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Beilstein Journal of Organic Chemistry

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https://www.readbyqxmd.com/read/28503210/synthesis-of-ribavirin-2-me-c-nucleoside-analogues
#1
Fanny Cosson, Aline Faroux, Jean-Pierre Baltaze, Jonathan Farjon, Régis Guillot, Jacques Uziel, Nadège Lubin-Germain
An efficient synthetic pathway leading to two carbonated analogues of ribavirin is described. The key-steps in the synthesis of these ribosyltriazoles bearing a quaternary carbon atom in the 2'-position are an indium-mediated alkynylation and a 1,3-dipolar cyclization.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28503209/continuous-flow-processes-for-the-catalytic-partial-hydrogenation-reaction-of-alkynes
#2
REVIEW
Carmen Moreno-Marrodan, Francesca Liguori, Pierluigi Barbaro
The catalytic partial hydrogenation of substituted alkynes to alkenes is a process of high importance in the manufacture of several market chemicals. The present paper shortly reviews the heterogeneous catalytic systems engineered for this reaction under continuous flow and in the liquid phase. The main contributions appeared in the literature from 1997 up to August 2016 are discussed in terms of reactor design. A comparison with batch and industrial processes is provided whenever possible.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28503208/fluorinated-cyclohexanes-synthesis-of-amine-building-blocks-of-the-all-cis-2-3-5-6-tetrafluorocyclohexylamine-motif
#3
Tetiana Bykova, Nawaf Al-Maharik, Alexandra M Z Slawin, David O'Hagan
This paper reports the synthesis of three amine stereoisomers 5a-c of the tetrafluorocyclohexyl ring system, as building blocks for discovery chemistry programmes. The synthesis starts from a Birch reduction of benzonitrile, followed by an in situ methyl iodide quench. The resultant 2,5-cyclohexadiene was progressed via double epoxidations and then hydrofluorination ring opening reactions. The resultant fluorohydrin moieties were then converted to different stereoisomers of the tetrafluorocyclohexyl ring system, and then reductive hydrogenation of the nitrile delivered three amine stereoisomers...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28503207/membrane-properties-of-hydroxycholesterols-related-to-the-brain-cholesterol-metabolism
#4
Malte Hilsch, Ivan Haralampiev, Peter Müller, Daniel Huster, Holger A Scheidt
Compared to cholesterol, hydroxycholesterols contain an additional hydroxy group in the alkyl chain and are able to efficiently cross the brain-blood barrier. Therefore, they are responsible for the sterol transfer between brain and circulation. The current study compares the membrane properties of several hydroxycholesterols with those of cholesterol using (2)H NMR spectroscopy, a membrane permeability assay, and fluorescence microscopy experiments. It is shown that hydroxycholesterols do not exert the unique impact on membrane properties characteristic for cholesterol with regard to the influence on lipid chain order, membrane permeability and formation of lateral domains...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28503206/inclusion-complexes-of-%C3%AE-cyclodextrin-with-tricyclic-drugs-an-x-ray-diffraction-nmr-and-molecular-dynamics-study
#5
Franca Castiglione, Fabio Ganazzoli, Luciana Malpezzi, Andrea Mele, Walter Panzeri, Giuseppina Raffaini
Tricyclic fused-ring cyclobenzaprine (1) and amitriptyline (2) form 1:1 inclusion complexes with β-cyclodextrin (β-CD) in the solid state and in water solution. Rotating frame NOE experiments (ROESY) showed the same geometry of inclusion for both 1/β-CD and 2/β-CD complexes, with the aromatic ring system entering the cavity from the large rim of the cyclodextrin and the alkylammonium chain protruding out of the cavity and facing the secondary OH rim. These features matched those found in the molecular dynamics (MD) simulations in solution and in the solid state from single-crystal X-ray diffraction of 1/β-CD and 2/β-CD complexes...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28503205/substitution-of-fluorine-in-m-c6f5bf3-with-organolithium-compounds-distinctions-between-o-and-n-nucleophiles
#6
Anton Yu Shabalin, Nicolay Yu Adonin, Vadim V Bardin
Borates M[C6F5BF3] (M = K, Li, Bu4N) react with organolithium compounds, RLi (R = Me, Bu, Ph), in 1,2-dimethoxyethane or diglyme to give M[4-RC6F4BF3] and M[2-RC6F4BF3]. When R is Me or Bu, the nucleophilic substitution of the fluorine atom at the para position to boron is the predominant route. When R = Ph, the ratio M[4-RC6F4BF3]/M[2-RC6F4BF3] is ca. 1:1. Substitution of the fluorine atom at the ortho position to boron is solely caused by the coordination of RLi via the lithium atom with the fluorine atoms of the BF3 group...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28503204/ultrasound-promoted-organocatalytic-enamine-azide-3-2-cycloaddition-reactions-for-the-synthesis-of-arylselanyl-phenyl-1h-1-2-3-triazol-4-yl-ketones
#7
Gabriel P Costa, Natália Seus, Juliano A Roehrs, Raquel G Jacob, Ricardo F Schumacher, Thiago Barcellos, Rafael Luque, Diego Alves
The use of sonochemistry is described in the organocatalytic enamine-azide [3 + 2] cycloaddition between 1,3-diketones and aryl azidophenyl selenides. These sonochemically promoted reactions were found to be amenable to a range of 1,3-diketones or aryl azidophenyl selenides, providing an efficient access to new ((arylselanyl)phenyl-1H-1,2,3-triazol-4-yl)ketones in good to excellent yields and short reaction times. In addition, this protocol was extended to β-keto esters, β-keto amides and α-cyano ketones...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28503203/fluorescent-carbon-dots-from-mono-and-polysaccharides-synthesis-properties-and-applications
#8
REVIEW
Stephen Hill, M Carmen Galan
Fluorescent carbon dots (FCDs) are an emerging class of nanomaterials made from carbon sources that have been hailed as potential non-toxic replacements to traditional semiconductor quantum dots (QDs). Particularly in the areas of live imaging and drug delivery, due to their water solubility, low toxicity and photo- and chemical stability. Carbohydrates are readily available chiral biomolecules in nature which offer an attractive and cheap starting material from which to synthesise FCDs with distinct features and interesting applications...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28487761/how-and-why-kinetics-thermodynamics-and-chemistry-induce-the-logic-of-biological-evolution
#9
Addy Pross, Robert Pascal
Thermodynamic stability, as expressed by the Second Law, generally constitutes the driving force for chemical assembly processes. Yet, somehow, within the living world most self-organisation processes appear to challenge this fundamental rule. Even though the Second Law remains an inescapable constraint, under energy-fuelled, far-from-equilibrium conditions, populations of chemical systems capable of exponential growth can manifest another kind of stability, dynamic kinetic stability (DKS). It is this stability kind based on time/persistence, rather than on free energy, that offers a basis for understanding the evolutionary process...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28487760/isoxazole-derivatives-as-new-nitric-oxide-elicitors-in-plants
#10
Anca Oancea, Emilian Georgescu, Florentina Georgescu, Alina Nicolescu, Elena Iulia Oprita, Catalina Tudora, Lucian Vladulescu, Marius-Constantin Vladulescu, Florin Oancea, Calin Deleanu
Several 3,5-disubstituted isoxazoles were obtained in good yields by regiospecific 1,3-dipolar cycloaddition reactions between aromatic nitrile oxides, generated in situ from the corresponding hydroxyimidoyl chlorides, with non-symmetrical activated alkynes in the presence of catalytic amounts of copper(I) iodide. Effects of 3,5-disubstituted isoxazoles on nitric oxide and reactive oxygen species generation in Arabidopsis tissues was studied using specific diaminofluoresceine dyes as fluorescence indicators...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28487759/sulfamide-chemistry-applied-to-the-functionalization-of-self-assembled-monolayers-on-gold-surfaces
#11
Loïc Pantaine, Vincent Humblot, Vincent Coeffard, Anne Vallée
Aniline-terminated self-assembled monolayers (SAMs) on gold surfaces have successfully reacted with ArSO2NHOSO2Ar (Ar = 4-MeC6H4 or 4-FC6H4) resulting in monolayers with sulfamide moieties and different end groups. Moreover, the sulfamide groups on the SAMs can be hydrolyzed showing the partial regeneration of the aniline surface. SAMs were characterized by water contact angle (WCA) measurements, Fourier-transform infrared reflection absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS)...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28487758/exploring-endoperoxides-as-a-new-entry-for-the-synthesis-of-branched-azasugars
#12
Svenja Domeyer, Mark Bjerregaard, Henrik Johansson, Daniel Sejer Pedersen
A new class of nitrogen-containing endoperoxides were synthesised by a photochemical [4 + 2]-cycloaddition between a diene and singlet oxygen. The endoperoxides were dihydroxylated and protected to provide a series of endoperoxide building blocks for organic synthesis, with potential use as precursors for the synthesis of branched azasugars. Preliminary exploration of the chemistry of these building blocks provided access to a variety of derivatives including tetrahydrofurans, epoxides and protected amino-tetraols...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28487757/unpredictable-cycloisomerization-of-1-11-dien-6-ynes-by-a-common-cobalt-catalyst
#13
Abdusalom A Suleymanov, Dmitry V Vasilyev, Valentin V Novikov, Yulia V Nelyubina, Dmitry S Perekalin
1,11-Dien-6-ynes undergo cycloisomerization in the presence of the cobalt catalytic system CoBr2/phosphine ligand/Zn/ZnI2 giving cyclohexene, diene or cyclopropane structures depending on the type of the phosphine ligand. This unpredictable behaviour suggests that, although the availability of the cobalt catalytic system is appealing, the development of well-defined catalysts is desirable for further progress.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28487756/n-propargylamines-versatile-building-blocks-in-the-construction-of-thiazole-cores
#14
REVIEW
S Arshadi, E Vessally, L Edjlali, R Hosseinzadeh-Khanmiri, E Ghorbani-Kalhor
Thiazoles and their hydrogenated analogues are not only key structural units in a wide variety of natural products but they also constitute important building blocks in medicinal chemistry. Therefore, the synthesis of these compounds using new protocols is always interesting. It is well known that N-propargylamines can undergo a number of cyclization reactions to produce various nitrogen-containing heterocycles. In this review, we highlight the most important developments on the synthesis of thiazole and its derivatives starting from N-propargylamines...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28487755/conjecture-and-hypothesis-the-importance-of-reality-checks
#15
David Deamer
In origins of life research, it is important to understand the difference between conjecture and hypothesis. This commentary explores the difference and recommends alternative hypotheses as a way to advance our understanding of how life can begin on the Earth and other habitable planets. As an example of how this approach can be used, two conditions have been proposed for sites conducive to the origin of life: hydrothermal vents in salty seawater, and fresh water hydrothermal fields associated with volcanic landmasses...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28487754/synthesis-of-new-pyrrolidine-based-organocatalysts-and-study-of-their-use-in-the-asymmetric-michael-addition-of-aldehydes-to-nitroolefins
#16
Alejandro Castán, Ramón Badorrey, José A Gálvez, María D Díaz-de-Villegas
New pyrrolidine-based organocatalysts with a bulky substituent at C2 were synthesized from chiral imines derived from (R)-glyceraldehyde acetonide by diastereoselective allylation followed by a sequential hydrozirconation/iodination reaction. The new compounds were found to be effective organocatalysts for the Michael addition of aldehydes to nitroolefins and enantioselectivities up to 85% ee were achieved.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28405239/transition-metal-catalyzed-synthesis-of-phenols-and-aryl-thiols
#17
REVIEW
Yajun Liu, Shasha Liu, Yan Xiao
Phenols and aryl thiols are fundamental building blocks in organic synthesis and final products with interesting biological activities. Over the past decades, substantial progress has been made in transition-metal-catalyzed coupling reactions, which resulted in the emergence of new methods for the synthesis of phenols and aryl thiols. Aryl halides have been extensively studied as substrates for the synthesis of phenols and aryl thiols. In very recent years, C-H activation represents a powerful strategy for the construction of functionalized phenols directly from various arenes...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28405238/derivatives-of-the-triaminoguanidinium-ion-5-acylation-of-triaminoguanidines-leading-to-symmetrical-tris-acylamino-guanidines-and-mesoionic-1-2-4-triazolium-3-aminides
#18
Jan Szabo, Julian Greiner, Gerhard Maas
Depending on the reaction conditions, N,N',N''-tris(benzylamino)guanidinium salts can react with carboxylic acid chlorides to form either symmetrical N,N',N''-tris(N-acyl-N-benzylamido)guanidines 6 or mesoionic 4-amino-1,2,4-triazolium-3-hydrazinides 7. The latter were converted into 1,2,4-triazolium salts by protonation or methylation at the hydrazinide nitrogen atom. Neutral 1,2,4-triazoles 10 were obtained by catalytic hydrogenation of an N-benzyl derivative. Crystal structure analyses of a 4-benzylamino-1,2,4-triazolium-3-hydrazinide and of two derived 1,2,4-triazolium salts are presented...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28405237/studies-directed-toward-the-exploitation-of-vicinal-diols-in-the-synthesis-of-nebivolol-intermediates
#19
Runjun Devi, Sajal Kumar Das
While the exploitation of the Sharpless asymmetric dihydroxylation as the source of chirality in the synthesis of acyclic molecules and saturated heterocycles has been tremendous, its synthetic utility toward chiral benzo-annulated heterocycles is relatively limited. Thus, in the search for wider applications of Sharpless asymmetric dihydroxylation-derived diols for the synthesis of benzo-annulated heterocycles, we report herein our studies in the asymmetric synthesis of (R)-1-((R)-6-fluorochroman-2-yl)ethane-1,2-diol, (R)-1-((S)-6-fluorochroman-2-yl)ethane-1,2-diol and (S)-6-fluoro-2-((R)-oxiran-2-yl)chroman, which have been used as late-stage intermediates for the asymmetric synthesis of the antihypertensive drug (S,R,R,R)-nebivolol...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28405236/pd-and-cu-catalyzed-approaches-in-the-syntheses-of-new-cholane-aminoanthraquinone-pincer-like-ligands
#20
Nikolay V Lukashev, Gennadii A Grabovyi, Dmitry A Erzunov, Alexey V Kazantsev, Gennadij V Latyshev, Alexei D Averin, Irina P Beletskaya
Cu- and Pd-catalyzed arylation of aminocholanes has been described for the first time. While this Cu-catalyzed protocol provides high yields in reactions of aminocholanes with iodoarenes, Pd catalysis was found to be preferable for the reactions of aminocholanes with dichloroanthraquinones. UV-vis titration of bis(cholanylamino)anthraquinones with a series of cations demonstrated their high binding affinity to Cu(2+), Al(3+), and Cr(3+).
2017: Beilstein Journal of Organic Chemistry
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