Konjugierte Addition von Organozinkverbindungen an Nitroalkene

Rimkus A. Konjugierte Addition von Organozinkverbindungen an Nitroalkene. Bielefeld (Germany): Bielefeld University; 2002.Die stereoselektive 1,4-Addition von Diorganozinkverbindungen an synthetisierte Nitroalkene, katalysiert durch Phosphoramidit-Kupfer(I)-Komplexe, wurde untersucht. Die Synthese von aliphatischen und aromatischen Nitroalkenen wurde durch Henry-Reaktion durchgeführt. Neben der Synthese bekannter Phosphoramidit-Liganden wurden auch 3,3'-dimethylierte Phosphoramidite dargestellt. Die Cu(I)-katalysierte enantioselektive 1,4-Addition von Diorganozinkverbindungen an synthetisierte Nitroalkene zeigte eine starke Temperatur- und Lösungsmittelabhängigkeit. Dabei wurden akzeptable bis exzellente Enantioselektivitäten (bis 92 v.H. ee) und sehr gute Ausbeuten (bis 94 v.H.) erzielt. Ein neues modulares Synthesekonzept für die katalytische asymmetrische Synthese von enantiomerenreinen [beta]2-Homoaminosäuren wurde bearbeitet. Das Konzept beruht auf stereoselektiver katalytischer 1,4-Addition von Diorganozinkverbindungen an 3-Nitropropensäureester

Conjugate addition of organozinc compounds to nitroolefins

Rimkus A, Sewald N. Conjugate addition of organozinc compounds to nitroolefins. Synthesis. 2004;2004(1):135-146.Symmetrical (R2Zn) or mixed diorganozinc compounds ((RZnR2)-Zn-1) smoothly react with a series of nitroolefins in the presence of catalytic amounts of copper(I) salts and provide synthetically versatile nitro compounds in moderate to good yields. Simple alkyl groups, functionalized residues, or mixed trimethylsilylmethyl organozinc compounds (TMSM)ZnR may be employed for conjugate addition, while the TMSM group is not being transferred. ipso-Substitution is observed in absence of the copper(I) salt. Enantiomerically pure copper(I) complexes with BINOL based chiral phosphoramidite ligands efficiently catalyze the addition of dialkylzinc compounds to nitroalkenes. For instance, diethylzinc addition occurs with high yields and excellent enantioselectivity. Nitrostyrene, 3-nitroacrolein dimethylacetal, and 3-nitroacrylates have been used as substrates. The nitroolefin moiety predominates over the acrylate moiety and acts as the more powerful Michael acceptor. 2-Alkyl-3-nitropropanoates are exclusively obtained with excellent yield and enantioselectivity. The products can easily be transformed into beta(2)-homoamino acids, compounds of high relevance for different areas of preparative organic chemistry. 1 Introduction 2 Synthesis of Nitroolefins 3 Conjugate Addition of Organozinc Compounds 3.1 Conjugate Addition of Functionalized Organozinc Cuprates and Diorganozine Compounds 3.2 Conjugate Addition of Alkyl Trimethylsilylmethylzinc Compounds 3.3 Enantioselective Catalytic Conjugate Addition of Dialkylzinc Compounds 3.3.1 Chiral Catalysts 3.3.2 Addition to 3-Nitroacrylates 3.3.3 Addition to 3-Alkyl Substituted 3-Nitroacrylates 3.3.4 Addition to Nitrostyrene and 3-Nitroacrolein Dimethylacetal 4 Synthesis of beta(2)-Homoaminoacids 5 Conclusions

Internal Combustion Engine Analysis of Energy Ecological Parameters by Neutrosophic MULTIMOORA and SWARA Methods

The investigation for new innovative solutions to reduce transport pollution is a priority for the European Union (EU). This study includes energy and a sustainable environment, as well as transport, logistics, and information and communication technologies. Energy ecological parameters of internal combustion depend on many factors: fuel, the fuel injection time, engine torque, etc. The engine’s energy ecological parameters were studied by changing engine torques, using different fuels, and changing the start of the fuel injection time. The selection of the optimum parameters is a complex problem. Multicriteria decision-making methods (MCDM) present powerful and flexible techniques for the solution of many sustainability problems. The article presents a new way of tackling transport pollution. The analysis of the energy ecological parameters of the experimental internal combustion engine is performed using the neutrosophic multi-objective optimization by a ratio analysis plus the full multiplicative form (MULTIMOORA) and step-wise weight assessment ratio analysis (SWARA) methods. The application of MCDM methods provides us with the opportunity to establish the best alternatives which reflect the best energy ecological parameters of the internal combustion engine

Internal Combustion Engine Analysis of Energy Ecological Parameters by Neutrosophic MULTIMOORA and SWARA Methods

The investigation for new innovative solutions to reduce transport pollution is a priority for the European Union (EU). This study includes energy and a sustainable environment, as well as transport, logistics, and information and communication technologies. Energy ecological parameters of internal combustion depend on many factors: fuel, the fuel injection time, engine torque, etc. The engine’s energy ecological parameters were studied by changing engine torques, using different fuels, and changing the start of the fuel injection time. The selection of the optimum parameters is a complex problem. Multicriteria decision-making methods (MCDM) present powerful and flexible techniques for the solution of many sustainability problems. The article presents a new way of tackling transport pollution. The analysis of the energy ecological parameters of the experimental internal combustion engine is performed using the neutrosophic multi-objective optimization by a ratio analysis plus the full multiplicative form (MULTIMOORA) and step-wise weight assessment ratio analysis (SWARA) methods. The application of MCDM methods provides us with the opportunity to establish the best alternatives which reflect the best energy ecological parameters of the internal combustion engine.This article belongs to the Special Issue Sustainable Energy Development Strategies: Energy Efficiency and Renewable

Supercontinuum generation by co-filamentation of two color femtosecond laser pulses

In this paper, we experimentally investigate supercontinuum generation via collinear two-color filamentation in sapphire crystal, by launching two femtosecond pulses at fundamental (1030 nm) and second harmonic (515 nm) wavelengths from an amplified Yb:KGW laser. By changing the time delay between the incident pulses, we observe dramatic changes in the supercontinuum spectrum, transmitted energy, position of the nonlinear focus and intensity distribution along the filament-induced luminescence traces. In particular, we show that at some delays the two pump wavelengths can assist each other in generating supercontinuum, whilst at other delays large portions of the supercontinuum spectrum are completely extinguished. The transition between supercontinuum generation and its extinction occurs within a very short (20 fs) span of the delay times, despite the fact that the pump pulses are 220 fs long. We propose that the observed non-trivial spectral dynamics can be interpreted by a mechanism, where co-propagating two pump pulses perturb the nonlinear refractive properties of the medium via Kerr effect and generation of free electron plasma thereby affecting pulse splitting and pulse front steepening, which are the key players in the process of supercontinuum generation in a normally dispersive medium

Transthyretin cardiac amyloidosis in aortic stenosis: prevalence, diagnostic challenges and clinical implications.

Transthyretin cardiac amyloidosis (ATTR-CA) is a challenging and underdiagnosed cause of heart failure. Advances in cardiac imaging enabled noninvasive diagnosis of ATTR-CA, causing the recent upsurge in disease awareness and detection. ATTR-CA has been increasingly recognized in patients with degenerative aortic stenosis (AS). With the growing number of elderly patients undergoing aortic valve intervention, the identification of ATTR-CA in this group of patients is of high clinical importance. Timely and correct diagnosis is essential for amyloid directed therapies, as well as deciding on AS treatment strategy. This review provides a comprehensive overview of the recent studies investigating coexistence of these two entities. We present the data on the prevalence of ATTR-CA in AS and their prognostic associations. Since diagnosis of ATTR-CA may be challenging, special attention is paid to the diagnostic utility of different imaging modalities, echocardiography, cardiovascular magnetic resonance, nuclear imaging, and distinctive imaging features in patients with dual pathology. We also present a flow diagram summarizing integrated imaging in patients with suspected ATTR-CA