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https://www.readbyqxmd.com/read/27911033/regioselective-synthesis-of-%C3%AE-fluorinated-cyclopentenones-via-organocatalytic-difluorocyclopropanation-and-fluorine-directed-and-activated-nazarov-cyclization
#1
Kohei Fuchibe, Ryo Takayama, Takaharu Yokoyama, Junji Ichikawa
Silyl dienol ethers, prepared from α,β-unsaturated ketones, underwent proton sponge-catalyzed difluorocyclopropanation with trimethylsilyl 2,2-difluoro-2-fluorosulfonylacetate (TFDA) in a regioselective manner, leading to 1,1-difluoro-2-siloxy-2-vinylcyclopropanes in good yields. The cyclopropanes thus obtained were in turn subjected to fluoride ion-catalyzed ring opening to afford 1-fluorovinyl vinyl ketones (i.e., Nazarov precursors). Treatment of the precursors with Me3Si+ B(OTf)4- regioselectively promoted the Nazarov cyclization, whose rate and regioselectivity were drastically enhanced by the fluorine substituent, thereby facilitating efficient synthesis of biologically promising α-fluorocyclopentenone derivatives...
December 2, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27910194/stereospecific-construction-of-contiguous-quaternary-all-carbon-centers-by-oxidative-ring-contraction
#2
Xin Yu, Jiadong Hu, Zhigao Shen, Hui Zhang, Jin-Ming Gao, Weiqing Xie
Oxidative ring contraction of cyclic α-formyl ketones was facilitated by the action of H2 O2 under operationally simple and environmentally benign reaction conditions. The process was highly regioselective and enables stereospecific construction of contiguous quaternary all-carbon centers from stereodefined all-substituted all-cyclic ketones. The asymmetric syntheses of (+)-cuparene and (+)-tochuinyl acetate were also successively achieved by taking advantage of this novel protocol.
December 2, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27910186/diverse-activation-modes-in-the-hydroboration-of-aldehydes-and-ketones-with-germanium-tin-and-lead-lewis-pairs
#3
Julia Schneider, Christian P Sindlinger, Sarah M Freitag, Hartmut Schubert, Lars Wesemann
Intramolecular germylene, stannylene, and plumbylene Lewis pairs were reacted with hexanal and yielded the cyclic addition products only with the germanium and tin reagents. In further reactivity studies, the hydroboration of aldehydes and ketones catalyzed by intramolecular germylene, stannylene, and plumbylene Lewis pairs was studied. In the case of the cyclic germylene Lewis pair, the product of the oxidative addition of pinacolborane at the germylene moiety was observed. According to stoichiometric as well as catalytic experiments, the intramolecular germylene Lewis pair acts as a catalyst in the hydroboration of aldehydes and ketones...
December 2, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27909352/solid-phase-extraction-of-tritiated-contaminants-from-tritium-containing-waste-oils
#4
Andrzej Olejniczak, Jacek Fall, Katarzyna Olejniczak, Marina V Gustova, Alexandr G Shostenko
A solid phase extraction method for removing polar tritiated contaminants from tritium-containing waste oils has been developed. The composition of the degradation products present in the waste oil was determined. The results indicated that upon exposure to tritium gas, fragment methyl ketones, carboxylic acids, and lactones were the main polar products of the mineral-based oil oxidation. The nonpolar fragmentation products included n-alkanes, monomethylalkanes, and acyclic isoprenoids and were analogous to those formed during [Formula: see text]-irradiation of the oil...
2016: Journal of Radioanalytical and Nuclear Chemistry
https://www.readbyqxmd.com/read/27908782/adaptive-responses-of-neuronal-mitochondria-to-bioenergetic-challenges-roles-in-neuroplasticity-and-disease-resistance
#5
REVIEW
Sophia M Raefsky, Mark P Mattson
An important concept in neurobiology is "neurons that fire together, wire together" which means that the formation and maintenance of synapses is promoted by activation of those synapses. Very similar to the effects of the stress of exercise on muscle cells, emerging findings suggest that neurons respond to activity by activating signaling pathways (e.g., Ca(2+), CREB, PGC-1α, NF-κB) that stimulate mitochondrial biogenesis and cellular stress resistance. These pathways are also activated by aerobic exercise and food deprivation, two bioenergetic challenges of fundamental importance in the evolution of the brains of all mammals, including humans...
November 28, 2016: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/27905516/discovery-and-structural-characterisation-of-new-fold-type-iv-transaminases-exemplify-the-diversity-of-this-enzyme-fold
#6
Tea Pavkov-Keller, Gernot A Strohmeier, Matthias Diepold, Wilco Peeters, Natascha Smeets, Martin Schürmann, Karl Gruber, Helmut Schwab, Kerstin Steiner
Transaminases are useful biocatalysts for the production of amino acids and chiral amines as intermediates for a broad range of drugs and fine chemicals. Here, we describe the discovery and characterisation of new transaminases from microorganisms which were enriched in selective media containing (R)-amines as sole nitrogen source. While most of the candidate proteins were clearly assigned to known subgroups of the fold IV family of PLP-dependent enzymes by sequence analysis and characterisation of their substrate specificity, some of them did not fit to any of these groups...
December 1, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27904082/design-and-synthesis-of-non-peptide-rgd-mimics-for-evaluation-of-their-utility-as-anti-platelet-agents
#7
Kazuhiro Higuchi, Hideki Hikita, Asumi Murayama, Daichi Yuri, Natsu Kobayakawa, Takashi Takahashi, Shigeru Kojima, Hiroko Ueno, Tomomi Hatakeyama, Airi Kato, Masanori Tayu, Etsuko Oyama, Shigeo Sugiyama, Kazuyuki Ishii, Hidenobu Takahashi, Tomomi Kawasaki
Arg-Gly-Asp (RGD) mimics were synthesized and their anti-platelet activity was evaluated. A concise method was developed for the synthesis of the target compounds from dehydroepiandrosterone and Wieland-Miescher and Hajos-Parrish ketones, which are suitable for readily available platform. Among the synthesized compounds, the perhydronaphthalene framework with a 3-(4-piperidinyl)propoxyl structure 3e possessed the highest anti-aggregative activity. The IC50 values of 3e were 0.91 mM (ADP initiation) and 0...
2016: Chemical & Pharmaceutical Bulletin
https://www.readbyqxmd.com/read/27901153/structure-activity-relationship-for-the-solid-state-emission-of-a-new-family-of-push-pull-%C3%AF-extended-chromophores
#8
Andrea Nitti, Francesca Villafiorita-Monteleone, Aurora Pacini, Chiara Botta, Tersilla Virgili, Alessandra Forni, Elena Cariati, Massimo Boiocchi, Dario Pasini
We report the design, synthesis, molecular optical properties, and solid state emissive behaviour of a series of novel compounds, which, similar to the archetypal AIE luminogen tetraphenylethene, are formed of a central olefin stator and decorated with either three or four rotors. These rotors, being either electron-rich substituted benzenes, or electron-withdrawing functional groups (esters, ketones, cyano groups) confer a "push-pull" character to the overall molecular structure. Building on both new and already published contributions, a comprehensive picture of the properties and the potential of these compounds is provided...
November 30, 2016: Faraday Discussions
https://www.readbyqxmd.com/read/27899882/tumor-metabolism-the-ketogenic-diet-and-%C3%AE-hydroxybutyrate-novel-approaches-to-adjuvant-brain-tumor-therapy
#9
REVIEW
Eric C Woolf, Nelofer Syed, Adrienne C Scheck
Malignant brain tumors are devastating despite aggressive treatments such as surgical resection, chemotherapy and radiation therapy. The average life expectancy of patients with newly diagnosed glioblastoma is approximately ~18 months. It is clear that increased survival of brain tumor patients requires the design of new therapeutic modalities, especially those that enhance currently available treatments and/or limit tumor growth. One novel therapeutic arena is the metabolic dysregulation that results in an increased need for glucose in tumor cells...
2016: Frontiers in Molecular Neuroscience
https://www.readbyqxmd.com/read/27899283/a-high-throughput-microtiter-plate-assay-for-the-discovery-of-active-and-enantioselective-amino-alcohol-specific-transaminases
#10
Jian-Dong Zhang, Hua-Lei Wu, Tong Meng, Chao-Feng Zhang, Xiao-Jun Fan, Hong-Hong Chang, Wen-Long Wei
Chiral vicinal amino alcohols are important chiral building blocks and intermediates in the pharmaceutical industry. The transaminase (TAm) catalyzed kinetic resolution of racemic amino alcohols provides a straightforward approach to access these important compounds. This study describes the development of a novel microtiter plate assay to screen vicinal amino alcohol-specific TAms using a tetrazolium red-based colorimetric assay to monitor the rate of α-hydroxy ketone formation at 510 nm. This approach is the first to determine the Michaelis-Menten parameters for a recombinant TAm (PpbauA) from Pseudomonas putida NBRC14164...
November 26, 2016: Analytical Biochemistry
https://www.readbyqxmd.com/read/27898966/postweaning-changes-in-the-expression-of-chemerin-and-its-receptors-in-calves-are-associated-with-the-modification-of-glucose-metabolism
#11
Y Suzuki, S Haga, M Nakano, H Ishizaki, M Nakano, S Song, K Katoh, S Roh
Chemerin, originally known as a chemoattractant derived from adipose tissue and the liver, has been reported to have regulatory functions in gluconeogenesis, peripheral insulin sensitivity, and insulin secretion. This study was conducted to assess the postweaning changes in expression of this cytokine and its physiological role in the modification of glucose metabolism associated with weaning. Eighteen tissue samples were collected from Holstein calves (90 d of age; n = 4) to investigate the tissue distributions of chemerin and its receptors genes...
November 2016: Journal of Animal Science
https://www.readbyqxmd.com/read/27897349/bulky-ytterbium-formamidinates-stabilise-complexes-with-radical-ligands-and-related-samarium-tetracyclone-chemistry
#12
Peter Courtney Junk, Daniel Werner, Xuefei Zhao, Stephen Best, Laurent Maron, Glen Deacon
Divalent [Yb(DippForm)2(thf)n] (n = 2 (1a), or 1 (1b); DippForm = N,N'-bis(2,6-diisopropylphenyl)formamidinate) complexes were treated with the ketones: 9-fluorenone (fn), or 2,3,4,5-tetraphenylcyclopentadienone (tpc, tetracyclone), giving ketyl† complexes: [Yb(DippForm)2(fn˙-O)(thf)] (2), and [Yb(DippForm)2(tpc˙-O)] (3) respectively. By contrast, when perfluorobenzophenone (pfb) was treated with either 1a or 1b, transitory ketyl formation was followed by rapid decomposition via a C-F activation pathway, giving [YbF(DippForm)2(thf)] (4a) and a highly unusual fluoride/oxide bridged species: [Yb5F6O2(DippForm)5] (4b)...
November 29, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27896953/highly-selective-upgrading-of-biomass-derived-alcohol-mixtures-for-jet-diesel-fuel-components
#13
Qiang Liu, Guoqiang Xu, Xicheng Wang, Xiaoran Liu, Xindong Mu
In light of the increasing concern about the energy and environmental problems caused by the combustion of petroleum-based fuels (e.g., jet and diesel fuels), the development of new procedures for their sustainable production from renewable biomass-derived platform compounds has attracted tremendous attention recently. Long-chain ketones/alcohols are promising fuel components owing to the fuel properties that closely resemble those of traditional fuels. The focus of this report is the production of long-chain ketones/alcohols by direct upgrading of biomass-derived short-chain alcohol mixtures (e...
November 29, 2016: ChemSusChem
https://www.readbyqxmd.com/read/27891833/metabolomics-guided-insights-on-bariatric-surgery-versus-behavioral-interventions-for-weight-loss
#14
REVIEW
Sara Tulipani, Jules Griffin, Magali Palau-Rodriguez, Ximena Mora-Cubillos, Rosa M Bernal-Lopez, Francisco J Tinahones, Barbara E Corkey, Cristina Andres-Lacueva
OBJECTIVE: To review the metabolomic studies carried out so far to identify metabolic markers associated with surgical and dietary treatments for weight loss in subjects with obesity. METHODS: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. RESULTS: Thirty-two studies successfully met the eligibility criteria. The metabolic adaptations shared by surgical and dietary interventions mirrored a state of starvation ketoacidosis (increase of circulating ketone bodies), an increase of acylcarnitines and fatty acid β-oxidation, a decrease of specific amino acids including branched-chain amino acids (BCAA) and (lyso)glycerophospholipids previously associated with obesity, and adipose tissue expansion...
December 2016: Obesity
https://www.readbyqxmd.com/read/27891755/strategic-utilization-of-multifunctional-carbene-for-direct-synthesis-of-carboxylic-phosphinic-mixed-anhydride-from-co2
#15
Yoichi Hoshimoto, Takahiro Asada, Sunit Hazra, Takuya Kinoshita, Panukorn Sombut, Ravindra Kumar, Masato Ohashi, Sensuke Ogoshi
Direct synthesis of carboxylic-phosphinic mixed anhydrides has been achieved by treating carbon dioxide with N-phosphine oxide-substituted imidazolylidenes (PoxIms) that contain both nucleophilic carbene and electrophilic phosphorus moieties. This novel mixed anhydride was efficiently derivatized into an ester, an amide, and an unsymmetrical ketone via transformation into its corresponding imidazolium salt followed by a dual substitution reaction. The presented work used well-designed multifunctional carbene reagents to establish a novel utility for carbon dioxide in organic synthesis...
November 28, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27891154/preparation-of-ecofriendly-formulations-containing-biologically-active-monoterpenes-with-their-fumigant-and-residual-toxicities-against-adults-of-culex-pipiens
#16
Mohamed E I Badawy, Nehad E M Taktak, Osama M Awad, Souraya A Elfiki, Nadia E Abou El-Ela
Different mixtures of monoterpenes (ketone, alcohol, and alkene) were loaded on paper discs and wax and their knockdown activities were evaluated against Culex pipiens adults. Some individual monoterpenes were also evaluated by residual toxicity technique. Citronella oil as a reference was also loaded separately or in combination with monoterpenes on paper discs and wax. The ketone monoterpenes mixture (camphor, menthone, carvone, and fenchone) on paper discs was the most active (KT50 = 17.20 min) followed by ketone monoterpenes with citronella oil (KT50 = 20...
2016: Journal of Tropical Medicine
https://www.readbyqxmd.com/read/27889941/an-adductomic-approach-to-identify-electrophiles-in-vivo
#17
Henrik Carlsson, Margareta Törnqvist
Humans are exposed to many reactive electrophiles, both formed endogenously and from exogenous exposures. Such compounds could react with cellular biomolecules and form stable reaction products, adducts, at nucleophilic sites in proteins and DNA, constituting a risk for toxic effects. Adductomic approaches aim to study the totality of adducts, to specific biomolecules, by mass spectrometric screening. This MiniReview focuses on the development and application of an adductomic approach for the screening of unknown adducts to N-terminal valine (Val) in hemoglobin (Hb) by liquid chromatography tandem mass spectrometry (LC-MS/MS)...
November 27, 2016: Basic & Clinical Pharmacology & Toxicology
https://www.readbyqxmd.com/read/27888739/microwave-assisted-one-pot-synthesis-characterization-biological-evaluation-and-molecular-docking-studies-of-steroidal-thiazoles
#18
Mohd Asif, Abad Ali, Atif Zafar, Mohd Farhan, Hena Khanam, S M Hadi, Shamsuzzaman
In the present manuscript, a series of steroidal thiazole derivatives (4-6, 8) have been synthesized in efficient manner by one step reaction methodology employing microwave irradiation. The synthesis involves the reaction of steroidal ketones (1-3, 7) with thiosemicarbazide and phenacyl bromide. Structural assignment of the products was confirmed on the basis of IR, (1)H NMR, (13)C NMR, MS and analytical data. The synthesized compounds were screened for in vitro antioxidant activity by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) method...
November 15, 2016: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/27887013/severe-cervical-spondylotic-myelopathy-with-complete-neurological-and-neuroradiological-recovery-within-a-month-after-surgery
#19
Th Marios, Zevgaridis Dimitrios, Th Theologos, Tsonidis Christos
Cervical spondylotic myelopathy is a complex syndrome evolving in the presence of degenerative changes. The choice of care and prognostic factors are controversial. The use of appropriate surgical technique is very important. Posterior approach may be chosen when pathology is present dorsally and/or in the presence of neutral to lordotic alignment. Anterior approach is the golden standard in patients with kyphosis and/or stenosis due to ventral lesions, even with three or more affected levels. A 67-year-old man presented with progressive weakness and clumsiness (mJOA: 5; Nurick: 4)...
November 24, 2016: Journal of Surgical Case Reports
https://www.readbyqxmd.com/read/27886283/gold-nanoparticles-on-oms-2-for-heterogeneously-catalyzed-aerobic-oxidative-%C3%AE-%C3%AE-dehydrogenation-of-%C3%AE-heteroatom-substituted-ketones
#20
Daichi Yoshii, Xiongjie Jin, Takafumi Yatabe, Jun-Ya Hasegawa, Kazuya Yamaguchi, Noritaka Mizuno
In the presence of Au nanoparticles supported on manganese oxide OMS-2 (Au/OMS-2), various kinds of β-heteroatom-substituted α,β-unsaturated ketones (heteroatom = N, O, S) can be synthesized through α,β-dehydrogenation of the corresponding saturated ketones using O2 (in air) as the oxidant. The catalysis of Au/OMS-2 is truly heterogeneous, and the catalyst can be reused.
November 25, 2016: Chemical Communications: Chem Comm
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