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Beilstein Journal of Organic Chemistry

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https://www.readbyqxmd.com/read/29259673/electrophilic-trifluoromethylselenolation-of-terminal-alkynes-with-se-trifluoromethyl-4-methylbenzenesulfonoselenoate
#1
Clément Ghiazza, Anis Tlili, Thierry Billard
Herein the nucleophilic addition of Se-(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.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29259672/regioselective-decarboxylative-addition-of-malonic-acid-and-its-mono-thio-esters-to-4-trifluoromethylpyrimidin-2-1h-ones
#2
Sergii V Melnykov, Andrii S Pataman, Yurii V Dmytriv, Svitlana V Shishkina, Mykhailo V Vovk, Volodymyr A Sukach
Background: 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. Results: In this paper we show that 4-trifluoromethylpyrimidin-2(1H)-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...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29259671/palladium-catalyzed-heck-type-reaction-of-secondary-trifluoromethylated-alkyl-bromides
#3
Tao Fan, Wei-Dong Meng, Xingang Zhang
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.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29259670/a-semisynthesis-of-3-o-ethyl-5-6-dihydrospinosyn-j-based-on-the-spinosyn-a-aglycone
#4
Kai Zhang, Shenglan Liu, Anjun Liu, Hongxin Chai, Jiarong Li, Lamusi A
Spinetoram, a mixture of 3'-O-ethyl-5,6-dihydrospinosyn J (XDE-175-J, major component) and 3'-O-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'-O-ethyl-5,6-dihydrospinosyn J from spinosyn A aglycone. The C9-OH and C17-OH of the aglycone are successively connected to 3-O-ethyl-2,4-di-O-methylrhamnose and D-forosamine after selective protection and deprotection steps...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29259669/consecutive-hydrazino-ugi-azide-reactions-synthesis-of-acylhydrazines-bearing-1-5-disubstituted-tetrazoles
#5
Angélica de Fátima S Barreto, Veronica Alves Dos Santos, Carlos Kleber Z Andrade
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. Our strategy was accomplished in only three steps: first, a one-pot hydrazino-Ugi-azide four-component reaction; second a hydrazinolysis and finally an additional hydrazino-Ugi-azide reaction...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29259668/what-contributes-to-an-effective-mannose-recognition-domain
#6
REVIEW
Christoph P Sager, Deniz Eriş, Martin Smieško, Rachel Hevey, Beat Ernst
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...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29259667/synthesis-of-1-3-cis-disubstituted-sterically-encumbered-imidazolidinone-organocatalysts
#7
Jan Wallbaum, Daniel B Werz
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.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29259666/rh-ii-mediated-domino-4-1-annulation-of-%C3%AE-cyanothioacetamides-using-diazoesters-a-new-entry-for-the-synthesis-of-multisubstituted-thiophenes
#8
Jury J Medvedev, Ilya V Efimov, Yuri M Shafran, Vitaliy V Suslonov, Vasiliy A Bakulev, Valerij A Nikolaev
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)...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29259665/a-novel-synthetic-approach-to-hydroimidazo-1-5-b-pyridazines-by-the-recyclization-of-itaconimides-and-hplc-hrms-monitoring-of-the-reaction-pathway
#9
Dmitry Yu Vandyshev, Khidmet S Shikhaliev, Andrey Yu Potapov, Michael Yu Krysin, Fedor I Zubkov, Lyudmila V Sapronova
The novel cascade two-stage reaction between itaconimides and 1,2-diamino-4-phenylimidazole proceeds regio- and chemoselectively to form tetrahydroimidazo[1,5-b]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.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29259664/a-concise-flow-synthesis-of-indole-3-carboxylic-ester-and-its-derivatisation-to-an-auxin-mimic
#10
Marcus Baumann, Ian R Baxendale, Fabien Deplante
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.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29259663/15n-labelling-and-structure-determination-of-adamantylated-azolo-azines-in-solution
#11
Sergey L Deev, Alexander S Paramonov, Tatyana S Shestakova, Igor A Khalymbadzha, Oleg N Chupakhin, Julia O Subbotina, Oleg S Eltsov, Pavel A Slepukhin, Vladimir L Rusinov, Alexander S Arseniev, Zakhar O Shenkarev
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 conventional 1H-1H and 1H-13C NMR correlation experiments (COSY and HMBC, respectively) or nuclear Overhauser effect spectroscopy (NOESY or ROESY)...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29259662/pyrene-nucleobase-conjugates-synthesis-oligonucleotide-binding-and-confocal-bioimaging-studies
#12
Artur Jabłoński, Yannic Fritz, Hans-Achim Wagenknecht, Rafał Czerwieniec, Tytus Bernaś, Damian Trzybiński, Krzysztof Woźniak, Konrad Kowalski
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)CH2CH2-thymine (2) conjugate reveals dimers of molecules 2 stabilized by hydrogen bonds between the thymine moieties. The photochemical characterization showed structure-dependent fluorescence properties of the investigated compounds. The conjugates bearing a carbonyl function represent weak emitters as compared to compounds with a hydroxy function in the linker...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29259661/synthesis-and-supramolecular-properties-of-regioisomers-of-mononaphthylallyl-derivatives-of-%C3%AE-cyclodextrin
#13
Markéta Bláhová, Sergey K Filippov, Lubomír Kováčik, Jiří Horský, Simona Hybelbauerová, Zdenka Syrová, Tomáš Křížek, Jindřich Jindřich
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 2I-O-, 3I-O-, and 6I-O-(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-O-allyl derivatives of γ-CD and 2-vinylnaphthalene which gives yields of about 16-25% (2-5% starting from γ-CD)...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29234477/one-pot-three-component-route-for-the-synthesis-of-s-trifluoromethyl-dithiocarbamates-using-togni-s-reagent
#14
Azim Ziyaei Halimehjani, Martin Dračínský, Petr Beier
A one-pot three-component route for the synthesis of S-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. A variable temperature NMR study revealed a rotational barrier of 14.6, 18.8, and 15.9 kcal/mol for the C-N bond in the dithiocarbamate moiety of piperidine, pyrrolidine, and diethylamine adducts, respectively...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29234476/syntheses-structures-and-stabilities-of-aliphatic-and-aromatic-fluorous-iodine-i-and-iodine-iii-compounds-the-role-of-iodine-lewis-basicity
#15
Tathagata Mukherjee, Soumik Biswas, Andreas Ehnbom, Subrata K Ghosh, Ibrahim El-Zoghbi, Nattamai Bhuvanesh, Hassan S Bazzi, John A Gladysz
The title molecules are sought in connection with various synthetic applications. The aliphatic fluorous alcohols Rfn CH2OH (Rfn = CF3(CF2) n-1; n = 11, 13, 15) are converted to the triflates Rfn CH2OTf (Tf2O, pyridine; 22-61%) and then to Rfn CH2I (NaI, acetone; 58-69%). Subsequent reactions with NaOCl/HCl give iodine(III) dichlorides Rfn CH2ICl2 (n = 11, 13; 33-81%), which slowly evolve Cl2. The ethereal fluorous alcohols CF3CF2CF2O(CF(CF3)CF2O) x CF(CF3)CH2OH (x = 2-5) are similarly converted to triflates and then to iodides, but efforts to generate the corresponding dichlorides fail...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29234475/a-permutation-approach-to-the-assignment-of-the-configuration-to-diastereomeric-tetrads-by-comparison-of-experimental-and-ab-initio-calculated-differences-in-nmr-data
#16
Przemysław J Boratyński
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 diastereomeric Cinchona alkaloid derivatives, where 13C NMR data always identified the proper configuration. The presented approach is also an attempt to quantify the assignment by exclusion.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29234474/diastereoselective-mannich-reactions-of-pseudo-c2-symmetric-glutarimide-with-activated-imines
#17
Tatsuya Ishikawa, Tomoko Kawasaki-Takasuka, Toshio Kubota, Takashi Yamazaki
As an extension of the boron enolate-based aldol reactions, the oxazolidinone-installed bisimide 1a from 3-(trifluoromethyl)glutaric acid was employed for Mannich reactions with tosylated imines 2 as electrophiles to successfully obtain the corresponding adducts in a stereoselective manner.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29234473/synthesis-of-naturally-derived-macromolecules-through-simplified-electrochemically-mediated-atrp
#18
Paweł Chmielarz, Tomasz Pacześniak, Katarzyna Rydel-Ciszek, Izabela Zaborniak, Paulina Biedka, Andrzej Sobkowiak
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(tert-butyl acrylate) (PtBA) side arms was synthesized via a simplified electrochemically mediated ATRP (seATRP), utilizing only 78 ppm by weight (wt) of a catalytic CuII complex. To demonstrate the possibility of temporal control, seATRP was carried out utilizing a multiple-step potential electrolysis...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29234472/herpetopanone-a-diterpene-from-herpetosiphon-aurantiacus-discovered-by-isotope-labeling
#19
Xinli Pan, Nicole Domin, Sebastian Schieferdecker, Hirokazu Kage, Martin Roth, Markus Nett
The genome of the predatory bacterium Herpetosiphon aurantiacus 114-95T harbors a number of biosynthesis genes, including four terpene cyclase genes. To identify the terpenes biosynthesized from H. aurantiacus 114-95T, we fed the strain with 13C-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...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29234471/hydrolysis-polarity-and-conformational-impact-of-c-terminal-partially-fluorinated-ethyl-esters-in-peptide-models
#20
Vladimir Kubyshkin, Nediljko Budisa
Fluorinated moieties are highly valuable to chemists due to the sensitive NMR detectability of the 19F 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. One of these methods involves esterification of the C-terminus of peptides using a diazomethane species...
2017: Beilstein Journal of Organic Chemistry
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