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Beilstein Journal of Organic Chemistry

Marcelo D T Torres, Gislaine P Andrade, Roseli H Sato, Cibele N Pedron, Tania M Manieri, Giselle Cerchiaro, Anderson O Ribeiro, Cesar de la Fuente-Nunez, Vani X Oliveira
About 1 in 8 U.S. women (≈12%) will develop invasive breast cancer over the course of their lifetime. Surgery, chemotherapy, radiotherapy, and hormone manipulation constitute the major treatment options for breast cancer. Here, we show that both a natural antimicrobial peptide (AMP) derived from wasp venom (decoralin, Dec-NH2 ), and its synthetic variants generated via peptide design, display potent activity against cancer cells. We tested the derivatives at increasing doses and observed anticancer activity at concentrations as low as 12...
2018: Beilstein Journal of Organic Chemistry
Mokgethwa Bruce Marakalala, Edwin M Mmutlane, Henok H Kinfe
Sulfur-containing natural products are ubiquitous in nature, their most abundant source being marine organisms since sulfur, in the form of the sulfate ion, is the second most abundant anion in sea water after chloride. As part of natural products, sulfur can appear in a multitude of combinations and oxidation states: thiol, sulfide (acyclic or heterocyclic), disulfide, sulfoxide, sulfonate, thioaminal, hemithioacetal, various thioesters, thiocarbamate and isothiocyanate. This review article focuses on β-hydroxy sulfides and analogs; their presence in natural products, general protocols for their synthesis, and examples of their application in target oriented synthesis...
2018: Beilstein Journal of Organic Chemistry
Ying Han, Li-Ming Xu, Cui-Yun Nie, Shuo Jiang, Jing Sun, Chao-Guo Yan
The pillar[5]arene mono- and di(oxyalkoxy)benzoic acids were successfully prepared in high yields by sequential alkylation of ω-bromoalkoxy-substituted pillar[5]arenes with methyl or ethyl p -hydroxybenzoate followed by a hydrolytic reaction under basic conditions. Under catalysis of HOBt/EDCl, the amidation reaction of pillar[5]arene mono(oxybutoxy)benzoic acid with monoamido-functionalized pillar[5]arenes afforded diamido-bridged bis-pillar[5]arenes. 1 H NMR and 2D NOESY spectra clearly indicated that [1]rotaxanes were formed by insertion of longer diaminoalkylene unit into the cavity of one pillar[5]arene with another pillar[5]arene acting as a stopper...
2018: Beilstein Journal of Organic Chemistry
Ugo Azzena, Massimo Carraro, Gloria Modugno, Luisa Pisano, Luigi Urtis
The application of heterogeneous catalysis and green solvents to the set up of widely employed reactions is a challenge in contemporary organic chemistry. We applied such an approach to the synthesis and further conversion of tetrahydropyranyl ethers, an important class of compounds widely employed in multistep syntheses. Several alcohols and phenols were almost quantitatively converted into the corresponding tetrahydropyranyl ethers in cyclopentyl methyl ether or 2-methyltetrahydrofuran employing NH4 HSO4 supported on SiO2 as a recyclable acidic catalyst...
2018: Beilstein Journal of Organic Chemistry
Dominic Bernhard, Fabian Dietrich, Mariyam Fatima, Cristóbal Pérez, Hannes C Gottschalk, Axel Wuttke, Ricardo A Mata, Martin A Suhm, Melanie Schnell, Markus Gerhards
The structure of the isolated aggregate of phenyl vinyl ether and methanol is studied by combining a multi-spectroscopic approach and quantum-chemical calculations in order to investigate the delicate interplay of noncovalent interactions. The complementary results of vibrational and rotational spectroscopy applied in molecular beam experiments reveal the preference of a hydrogen bond of the methanol towards the ether oxygen (OH∙∙∙O) over the π-docking motifs via the phenyl and vinyl moieties, with an additional less populated OH∙∙∙P(phenyl)-bound isomer detected only by microwave spectroscopy...
2018: Beilstein Journal of Organic Chemistry
Vyacheslav I Supranovich, Vitalij V Levin, Marina I Struchkova, Jinbo Hu, Alexander D Dilman
A method for the reductive difluoroalkylation of electron-deficient alkenes using 1,1-difluorinated iodides mediated by irradiation with blue light is described. The reaction involves radical addition of 1,1-difluorinated radicals at the double bond followed by hydrogen atom transfer from sodium cyanoborohydride.
2018: Beilstein Journal of Organic Chemistry
Julia Hain, Patrick Rollin, Werner Klaffke, Thisbe K Lindhorst
The Mitsunobu reaction basically consists in the conversion of an alcohol into an ester under inversion of configuration, employing a carboxylic acid and a pair of two auxiliary reagents, mostly triphenylphosphine and a dialkyl azodicarboxylate. This reaction has been frequently used in carbohydrate chemistry for the modification of sugar hydroxy groups. Modification at the anomeric position, leading mainly to anomeric esters or glycosides, is of particular importance in the glycosciences. Therefore, this review focuses on the use of the Mitsunobu reaction for modifications of sugar hemiacetals...
2018: Beilstein Journal of Organic Chemistry
Yuichi Yoshimura, Hideaki Wakamatsu, Yoshihiro Natori, Yukako Saito, Noriaki Minakawa
To synthesize nucleoside and oligosaccharide derivatives, we often use a glycosylation reaction to form a glycoside bond. Coupling reactions between a nucleobase and a sugar donor in the former case, and the reaction between an acceptor and a sugar donor of in the latter are carried out in the presence of an appropriate activator. As an activator of the glycosylation, a combination of a Lewis acid catalyst and a hypervalent iodine was developed for synthesizing 4'-thionucleosides, which could be applied for the synthesis of 4'-selenonucleosides as well...
2018: Beilstein Journal of Organic Chemistry
Livia Polgár, Eszter Lajkó, Pál Soós, Orsolya Láng, Marilena Manea, Béla Merkely, Gábor Mező, László Kőhidai
Background: Cardiomyopathy induced by the chemotherapeutic agents doxorubicin and daunorubicin is a major limiting factor for their application in cancer therapy. Chemotactic drug targeting potentially increases the tumor selectivity of drugs and decreases their cardiotoxicity. Increased expression of gonadotropin-releasing hormone (GnRH) receptors on the surface of tumor cells has been reported. Thus, the attachment of the aforementioned chemotherapeutic drugs to GnRH-based peptides may result in compounds with increased therapeutic efficacy...
2018: Beilstein Journal of Organic Chemistry
Tile Gieshoff, Vinh Trieu, Jan Heijl, Siegfried R Waldvogel
Organic carbonates are an important source for polycarbonate synthesis. However, their synthesis generally requires phosgene, sophisticated catalysts, harsh reaction conditions, or other highly reactive chemicals. We present the first direct electrochemical generation of mesityl methyl carbonate by C-H activation. Although this reaction pathway is still challenging concerning scope and efficiency, it outlines a new strategy for carbonate generation.
2018: Beilstein Journal of Organic Chemistry
Liu-Pan Yang, Song-Bo Lu, Arto Valkonen, Fangfang Pan, Kari Rissanen, Wei Jiang
Large amplitude conformational change is one of the features of biomolecular recognition and is also the basis for allosteric effects and signal transduction in functional biological systems. However, synthetic receptors with controllable conformational changes are rare. In this article, we present a thorough study on the host-guest chemistry of a conformationally adaptive macrocycle, namely per- O -ethoxyzorb[4]arene ( ZB4 ). Similar to per- O -ethoxyoxatub[4]arene, ZB4 is capable of accommodating a wide range of organic cations...
2018: Beilstein Journal of Organic Chemistry
Timo Weinrich, Eva A Jaumann, Ute M Scheffer, Thomas F Prisner, Michael W Göbel
TEMPO spin labels protected with 2-nitrobenzyloxymethyl groups were attached to the amino residues of three different nucleosides: deoxycytidine, deoxyadenosine, and adenosine. The corresponding phosphoramidites could be incorporated by unmodified standard procedures into four different self-complementary DNA and two RNA oligonucleotides. After photochemical removal of the protective group, elimination of formic aldehyde and spontaneous air oxidation, the nitroxide radicals were regenerated in high yield. The resulting spin-labeled palindromic duplexes could be directly investigated by PELDOR spectroscopy without further purification steps...
2018: Beilstein Journal of Organic Chemistry
Lucky S Mulwa, Rolf Jansen, Dimas F Praditya, Kathrin I Mohr, Patrick W Okanya, Joachim Wink, Eike Steinmann, Marc Stadler
Lanyamycin ( 1 / 2 ), a secondary metabolite occurring as two epimers, was isolated from the myxobacterium Sorangium cellulosum , strain Soce 481. The structures of both epimers were elucidated from HRESIMS and 1D and 2D NMR data and the relative configuration of their macrolactone ring was assigned based on NOE and vicinal 1 H NMR coupling constants and by calculation of a 3D model. Lanyamycin inhibited HCV infection into mammalian liver cells with an IC50 value of 11.8 µM, and exhibited a moderate cytotoxic activity against the mouse fibroblast cell line L929 and the human nasopharyngeal cell line KB3 with IC50 values of 3...
2018: Beilstein Journal of Organic Chemistry
Santhivardhana Reddy Yetra, Zhigao Shen, Hui Wang, Lutz Ackermann
Versatile C-H amidations of synthetically useful ferrocenes were accomplished by weakly-coordinating thiocarbonyl-assisted cobalt catalysis. Thus, carboxylates enabled ferrocene C-H nitrogenations with dioxazolones, featuring ample substrate scope and robust functional group tolerance. Mechanistic studies provided strong support for a facile organometallic C-H activation manifold.
2018: Beilstein Journal of Organic Chemistry
Eric Detmar, Valentin Müller, Daniel Zell, Lutz Ackermann, Martin Breugst
Carboxylate-assisted cobalt(III)-catalyzed C-H cyanations are highly efficient processes for the synthesis of (hetero)aromatic nitriles. We have now analyzed the cyanation of differently substituted 2-phenylpyridines in detail computationally by density functional theory and also experimentally. Based on our investigations, we propose a plausible reaction mechanism for this transformation that is in line with the experimental observations. Additional calculations, including NCIPLOT, dispersion interaction densities, and local energy decomposition analysis, for the model cyanation of 2-phenylpyridine furthermore highlight that London dispersion is an important factor that enables this challenging C-H transformation...
2018: Beilstein Journal of Organic Chemistry
Nicole C Neyt, Darren L Riley
We recently reported a novel hybrid batch-flow synthesis of the antipsychotic drug clozapine in which the reduction of a nitroaryl group is described under flow conditions using sodium dithionite. We now report the expansion of this method to include the reduction of aldehydes. The method developed affords yields which are comparable to those under batch conditions, has a reduced reaction time and improved space-time productivity. Furthermore, the approach allows the selective reduction of aldehydes in the presence of ketones and has been demonstrated as a continuous process...
2018: Beilstein Journal of Organic Chemistry
Gwendal Grelier, Benjamin Darses, Philippe Dauban
Most of the polyvalent organoiodine compounds derive from iodoarenes, which are released in stoichiometric amounts in any reaction mediated by λ3 - or λ5 -iodanes. In parallel to the development of solid-supported reagents or reactions catalytic in iodine, a third strategy has emerged to address this issue in terms of sustainability. The atom-economy of transformations involving stoichiometric amounts of λ3 - or λ5 -iodanes, thus, has been improved by designing tandem reactions that allows for incorporating the aryl motif into the products through a subsequent one-pot nucleophilic addition or catalytic coupling reaction...
2018: Beilstein Journal of Organic Chemistry
Alberto Spinella, Marco Russo, Antonella Di Vincenzo, Delia Chillura Martino, Paolo Lo Meo
New calixarene-based nanosponges ( Ca NSs), i.e., hyper-reticulated polymers constituted by calixarene monomer units joined by means of bis(1,2,3-trialzolyl)alkyl linkers, were synthesized, characterized and subjected to preliminary tests to assess their supramolecular absorption abilities towards a set of suitable organic guests, selected as pollutant models. The synthesis was accomplished by means of a CuAAC reaction between a tetrakis(propargyloxy)calix[4]arene and an alkyl diazide. The formation of the polymeric network was assessed by means of FTIR and 13 C{1 H} CP-MAS solid-state NMR techniques, whereas morphological characterization was provided by SEM microghaphy...
2018: Beilstein Journal of Organic Chemistry
Gabriella Kervefors, Antonia Becker, Chandan Dey, Berit Olofsson
A transition metal-free formal synthesis of phenoxazine is presented. The key step of the sequence is a high-yielding O -arylation of a phenol with an unsymmetrical diaryliodonium salt to provide an ortho -disubstituted diaryl ether. This species was cyclized to acetylphenoxazine in moderate yield. The overall yield in the three-step sequence is 72% based on recovered diaryl ether. An interesting, unusually stable iodine(III) intermediate in the O -arylation was observed by NMR and could be converted to the product upon longer reaction time...
2018: Beilstein Journal of Organic Chemistry
Ganna Gryn'ova, Clémence Corminboeuf
Non-covalent interactions between neutral, sterically hindered organic molecules generally involve a strong stabilizing contribution from dispersion forces that in many systems turns the 'steric repulsion' into a 'steric attraction'. In addition to London dispersion, such systems benefit from electrostatic stabilization, which arises from a short-range effect of charge penetration and gets bigger with increasing steric bulk. In the present work, we quantify this contribution for a diverse set of molecular cores, ranging from unsubstituted benzene and cyclohexane to their derivatives carrying tert -butyl, phenyl, cyclohexyl and adamantyl substituents...
2018: Beilstein Journal of Organic Chemistry
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