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Beilstein Journal of Organic Chemistry

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https://www.readbyqxmd.com/read/30202483/the-enzymes-of-microbial-nicotine-metabolism
#1
REVIEW
Paul F Fitzpatrick
Because of nicotine's toxicity and the high levels found in tobacco and in the waste from tobacco processing, there is a great deal of interest in identifying bacteria capable of degrading it. A number of microbial pathways have been identified for nicotine degradation. The first and best-understood is the pyridine pathway, best characterized for Arthrobacter nicotinovorans , in which the first reaction is hydroxylation of the pyridine ring. The pyrrolidine pathway, which begins with oxidation of a carbon-nitrogen bond in the pyrrolidine ring, was subsequently characterized in a number of pseudomonads...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202482/determining-the-predominant-tautomeric-structure-of-iodine-based-group-transfer-reagents-by-17-o-nmr-spectroscopy
#2
Nico Santschi, Cody Ross Pitts, Benson J Jelier, René Verel
Cyclic benziodoxole systems have become a premier scaffold for the design of electrophilic transfer reagents. A particularly intriguing aspect is the fundamental II -IIII tautomerism about the hypervalent bond, which has led in certain cases to a surprising re-evaluation of the classic hypervalent structure. Thus, through a combination of 17 O NMR spectroscopy at natural abundance with DFT calculations, we establish a convenient method to provide solution-phase structural insights for this class of ubiquitous reagents...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202481/hydroarylations-by-cobalt-catalyzed-c-h-activation
#3
REVIEW
Rajagopal Santhoshkumar, Chien-Hong Cheng
As an earth-abundant first-row transition metal, cobalt catalysts offer a broad range of economical methods for organic transformations via C-H activation. One of the transformations is the addition of C-H to C-X multiple bonds to afford alkylation, alkenation, amidation, and cyclization products using low- or high-valent cobalt catalysts. This hydroarylation is an efficient approach to build new C-C bonds in a 100% atom-economical manner. In this review, the recent developments of Co-catalyzed hydroarylation reactions and their mechanistic studies are summarized...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202480/cobalt-bis-acetylacetonate-tert-butyl-hydroperoxide-triethylsilane-a-general-reagent-combination-for-the-markovnikov-selective-hydrofunctionalization-of-alkenes-by-hydrogen-atom-transfer
#4
Xiaoshen Ma, Seth B Herzon
We show that cobalt bis(acetylacetonate) [Co(acac)2 ], tert -butyl hydroperoxide (TBHP), and triethylsilane (Et3 SiH) constitute an inexpensive, general, and practical reagent combination to initiate a broad range of Markovnikov-selective alkene hydrofunctionalization reactions. These transformations are believed to proceed by cobalt-mediated hydrogen atom transfer (HAT) to the alkene substrate, followed by interception of the resulting alkyl radical intermediate with a SOMOphile. In addition, we report the first reductive couplings of unactivated alkenes and aryldiazonium salts by an HAT pathway...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202479/novel-photochemical-reactions-of-carbocyclic-diazodiketones-without-elimination-of-nitrogen-a-suitable-way-to-n-hydrazonation-of-c-h-bonds
#5
Liudmila L Rodina, Xenia V Azarova, Jury J Medvedev, Dmitrij V Semenok, Valerij A Nikolaev
The sensitized photoexcitation of 2-diazocyclopentane-1,3-diones in the presence of THF leads to the insertion of the terminal N-atom of the diazo group into the α-С-Н bond of THF, producing the associated N -alkylhydrazones in yields of up to 63-71%. Further irradiation of hydrazones derived from furan-fused tricyclic diazocyclopentanediones culminates in the cycloelimination of furans to yield 2- N -(alkyl)hydrazone of cyclopentene-1,2,3-trione. By contrast, the direct photolysis of carbocyclic diazodiketones gives only Wolff rearrangement products with up to 90-97% yield...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202478/coordination-driven-self-assembly-of-discrete-ru-6-pt-6-prismatic-cages
#6
Aderonke Ajibola Adeyemo, Partha Sarathi Mukherjee
The coordination-driven self-assembly of two new Ru6 -Pt6 hexanuclear trigonal prismatic cages comprising arene-ruthenium(II) clips ( 1a(NO 3 ) 2 and 1b(NO 3 ) 2 ) and a tritopic platinum(II) metalloligand 2 has been performed in methanol at room temperature. The [3 + 2] hexanuclear cages 3a and 3b were isolated in good yields and characterized by well-known spectroscopic techniques including multinuclear NMR, mass spectrometry, UV-vis and infrared studies. Geometry optimization revealed the shapes and sizes of these hexanuclear prismatic cages...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202477/synthesis-of-a-water-soluble-2-2-biphen-4-arene-and-its-efficient-complexation-and-sensitive-fluorescence-enhancement-towards-palmatine-and-berberine
#7
Xiayang Huang, Xinghua Zhang, Tianxin Qian, Junwei Ma, Lei Cui, Chunju Li
A water-soluble 2,2'-biphen[4]arene (2,2'-CBP4) containing eight carboxylato moieties was synthesized and characterized. Its complexation behavior towards two alkaloids, palmatine ( P ) and berberine ( B ), was investigated by means of fluorescence and 1 H NMR spectroscopy in aqueous phosphate buffer solution (pH 7.4). In the presence of 2,2'-CBP4, 1 H NMR signals of P and B displayed very large upfield shifts, indicating the formation of inclusion complexes with strong binding affinities. Fluorescence titration experiments showed that P and B exhibited dramatic fluorescence enhancement of more than 600 times upon complexation with 2,2'-CBP4...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202476/investigation-of-the-electrophilic-reactivity-of-the-biologically-active-marine-sesquiterpenoid-onchidal-and-model-compounds
#8
Melissa M Cadelis, Brent R Copp
The structure of the sesquiterpene onchidal ( 6 ), a component of the defensive secretion of the shell-less mollusc Onchidella binneyi , contains a masked α,β-unsaturated 1,4-dialdehyde moiety, the presence of which has been proposed to be the cause of the feeding deterrent activity exhibited by the mollusc. We have found onchidal acts as an electrophile, reacting rapidly with the model nucleophile n -pentylamine forming diastereomeric aminated pyrrole adducts. Somewhat surprisingly, no reaction was observed between onchidal and n -pentanethiol...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202475/a-general-and-atom-efficient-continuous-flow-approach-to-prepare-amines-amides-and-imines-via-reactive-n-chloramines
#9
Katherine E Jolley, Michael R Chapman, A John Blacker
Chloramines are an important class of reagents, providing a convenient source of chlorine or electrophilic nitrogen. However, the instability of these compounds is a problem which makes their isolation and handling difficult. To overcome these hazards, a continuous-flow approach is reported which generates and immediately reacts N -chloramines directly, avoiding purification and isolation steps. 2-Chloramines were produced from the reaction of styrenes with N -alkyl- N -sulfonyl- N -chloramines, whilst N -alkyl or N,N' -dialkyl- N -chloramines reacted with anisaldehyde in the presence of t -BuO2 H oxidant to afford amides...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202474/dynamic-light-scattering-studies-of-the-effects-of-salts-on-the-diffusivity-of-cationic-and-anionic-cavitands
#10
Anthony Wishard, Bruce C Gibb
Although alkali halide salts play key roles in all living systems, the physical models used to describe the properties of aqueous solutions of salts do not take into account specific ion-ion interactions. To identify specific ion-ion interactions possibly contributing to the aggregation of proteins, we have used dynamic light scattering (DLS) to probe the aggregation of charged cavitands. DLS measurements of negatively charged 1 in the presence of a range of alkali metal halides reveal no significant aggregation of host 1 as a function of the nature of the cation of the added salt...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202473/selective-formation-of-a-zwitterion-adduct-and-bicarbonate-salt-in-the-efficient-co-2-fixation-by-n-benzyl-cyclic-guanidine-under-dry-and-wet-conditions
#11
Yoshiaki Yoshida, Naoto Aoyagi, Takeshi Endo
The efficient CO2 fixation by N -benzyl cyclic guanidine 1 was achieved by bubbling dry CO2 through CH3 CN at 25 °C for 2 h. In addition, the zwitterion adduct 2 and bicarbonate salt 3 were selectively prepared from 1 under dry (in anhydrous CH3 CN) and wet (in CH3 CN containing an equimolar amount of water for 1 ) conditions, respectively. Both compounds 2 and 3 were isolated as white solids and their structures were characterized in detail by elemental analysis, FTIR-ATR, solid-state NMR, TGA, and DFT calculation...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202472/bi-mediated-allylation-of-aldehydes-in-bmim-br-a-mechanistic-investigation
#12
Mrunesh Koli, Sucheta Chatterjee, Subrata Chattopadhyay, Dibakar Goswami
The inexpensive room temperature ionic liquid (RTIL), [bmim][Br] has been found to be a superior medium for the Bi-mediated Barbier-type allylation of aldehydes compared to other conventional solvents. It plays the dual role of a solvent and a metal activator enabling higher yields of the products in a shorter reaction time using stoichiometric/near-stoichiometric amounts of reagents. Plausibly, [bmim][Br] activates Bi metal by a charge transfer mechanism. The 1 H VT-NMR studies suggested that both the allylating species, allylbismuth dibromide and diallylbismuth bromide, are generated in situ...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202471/synthesis-and-post-functionalization-of-alternate-linked-meta-para-2-n-1-n-thiacyclophanes
#13
Wout De Leger, Koen Adriaensen, Koen Robeyns, Luc Van Meervelt, Joice Thomas, Björn Meijers, Mario Smet, Wim Dehaen
In recent decades, considerable research attention has been devoted to new synthetic procedures for thiacyclophanes. Thiacyclophanes are widely used as host molecules for the molecular recognition of organic compounds as well as metals. Herein, we report the selective and high-yielding synthesis of novel alternate-linked- meta-para- thiacyclophanes. These novel thiacyclophanes are selectively synthesized in high-yielding procedures. Furthermore, post-functionalization of the phenolic moieties was successfully performed...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202470/synergistic-electrodeposition-of-bilayer-films-and-analysis-by-raman-spectroscopy
#14
Saadeldin E T Elmasly, Luca Guerrini, Joseph Cameron, Alexander L Kanibolotsky, Neil J Findlay, Karen Faulds, Peter J Skabara
A novel methodology towards fabrication of multilayer organic devices, employing electrochemical polymer growth to form PEDOT and PEDTT layers, is successfully demonstrated. Moreover, careful control of the electrochemical conditions allows the degree of doping to be effectively altered for one of the polymer layers. Raman spectroscopy confirmed the formation and doped states of the PEDOT/PEDTT bilayer. The electrochemical deposition of a bilayer containing a de-doped PEDTT layer on top of doped PEDOT is analogous to a solution-processed organic semiconductor layer deposited on top of a PEDOT:PSS layer without the acidic PSS polymer...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202469/tetrathiafulvalene-a-redox-switchable-building-block-to-control-motion-in-mechanically-interlocked-molecules
#15
REVIEW
Hendrik V Schröder, Christoph A Schalley
With the rise of artificial molecular machines, control of motion on the nanoscale has become a major contemporary research challenge. Tetrathiafulvalenes (TTFs) are one of the most versatile and widely used molecular redox switches to generate and control molecular motion. TTF can easily be implemented as functional unit into molecular and supramolecular structures and can be reversibly oxidized to a stable radical cation or dication. For over 20 years, TTFs have been key building blocks for the construction of redox-switchable mechanically interlocked molecules (MIMs) and their electrochemical operation has been thoroughly investigated...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202468/synthesis-of-1-4-imino-l-lyxitols-modified-at-c-5-and-their-evaluation-as-inhibitors-of-gh38-%C3%AE-mannosidases
#16
Maroš Bella, Sergej Šesták, Ján Moncoľ, Miroslav Koóš, Monika Poláková
A synthetic approach to 1,4-imino-L-lyxitols with various modifications at the C-5 position is reported. These imino-L-lyxitol cores were used for the preparation of a series of N -(4-halobenzyl)polyhydroxypyrrolidines. An impact of the C-5 modification on the inhibition and selectivity against GH38 α-mannosidases from Drosophila melanogaster , the Golgi (GMIIb) and lysosomal (LManII) mannosidases and commercial jack bean α-mannosidase from Canavalia ensiformis was evaluated. The modification at C-5 affected their inhibitory activity against the target GMIIb enzyme...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202467/hypervalent-iodine-compounds-for-anti-markovnikov-type-iodo-oxyimidation-of-vinylarenes
#17
Igor B Krylov, Stanislav A Paveliev, Mikhail A Syroeshkin, Alexander A Korlyukov, Pavel V Dorovatovskii, Yan V Zubavichus, Gennady I Nikishin, Alexander O Terent'ev
The iodo-oxyimidation of styrenes with the N -hydroxyimide/I2 /hypervalent iodine oxidant system was proposed. Among the examined hypervalent iodine oxidants (PIDA, PIFA, IBX, DMP) PhI(OAc)2 proved to be the most effective; yields of iodo-oxyimides are 34-91%. A plausible reaction pathway includes the addition of an imide- N -oxyl radical to the double C=C bond and trapping of the resultant benzylic radical by iodine. It was shown that the iodine atom in the prepared iodo-oxyimides can be substituted by various nucleophiles...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202466/evaluation-of-dispersion-type-metal%C3%A2-%C3%A2-%C3%A2-%C3%AF-arene-interaction-in-arylbismuth-compounds-an-experimental-and-theoretical-study
#18
Ana-Maria Preda, Małgorzata Krasowska, Lydia Wrobel, Philipp Kitschke, Phil C Andrews, Jonathan G MacLellan, Lutz Mertens, Marcus Korb, Tobias Rüffer, Heinrich Lang, Alexander A Auer, Michael Mehring
The dispersion type Bi···π arene interaction is one of the important structural features in the assembly process of arylbismuth compounds. Several triarylbismuth compounds and polymorphs are discussed and compared based on the analysis of single crystal X-ray diffraction data and computational studies. First, the crystal structures of polymorphs of Ph3 Bi ( 1 ) are described emphasizing on the description of London dispersion type bismuth···π arene interactions and other van der Waals interactions in the solid state and the effect of it on polymorphism...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202465/calix-6-arene-based-atropoisomeric-pseudo-2-rotaxanes
#19
Carmine Gaeta, Carmen Talotta, Placido Neri
Some examples of atropoisomeric pseudorotaxanes in which the isomerism arises by the different conformations adopted by the wheel are reported here. Upon threading hexahexyloxycalix[6]arene 1 with ammonium axles 2 + or 3 + , bearing biphenyl or trifluoromethylbenzyl moieties, respectively, two atropoisomeric pseudorotaxanes were formed in which the calix[6]-wheel 1 adopts the 1,2,3-alternate and cone conformations. The interconversion between them cannot be obtained by simple rotation around the ArCH2 Ar bonds of the calixarene wheel, which is blocked by the presence of the axle inside its cavity...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30202464/studies-towards-the-synthesis-of-hyperireflexolide-a
#20
G Hari Mangeswara Rao
The first approach to hyperireflexolide A, based on the synthesis of γ-lactone-fused cyclopentane 5 , a functionalized key intermediate, is presented. Compound 5 is involved in hydrolysis, α-allylation at C-8 and α-methylation at C-10 stereoselectively from the convex face. Then it is subjected to cross metathesis to give α , β-unsaturated ketone 11 as precursor in the total synthesis of hyperireflexolide A.
2018: Beilstein Journal of Organic Chemistry
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