2018
2 Reads

An air-stable bisboron complex: a practical bidentate Lewis acid catalyst.

Beilstein J Org Chem 2018 13;14:618-625. Epub 2018 Mar 13.

Institute of Organic Chemistry, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany.

We report an air-stable bisboron complex as an efficient catalyst for the inverse electron-demand Diels-Alder (IEDDA) reaction of 1,2-diazine as well as 1,2,4,5-tetrazine. Its stability towards air and moisture was demonstrated by NMR studies enabling its application in organic transformations without glovebox. A one-pot procedure for its synthesis was developed starting from 1,2-bis(trimethylsilyl)benzene greatly enhancing its practicality. Read More

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March 2018
1 Read

Enzyme-free genetic copying of DNA and RNA sequences.

Beilstein J Org Chem 2018 12;14:603-617. Epub 2018 Mar 12.

Institute of Organic Chemistry, University of Stuttgart, 70569 Stuttgart, Germany.

The copying of short DNA or RNA sequences in the absence of enzymes is a fascinating reaction that has been studied in the context of prebiotic chemistry. It involves the incorporation of nucleotides at the terminus of a primer and is directed by base pairing. The reaction occurs in aqueous medium and leads to phosphodiester formation after attack of a nucleophilic group of the primer. Read More

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March 2018
1 Read

Diastereoselective auxiliary- and catalyst-controlled intramolecular aza-Michael reaction for the elaboration of enantioenriched 3-substituted isoindolinones. Application to the synthesis of a new pazinaclone analogue.

Beilstein J Org Chem 2018 9;14:593-602. Epub 2018 Mar 9.

Univ, Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181-UCCS-Unité de Catalyse et Chimie du Solide, F-59000 Lille, France.

A new asymmetric organocatalyzed intramolecular aza-Michael reaction by means of both a chiral auxiliary and a catalyst for stereocontrol is reported for the synthesis of optically active isoindolinones. A selected cinchoninium salt was used as phase-transfer catalyst in combination with a chiral nucleophile, a Michael acceptor and a base to provide 3-substituted isoindolinones in good yields and diastereomeric excesses. This methodology was applied to the asymmetric synthesis of a new pazinaclone analogue which is of interest in the field of benzodiazepine-receptor agonists. Read More

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March 2018
3 Reads

High-yielding continuous-flow synthesis of antimalarial drug hydroxychloroquine.

Beilstein J Org Chem 2018 8;14:583-592. Epub 2018 Mar 8.

Department of Chemistry and Department of Chemical and Life Science Engineering, Virginia Commonwealth University, 601 W. Main St., Richmond, VA 23220, USA.

Numerous synthetic methods for the continuous preparation of fine chemicals and active pharmaceutical ingredients (API's) have been reported in recent years resulting in a dramatic improvement in process efficiencies. Herein we report a highly efficient continuous synthesis of the antimalarial drug hydroxychloroquine (HCQ). Key improvements in the new process include the elimination of protecting groups with an overall yield improvement of 52% over the current commercial process. Read More

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March 2018
2 Reads

Copper-catalyzed asymmetric methylation of fluoroalkylated pyruvates with dimethylzinc.

Beilstein J Org Chem 2018 7;14:576-582. Epub 2018 Mar 7.

Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan.

The catalytic asymmetric methylation of fluoroalkylated pyruvates is shown with dimethylzinc as a methylating reagent in the presence of a copper catalyst bearing a chiral phosphine ligand. This is the first catalytic asymmetric methylation to synthesize various α-fluoroalkylated tertiary alcohols with CF, CFH, CFBr, and -C F ( = 2, 3, 8) groups in good-to-high yields and enantioselectivities. Axial backbones and substituents on phosphorus atoms of chiral phosphine ligands critically influence the enantioselectivity. Read More

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March 2018
2 Reads

Mannich base-connected syntheses mediated by -quinone methides.

Beilstein J Org Chem 2018 6;14:560-575. Epub 2018 Mar 6.

Institute of Pharmaceutical Chemistry and Research Group for Stereochemistry, Hungarian Academy of Sciences, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary.

This article provides an overview about specifically modified Mannich reactions where the process involves an -quinone methide (-QM) intermediate. The reactions are classified on the basis of the -QM source followed by the reactant, e.g. Read More

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March 2018
2 Reads

Investigations towards the stereoselective organocatalyzed Michael addition of dimethyl malonate to a racemic nitroalkene: possible route to the 4-methylpregabalin core structure.

Beilstein J Org Chem 2018 5;14:553-559. Epub 2018 Mar 5.

Department of Organic Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, Ilkovičova 6, SK-842 15 Bratislava, Slovakia.

Chiral derivatives of γ-aminobutyric acid are widely used as medicines and can be obtained by organocatalytic Michael additions. We show here the stereoselective synthesis of 4-methylpregabalin stereoisomers using a Michael addition of dimethyl malonate to a racemic nitroalkene. The key step of the synthesis operates as a kinetic resolution with a chiral squaramide catalyst. Read More

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March 2018
2 Reads

Electrochemical Corey-Winter reaction. Reduction of thiocarbonates in aqueous methanol media and application to the synthesis of a naturally occurring α-pyrone.

Beilstein J Org Chem 2018 2;14:547-552. Epub 2018 Mar 2.

Centro Conjunto de Investigaciones en Química Sustentable UAEMéx-UNAM, Km 14.5 Carretera Toluca Atlacomulco San Cayetano-Toluca, 50200 Estado de México, México.

An electrochemical version of the Corey-Winter reaction was developed giving excellent results in aqueous methanol media (MeOH/HO (80:20) with AcOH/AcONa buffer 0.5 M as supporting electrolyte), using a reticulated vitreous carbon as cathode in a divided cell. The electrochemical version is much more environmentally friendly than the classical reaction, where a large excess of trialkyl phosphite as reducing agent and high temperatures are required. Read More

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March 2018
2 Reads

An alternative to hydrogenation processes. Electrocatalytic hydrogenation of benzophenone.

Beilstein J Org Chem 2018 1;14:537-546. Epub 2018 Mar 1.

Instituto de Electroquímica, Universidad de Alicante, Apartado 99, 03080 Alicante, Spain.

The electrocatalytic hydrogenation of benzophenone was performed at room temperature and atmospheric pressure using a polymer electrolyte membrane electrochemical reactor (PEMER). Palladium (Pd) nanoparticles were synthesised and supported on a carbonaceous matrix (Pd/C) with a 28 wt % of Pd with respect to carbon material. Pd/C was characterised by transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). Read More

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March 2018
2 Reads

Oxidative cycloaddition of hydroxamic acids with dienes or guaiacols mediated by iodine(III) reagents.

Beilstein J Org Chem 2018 28;14:531-536. Epub 2018 Feb 28.

Division of Applied Chemistry, Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan.

[Bis(trifluoroacetoxy)iodo]benzene (BTI) and (diacetoxyiodo)benzene (DIB) efficiently promote the formation of acylnitroso species from hydroxamic acids in the presence of various dienes to give the corresponding hetero-Diels-Alder (HDA) adducts in moderate to high yields. The present method could be applied to the HDA reactions of acylnitroso species with -benzoquinones generated by the oxidative dearomatization of guaiacols. Read More

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February 2018
3 Reads

Synthesis and stability of strongly acidic benzamide derivatives.

Beilstein J Org Chem 2018 27;14:523-530. Epub 2018 Feb 27.

Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.

Reactivity studies of strong organic acids based on the replacement of one or both of the oxygens in benzoic acids with the trifluoromethanesulfonamide group are reported. Novel derivatives of these types of acids were synthesized in good yields. The generated -triflylbenzamides were further functionalized through cross-coupling and nucleophilic aromatic substitution reactions. Read More

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February 2018
2 Reads

Addition of dithi(ol)anylium tetrafluoroborates to α,β-unsaturated ketones.

Beilstein J Org Chem 2018 26;14:515-522. Epub 2018 Feb 26.

Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Campus North, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.

In the presented study, dithi(ol)anylium tetrafluoroborates are added to α,β-unsaturated ketones in a Michael-type reaction yielding diverse substituted ketene diothi(ol)anes. The reactions proceed at room temperature in 1 or 13 h without the need of further additives. The presented procedure is in particular useful for dithi(ol)anylium tetrafluoroborates without electron-withdrawing groups in α-position. Read More

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February 2018
3 Reads

Microfluidic radiosynthesis of [F]FEMPT, a high affinity PET radiotracer for imaging serotonin receptors.

Beilstein J Org Chem 2017 29;13:2922-2927. Epub 2017 Dec 29.

Molecular Imaging and Neuropathology Division, New York State Psychiatric Institute, New York, NY, USA.

Continuous-flow microfluidics has shown increased applications in radiochemistry over the last decade, particularly for both pre-clinical and clinical production of fluorine-18 labeled radiotracers. The main advantages of microfluidics are the reduction in reaction times and consumption of reagents that often result in increased radiochemical yields and rapid optimization of reaction parameters for F-labeling. In this paper, we report on the two-step microfluidic radiosynthesis of the high affinity partial agonist of the serotonin 1A receptor, [F]FEMPT (p = 9. Read More

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December 2017
4 Reads

Conformational preferences of α-fluoroketones may influence their reactivity.

Authors:
Graham Pattison

Beilstein J Org Chem 2017 29;13:2915-2921. Epub 2017 Dec 29.

Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK.

Fluorine has been shown in many cases to impart specific and predictable effects on molecular conformation. Here it is shown that these conformational effects may have an influence on reactivity through studying the relative reactivity of various α-halogenated ketones towards borohydride reduction. These results demonstrate that the α-fluoro ketones are in fact a little less reactive than the corresponding α-chloro and α-bromo derivatives. Read More

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December 2017
2 Reads

Halogen-containing thiazole orange analogues - new fluorogenic DNA stains.

Beilstein J Org Chem 2017 28;13:2902-2914. Epub 2017 Dec 28.

Departments of Organic and Physical Chemistry, University of Alcala, 28871-Alcala de Henares, Madrid, Spain.

Novel asymmetric monomeric monomethine cyanine dyes , which are analogues of the commercial dsDNA fluorescence binder thiazole orange (), have been synthesized. The synthesis was achieved by using a simple, efficient and environmetally benign synthetic procedure to obtain these cationic dyes in good to excellent yields. Interactions of the new derivatives of with dsDNA have been investigated by absorption and fluorescence spectroscopy. Read More

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December 2017
2 Reads

Quinone-catalyzed oxidative deformylation: synthesis of imines from amino alcohols.

Beilstein J Org Chem 2017 28;13:2895-2901. Epub 2017 Dec 28.

Department of Chemistry, The University of Kansas, 2010 Malott Hall, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, United States.

A new method for imine synthesis by way of quinone-catalyzed oxidative deformylation of 1,2-amino alcohols is reported. A wide range of readily accessible amino alcohols and primary amines can be reacted to provide N-protected imine products. The methodology presented provides a novel organocatalytic approach for imine synthesis and demonstrates the synthetic versatility of quinone-catalyzed oxidative C-C bond cleavage. Read More

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December 2017
2 Reads

Acid-catalyzed ring-opening reactions of a cyclopropanated 3-aza-2-oxabicyclo[2.2.1]hept-5-ene with alcohols.

Beilstein J Org Chem 2017 27;13:2888-2894. Epub 2017 Dec 27.

Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, Department of Chemistry, University of Guelph, Guelph, Ontario, N1G 2W1, Canada.

The acid-catalyzed ring-opening reactions of a cyclopropanated 3-aza-2-oxabicylic alkene using alcohol nucleophiles were investigated. Although this acid-catalyzed ring-opening reaction did not cleave the cyclopropane unit as planned, this represent the first examples of ring-openings of cyclopropanated 3-aza-2-oxabicyclo[2.2. Read More

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December 2017
3 Reads