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Fei Zhou, Sheng Liu, Bernard D Santarsiero, Donald J Wink, Damien Boudinet, Antonio Facchetti, Tom G Driver
A series of N-heteroheptacenes was synthesized from ortho-thiophene-substituted aryl azides using a Rh2(II)-catalyzed C-H bond amination reaction to construct the thienoindole moieties. This reaction tolerated the presence of electron-donating or withdrawing groups on the aryl azide without adversely affecting the yield of the amination reaction. The central thiophene ring was created from two thienoindole pieces through a Pd-catalyzed Stille reaction to install the thioether followed by a Cu-mediated Ullman reaction to trigger the cyclization...
July 18, 2017: Chemistry: a European Journal
Selvam Raju, Pratheepkumar Annamalai, Pei-Ling Chen, Yi-Hung Liu, Shih-Ching Chuang
A palladium-catalyzed C-H bond activation reaction, via a redox-neutral pathway, for the preparation of dihydrophenanthridine, phenanthridine, and carbazole derivatives from biaryl 2-iminoquinones is developed. The preinstalled iminoquinone was designed to act as a directing group for ortho C-H activation and an internal oxidant or a co-oxidant. This catalysis proceeded through the following sequence: C-H bond activation, coordination and insertion of activated olefins, β-hydride elimination, H-shift, insertion, and protonation or β-hydride elimination...
July 18, 2017: Organic Letters
Igor V Chernushevich, Samuel I Merenbloom, Suya Liu, Nic Bloomfield
Orthogonal injection time-of-flight (orthoTOF) mass spectrometry (MS) is the most prevalent form of TOFMS, owing to its greater control over incoming ion energy, the ability to correct for aberrations in incoming ion velocity and position, and its ability to provide an entire mass spectrum within a single scan. However, the duty cycle of orthoTOFMS is low compared with scanning analyzers, which can have 100% duty cycle when measuring a single type of ion. Typical duty cycles for orthoTOFMS range from 1% to 30%, depending on instrument geometry...
July 17, 2017: Journal of the American Society for Mass Spectrometry
Yuemeng Ji, Jun Zhao, Hajime Terazono, Kentaro Misawa, Nicholas P Levitt, Yixin Li, Yun Lin, Jianfei Peng, Yuan Wang, Lian Duan, Bowen Pan, Fang Zhang, Xidan Feng, Taicheng An, Wilmarie Marrero-Ortiz, Jeremiah Secrest, Annie L Zhang, Kazuhiko Shibuya, Mario J Molina, Renyi Zhang
Photochemical oxidation of aromatic hydrocarbons leads to tropospheric ozone and secondary organic aerosol (SOA) formation, with profound implications for air quality, human health, and climate. Toluene is the most abundant aromatic compound under urban environments, but its detailed chemical oxidation mechanism remains uncertain. From combined laboratory experiments and quantum chemical calculations, we show a toluene oxidation mechanism that is different from the one adopted in current atmospheric models...
July 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
A Ehsani, E Kowsari, F Boorboor Ajdari, R Safari, H Mohammad Shiri
In present work, for improving the electrochemical performance of conductive polymer, POAP/3-methyl-1-[2-(2-{2-[2-[(3-methyl-1-H-imidazol-3-ium-1-yl)ethoxy]ethoxy}-ethoxy)ethyl]-1-H-imidazol-3-ium dichloride (MIEID) composite films have been fabricated by poly ortho aminophenol (POAP) electropolymerization in the presence of MIEID as active electrodes for electrochemical supercapacitors. Different electrochemical methods including galvanostatic charge discharge experiments, cyclic voltammetry and electrochemical impedance spectroscopy have been applied to study the system performance...
July 3, 2017: Journal of Colloid and Interface Science
Alok Patel, Km Sartaj, Neha Arora, Vikas Pruthi, Parul A Pruthi
Phenol is reported to be one of the most toxic environmental pollutants present in the discharge of various industrial effluents causing a serious threat to the existing biome. Biodegradation of phenol by oleaginous yeast Rhodosporidium kratochvilovae HIMPA1 was found to degrade 1000mg/l phenol. The pathways for phenol degradation by both ortho and meta-cleavage were proposed by the identification of metabolites and enzymatic assays of ring cleavage enzymes in the cell extracts. Results suggest that this oleaginous yeast degrade phenol via meta-cleavage pathway and accumulates a high quantity of lipid content (64...
July 6, 2017: Journal of Hazardous Materials
Zhe Hu, Xi Wang, Haitai Dong, Shangyi Li, Xukai Li, Laisheng Li
TiO2-Cu2O photocatalyst composite film with a heterostructure was synthesized on a copper substrate for 2,2',4,4'-tetrabromodiphenyl ether (BDE47) reduction. First, Cu2O film was synthesized by the electrochemical deposition method, and then TiO2 was coated on the surface of the Cu2O film. The morphology, surface chemical composition and optical characteristics of TiO2-Cu2O film were characterized. The degradation efficiency of BDE47 and hydrogen production by TiO2-Cu2O films was higher than those by pure TiO2 or Cu2O films...
July 5, 2017: Journal of Hazardous Materials
Alexander V Tschulakow, Klaus Dittmann, Stephan M Huber, Dominik Klumpp, Benjamin Stegen, Ulrich Schraermeyer, H Peter Rodemann, Sylvie Julien-Schraermeyer
BACKGROUND: Radiotherapy (RT) is used to treat retinoblastoma (Rb), the most frequent ocular tumour in children. Besides eradicating the tumour, RT can cause severe side effects including secondary malignancies. This study aimed to define whether the radioprotector ortho-phospho-L-tyrosine (pTyr) prevents RT-induced side effects and affects local tumour control in a xenograft and a genetic orthotopic Rb mouse model. METHODS: B6;129-Rb1tm3Tyj/J (Rb(+/-)) and Y79-Rb cell-xenografted nude mice were fractionated external beam irradiated (15 fractions of 5Gy 6MV photons during 3weeks) with or without pTyr pre-treatment (100mg/kg BW, 16h prior to each irradiation)...
July 12, 2017: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
Subramaniam Pennathur, Mamta Jaiswal, Elizabeth A White, Lynn Ang, David M Raffel, Melvyn Rubenfire, Rodica Pop-Busui
AIMS: To assess the role of oxidative stress in mediating adverse outcomes in metabolic syndrome (MetS) and resultant cardiovascular autonomic neuropathy (CAN), and to evaluate the effects of lifestyle interventions on measures of oxidative stress and CAN in subjects with MetS. METHODS: Pilot study in 25 non-diabetic subjects with MetS (age 49±10years, 76% females) participating in a 24-week lifestyle intervention (supervised aerobic exercise/Mediterranean diet), and 25 age-matched healthy controls...
May 2, 2017: Journal of Diabetes and its Complications
James A Walker, Kevin L Vickerman, Jenna N Humke, Levi M Stanley
We report nickel-catalyzed formal carboacylation of ortho-allylbenzamides with arylboronic acid pinacol esters. These carboacylation reactions are triggered by the oxidative addition of an activated amide C-N bond to a nickel(0) catalyst and proceed via alkene insertion into a nickel(II)-acyl bond. The exo-selective carboacylation reactions generate 2-benzyl-2,3-dihydro-1H-inden-1-ones in moderate-to-high yields (46-99%) from a variety of arylboronic acid pinacol esters and substituted ortho-allylbenzamides...
July 14, 2017: Journal of the American Chemical Society
Raiza Paul, Julia Moltó, Nuria Ortuño, Alejandro Romero, Carlos Bezos, Jon Aizpurúa, Mª José Gómez-Torres
The relationship between dioxin-like polychlorinated biphenyl (DL-PCB) levels in serum and semen parameters were investigated. Our case-control included two groups of patients. Total concentrations of PCBs were significantly higher in the low semen quality (n=24) than in the normal semen quality (n=26) group. A significant negative correlation was found between PCB 126 and viability in men with low semen quality, while PCBs 77 and 81 were positively correlated with morphology, and PCB 118, mono-ortho and total DL-PCBs were positively correlated with volume...
July 10, 2017: Reproductive Toxicology
Minoo Dabiri, Noushin Farajinia Lehi, Siyavash Kazemi Movahed, Hamid Reza Khavasi
A Pd-catalyzed ortho-selective halogenation of benzoxazinone and quinazolinone scaffolds has been described employing N-halosuccinimide as both a halogen source and an oxidant reagent via C-H bond activation. This transformation shows high chemo- and regioselectivities and demonstrates a broad range of benzoxazinone and quinazolinone substrates with different functional groups and has been scaled up to the gram level.
July 12, 2017: Organic & Biomolecular Chemistry
Josene M Toldo, Mario Barbatti, Paulo F B Gonçalves
A three-state model for the photo-Fries rearrangement (PFR) is proposed based on multiconfigurational calculations. It provides a comprehensive mechanistic picture of all steps of the reaction, from the photoabsorption to the final tautomerization. The three states participating in the PFR are an aromatic (1)ππ*, which absorbs the radiation; a pre-dissociative (1)nπ*, which transfers the energy to the dissociative region; and a (1)πσ*, along which dissociation occurs. The transfer from (1)ππ* to (1)nπ* involves pyramidalization of the carbonyl carbon, while transfer from (1)nπ* to (1)πσ* takes place through CO stretching...
July 12, 2017: Physical Chemistry Chemical Physics: PCCP
Kavita Srivastava, Ashwani Kumar Rathore, Deepak Srivastava
Cashew nut shell liquid (CNSL), an agricultural renewable resource material, produces natural phenolic distillates such as cardanol. Cardanol condenses with formaldehyde at the ortho- and para-position of the phenolic ring under acidic or alkaline condition to yield a series of polymers of novolac- or resol-type phenolic resins. These phenolic resins may further be modified by epoxidation with epichlorohydrin to duplicate the performance of such phenolic-type novolacs (CFN). The structural changes during curing of blend samples of epoxy and carboxyl terminated poly (butadiene-co-acrylonitrile) (CTBN) were studies by Fourier-transform infrared (FTIR) spectrophotometer...
July 3, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
M Elena de Orbe, Laura Amenós, Mariia S Kirillova, Yahui Wang, Verónica López-Carrillo, Feliu Maseras, Antonio M Echavarren
The intermolecular gold(I)-catalyzed reaction between aryl alkynes and alkenes leads to cyclobutenes by a [2+2] cycloaddition. However, 1,3-dienes are formed in the case of ortho-substituted aryl alkynes by a metathesis-type process. A comprehensive mechanism for the gold(I)-catalyzed reaction of alkynes with alkenes is proposed based on DFT calculations and by independently generating the key intermediate cyclopropyl gold(I) carbenes by retro-Bucher reaction.
July 12, 2017: Journal of the American Chemical Society
Futoshi Hasegawa, Kazushi Kawamura, Hiroshi Tsuchikawa, Michio Murata
We report herein the stable C-N axial chirality in a 1-phenyl-6-aminouracil scaffold owing to the presence of various functional groups at the ortho-position of the N(1)-phenyl group. Racemic 1-phenyl-6-aminouracils were first separated by chiral HPLC or converting them to the corresponding diastereomers using a chiral resolving agent. We then determined the rotational barrier of each atropisomer by a thermal racemization method and found that these compounds have rotational barriers similar to other C-N axially chiral biaryls...
June 27, 2017: Bioorganic & Medicinal Chemistry
Benedikt Ómarsson, Ragnar Bjornsson, Oddur Ingolfsson
Here we present a combined experimental and theoretical study on the fragmentation of ortho- and para-tetrafluorohydroquinone upon low energy electron attachment. Despite an identical ring-skeleton and identical functional groups in these constitutional isomers, they show distinctly different fragmentation patterns, a phenomenon that cannot be explained by distinct resonances or different thermochemistry. Using high-level quantum chemical calculations with the computationally affordable domain localized pair natural orbital approach, DLPNO-CCSD(T), we are able to provide a complete and accurate description of the respective reaction dynamics, revealing proton shuttling and transition states for competing channels as the explanation for this different behavior of the isomers...
July 11, 2017: Journal of Physical Chemistry. A
Ekaterina Mikhailovna Chainikova, Alfia R Yusupova, Sergey L Khursan, Aigul N Teregulova, Alexander N Lobov, Marat Faritovich Abdullin, Leniza V Enikeeva, Irek Marsovich Gubaydullin, Rustam Lutfullovich Safiullin
The mechanism of the photooxidation of aromatic azides containing a substituent at one of the ortho positions (2,4-dimethoxyphenyl azide (1a) and 2-methyl-4-[(2E)-1-methylbut-2-en-1-yl]phenyl azide (1b)) was studied in acetonitrile. The electronic spectra and the kinetic regularities of the consumption of corresponding nitroso oxides, which are the reaction intermediates, were investigated by flash photolysis. Owing to the one-and-a-half order of the C N and N O bonds and asymmetric molecule structure these nitroso oxides exist as four conformers (cis/syn, cis/anti, trans/syn, and trans/anti)...
July 11, 2017: Journal of Organic Chemistry
Andrea Baschieri, Luana Pulvirenti, Vera Muccilli, Riccardo Amorati, Corrado Tringali
Chemical modification of magnolol, an uncommon dimeric neolignan contained in Magnolia genus trees, provides a unique array of polyphenols having interesting biological activity potentially related to radical scavenging. The chain-breaking antioxidant activity of four new hydroxylated and methoxylated magnolol derivatives was explored by experimental and computational methods. The measurement of the rate constant of the reaction with ROO˙ radicals (kinh) in an apolar solvent showed that the introduction of hydroxyl groups ortho to the phenolic OH in magnolol increased the kinh value, being 2...
July 11, 2017: Organic & Biomolecular Chemistry
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
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