Decarboxylative Alkyl–Alkyl Cross‐Coupling Reactions

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137566/1/anie201605593_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137566/2/anie201605593.pd

Implementation of Global Supply Chains as a Strategy for Increasing National Competitiveness

Abstract— Today competitiveness depends not only on price but also on customer service and delivery time. The creation of an effective infrastructure and the development of global supply chains is the key condition for increasing competitiveness. The study is based on the analysis of peer-reviewed literature, as well as the information publicly available on official websites. The purpose of the research is to conduct a thorough analysis and compare the level of competitiveness and efficiency throughout the supply chain of logistics services in different countries. The logistics efficiency and global competitiveness indicators have been analyzed. It has been concluded that favorable conditions in the country evidenced by its high ranking in the International Logistics Performance Index determine the potential for the implementation of global chains and provide opportunities for increasing competitiveness

Model of the life cycle of the information security system

When building an information security system, one of the key problems is the creation of regulatory documents. Regulators in the field of information security determine the list of necessary documentation mainly in relation to protection mechanisms (authentication, anti-virus protection, etc.) and practically do not take into account the stages of the life cycle of information security tools and personnel of the organization. The article proposes an approach to formalization of the list of information security management processes that need regulation. This approach allows the formation of information security policy to take into account the processes of personnel management and the complex of software and hardware information security, which is necessary to ensure a high level of security of critical information infrastructure

Рентгенодиагностика хронического олигоартрита у детей

Juvenile arthritis continues to be a serious diagnostic problem of pediatric rheumatology despite the improvement of clinical, immunological and instrumental methods of examination. Clinical heterogeneity, nonspecificity of instrumental picture and limited application of some examination methods account for the diagnostic difficulties of articular pathology in young children. Chronic oligoarthritis in young children presents a particular challenge due to a frequent vague onset and minimally symptomatic course which can result in a late diagnosis and a high risk of early disability. This paper identifies the problem of diagnosis of childhood arthropathy in relation to its informative value and the practical and clinical significance of basic instrumental methods of chronic arthritis visualization. Special attention is paid to particular roentgenologic features and interpretation of MR images in diagnosis of juvenile olighoarthritis. This article aims at systematizing and expanding the views of pediatricians and rheumatologists on the importance of radiography methods in the diagnosis of joint pathology in children.Несмотря на совершенствование клинико-иммунологических и инструментальных методов обследования, диагностика ювенильного артрита продолжает оставаться серьезной проблемой детской ревматологии. Клиническая гетерогенность, неспецифичность инструментальной картины и ограниченность применения некоторых методик обследования определяют сложность вопросов диагностики суставной патологии детского возраста. Хронический олигоартрит у детей представляет собой особую сложность в связи с нередким малозаметным началом и отсутствием жалоб у ребенка, что может приводить к позднему выявлению заболевания, высокому риску ранней инвалидизации.В данной статье обозначена проблема диагностики артропатий детского возраста применительно к информативности, практичности и клинической значимости основных инструментальных методов визуализации хронического артрита. Ключевое внимание уделено частным проблемам рентгенодиагностики ювенильного олигоартрита, затронуты вопросы трактовки магнитно-резонансной томографии. Целью данной статьи является систематизирование и расширение представлений педиатров и врачей-ревматологов о значимости методов рентгенографии в структуре диагностики суставной патологии у детей

Mixed plastics waste valorization through tandem chemical oxidation and biological funneling

115 p.-4 fig.-45 fig. supl.-14 tab supl.Mixed plastics waste represents an abundant and largely untapped feedstock for the production of valuable products. The chemical diversity and complexity of thesematerials, however, present major barriers to realizing this opportunity. In this work, we show that metal-catalyzed autoxidation depolymerizes comingled polymers into a mixture of oxygenated small molecules that are advantaged substrates for biological conversion. We engineer a robust soil bacterium, Pseudomonas putida, to funnel these oxygenated compounds into a single exemplary chemical product, either b-ketoadipate or polyhydroxyalkanoates. This hybrid process establishes a strategy for the selective conversion of mixed plastics waste into useful chemical products.Funding was provided by the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office (AMO), and Bioenergy Technologies Office (BETO). This work was performed as part of the BOTTLE Consortium and was supported by AMO and BETO under contract no. DE-AC36- 08GO28308 with the National Renewable Energy Laboratory (NREL),operated by the Alliance for Sustainable Energy, LLC. The BOTTLE Consortium includes members from MIT, funded under contract no. DE-AC36-08GO28308 with NREL. Contributions by S.S.S. were supported by the US Department of Energy, Office of Basic Energy Sciences, under award no. DEFG02-05ER15690.Peer reviewe

Development of Nickel-Catalyzed Coupling Reactions: Intramolecular Alkyl-Heck and Reductive Cross-Electrophile Cyclizations and Hydroarylation of Alkynes

Transition metal catalyzed reactions are ubiquitous in the realm of synthetic chemistry, allowing for the strategic construction of complex molecular frameworks of pharmaceuticals, natural products, and synthetic materials. Palladium-catalyzed cross-coupling reactions are part of the foundation of these transformations, insofar as they were recognized with the 2010 Nobel Prize in chemistry. Traditionally, these reactions have relied on aryl and vinyl electrophiles, whereas the alkyl counterparts have only recently begun to emerge in the literature. Nickel has been on the forefront of enantioconvergent alkyl cross-coupling reactions due to its propensity to undergo single electron chemistry. However, under special conditions, it has a unique ability to break strong carbon–oxygen bonds in a stereospecific manner, making research into its reactivity a valuable endeavor to the field of organometallic chemistry. Chapter 1 describes the development of a stereospecific intramolecular alkyl-Heck cyclization of benzylic ethers. The reaction proceeds with inversion at the electrophilic carbon, for the synthesis of methylenecyclopentanes of both extended π-electron and simple aromatic systems. The enantioenriched products can be effectively derivatized to cyclic α-aryl ketones in good yields with good transfer of chirality. Avenues to expand the utility of this reaction have been identified and further studies are ongoing.Chapter 2 discusses the development of nickel-catalyzed cross-electrophile coupling reactions of benzylic esters and aryl halides. An intermolecular reaction proceeds in high yields for primary benzylic esters for the synthesis of pharmacologically relevant diarylmethanes. The corresponding intramolecular cyclization proceeds under mild conditions, demonstrating the first example of a stereospecific cross-electrophile coupling of secondary benzylic esters. A variety of heterocyclic and functionalized substrates are tolerated under the reaction conditions.Chapter 3 examines the development a regio- and stereoselective nickel-catalyzed hydroarylation of alkynes with arylboronic acids. The reaction is facilitated by propargyl carbamates as directing groups. The reaction is tolerant of a range of functional groups and heterocycles. Mechanistic studies reveal that the acidic protons of the arylboronic acid coupling partner serve as the origin of hydrogen. Furthermore, the synthesis of tamoxifen can be completed in two steps from a simple hydroarylation product

Electrochemical Measurement of Interfacial Distribution and Diffusion Coefficients of Electroactive Species for Ion-Exchange Membranes: Application to Br2/Br− Redox Couple

A novel method has been proposed for rapid determination of principal transmembrane transport parameters for solute electroactive co-ions/molecules, in relation to the crossover problem in power sources. It is based on direct measurements of current for the electrode, separated from solution by an ion-exchange membrane, under voltammetric and chronoamperometric regimes. An electroactive reagent is initially distributed within the membrane/solution space under equilibrium. Then, potential change induces its transformation into the product at the electrode under the diffusion-limited regime. For the chronoamperometric experiment, the electrode potential steps backward after the current stabilization, thus inducing an opposite redox transformation. Novel analytical solutions for nonstationary concentrations and current have been derived for such two-stage regime. The comparison of theoretical predictions with experimental data for the Br2/Br− redox couple (where only Br− is initially present) has provided the diffusion coefficients of the Br− and Br2 species inside the membrane, D(Br−) = (2.98 ± 0.27) 10−6 cm2/s and D(Br2) = (1.10 ± 0.07) 10−6 cm2/s, and the distribution coefficient of the Br− species at the membrane/solution boundary, K(Br−) = 0.190 ± 0.005, for various HBr additions (0.125–0.75 M) to aqueous 2 M H2SO4 solution. This possibility to determine transport characteristics of two electroactive species, the initial solute component and its redox product, within a single experiment, represents a unique feature of this study

Electroactive polymeric material with condensed structure on the basis of magnesium(II) polyporphine

International audiencePrevious publication of the authors presented evidences that electroch emical oxidation of Mg(II) porphine (fully unsubstituted porphyrin, MgP) in acetonitrile (AN) at a very low potential leads to deposition of films at electrode surface corresponding to typical electroactive polymers, with their reversible transition betwee n the electronconducting and insulating states depending on the electrode potential/oxidation level ("film of type I"). It is demonstrated in the actual publication that these films in contact with a monomer-free solution are subject to an irreversible transformation to quite a different material ("film of type II") under the influence of a higher positive potential (above 0.5-0.6 V vs. Ag/Ag + in AN). Films with the same properties may also be obtained directly by electrooxidation of the monomer, MgP, at a sufficiently high potential. Films of type II possess a high redox activity and electronic conductivity within the whole potential interval of above 3 V in the width. Their grayish color is related to a constant absorption intensity within the whole range of wavelengths studied (320-1000 nm). On the basis of a combination of experimental observations (ATR IR ad XPS) and literature data the molecular structure of this new material is assumed to be polymer chains of directly linked porphine units (with a par tial loss of Mg cations), probably with multiple bonds (meso-meso and β-β type) between the neighboring units

Surprising dependence of the current density of bromate electroreduction on the microelectrode radius as manifestation of the autocatalytic redox-cycle (EC″) reaction mechanism

Bromate reduction from strongly acidic solutions under steady-state conditions in the presence of a very small amount of bromine has been studied voltammetrically at disk microelectrodes of various radii. In conformity with theoretical predictions the intensity of the average current density depends on the electrode size in a non-monotonous manner, passing through a maximum for a certain radius. This behavior is a direct consequence of the autocatalytic character of this process where the non-electroactive bromate anion is reduced owing to the catalytic cycle based on the bromine/bromide redox-mediator couple. The experimentally observed dependence of the maximal current density, jmax, on the inverse disc radius, 1/r0, for electrodes of larger sizes approaches a straight line corresponding to the “strong current limit”, which exceeds the diffusion-limited current density for bromate ion. Keywords: Autocatalytic cycle, Bromine/bromide redox mediation, Comproportionation reaction, Disk microelectrod