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https://www.readbyqxmd.com/read/30247029/direct-sulfide-catalyzed-diastereoselective-4-1-annulations-of-ortho-quinone-methides-and-bromides
#1
Yan-Qing Liu, Qing-Zhu Li, Hong-Ping Zhu, Xin Feng, Cheng Peng, Wei Huang, Jun-Long Li, Bo Han
Direct sulfide organocatalysis is an emerging topic in research on synthetic chemistry. Here, an unprecedented sulfide-catalyzed diastereoselective [4+1] annulation of (in situ generated) ortho-quinone methides and bromides is reported. Notably, the robustness of such sulfide organocatalysis was demonstrated by performing the catalytic reaction under oxidative conditions without significantly affecting the reaction outcome. Various dihydrobenzofurans with diverse substituents were obtained with high isolated yields of up to 98% and remarkable diastereoselectivity (>19:1 dr in general)...
October 8, 2018: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30188283/renaissance-of-an-old-topic-from-borazines-to-bn-doped-nanographenes
#2
María Mercedes Lorenzo-García, Davide Bonifazi
Graphene is one of the leading materials in today's science, but the lack of a band gap limits its application to replace semiconductors in optoelectronic devices. To overcome this limitation, the replacement of C=C bonds by isostructural and isoelectronic bonds is emerging as an effective strategy to open a band gap in monoatomic graphene layers. First prepared by Stock and Pohland in 1926, borazine is the isoelectronic and isostructural inorganic analogue of benzene, where the C=C bonds are replaced by B-N couples...
September 27, 2017: Chimia
https://www.readbyqxmd.com/read/30182110/mechanistic-view-of-ru-catalyzed-c-h-bond-activation-and-functionalization-computational-advances
#3
REVIEW
Chunhui Shan, Lei Zhu, Ling-Bo Qu, Ruopeng Bai, Yu Lan
Ru-Catalyzed aromatic C-H bond activation and functionalization have emerged as important topics because they have resulted in remarkable progress in organic synthesis. Both experimental and theoretical studies of their mechanisms are important for the design of new synthetic methodologies. In this review, a mechanistic view of the Ru-mediated C-H bond cleavage step is first given to reveal the C-H bond activation modes, including oxidative addition, metathesis and base-assisted deprotonation. In this process, directing groups play an important role in determining the reactivity of the C-H bond...
September 5, 2018: Chemical Society Reviews
https://www.readbyqxmd.com/read/30078974/comparisons-of-metabolite-profile-from-paired-serum-and-ethylenediaminetetraacetic-acid-plasma-samples-using-dry-chemistry-technology-an-emergency-department-perspective
#4
Lokesh Kumar Sharma, Deep Dutta, Neera Sharma, Bhaskar Thakur
BACKGROUND: No data is available evaluating the difference in serum versus plasma sample assay of commonly tested parameters in the emergency department, where the sample processing time can be significantly reduced if plasma is used for analysis instead of conventionally used serum. Hence, this study aimed to evaluate the differences in serum versus plasma sample estimation of commonly evaluated biochemical parameters using dry chemistry technology. MATERIALS AND METHODS: Paired blood samples were collected from a single venipuncture of 405 patients admitted to the emergency department...
July 2018: Journal of Laboratory Physicians
https://www.readbyqxmd.com/read/30029353/nano-liquid-chromatography-high-resolution-mass-spectrometry-for-the-identification-of-metabolites-of-the-two-new-psychoactive-substances-n-ortho-methoxybenzyl-3-4-dimethoxyamphetamine-and-n-ortho-methoxybenzyl-4-methylmethamphetamine
#5
Achim T Caspar, Markus R Meyer, Folker Westphal, Armin A Weber, Hans H Maurer
Among the emerging new psychoactive substances (NPS), compounds carrying an N-ortho-methoxybenzyl substituent, the so-called NBOMes, represented a highly potent group of new hallucinogens. Recently, 3,4-dimethoxyamphetamine (3,4-DMA)-NBOMe and 4-methylmethamphetamine (4-MMA)-NBOMe occurred, but no data on their pharmacokinetics were available. According to other NBOMes, they are expected to be extensively metabolized. For detection and identification of their phase I and II metabolites, nano liquid chromatography coupled to high resolution tandem mass spectrometry (nanoLC-HRMS/MS) was used...
October 1, 2018: Talanta
https://www.readbyqxmd.com/read/30028610/radical-arene-addition-vs-radical-reduction-why-organometal-hydride-chain-reactions-stop-and-how-to-make-them-go
#6
Vincent W Bowry, Chryssostomos Chatgilialoglu
Nonideal kinetic chain analysis was used to examine the kinetic limitations of free-radical synthesis. Homolytic aromatic substitution (HAS: ArH + R• → ArR + H• ) occurs in a chain-terminating side reaction to the tributyltin hydride ( SnH) reduction chain (RX + SnH + ( i• )cat. → RH + SnX). Kinetic modeling of premixed and slow reagent addition reactions have clarified the mechanisms of SM HAS, with the azo initiator ( iNN i) acting not only as radical source but also (as an H• acceptor) as the redox catalyst for aromatization, and/or as a postaddition oxidant...
September 7, 2018: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/30020765/dihydroindenofluorene-positional-isomers
#7
Cyril Poriel, Joëlle Rault-Berthelot
Bridged oligophenylenes are very important organic semiconductors (OSCs) in organic electronics (OE). The fluorene unit, which is a bridged biphenyl, is the spearhead of this class of materials and has, over the last 20 years, led to fantastic breakthroughs in organic light-emitting diodes. Dihydroindenofluorenes belong to the family of bridged terphenyls and can be viewed as the fusion of a fluorene unit with an indene fragment. Dihydroindenofluorenes have also appeared as very promising building blocks for OE applications...
August 21, 2018: Accounts of Chemical Research
https://www.readbyqxmd.com/read/29952275/comparative-study-on-photodynamic-activation-of-ortho-toluidine-blue-and-methylene-blue-loaded-mesoporous-silica-nanoparticles-against-resistant-microorganisms
#8
Ashka Amina, Deepali V Kaduskar
AIMS AND BACKGROUND: Number of pathogenic microorganisms have been increasing over the years, and so as these microorganisms been developing resistance against various antibiotics. Antimicrobial photodynamic therapy (aPDT), also called photodynamic inactivation, is emerging as a promising alternative to treatments based on conventional antibiotics. Recent patents on structured silver mesoporous silica nanoparticles having antimicrobial activity (WO2010/071831 A2), photosensitiser modified core-shell structure nanocomposites (CN 103536935(A)), and Chitosan-coated magnetic mesoporous silica nanoparticles (CN 104785214(A)) helped in selecting method of synthesis of MSN and photosensitizers...
June 26, 2018: Recent Patents on Drug Delivery & Formulation
https://www.readbyqxmd.com/read/29932631/class-i-histone-deacetylase-inhibition-by-tianeptinaline-modulates-neuroplasticity-and-enhances-memory
#9
Wen-Ning Zhao, Balaram Ghosh, Marshall Tyler, Jasmin Lalonde, Nadine F Joseph, Nina Kosaric, Daniel M Fass, Li-Huei Tsai, Ralph Mazitschek, Stephen J Haggarty
Through epigenetic and other regulatory functions, the histone deacetylase (HDAC) family of enzymes has emerged as a promising therapeutic target for central nervous system and other disorders. Here we report on the synthesis and functional characterization of new HDAC inhibitors based structurally on tianeptine, a drug used primarily to treat major depressive disorder (MDD) that has a poorly understood mechanism of action. Since the chemical structure of tianeptine resembles certain HDAC inhibitors, we profiled the in vitro HDAC inhibitory activity of tianeptine and demonstrated its ability to inhibit the lysine deacetylase activity of a subset of class I HDACs...
June 22, 2018: ACS Chemical Neuroscience
https://www.readbyqxmd.com/read/29906109/modular-ipso-ortho-difunctionalization-of-aryl-bromides-via-palladium-norbornene-cooperative-catalysis
#10
Zhe Dong, Gang Lu, Jianchun Wang, Peng Liu, Guangbin Dong
Palladium/norbornene (Pd/NBE) cooperative catalysis has emerged as a useful tool for preparing poly substituted arenes; however, its substrate scope has been largely restricted to aryl iodides. While aryl bromides are considered as standard substrates for Pd-catalyzed cross coupling reactions, their use in Pd/NBE catalysis remains elusive. Here we describe the development of general approaches for aryl bromide-mediated Pd/NBE cooperative catalysis. Through careful tuning the phosphine ligands and quenching nucleophiles, ortho amination, acylation and alkylation of aryl bromides have been realized in good efficiency...
July 11, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29673128/synthesis-analytical-characterization-and-monoamine-transporter-activity-of-the-new-psychoactive-substance-4-methylphenmetrazine-4-mpm-with-differentiation-from-its-ortho-and-meta-positional-isomers
#11
Gavin McLaughlin, Michael H Baumann, Pierce V Kavanagh, Noreen Morris, John D Power, Geraldine Dowling, Brendan Twamley, John O'Brien, Gary Hessman, Folker Westphal, Donna Walther, Simon D Brandt
The availability of new psychoactive substances (NPS) on the recreational drug market continues to create challenges for scientists in the forensic, clinical and toxicology fields. Phenmetrazine (3-methyl-2-phenylmorpholine) and an array of its analogs form a class of psychostimulants that are well documented in the patent and scientific literature. The present study reports on two phenmetrazine analogs that have been encountered on the NPS market following the introduction of 3-fluorophenmetrazine (3-FPM), namely 4-methylphenmetrazine (4-MPM), and 3-methylphenmetrazine (3-MPM)...
April 19, 2018: Drug Testing and Analysis
https://www.readbyqxmd.com/read/29491420/femtosecond-laser-mass-spectrometry-and-high-harmonic-spectroscopy-of-xylene-isomers
#12
Abdullah Alharbi, Andrey E Boguslavskiy, Dane Austin, Nicolas Thiré, D Wood, P Hawkins, Felicity McGrath, A S Johnson, I Lopez-Quintas, Bruno Schmidt, Francois Légaré, J P Marangos, Anh-Thu Le, Ravi Bhardwaj
Structural isomers, molecules having the same chemical formula but with atoms bonded in different order, are hard to identify using conventional spectroscopy and mass spectrometry. They exhibit virtually indistinguishable mass spectra when ionized by electrons. Laser mass spectrometry based on photoionization of the isomers has emerged as a promising alternative but requires shaped ultrafast laser pulses. Here we use transform limited femtosecond pulses to distinguish the isomers using two methods. First, we probe doubly charged parent ions with circularly polarized light...
February 28, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29423487/the-emergence-of-aqueous-chemiluminescence-new-promising-class-of-phenoxy-1-2-dioxetane-luminophores
#13
Samer Gnaim, Ori Green, Doron Shabat
The majority of known chemiluminescent compounds produce light through oxidation-dependent mechanisms. The unique notion of triggering chemiluminescence by a chemical reaction other than oxidation was first introduced by Schaap in 1987 with the development of chemically and enzymatically activated phenoxy-dioxetanes. Such dioxetanes are distinctive among chemiluminescent molecules since the oxidized high-energy species, the dioxetane, is stable for years at room temperature. Light emission is selectively activated by deprotection of the phenol-protecting group...
February 22, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29364271/detecting-estrogenic-ligands-in-personal-care-products-using-a-yeast-estrogen-screen-optimized-for-the-undergraduate-teaching-laboratory
#14
Thea M Edwards, Howard E Morgan, Coralia Balasca, Naveen K Chalasani, Lauren Yam, Alison M Roark
The Yeast Estrogen Screen (YES) is used to detect estrogenic ligands in environmental samples and has been broadly applied in studies of endocrine disruption. Estrogenic ligands include both natural and manmade "Environmental Estrogens" (EEs) found in many consumer goods including Personal Care Products (PCPs), plastics, pesticides, and foods. EEs disrupt hormone signaling in humans and other animals, potentially reducing fertility and increasing disease risk. Despite the importance of EEs and other Endocrine Disrupting Chemicals (EDCs) to public health, endocrine disruption is not typically included in undergraduate curricula...
January 1, 2018: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/29112403/selective-ortho-c-h-activation-of-pyridines-directed-by-lewis-acidic-boron-of-pbp-pincer-iridium-complexes
#15
Wei-Chun Shih, Oleg V Ozerov
Transition-metal mediated C-H functionalization has emerged as a powerful method in the chemistry relevant to the synthesis of pharmaceuticals, agrochemicals, and advanced materials. Because organic molecules typically contain multiple types of C-H bonds, selective C-H functionalization is a major ongoing challenge. C-H activation of heteroatom-containing organics has often been approached via the use of the directing effect, whereby the coordination to the basic heteroatom directs the reactive metal center to a specific C-H bond...
December 6, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28967982/conformational-aspects-in-the-design-of-inhibitors-for-serine-hydroxymethyltransferase-shmt-biphenyl-aryl-sulfonamide-and-aryl-sulfone-motifs
#16
Geoffrey Schwertz, Michelle S Frei, Matthias C Witschel, Matthias Rottmann, Ubolsree Leartsakulpanich, Penchit Chitnumsub, Aritsara Jaruwat, Wanwipa Ittarat, Anja Schäfer, Raphael A Aponte, Nils Trapp, Kerstin Mark, Pimchai Chaiyen, François Diederich
Malaria remains a major threat to mankind due to the perpetual emergence of resistance against marketed drugs. Twenty-one pyrazolopyran-based inhibitors bearing terminal biphenyl, aryl sulfonamide, or aryl sulfone motifs were synthesized and tested towards serine hydroxymethyltransferase (SHMT), a key enzyme of the folate cycle. The best ligands inhibited Plasmodium falciparum (Pf) and Arabidopsis thaliana (At) SHMT in target, as well as PfNF54 strains in cell-based assays in the low nanomolar range (18-56 nm)...
October 12, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28836708/tuning-the-pk-a-of-fluorescent-rhodamine-ph-probes-through-substituent-effects
#17
Sarah G Stratton, Grace H Taumoefolau, Grace E Purnell, Mona Rasooly, William L Czaplyski, Elizabeth J Harbron
Rhodamine spirolactams (RSLs) have recently emerged as popular fluorescent pH probes due to their fluorescence turn-on capability and ease of functionalization at the spirolactam nitrogen. Design of RSLs is often driven by biological targeting or compatibility concerns, rather than the pH sensitivity of the probe, and the relationship between RSL structure and pKa is not well understood. To elucidate the relationship between pKa values and the properties of substituents attached to the spirolactam nitrogen, a series of 19 aniline-derived RSLs is presented...
October 9, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28695201/templated-deprotonative-metalation-of-polyaryl-systems-facile-access-to-simple-previously-inaccessible-multi-iodoarenes
#18
Antonio J Martínez-Martínez, Stephen Justice, Ben J Fleming, Alan R Kennedy, Iain D H Oswald, Charles T O'Hara
The development of new methodologies to affect non-ortho-functionalization of arenes has emerged as a globally important arena for research, which is key to both fundamental studies and applied technologies. A range of simple arene feedstocks (namely, biphenyl, meta-terphenyl, para-terphenyl, 1,3,5-triphenylbenzene, and biphenylene) is transformed to hitherto unobtainable multi-iodoarenes via an s-block metal sodium magnesiate templated deprotonative approach. These iodoarenes have the potential to be used in a whole host of high-impact transformations, as precursors to key materials in the pharmaceutical, molecular electronic, and nanomaterials industries...
June 2017: Science Advances
https://www.readbyqxmd.com/read/28681990/c-h-activation-and-alkyne-annulation-via-automatic-or-intrinsic-directing-groups-towards-high-step-economy
#19
REVIEW
Liyao Zheng, Ruimao Hua
Direct transformation of carbon-hydrogen bond (C-H) has emerged to be a trend for construction of molecules from building blocks with no or less prefunctionalization, leading high atom and step economy. Directing group (DG) strategy is widely used to achieve higher reactivity and selectivity, but additional steps are usually needed for installation and/or cleavage of DGs, limiting step economy of the overall transformation. To meet this challenge, we proposed a concept of automatic DG (DGauto ), which is auto-installed and/or auto-cleavable...
June 2018: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
https://www.readbyqxmd.com/read/28671638/sites-for-dynamic-protein-carbohydrate-interactions-of-o-and-c-linked-mannosides-on-the-e-coli-fimh-adhesin
#20
Mohamed Touaibia, Eva-Maria Krammer, Tze C Shiao, Nao Yamakawa, Qingan Wang, Anja Glinschert, Alex Papadopoulos, Leila Mousavifar, Emmanuel Maes, Stefan Oscarson, Gerard Vergoten, Marc F Lensink, René Roy, Julie Bouckaert
Antagonists of the Escherichia coli type-1 fimbrial adhesin FimH are recognized as attractive alternatives for antibiotic therapies and prophylaxes against acute and recurrent bacterial infections. In this study α-d-mannopyranosides O - or C -linked with an alkyl, alkene, alkyne, thioalkyl, amide, or sulfonamide were investigated to fit a hydrophobic substituent with up to two aryl groups within the tyrosine gate emerging from the mannose-binding pocket of FimH. The results were summarized into a set of structure-activity relationships to be used in FimH-targeted inhibitor design: alkene linkers gave an improved affinity and inhibitory potential, because of their relative flexibility combined with a favourable interaction with isoleucine-52 located in the middle of the tyrosine gate...
July 3, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
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