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https://www.readbyqxmd.com/read/28549256/assembly-and-inhibitory-activity-of-monovalent-mannosides-terminated-with-aromatic-methyl-esters-the-effect-of-naphthyl-groups
#1
Hussein Al-Mughaid, Raed M Al-Zoubi, Maha Khazaaleh, T Bruce Grindley
A series of monovalent α-D-mannoside ligands terminated with aromatic methyl esters have been synthesized in excellent yields using the Cu(I) catalyzed azide-alkyne 1,3-dipolar cycloaddition ("click chemistry"). These mannosides were designed to have a unique aglycone moiety (tail) that combines a triazole ring attached to aromatic methyl esters via a six carbon alkyl chain. The mannose unit of these ligands was linked at the ortho, meta, and para positions of substituted methyl benzoates and 1-, 3-, and 6-substituted methyl 2-napthaoates...
March 29, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28548314/scorpionate-complexes-of-aza-18-crown-6-containing-fluoronitrophenyl-substituents-as-studied-by-esi-ms
#2
Rafał Frański, Magdalena Onyszkiewicz, Błażej Gierczyk
RATIONALE: Coordination of a metal cation by a nitro group is rare and the interaction between them is usually weak. Examples of complexes in which such an interaction takes place are metal complexes of cyclams containing nitrophenyl or nitrobenzyl substituents. It seemed to be interesting to check if in the complexes of respective crown ether conjugates the interaction can also take place. METHODS: We synthesized the respective conjugates of aza-18-crown-6, namely fluoro-substituted N-nitrophenylaza-18C6 conjugates...
May 26, 2017: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28546843/first-total-synthesis-of-kipukasin-a
#3
Chuang Li, Haixin Ding, Zhizhong Ruan, Yirong Zhou, Qiang Xiao
In this paper, a practical approach for the total synthesis of kipukasin A is presented with 22% overall yield by using tetra-O-acetyl-β-D-ribose as starting material. An improved iodine-promoted acetonide-forming reaction was developed to access 1,2-O-isopropylidene-α-D-ribofuranose. For the first time, ortho-alkynylbenzoate was used as protecting group for the 5-hydoxy group. After subsequent Vorbrüggen glycosylation, the protecting group could be removed smoothly in the presence of 5 mol % Ph3PAuOTf in dichloromethane to provide kipukasin A in high yield and regioselectivity...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28544634/hydrogen-bond-driven-self-assembly-between-amidinium-cations-and-carboxylate-anions-a-combined-molecular-dynamics-nmr-spectroscopy-and-single-crystal-x-ray-diffraction-study
#4
Michael Thomas, Thomas Anglim Lagones, Martyna Judd, Mahbod Morshedi, Megan L O'Mara, Nicholas G White
A combination of molecular dynamics (MD), NMR spectroscopy, and single crystal X-ray diffraction (SCXRD) techniques was used to probe the self-assembly of para- and meta-bis(amidinium) compounds with para-, meta-, and ortho-dicarboxylates. Good concordance was observed between the MD and experimental results. In DMSO solution, the systems form several rapidly exchanging assemblies, in part because a range of hydrogen bonding interactions is possible between the amidinium and carboxylate moieties. Upon crystallization, the majority of the systems form 1D supramolecular polymers, which are held together by short N-H⋅⋅⋅O hydrogen bonds...
May 23, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28543880/the-role-of-the-co-activation-and-ligand-functionalization-in-neutral-methallyl-nickel-ii-catalysts-for-oligomerization-and-polymerization-of-ethylene
#5
Daniela E Ortega, Diego Cortés-Arriagada, Oleksandra S Trofymchuk, Diana Yepes, Soledad Gutierrez-Oliva, René S Rojas, Alejandro Toro-Labbe
It is presented a detailed quantum chemical study analyzing the mechanism of ethylene oligomerization and polymerization by means of a family of four neutral methallyl NiII catalysts. The role of the boron co-activators [BF₃ or B(C₆F₅)₃] and ligand functionalization (in ortho or para position of the N-arylcyano moiety of the catalysts) was investigated to explain the chain length of the obtained polymers. The chain initialization proceeds with higher activation barriers for the ortho functionalized complexes (19 kcal mol¯¹) compared to the para isomers (17-18 kcal mol¯¹)...
May 24, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28539708/assessment-of-mexican-arnica-heterotheca-inuloides-cass-and-rosemary-rosmarinus-officinalis-extracts-on-dopamine-and-selected-biomarkers-of-oxidative-stress-in-stomach-and-brain-of-salmonella-typhimurium-infected-rats
#6
David Calderón Guzmàn, Maribel Ortiz Herrera, Norma Osnaya Brizuela, Gerardo Barragàn Mejía, Ernestina Hernàndez García, Hugo Juàrez Olguín, Armando Valenzuela Peraza, Norma Labra Ruíz, Daniel Santamaría Del Angel
BACKGROUND: The effects of some natural products on dopamine (DA) and 5-hydroxyindole acetic acid (5-HIAA) in brain of infected models are still unclear. OBJECTIVE: The purpose of this study was to measure the effect of Mexican arnica/rosemary (MAR) water extract and oseltamivir on both biogenic amines and some oxidative biomarkers in the brain and stomach of young rats under infection condition. METHODS: Female Wistar rats (weight 80 g) in the presence of MAR or absence (no-MAR) were treated as follows: group 1, buffer solution (controls); oseltamivir (100 mg/kg), group 2; culture of Salmonella typhimurium (S...
April 2017: Pharmacognosy Magazine
https://www.readbyqxmd.com/read/28537740/cationic-n-heterocyclic-carbene-copper-catalyzed-1-3-alkoxy-rearrangement-of-n-alkoxyanilines
#7
Itaru Nakamura, Takeru Jo, Yasuhiro Ishida, Hiroki Tashiro, Masahiro Terada
The [1,3]-alkoxy rearrangement reactions of N-alkoxyanilines were efficiently catalyzed by cationic N-heterocyclic carbene (NHC)-Cu catalysts in affording 2-alkoxyaniline derivatives in good to excellent yields with high functional group compatibility. For N-alkoxyanilines having an electron-withdrawing substituent at the meta-position, the alkoxy group selectively migrated to the more hindered ortho-position. In contrast, the alkoxy group migrated to the less hindered ortho-position for N-alkoxyanilines having an electron-donating substituent...
May 24, 2017: Organic Letters
https://www.readbyqxmd.com/read/28537589/reactions-of-hexadehydro-diels-alder-benzynes-with-structurally-complex-multifunctional-natural-products
#8
Sean P Ross, Thomas R Hoye
An important question in organic chemistry concerns the extent to which benzynes-one of the classical reactive intermediates in organic chemistry-can react in discriminating fashion with trapping reagents. In particular, whether these species can react selectively with substrates containing multiple functional groups and possible sites of reactivity has remained unanswered. Natural products comprise a palette of multifunctional compounds with which to address this question. Here, we show that benzynes produced by the hexadehydro-Diels-Alder (HDDA) reaction react with many secondary metabolites with a preference for one among several pathways...
June 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28533567/synthesis-and-incorporation-of-a-caged-tyrosine-amino-acid-possessing-a-bioorthogonal-handle
#9
Marshall S Padilla, Christopher A Farley, Lindsay E Chatkewitz, Douglas D Young
Reversing a bioconjugation in a spatial and temporal fashion has widespread applications, especially toward targeted drug delivery. We report the synthesis and incorporation of an unnatural amino acid with an alkyne modified dimethoxy-ortho-nitrobenzyl caging group. This unnatural amino acid can be utilized in a Glaser-Hay conjugation to generate a bioconjugate, but also is able to disrupt the bioconjugate when irradiated with light. These combined features allow for the preparation of bioconjugates with a high degree of site-specificity and allow for the separation of the two components if necessary...
October 19, 2016: Tetrahedron Letters
https://www.readbyqxmd.com/read/28529794/crystal-structures-of-two-alkaline-earth-m-ba-and-sr-dimanganese-ii-iron-iii-tris-orthophosphates
#10
Ghaleb Alhakmi, Abderrazzak Assani, Mohamed Saadi, Lahcen El Ammari
Two new orthophosphates, BaMn2Fe(PO4)3 [barium dimanganese(II) iron(III) tris-(orthophosphate)] and SrMn2Fe(PO4)3 [strontium dimanganese(II) iron(III) tris-(orthophosphate)], were synthesized by solid-state reactions. They are isotypic and crystallize in the ortho-rhom-bic system with space group type Pbcn. Their crystal structures comprise infinite zigzag chains of edge-sharing FeO6 octa-hedra (point group symmetry .2.) and Mn2O10 double octa-hedra running parallel to [001], linked by two types of PO4 tetra-hedra...
May 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
https://www.readbyqxmd.com/read/28527297/hyaluronic-acid-nanogels-prepared-via-ortho-ester-linkages-show-ph-triggered-behavior-enhanced-penetration-and-antitumor-efficacy-in-3-d-tumor-spheroids
#11
Guanqing Yang, Shengxiang Fu, Weijing Yao, Xin Wang, Qian Zha, Rupei Tang
A new type of pH-triggered hyaluronic acid nanogel system (HA-NGs) was successfully developed for tumor-targeted delivery of drugs. HA-NGs were obtained by copolymerization between methacrylate HA and a new cross-linker containing ortho ester groups in an aqueous solution. The therapeutic drug (DOX) was loaded into the HA-NGs (DOX@HA-NGs) and exhibited appropriate loading of about 17.3% with a size of around 200nm. Such new pH-triggered HA-NGs are found to be highly desirable for targeted cancer therapy because it could significantly minimize the amount of premature drug release in neutral pH, and also provide a sufficient amount of drug to effectively kill the cancer cells caused by the degradation of ortho ester groups at acid pH values...
May 12, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28520424/insights-on-the-reactivity-of-terminal-phosphanido-metal-complexes-toward-activated-alkynes-from-theoretical-computations
#12
Daniel Álvarez, Raúl Mera-Adasme, Lucía Riera, Gloria I Cárdenas-Jirón, Julio Pérez, Jesús Díaz, M Isabel Menéndez, Ramón López
Herein we present a theoretical study on the reaction of [Re(PPh2) (CO)3(phen)] (phen = 1,10-phenanthroline) and [Re(PPh2) (CO)3(bipy)] (bipy = 2,2'-bipyridine) toward methyl propiolate. In agreement with experimental results for the phen ligand, the coupling of the substituted acetylenic carbon with the nonsubstituted ortho carbon of the phen ligand is the preferred route from both kinetic and thermodynamic viewpoints with a Gibbs energy barrier of 18.8 kcal/mol and an exoergicity of 11.1 kcal/mol. There are other two routes, the insertion of the acetylenic fragment into the P-Re bond and the coupling between the substituted acetylenic carbon and a carbonyl ligand in cis disposition, which are kinetically less favorable than the preferred route (by 2...
May 18, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28513969/effect-of-steady-state-faldaprevir-on-pharmacokinetics-of-atorvastatin-or-rosuvastatin-in-healthy-volunteers-a-prospective-open-label-fixed-sequence-crossover-study
#13
Fenglei Huang, Kristell Marzin, Rüdiger Koenen, Klaus Peter Kammerer, Natalja Strelkowa, Mabrouk Elgadi, Anne-Marie Quinson, Sebastian Haertter
Faldaprevir (FDV) is a potent, orally administered inhibitor of hepatitis C virus protease. It inhibits multiple cytochrome P-450 enzymes and multiple membrane transporters. The objective of this study was to evaluate the effect of steady-state faldaprevir on the pharmacokinetics (PK) of a single dose of atorvastatin or rosuvastatin. In this single-center, open-label, fixed-sequence crossover study, 33 healthy adult male and female volunteers were given either atorvastatin 10 mg (n = 16) or rosuvastatin 10 mg (n = 17) on day 1...
May 17, 2017: Journal of Clinical Pharmacology
https://www.readbyqxmd.com/read/28511387/erythrocyte-alloimmunization-and-autoimmunization-among-blood-donors-and-recipients-visiting-a-tertiary-care-hospital
#14
Daljit Kaur, Lovenish Bains, Manoj Kandwal, Indu Parmar
INTRODUCTION: The ultimate aim of pretransfusion testing is the acceptable survival of donor red cells in recipient's body and antibody detection plays a critical role in achieving the same. The cornerstone of antibody detection method is detecting an unexpected antibody as against the expected antibodies of ABO blood group system. Autoantibodies can also interfere with the detection of clinically significant alloantibodies. AIM: To study the frequency of alloantibodies and autoantibodies in the healthy blood donors and patient population visiting our hospital...
March 2017: Journal of Clinical and Diagnostic Research: JCDR
https://www.readbyqxmd.com/read/28511010/%C3%AF-extended-and-curved-anti-aromatic-polycyclic-hydrocarbons
#15
Junzhi Liu, Ji Ma, Ke Zhang, Prince Ravat, Peter Machata, Stanislav M Avdoshenko, Felix Hennersdorf, Hartmut Komber, Wojciech Pisula, Jan J Weigand, Alexey A Popov, Reinhard Berger, Klaus Müllen, Xinliang Feng
Synthesis of anti-aromatic polycyclic hydrocarbons (PHs) is challenging because the high energy of their highest occupied molecular orbital (HOMO) and low energy of their lowest unoccupied molecular orbital (LUMO) cause them to be reactive and unstable. In this work, two large anti-aromatic acene analogues, namely cyclopenta[pqr]indeno[2,1,7-ijk]tetraphene (CIT, 1a) and cyclopenta[pqr]indeno[7,1,2-cde]picene (CIP, 1b), as well as a curved anti-aromatic molecule with 48 π-electrons, dibenzo[a,c]diindeno[7,1,2-fgh:7',1',2'-mno]phenanthro[9,10-k]tetraphene (DPT, 1c), are synthesized based on the corona of indeno[1,2-b]fluorene...
May 16, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28510348/regioselective-synthesis-of-polycyclic-and-heptagon-embedded-aromatic-compounds-through-a-versatile-%C3%AF-extension-of-aryl-halides
#16
Wai Chung Fu, Zheng Wang, Wesley Ting Kwok Chan, Zhenyang Lin, Fuk Yee Kwong
A versatile π-extension reaction was developed based on the three-component cross-coupling of aryl halides, 2-haloarylcarboxylic acids, and norbornadiene. The transformation is driven by the direction and subsequent decarboxylation of the carboxyl group, while norbornadiene serves as an ortho-C-H activator and ethylene synthon via a retro-Diels-Alder reaction. Comprehensive DFT calculations were performed to account for the catalytic intermediates.
May 16, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28507696/highly-chemoselective-ruthenium-ii-catalyzed-direct-arylation-of-cyclic-and-n-n-dialkyl-benzamides-with-aryl-silanes
#17
Pradeep Nareddy, Frank Jordan, Michal Szostak
The ruthenium(ii)-catalyzed oxidative cross-coupling of C(sp(2))-H bonds with organosilanes has been accomplished for the first time. This novel protocol enlists challenging cyclic and N,N-dialkyl benzamides as weakly-coordinating substrates to achieve highly regioselective C(sp(2))-H arylation as a proof-of-concept, taking advantage of the attractive features of organosilanes as coupling partners. This innovative method is characterized by very high chemoselectivity, installing halide functional groups (I, Br, Cl) that are incompatible with Ru(ii)-carboxylate systems employing halides as cross-coupling partners, while obviating the need for sensitive organometallic reagents and cryogenic temperatures typical to the classic directed-ortho-metallation (DoM) techniques, employing benzamides to afford bioactive structural motifs...
April 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28504515/the-catalytically-lignan-activation-based-approach-for-the-synthesis-of-epi-podophyllotoxin-derivatives
#18
Jun-Hao Wan, Yang Hu, Hui Liu, Yuan-Hong Tu, Zhong-Yi He, Jian-Song Sun
Under the effect of catalytic amount of Au(I) complex, 4-O-(2-cyclopropylethynyl)benzoyl-(epi)-podophyllotoxins, easily prepared via dehydrative condensation between (epi)-podophyllotoxin and ortho-cyclopropylethynylbenzoic acid, could couple with a variety of nucleophiles, including alcohol, phenol, aniline, and carbon nucleophiles efficiently to provide (epi)-podophyllotoxin derivatives. Thus, the first catalytic and lignan-activation-based approach for (epi)-podophyllotoxin derivatization was established...
May 15, 2017: 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
#19
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/28501025/effects-of-unintentional-pcbs-in-pigments-and-chemical-products-on-transcriptional-activity-via-aryl-hydrocarbon-and-nuclear-hormone-receptors
#20
Shinji Takeuchi, Katsunori Anezaki, Hiroyuki Kojima
In recent years, some pigments and chemical products have been reported to contain polychlorinated biphenyl (PCB) congeners as unintentional byproducts, and these have also been detected in residential environments from indoor air and house dust. In this study, using in vitro reporter gene assays, we characterized the agonistic and antagonistic activities of a total of 25 PCB congeners contained in pigments (PCB-1 to -16, -20, -35, -40, -52, -56, -77, -101, -126, and -153) against five nuclear hormone receptors, (estrogen receptor (ER) α/β, glucocorticoid receptor (GR), androgen receptor (AR), thyroid hormone receptor (TR) α1) and aryl hydrocarbon receptor (AhR)...
May 10, 2017: Environmental Pollution
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