keyword
MENU ▼
Read by QxMD icon Read
search

Ortho

keyword
https://www.readbyqxmd.com/read/28102688/reaction-of-arynes-with-vinyl-sulfoxides-highly-stereospecific-synthesis-of-ortho-sulfinylaryl-vinyl-ethers
#1
Yuanming Li, Armido Studer
The reaction of in situ generated arynes with aryl vinyl sulfoxides provides ortho-arylsulfinylaryl vinyl ethers via aryne σ-bond insertion into the S-O-bond and concomitant stereospecific S-O-vinyl migration. The cascade allows preparing di- or trisubstituted vinyl ethers with excellent stereospecificity. The reactions proceed under mild conditions, the substrate scope is broad, and the products obtained are valuable.
January 19, 2017: Organic Letters
https://www.readbyqxmd.com/read/28098962/gold-catalyzed-suzuki-coupling-of-ortho-substituted-hindered-aryl-substrates
#2
Nejib Dwadnia, Julien Roger, Nadine Pirio, Hélène Cattey, Ridha Ben Salem, Jean-Cyrille Hierso
A method that allows hindered ortho-substituted aryl iodides to be efficiently coupled to phenylboronic acid using a gold-catalyzed C-C bond formation is presented. The use of a molecularly-defined dinuclear gold chloride catalytic precursor that is stabilized by a new tetradentate (N,N')-diamino-(P,P')-diphosphino ferrocene hybrid ligand in a Suzuki-type reaction is described for the first time. Electron-rich isopropyl groups on phosphorus were found essential for a superior activity, while the performances of a set of analogous gold dinuclear complexes that were fully characterized by multinuclear NMR spectroscopy and XRD analysis, were investigated...
January 18, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28098286/tridentate-lewis-acids-based-on-triphenylsilane
#3
Janek Tomaschautzky, Beate Neumann, Hans-Georg Stammler, Andreas Mix, Norbert W Mitzel
Several derivatives of the propeller-shaped ortho-substituted triphenylsilanes, carrying metal- or silicon-based acceptor groups, are reported. They were synthesized starting from tris(2-bromophenyl)fluorosilane, tris(2-vinylphenyl)fluorosilane and tris(2-ethynylphenyl)fluorosilane to generate a scope of Lewis-acidic molecules with different cavities. An improved synthetic protocol for donor-free tris(2-lithiophenyl)silanes is described. First attempts in host-guest chemistry to probe the binding between a threefold alane-functionalised ortho-substituted triphenylsilane and a tridentate Lewis-basic guest molecule are presented...
January 18, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28094949/how-high-concentrations-of-proteins-stabilize-the-amorphous-state-of-calcium-orthophosphate-a-solid-state-nmr-study-of-the-casein-case
#4
Paulo De Sa Peixoto, Juliana Valle Costa Silva, Guillaume Pierre Laurent, Marc Schmutz, Daniel Thomas, Antoine Bouchoux, Genevieve Gesan-Guiziou
Understanding how proteins stabilize Amorphous Calcium ortho-Phosphate (ACP) phases is of great importance in biology and for pharmaceutical or food applications. Until now, most of the former investigations about ACP-protein stability and equilibrium were performed in conditions where ACP colloidal nanoclusters are surrounded by low to moderate concentrations of peptides or proteins (15-30 g.L-1). As a result, the question of ACP-protein interactions in highly concentrated protein systems has clearly been overlooked, whereas it corresponds to actual industrial conditions such as drying or membrane filtration in the dairy industry for instance...
January 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28094370/probing-sub-nano-level-molecular-packing-and-correlated-positron-annihilation-characteristics-of-ionic-cross-linked-chitosan-membranes-using-positron-annihilation-spectroscopy
#5
Rui Xia, Xingzhong Cao, Meizhen Gao, Peng Zhang, Minfeng Zeng, Baoyi Wang, Long Wei
Chitosan, CS, cross-linked with bivalent palladium has shown enhanced mechanical and thermal properties depending on the transformation of the structure at a microscopic scale. In the present study, CS directly cross-linked by palladium cation membranes (CS-cr-PM) was prepared through a solution-casting method. Mobility of chitosan chains were greatly reduced after crosslinking, making a great reduction in the swelling ratio studied by a water-swelling degree measurement, which led to an improvement in molecular chain rigidity...
January 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28093909/transition-metal-free-amination-of-pyridine-2-sulfonyl-chloride-and-related-n-heterocycles-using-magnesium-amides
#6
Moritz Balkenhohl, Cyril François, Daniela Sustac Roman, Pauline Quinio, Paul Knochel
A new transition-metal-free amination of pyridine-2-sulfonyl chloride and related N-heterocycles using magnesium amides of type R2NMgCl·LiCl is reported. Additionally, the directed ortho-magnesiation of pyridine-2-sulfonamides using TMPMgCl·LiCl was investigated. Reaction of the magnesium intermediates with various electrophiles and subsequent amination using magnesium amides led to a range of 2,3-functionalized pyridines. Also, cyclization reactions providing an aza-indole and an aza-carbazole were carried out...
January 17, 2017: Organic Letters
https://www.readbyqxmd.com/read/28093908/thermal-ring-contraction-reactions-of-9-aryl-5h-7h-1-2-5-thiadiazolo-3-4-h-2-3-4-benzothiadiazepine-6-6-dioxides-experimental-and-computational-studies-for-understanding-the-course-of-the-transformations
#7
Ferenc Bertha, Tamas Kegl, József Fetter, Balázs Molnár, András Dancsó, Gábor Németh, Gyula Simig, Balázs Volk
When refluxing with sodium hydrogencarbonate in acetonitrile, 7-chloro-5-(4-fluorophenyl)-1,3-dihydro-2,3,4-benzothiadiazepine 2,2-dioxide afforded, after loss of dinitrogen and subsequent ring contraction, the corresponding sulfone in 83% yield. Similar treatment of the related thiadiazolo-fused tricycles, i.e. 9-aryl-5H,7H-[1,2,5]thiadiazolo[3,4-h][2,3,4]benzothiadiazepine 6,6-dioxides, resulted in a substantially different product mixture: formation of sultines and benzocyclobutenes was observed, while only small amounts of the sulfones were formed, if any...
January 17, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28093872/nitrogenated-azaphilone-derivatives-through-a-silver-catalysed-reaction-of-imines-of-ortho-alkynylbenzaldehydes
#8
Félix Rodríguez, Patricia Fernández, Francisco Javier Fañanás
Nitrogenated azaphilones are interesting natural products with wide range of applications whose structure is characterized by the presence of an isoquinolinone framework. Herein, we describe a new multicomponent silver-catalysed reaction that allows the transformation of simple imines derived from ortho-alkynylbenzaldehydes into complex nitrogenated azaphilone-type molecules in a straightforward way. This atom-economical process is high yielding, technically very simple and proceeds through a series of cascade processes that imply cycloisomerization and formal cross-coupling reactions...
January 17, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28091644/chiral-bidentate-n-s-ferrocene-ligands-based-on-a-thiazoline-framework-synthesis-and-use-in-palladium-catalyzed-asymmetric-allylic-alkylation
#9
E P Sánchez-Rodríguez, F Hochberger-Roa, R Corona-Sánchez, J E Barquera-Lozada, R A Toscano, M Urrutigoïty, M Gouygou, M C Ortega-Alfaro, J G López-Cortés
An efficient method to obtain chiral 1,2-disubstituted ferrocenyl ligands has been developed. The introduction of planar chirality was accomplished by using 2-thiazoline as an ortho-directing lithiation group, and moreover, these kinds of ligands possess a central chirality from the amino alcohol used in their synthesis. The X-ray analysis and DFT calculations confirmed the diastereoselectivity of ortho-lithiation and the configuration of the planar chirality. The ability of these new bidentate [N,S]-ferrocene ligands to act in Pd-catalyzed asymmetric allylic alkylation has also been demonstrated and compared with their oxazoline counterparts...
January 16, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28090775/reaction-of-push-pull-enaminoketones-and-in-situ-generated-ortho-quinone-methides-synthesis-of-3-acyl-4h-chromenes-and-2-acyl-1h-benzo-f-chromenes-as-precursors-for-hydroxybenzylated-heterocycles
#10
Anton Vladimirovich Lukashenko, Vitaly Aleksandrovich Osyanin, Dmitry Vladimirovich Osipov, Yuri N Klimochkin
A simple and efficient method for the synthesis of 4H-chromenes and 1H-benzo[f]chromenes containing trifluoroacetyl or aroyl group in pyran ring from o-quinone methide precursors and push-pull enaminoketones has been developed. The chromenes are presumably formed through an initial oxa-Diels-Alder reaction followed by an elimination of amine. Possibility of further transformations of given chromenes to o-hydroxybenzylated pyrazoles, isoxazoles and pyridines has been demonstrated.
January 16, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28088023/a-novel-model-to-predict-gas-phase-hydroxyl-radical-oxidation-kinetics-of-polychlorinated-compounds
#11
Shuang Luo, Zongsu Wei, Richard Spinney, Zhihui Yang, Liyuan Chai, Ruiyang Xiao
In this study, a novel model based on aromatic meta-substituent grouping was presented to predict the second-order rate constants (k) for OH oxidation of PCBs in gas-phase. Since the oxidation kinetics are dependent on the chlorination degree and position, we hypothesized that it may be more accurate for k value prediction if we group PCB congeners based on substitution positions (i.e., ortho (o), meta (m), and para (p)). To test this hypothesis, we examined the correlation of polarizability (α), a quantum chemical based descriptor for k values, with an empirical Hammett constant (σ(+)) on each substitution position...
January 4, 2017: Chemosphere
https://www.readbyqxmd.com/read/28087485/stepwise-targeted-drug-delivery-to-liver-cancer-cells-for-enhanced-therapeutic-efficacy-by-galactose-grafted-ultra-ph-sensitive-micelles
#12
Guoqing Yan, Jun Wang, Liefeng Hu, Xin Wang, Guanqing Yang, Shengxiang Fu, Xu Cheng, Panpan Zhang, Rupei Tang
: To promote drug accumulation and cell-killing ability at tumor tissue, we have prepared a stepwise targeted drug delivery system that can remain stealthy and long-circulating in the blood vessels, improve drug retention at extracellular stimuli, enhance cellular uptake through special targeting ligands, and then achieve rapid drug release to improve toxicity to tumor cells at intracellular stimuli. Herein, galactose-grafted, ultra-pH-sensitive drug carriers (POEAd-g-LA-DOX micelles), which could respond to both extracellular and intracellular pH, and combine with galactose-receptors in cell membrane, were constructed by a facile method, therefore achieving: (i) remaining stable at pH 7...
January 10, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28087168/synthesis-structure-activity-relationships-studies-of-benzoxazinone-derivatives-as-%C3%AE-chymotrypsin-inhibitors
#13
Bishnu P Marasini, Fazal Rahim, Shahnaz Perveen, Aneela Karim, Khalid Mohammed Khan, Atta-Ur-Rahman, M Iqbal Choudhary
A series of benzoxazinones 1-28 were synthesized via reaction of anthranilic acid with various substituted benzoyl chlorides in the presence of triethylamine in chloroform. Compounds 1-18 showed a good inhibition of α-chymotrypsin with IC50±SEM values between 6.5 and 341.1μM. Preliminary structure-activity relationships studies indicated that the presence of substituents on benzene ring reduces the inhibitory potential of benzoxazinone. Also the increased inhibitory potential due to fluoro group at phenyl substituent was observed followed by chloro and bromo substituents...
January 4, 2017: Bioorganic Chemistry
https://www.readbyqxmd.com/read/28080122/continuing-our-organizational-mission-a-new-name-for-a-new-time
#14
Deborah Klein Walker, Ryan P Kilmer, Mary I Armstrong
This editorial explains the need for a new name for the American Orthopsychiatric Association (ORTHO). As ORTHO continues their work into the 21st century, they want to better reflect their global membership and focus, increasing the number of partnerships with individuals and organizations, and commitment to a just society. Therefore, ORTHO is changing their name to the Global Alliance for Behavioral Health and Social Justice. It is crucial to underscore that, although the organizations name is changing, the values and principles that inform their work will remain the same...
2017: American Journal of Orthopsychiatry
https://www.readbyqxmd.com/read/28080066/para-selective-alkylation-of-sulfonylarenes-by-cooperative-nickel-aluminum-catalysis
#15
Shogo Okumura, Yoshiaki Nakao
A method for the para-selective alkylation of a variety of arenesulfonamides and aromatic sulfones with 1-alkenes by cooperative nickel/aluminum catalysis has been developed. Taking advantage of the sulfornyl functionality serving as a removable ortho-directing group, the reaction can be applied to facile access to 1,3-dialkyl-substitued benzenes.
January 12, 2017: Organic Letters
https://www.readbyqxmd.com/read/28074964/how-the-alignment-of-adsorbed-ortho-h-pairs-determines-the-onset-of-selective-carbon-nanotube-etching
#16
U Khalilov, A Bogaerts, B Xu, T Kato, T Kaneko, E C Neyts
Unlocking the enormous technological potential of carbon nanotubes strongly depends on our ability to specifically produce metallic or semiconducting tubes. While selective etching of both has already been demonstrated, the underlying reasons, however, remain elusive as yet. We here present computational and experimental evidence on the operative mechanisms at the atomic scale. We demonstrate that during the adsorption of H atoms and their coalescence, the adsorbed ortho hydrogen pairs on single-walled carbon nanotubes induce higher shear stresses than axial stresses, leading to the elongation of HC-CH bonds as a function of their alignment with the tube chirality vector, which we denote as the γ-angle...
January 11, 2017: Nanoscale
https://www.readbyqxmd.com/read/28074260/accuracy-and-reproducibility-of-measurements-on-plaster-models-and-digital-models-created-using-an-intraoral-scanner
#17
Leonardo Tavares Camardella, Hero Breuning, Oswaldo de Vasconcellos Vilella
AIM: The purpose of the present study was to evaluate the accuracy and reproducibility of measurements made on digital models created using an intraoral color scanner compared to measurements on dental plaster models. METHODS: This study included impressions of 28 volunteers. Alginate impressions were used to make plaster models, and each volunteers' dentition was scanned with a TRIOS Color intraoral scanner. Two examiners performed measurements on the plaster models using a digital caliper and measured the digital models using Ortho Analyzer software...
January 10, 2017: Journal of Orofacial Orthopedics, Fortschritte der Kieferorthopädie
https://www.readbyqxmd.com/read/28071914/synthesis-and-nmr-analysis-of-a-conformationally-controlled-%C3%AE-turn-mimetic-torsion-balance
#18
Alyssa B Lypson, Craig S Wilcox
The molecular torsion balance concept was applied to a new conformationally controlled scaffold and synthesized to accurately evaluate pairwise amino acid interactions in an antiparallel β-sheet motif. The scaffold's core design combines (ortho-tolyl)amide and o,o,o'-trisubstituted biphenyl structural units to provide a geometry better-suited for intramolecular hydrogen bonding. Like the dibenzodiazocine hinge of the traditional torsion balance, the (ortho-tolyl)amide unit offers restricted rotation around an N-aryl bond...
January 10, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28070581/structural-and-magnetic-properties-of-semiquinonate-based-al-iii-and-ga-iii-complexes
#19
Chinmoy Das, Pragya Shukla, Lorenzo Sorace, Maheswaran Shanmugam
The reaction of anhydrous MCl3 (M = Al(iii) or Ga(iii)) with one-electron-reduced 3,5-di-tert-butyl-1,2-ortho-benzoquinone (using metallic sodium) led us to isolate two distinct metal complexes of Al(iii) and Ga(iii), which were structurally and magnetically characterized. Complex 1 crystallized in the monoclinic P21/n space group, whereas 2 crystallized in the triclinic P1[combining macron] space group. Interestingly, whereas the Al(iii) derivative was obtained as a dimer with the molecular formula [Al2(μ-HL(-))2(L˙(-))4] (1) (where L˙(-) is a semiquinonate radical and HL(-) is a monoanionic catecholate ligand), the Ga(iii) derivative crystallized as [Ga(L˙(-))3] (2), which is a polymorph of a previously reported complex...
January 10, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28070578/efficient-access-to-a-designed-phosphapalladacycle-catalyst-via-enantioselective-catalytic-asymmetric-hydrophosphination
#20
Xi-Rui Li, Xiang-Yuan Yang, Yongxin Li, Sumod A Pullarkat, Pak-Hing Leung
A chiral phosphine auxiliary was generated with excellent ee via catalytic asymmetric hydrophosphination of 3-(naphthalen-1-ylmethylene)pentane-2,4-dione. The subsequent metal complexation of the monophosphine yielded two different coordination complexes depending on the reaction conditions. The ortho-palladation of both coordination complexes resulted in the formation of a single dimeric phosphapalladacycle complex that could be further converted to the monomeric bisacetonitrile derivative. Moreover, the palladium complex exhibits interesting oxophilicity as the stable bisaquo derivative could be isolated and characterized crystallographically...
January 10, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
keyword
keyword
2761
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"