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https://www.readbyqxmd.com/read/29241011/silver-free-palladium-catalyzed-c-sp3-h-arylation-of-saturated-bicyclic-amine-scaffolds
#1
Charlotte E Coomber, Laure Benhamou, Dejan-Krešimir Bučar, Peter D Smith, Michael J Porter, Tom David Sheppard
Herein we report a silver-free Pd(II)-catalyzed C(sp3)-H arylation of saturated bicyclic and tricyclic amine scaffolds. The reaction provides good yields using a range of aryl iodides and aryl bromides including functionalized examples bearing aldehydes, ketones, esters, free phenols and heterocycles. The methodology has been applied to medicinally relevant scaffolds. Two of the intermediate palladium complexes in the catalytic cycle have been prepared and characterized, and a mechanism proposed. Removal of the directing group proceeded with good yield under relatively mild conditions...
December 14, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29240444/regio-and-diastereodivergent-4-2-cycloadditions-with-cyclic-2-4-dienones
#2
Wei Xiao, Qian-Qian Yang, Zhi Chen, Qin Ouyang, Wei Du, Ying-Chun Chen
By employing activated alkenes with bulky α-functional groups, such as α-cyano-α,β-unsaturated ketones and Meldrum's acid-based alkenes, a previously unreported cross-trienamine pathway of cyclic 2,4-dienones is adopted to deliver γ',δ-regioselective [4 + 2] cycloadducts catalyzed by cinchona-derived amines. In addition, a diastereodivergent [4 + 2] cycloaddition reaction is realized with Z-configured 4-alkylideneisoxazol-5(4H)-ones under similar catalytic conditions, even through a three- or four-component cascade process with simple starting materials...
December 14, 2017: Organic Letters
https://www.readbyqxmd.com/read/29240415/identifying-plant-stress-responses-to-roxarsone-in-soybean-root-exudates-new-insights-from-two-dimensional-correlation-spectroscopy
#3
Qing-Long Fu, Lee Blaney, Dong-Mei Zhou
Roxarsone (ROX) is an organoarsenic feed additive of increasing interest used in the poultry industry. Soybean responses to ROX stress were investigated in root exudates (REs) using two-dimensional correlation spectroscopy (2D-COS) with fluorescence and Fourier transform infrared spectra. Environmentally-relevant ROX concentrations caused negligible toxicity to crop growth and photosynthesis activity, but blackened soybean roots at high concentrations. 2D-COS analysis revealed that the protein-like fluorophore and C=C and C=O, aliphatic-OH, and polysaccharide C-O-H moieties in soybean REs were most sensitive to ROX stress...
December 14, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/29239616/tertiary-and-quaternary-carbon-formation-via-gallium-catalyzed-nucleophilic-addition-of-organoboronates-to-cyclopropanes
#4
Truong N Nguyen, Jeremy A May
GaCl3 and (IPr)GaCl3/AgSbF6 formed γ-tertiary and γ-quaternary carbons via homoconjugate addition of organoboron nucleophiles to diester- and ketone-functionalized cyclopropanes. Electron donor group cyclopropane substituents were not needed, allowing electron-deficient aryl, alkenyl, alkyl, and hydrogen-substituted cyclopropanes to be used. The catalytic conditions were compatible with alkenyl, alkynyl, and aryl nucleophiles, including ortho-substituted aromatics, to synthesize highly hindered quaternary carbons...
December 14, 2017: Organic Letters
https://www.readbyqxmd.com/read/29239507/synthesis-of-%C3%AE-chiral-ketones-and-chiral-alkanes-using-radical-polar-crossover-reactions-of-vinyl-boron-ate-complexes
#5
Carolin Gerleve, Marvin Kischkewitz, Armido Studer
Vinyl boron ate complexes of enantioenriched secondary alkyl pinacolboronic esters undergo stereospecific radical induced 1,2-migration in radical polar crossover reactions. In this three component process various commercially available alkyl iodides act as radical precursors and light is used for chain initiation. A subsequent oxidation or protodeborylation leads to valuable α-chiral ketones and chiral alkanes with excellent enantiopurity.
December 14, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29239185/chemoselective-reduction-of-sterically-demanding-n-n-di-iso-propyl-amides-to-aldehydes
#6
Peihong Xiao, Zhixing Tang, Kai Wang, Hua Chen, Qianyou Guo, Yang Chu, Lu Gao, Zhenlei Song
A sequential one-pot process for chemoselectively reducing sterically demanding N,N-di(iso-propyl) amides to aldehydes has been developed. In this reaction, amides are activated with EtOTf to form imidates, which are reduced with LiAlH(OR)3 [R = t-Bu, Et] to give aldehydes by hydrolysis of the resulting hemiaminals. The non-nucleophilic base 2,6-DTBMP remarkably improves reaction efficiency. The combination of EtOTf/2,6-DTBMP and LiAlH(Ot-Bu)3 was found to be optimal for reducing alkyl, alkenyl, alkynyl and 2-monosubstituted aryl N,N-di(iso-propyl) amides...
December 14, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29238872/characterization-of-two-carbonyl-reductases-from-ogataea-polymorpha-nbrc-0799
#7
Kimiyasu Isobe, Shinsuke Miki, Ryoko Ueda, Sayaka Shichida, Daisuke Matsui, Yuko Oku, Yasuhisa Asano
The enzyme responsible for the enantioselective production of (S)-1,1,1-trifluoro-2-propanol ((S)-TFP) from 1,1,1-trifluoroacetone (TFA) has been identified in Ogataea polymorpha NBRC 0799. We purified two carbonyl reductases, OpCRD-A and OpCRD-B from this strain, and revealed their characteristics. Both enzymes were specific to NADH, but the following characteristics were different: The molecular mass of subunit OpCRD-A was 40 kDa and that of OpCRD-B was 43 kDa. Amino acid sequences of both enzymes were only 21% identical...
December 13, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/29238767/real-time-monitoring-for-reforming-processes-of-liquid-hydrocarbon-fuel-air-pre-mixtures-by-non-thermal-plasmas-using-ion-attachment-mass-spectrometry
#8
Daiki Asakawa, Akira Kuramochi, Eiichi Takahashi, Naoaki Saito
Plasma induced reforming processes of fuel-air mixtures were investigated to understand the mechanism of the plasma-assisted combustion technique, which can improve the thermal efficiency and stability of internal combustion engines. In this study, a mixture of air with isooctane or n-heptane fuels was reformed by non-thermal plasma in a flow reactor, generated by a dielectric barrier discharge, and then directly analyzed using ion attachment mass spectrometry. Plasma irradiation of an air/hydrocarbon mixture produced an oxygen atom which then reacted with a hydrocarbon, leading to hydroxyl and alkyl radicals...
December 13, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29235869/correction-to-organocatalytic-enantioselective-cross-aldol-reaction-of-o-hydroxyarylketones-and-trifluoromethyl-ketones
#9
Pei Wang, Hong-Feng Li, Jia-Zhen Zhao, Zhi-Hong Du, Chao-Shan Da
No abstract text is available yet for this article.
December 13, 2017: Organic Letters
https://www.readbyqxmd.com/read/29235717/direct-asymmetric-michael-reaction-of-%C3%AE-%C3%AE-unsaturated-aldehydes-and-ketones-catalyzed-by-two-secondary-amine-catalysts
#10
Yujiro Hayashi, Nariyoshi Umekubo
Direct asymmetric Michael reaction of α,β-unsaturated aldehydes and ketones proceeds in the presence of two pyrrolidine-type catalysts, such as diphenylprolinol silyl ether and hydroxyproline, to afford synthetically useful δ-keto aldehydes with excellent diastereo- and enantioselectivities. Although there are several iminium ions and enamines in the reaction mixture, an iminium ion generated from the former catalyst reacts preferentially with an enamine generated from the latter catalyst.
December 13, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29235696/beyond-hydrofunctionalization-a-well-defined-calcium-compound-catalyzed-mild-and-efficient-carbonyl-cyanosilylation
#11
Sandeep Yadav, Ruchi Dixit, Kumar Vanka, Sakya S Sen
Organocalcium compounds have been reported as efficient catalysts for various transformations, for cases where one of the substrates contained a E-H (E=B, N, Si, P) bond. Here, we look at the possibility of employing an organocalcium compound for a transformation in which none of the precursors has a polar E-H bond. This study demonstrates the utilization of a well-defined amidinatocalcium iodide, [PhC(NiPr)2CaI] (1) for cyanosilylation of a variety of aldehydes and ketones with Me3SiCN under ambient conditions without the need of any co-catalyst...
December 13, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29234415/1h-nmr-based-serum-metabolomics-study-to-investigate-hepatoprotective-effect-of-qin-jiao-on-carbon-tetrachloride-induced-acute-hepatotoxicity-in-rats
#12
Zeyun Li, Ying Li, Lingpan Lu, Zhiheng Yang, Wenhua Xue, Xin Tian, Xiaojian Zhang
Gentiana macrophylla Radix, commonly known as Qin-Jiao (QJ), was recorded alone to treat jaundice in Compendium of Materia Medica and has been frequently prescribed for treatment of liver disease in China. However, the underlying mechanism remains unknown. In the present work, QJ of 1,2 g/kg or silybin of 40 mg/kg (positive control) was orally given to rats for 7 days to verify the protective effect on acute liver damage induced by tetrachloride (CCl4). Together with serum biochemistry and histopathological examination, 1H-NMR based metabolomics work was carried out to investigate the efficacy...
2017: Evidence-based Complementary and Alternative Medicine: ECAM
https://www.readbyqxmd.com/read/29230466/synthesis-and-reactions-of-4h-1-4-telluraborine
#13
Fu An Tsao, Douglas W Stephan
The B(C6F5)3-catalyzed reaction of the 1,4-telluraborine, Te(PhC[double bond, length as m-dash]C(C6F5))2BOCH2Ph 2 with PhSiH3 gives Te(PhC[double bond, length as m-dash]C(C6F5))2BH 3. Compound 3 acts as a synthetic precursor to Te(PhC[double bond, length as m-dash]C(C6F5))2BCl 4 and Te(PhC[double bond, length as m-dash]C(C6F5))2B(THF)(O3SCF3) 5. In addition, 3 undergoes reactions with alkenes, alkynes, ketones and aldehydes to give a series of hydroboration products, 6-16.
December 12, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29225776/the-sedentary-r-evolution-have-we-lost-our-metabolic-flexibility
#14
Jens Freese, Rainer Johannes Klement, Begoña Ruiz-Núñez, Sebastian Schwarz, Helmut Lötzerich
During the course of evolution, up until the agricultural revolution, environmental fluctuations forced the human species to develop a flexible metabolism in order to adapt its energy needs to various climate, seasonal and vegetation conditions. Metabolic flexibility safeguarded human survival independent of food availability. In modern times, humans switched their primal lifestyle towards a constant availability of energy-dense, yet often nutrient-deficient, foods, persistent psycho-emotional stressors and a lack of exercise...
2017: F1000Research
https://www.readbyqxmd.com/read/29225416/getting-peek-to-stick-to-bone-the-development-of-porous-peek-for-interbody-fusion-devices
#15
F Brennan Torstrick, David L Safranski, J Kenneth Burkus, James L Chappuis, Christopher S D Lee, Robert E Guldberg, Ken Gall, Kathryn E Smith
Interbody fusion cages are routinely implanted during spinal fusion procedures to facilitate arthrodesis of a degenerated or unstable vertebral segment. Current cages are most commonly made from polyether-ether-ketone (PEEK) due to its favorable mechanical properties and imaging characteristics. However, the smooth surface of current PEEK cages may limit implant osseointegration and may inhibit successful fusion. We present the development and clinical application of the first commercially available porous PEEK fusion cage (COHERE®, Vertera, Inc...
September 2017: Techniques in Orthopaedics: TIO
https://www.readbyqxmd.com/read/29225109/raspberry-ketone-protects-against-isoproterenol-induced-myocardial-infarction-in-rats
#16
Vasim Khan, Sumit Sharma, Uma Bhandari, Syed Mansoor Ali, Syed Ehtaishamul Haque
AIM: The cardioprotective role of raspberry ketone (RK) against isoproterenol (ISO)-induced myocardial infarction (MI) in rats was assessed. MATERIALS AND METHODS: Rats were randomly divided into Group I - Vehicle control; Group II - Toxic control ISO (85mg/kg, s.c.); Group III, IV and V - RK (50, 100 and 200mg/kg, respectively) with ISO; Group VI- RK (200mg/kg) alone; Group VII - Propranolol (10mg/kg) with ISO; and Group VIII - Propranolol (10mg/kg) alone. After twenty-four hours of the last dose, animals were sacrificed and creatine kinase-MB, lactate dehydrogenase, total cholesterol, triglycerides, high-density-lipoprotein, low-density-lipoprotein, very-low-density-lipoprotein, malondialdehyde, reduced glutathione, superoxide dismutase, catalase, Na+, K+-ATPase, nitric oxide, histopathological and immunohistochemical analysis (tumor necrosis factor-α and inducible nitric oxide synthase) were performed...
December 7, 2017: Life Sciences
https://www.readbyqxmd.com/read/29224624/baeyer-villiger-monooxygenases-from-yarrowia-lipolytica-catalyze-preferentially-sulfoxidations
#17
Sven Bordewick, Andy Beier, Kathleen Balke, Uwe T Bornscheuer
Nine new putative Baeyer-Villiger monooxygenase encoding genes were identified in the eukaryote Yarrowia lipolytica and eight were subsequently cloned and expressed. These enzymes, Yarrowia monooxygenases A-H (YMOA-H), were used in biocatalysis reactions with ketones, sulfides and sulfoxides as substrates. YMOB converts ketones and sulfides, albeit with low activities. However, YMOA did not convert any of the tested ketone substrates, but showed activity towards sulfides and sulfoxides and also showed very high stereoselectivity...
February 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29224350/mechanism-of-the-ullmann-biaryl-ether-synthesis-catalyzed-by-complexes-of-anionic-ligands-evidence-for-the-reaction-of-iodoarenes-with-ligated-anionic-cui-intermediates
#18
Ramesh Giri, Andrew Brusoe, Konstantin Troshin, Justin Y Wang, Marc Font, John F Hartwig
A series of experimental studies, along with DFT calculations, are reported that provide a detailed view into the mechanism of Ullmann coupling of phenols with aryl halides in the presence of catalysts generated from Cu(I) and bidentate, anionic ligands. These studies encompass catalysts containing anionic ligands formed by deprotonation of 8-hydroxyquinoline, 2-pyridylmethyl tert-butyl ketone, and 2,2,6,6-tetramethylheptane-3,5-dione. Three-coordinate, heteroleptic species [Cu(LX)OAr]- were shown by experiment and DFT calculations to be the most stable complexes in catalytic systems containing 8-hydroxyquinoline or 2-pyridylmethyl tert-butyl ketone and to be generated reversibly in the system containing 2,2,6,6-tetramethylheptane-3,5-dione...
December 10, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29223014/differentiation-of-dry-cured-hams-from-different-processing-methods-by-means-of-volatile-compounds-physico-chemical-and-sensory-analysis
#19
Sandra Petričević, Nives Marušić Radovčić, Katarina Lukić, Eddy Listeš, Helga Medić
The aim of this study was to characterize dry-cured hams from four different processing methods (differences in primary leg treatment, salting and smoking phase). Volatile compounds were isolated by using headspace-solid phase microextraction and analysed by gas chromatography/mass spectrometry (GC/MS). Samples were also evaluated by sensory and physico-chemical characteristics (moisture, protein, fat and NaCl content, aw, colour). 149 volatile compounds of dry-cured hams were identified and 15 of them were quantified...
December 5, 2017: Meat Science
https://www.readbyqxmd.com/read/29222891/effects-of-preoperative-oral-carbohydrate-therapy-on-perioperative-glucose-metabolism-during-oral-maxillofacial-surgery-randomised-clinical-trial
#20
Kanako Esaki, Masanori Tsukamoto, Eiji Sakamoto, Takeshi Yokoyama
BACKGROUND AND OBJECTIVES: Preoperative oral carbohydrate therapy has been suggested to attenuate postoperative insulin resistance. The purpose of this study was to investigate the effect of a carbohydrate-rich beverage given preoperatively on intraoperative glucose metabolism. METHODS AND STUDY DESIGN: This study was a randomised, open-label, placebo-controlled trial. Patients undergoing oral-maxillofacial surgery were divided into two groups. In the glucose group, patients took glucose (50 g/278 mL, p...
2018: Asia Pacific Journal of Clinical Nutrition
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