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Beilstein Journal of Organic Chemistry

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https://www.readbyqxmd.com/read/28228862/highly-bulky-and-stable-geometry-constrained-iminopyridines-synthesis-structure-and-application-in-pd-catalyzed-suzuki-coupling-of-aryl-chlorides
#1
Yi Lai, Zhijian Zong, Yujie Tang, Weimin Mo, Nan Sun, Baoxiang Hu, Zhenlu Shen, Liqun Jin, Wen-Hua Sun, Xinquan Hu
A series of bulky geometry-constrained iminopyridylpalladium chlorides were developed. The steric environment adjacent to the nitrogen atom in the pyridine rings and diimine parts enhanced the thermal stability of the palladium species. Bulkier groups at the imino group stabilized the palladium species and the corresponding palladium chlorides showed high activities in the coupling reaction of aryl chlorides.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28228861/interactions-between-photoacidic-3-hydroxynaphtho-1-2-b-quinolizinium-and-cucurbit-7-uril-influence-on-acidity-in-the-ground-and-excited-state
#2
Jonas Becher, Daria V Berdnikova, Darinka Dzubiel, Heiko Ihmels, Phil M Pithan
3-Hydroxynaphtho[1,2-b]quinolizinium was synthesized by cyclodehydration route and its optical properties in different media were investigated. The absorption and emission spectra of this compound depend on the pH of the solution. Thus, at higher pH values the deprotonation yields a merocyanine-type dye that exhibits significantly red-shifted absorption bands and causes a dual emisson, i.e., a combination of emission bands of the hydroxyquinolizinium and its deprotonated form. Whereas this compound is a weak acid in the ground state (pKa = 7...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28228860/efficient-access-to-%C3%AE-vinylporphyrin-derivatives-via-palladium-cross-coupling-of-%C3%AE-bromoporphyrins-with-n-tosylhydrazones
#3
Vinicius R Campos, Ana T P C Gomes, Anna C Cunha, Maria da Graça P M S Neves, Vitor F Ferreira, José A S Cavaleiro
This work describes a new approach to obtain new β-vinylporphyrin derivatives through palladium-catalyzed cross-coupling reaction of 2-bromo-5,10,15,20-tetraphenylporphyrinatozinc(II) with N-tosylhydrazones. This is the first report of the use of such synthetic methodology in porphyrin chemistry allowing the synthesis of new derivatives, containing β-arylvinyl substituents.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28228859/dynamics-and-interactions-of-ibuprofen-in-cyclodextrin-nanosponges-by-solid-state-nmr-spectroscopy
#4
Monica Ferro, Franca Castiglione, Nadia Pastori, Carlo Punta, Lucio Melone, Walter Panzeri, Barbara Rossi, Francesco Trotta, Andrea Mele
Two different formulations of cyclodextrin nanosponges (CDNS), obtained by polycondensation of β-cyclodextrin with ethylenediaminetetraacetic acid dianhydride (EDTAn), were treated with aqueous solutions of ibuprofen sodium salt (IbuNa) affording hydrogels that, after lyophilisation, gave two solid CDNS-drug formulations. (1)H fast MAS NMR and (13)C CP-MAS NMR spectra showed that IbuNa was converted in situ into its acidic and dimeric form (IbuH) after freeze-drying. (13)C CP-MAS NMR spectra also indicated that the structure of the nanosponge did not undergo changes upon drug loading compared to the unloaded system...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28228858/a-novel-method-for-heterocyclic-amide-thioamide-transformations
#5
Walid Fathalla, Ibrahim A I Ali, Pavel Pazdera
In this paper, we introduce a novel and convenient method for the transformation of heterocyclic amides into heteocyclic thioamides. A two-step approach was applied for this transformation: Firstly, we applied a chlorination of the heterocyclic amides to afford the corresponding chloroheterocycles. Secondly, the chloroherocycles and N-cyclohexyl dithiocarbamate cyclohexylammonium salt were heated in chloroform for 12 h at 61 °C to afford heteocyclic thioamides in excellent yields.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28228857/total-synthesis-of-a-streptococcus-pneumoniae-serotype-12f-cps-repeating-unit-hexasaccharide
#6
Peter H Seeberger, Claney L Pereira, Subramanian Govindan
The Gram-positive bacterium Streptococcus pneumoniae causes severe disease globally. Vaccines that prevent S. pneumoniae infections induce antibodies against epitopes within the bacterial capsular polysaccharide (CPS). A better immunological understanding of the epitopes that protect from bacterial infection requires defined oligosaccharides obtained by total synthesis. The key to the synthesis of the S. pneumoniae serotype 12F CPS hexasaccharide repeating unit that is not contained in currently used glycoconjugate vaccines is the assembly of the trisaccharide β-D-GalpNAc-(1→4)-[α-D-Glcp-(1→3)]-β-D-ManpNAcA, in which the branching points are equipped with orthogonal protecting groups...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28228856/self-optimisation-and-model-based-design-of-experiments-for-developing-a-c-h-activation-flow-process
#7
Alexander Echtermeyer, Yehia Amar, Jacek Zakrzewski, Alexei Lapkin
A recently described C(sp(3))-H activation reaction to synthesise aziridines was used as a model reaction to demonstrate the methodology of developing a process model using model-based design of experiments (MBDoE) and self-optimisation approaches in flow. The two approaches are compared in terms of experimental efficiency. The self-optimisation approach required the least number of experiments to reach the specified objectives of cost and product yield, whereas the MBDoE approach enabled a rapid generation of a process model...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28228855/a-new-class-of-organogelators-based-on-triphenylmethyl-derivatives-of-primary-alcohols-hydrophobic-interactions-alone-can-mediate-gelation
#8
Wangkhem P Singh, Rajkumar S Singh
In the present work, we have explored the use of the triphenylmethyl group, a commonly used protecting group for primary alcohols as a gelling structural component in the design of molecular gelators. We synthesized a small library of triphenylmethyl derivatives of simple primary alcohols and studied their gelation properties in different solvents. Gelation efficiency for some of the derivatives was moderate to excellent with a minimum gelation concentration ranging between 0.5-4.0% w/v and a gel-sol transition temperature range of 31-75 °C...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28228854/a-postsynthetically-2-clickable-uridine-with-arabino-configuration-and-its-application-for-fluorescent-labeling-and-imaging-of-dna
#9
Heidi-Kristin Walter, Bettina Olshausen, Ute Schepers, Hans-Achim Wagenknecht
The arabino-configured analog of uridine with a propargyl group at the 2'-position was synthesized and incorporated into DNA by solid-phase chemistry. The fluorescence quantum yields of DNA strands that were postsynthetically modified by blue and green emitting cyanine-styryl dyes were improved due to the arabino-configured anchor. These oligonucleotides were used as energy transfer donors in hybrids with oligonucleotides modified with acceptor dyes that emit in the yellow-red range. These combinations give energy transfer pairs with blue-yellow, blue-red and green-red emission color changes...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28228853/diels-alder-reactions-of-myrcene-using-intensified-continuous-flow-reactors
#10
Christian H Hornung, Miguel Á Álvarez-Diéguez, Thomas M Kohl, John Tsanaktsidis
This work describes the Diels-Alder reaction of the naturally occurring substituted butadiene, myrcene, with a range of different naturally occurring and synthetic dienophiles. The synthesis of the Diels-Alder adduct from myrcene and acrylic acid, containing surfactant properties, was scaled-up in a plate-type continuous-flow reactor with a volume of 105 mL to a throughput of 2.79 kg of the final product per day. This continuous-flow approach provides a facile alternative scale-up route to conventional batch processing, and it helps to intensify the synthesis protocol by applying higher reaction temperatures and shorter reaction times...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28228852/3d-printed-fluidics-with-embedded-analytic-functionality-for-automated-reaction-optimisation
#11
Andrew J Capel, Andrew Wright, Matthew J Harding, George W Weaver, Yuqi Li, Russell A Harris, Steve Edmondson, Ruth D Goodridge, Steven D R Christie
Additive manufacturing or '3D printing' is being developed as a novel manufacturing process for the production of bespoke micro- and milliscale fluidic devices. When coupled with online monitoring and optimisation software, this offers an advanced, customised method for performing automated chemical synthesis. This paper reports the use of two additive manufacturing processes, stereolithography and selective laser melting, to create multifunctional fluidic devices with embedded reaction monitoring capability...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28228851/solution-phase-automated-synthesis-of-an-%C3%AE-amino-aldehyde-as-a-versatile-intermediate
#12
Hisashi Masui, Sae Yosugi, Shinichiro Fuse, Takashi Takahashi
A solution-phase automated synthesis of the versatile synthetic intermediate, Garner's aldehyde, was demonstrated. tert-Butoxycarbonyl (Boc) protection, acetal formation, and reduction of the ester to the corresponding aldehyde were performed utilizing our originally developed automated synthesizer, ChemKonzert. The developed procedure was also useful for the synthesis of Garner's aldehyde analogues possessing fluorenylmethyloxycarbonyl (Fmoc) or benzyloxycarbonyl (Cbz) protection.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28228850/silyl-protective-groups-influencing-the-reactivity-and-selectivity-in-glycosylations
#13
REVIEW
Mikael Bols, Christian Marcus Pedersen
Silyl groups such as TBDPS, TBDMS, TIPS or TMS are well-known and widely used alcohol protective groups in organic chemistry. Cyclic silylene protective groups are also becoming increasingly popular. In carbohydrate chemistry silyl protective groups have frequently been used primarily as an orthogonal protective group to the more commonly used acyl and benzyl protective groups. However, silyl protective groups have significantly different electronic and steric requirements than acyl and alkyl protective groups, which particularly becomes important when two or more neighboring alcohols are silyl protected...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28179952/nucleophilic-displacement-reactions-of-5-derivatised-nucleosides-in-a-vibration-ball-mill
#14
Olga Eguaogie, Patrick F Conlon, Francesco Ravalico, Jamie S T Sweet, Thomas B Elder, Louis P Conway, Marc E Lennon, David R W Hodgson, Joseph S Vyle
Vibration ball-milling in a zirconia-lined vessel afforded clean and quantitative nucleophilic displacement reactions between 4-methoxybenzylthiolate salts and nucleoside 5'-halides or 5'-tosylates in five to 60 minutes. Under these conditions, commonly-encountered nucleoside cyclisation byproducts (especially of purine nucleosides) were not observed. Liquid-assisted grinding of the same 5'-iodide and 5'-tosylate substrates with potassium selenocyanate in the presence of DMF produced the corresponding 5'-selenocyanates in variable yields over the course of between one and eleven hours thereby avoiding the preparation and use of hygroscopic tetrabutylammonium salts...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28179951/the-synthesis-of-%C3%AE-aryl-%C3%AE-aminophosphonates-and-%C3%AE-aryl-%C3%AE-aminophosphine-oxides-by-the-microwave-assisted-pudovik-reaction
#15
Erika Bálint, Ádám Tajti, Anna Ádám, István Csontos, Konstantin Karaghiosoff, Mátyás Czugler, Péter Ábrányi-Balogh, György Keglevich
A family of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides was synthesized by the microwave-assisted solvent-free addition of dialkyl phosphites and diphenylphosphine oxide, respectively, to imines formed from benzaldehyde derivatives and primary amines. After optimization, the reactivity was mapped, and the fine mechanism was evaluated by DFT calculations. Two α-aminophosphonates were subjected to an X-ray study revealing a racemic dimer formation made through a N-H···O=P intermolecular hydrogen bridges pair...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28179950/extrusion-back-to-the-future-using-an-established-technique-to-reform-automated-chemical-synthesis
#16
REVIEW
Deborah E Crawford
Herein, the benefits which extrusion can provide for the automated continuous synthesis of organic compounds are highlighted. Extrusion is a well-established technique that has a vital role in the manufacturing processes of polymers, pharmaceuticals and food products. Furthermore, this technique has recently been applied to the solvent-free continuous synthesis of co-crystals and coordination compounds including metal-organic frameworks (MOFs). To date, a vast amount of research has already been conducted into reactive extrusion (REX), particularly in the polymer industry, which in many cases has involved organic transformations, however, it has not received significant recognition for this...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28179949/strategies-in-asymmetric-catalysis
#17
EDITORIAL
Tehshik P Yoon
No abstract text is available yet for this article.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28179948/synthesis-of-structurally-diverse-3-4-dihydropyrimidin-2-1h-ones-via-sequential-biginelli-and-passerini-reactions
#18
Andreas C Boukis, Baptiste Monney, Michael A R Meier
The Biginelli reaction was combined with the Passerini reaction for the first time in a sequential multicomponent tandem reaction approach. After evaluation of all possible linker components and a suitable solvent system, highly functionalized dihydropyrimidone-α-acyloxycarboxamide compounds were obtained in good to excellent yields. In a first reaction step, different 3,4-dihydropyrimidin-2(1H)-one acids were synthesized, isolated and fully characterized. These products were subsequently used in a Passerini reaction utilizing a dichloromethane/dimethyl sulfoxide solvent mixture...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28179947/phosphated-cyclodextrins-as-water-soluble-chiral-nmr-solvating-agents-for-cationic-compounds
#19
Cira Mollings Puentes, Thomas J Wenzel
The utility of phosphated α-, β- and γ-cyclodextrins as water-soluble chiral NMR solvating agents for cationic substrates is described. Two sets of phosphated cyclodextrins, one with degrees of substitution in the 2-6 range, the other with degrees of substitution in the 6-10 range, are examined. Results with 33 water-soluble cationic substrates are reported. We also explored the possibility that the addition of paramagnetic lanthanide ions such as praseodymium(III) and ytterbium(III) further enhances the enantiomeric differentiation in the NMR spectra...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28179946/diastereoselective-anodic-hetero-and-homo-coupling-of-menthol-8-methylmenthol-and-8-phenylmenthol-2-alkylmalonates
#20
Matthias C Letzel, Hans J Schäfer, Roland Fröhlich
Diastereoselective radical coupling was achieved with chiral auxiliaries. The radicals were generated by anodic decarboxylation of five malonic acid derivatives. These were prepared from benzyl malonates and four menthol auxiliaries. Coelectrolyses with 3,3-dimethylbutanoic acid in methanol at platinum electrodes in an undivided cell afforded hetero-coupling products in 22-69% yield with a diastereoselectivity ranging from 5 to 65% de. Electrolyses without a coacid led to diastereomeric homo-coupling products in 21-50% yield with ratios of diastereomers being 1...
2017: Beilstein Journal of Organic Chemistry
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