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61.
N‐Functionalized Ferrocenes: Subvalent Group XIV Element Chlorides and tert‐Butyllithium‐Induced C−C Bond Cleavage under Mild Conditions
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Dr. Bastian Nayyar Dr. Hazem Alnasr Prof. Dr. Wolf Hiller Prof. Dr. Klaus Jurkschat 《Angewandte Chemie (International ed. in English)》2018,57(19):5544-5547
The ferrocene derivative (η5‐Cp)Fe{η5‐C5H3‐1‐(ArNCH)‐2‐(CH2NMe2)} ( 1 ; Ar=2,6‐iPr2C6H3)) reacts diastereoselectively with LiR by carbolithiation and subsequent hydrolysis to give (η5‐Cp)Fe{η5‐C5H3‐1‐(ArHNCHR)‐2‐(CH2NMe2)} ( 3 : R=tBu; 4 : R=Ph; 5 : R=Me) in high yields. For R=tBu, the organolithium derivative (η5‐Cp)Fe{η5‐C5H3‐1‐(ArLiNCHR)‐2‐(CH2NMe2)} ( 2 ) was isolated. Compound 2 reacts with GeCl2?dioxane and SnCl2 to give the metallylene amide chlorides (η5‐Cp)Fe{η5‐C5H3‐1‐(ArMNCHtBu)‐2‐(CH2NMe2)} 6 (M=GeCl) and 7 (M=SnCl), respectively, which each contain three stereogenic centers. The potential of 7 as a ligand in transition‐metal chemistry is demonstrated by formation of its complex (η5‐Cp)Fe{η5‐C5H3‐1‐(ArMNCHtBu)‐2‐(CH2NMe2)} [ 9 , M= Sn(Cl)W(CO)5]. Treatment of 3 with tert‐butyllithium at room temperature causes an unprecedented carbon–carbon bond cleavage whereas under kinetic control, lithiation at the Cp‐3 position takes place, which leads to the isolation of (η5‐Cp)Fe{η5‐C5H3‐1‐(ArHNCHtBu)‐2‐(CH2NMe2)‐3‐SiMe3} ( 10 ). 相似文献
62.
Marie Thérèse Aimar Abdelkader Intissar Jean Martin Paoli 《Communications in Mathematical Physics》1993,156(1):169-177
We consider a closed densely defined linear operatorT in a Hilbert spaceE, and assume the existence of
0 (T) such thatK = (T -
0
I)-1 is compact and the existence ofp>0 such thats
n
(K)=o((n
–1/p)), whereS
n
(K) denotes the sequence of non-zero eigenvalues of the compact hermitian operator
. In this work, sufficient conditions (announced in [1]) are introduced to assure that the closed subspace ofE spanned by the generalized eigenvectors ofT coincides withE. These conditions are in particular verified by a family of non-self-adjoint operators arising in reggeon's field theory. 相似文献
63.
Abdelkader Intissar 《Communications in Mathematical Physics》1987,113(2):263-297
In this paper, we study a few spectral properties of a non-symmetrical operator arising in the Gribov theory. The first and second section are devoted to Bargmann's representation and the study of general spectral properties of the operator: $$\begin{gathered} H_{\lambda ',\mu ,\lambda ,\alpha } = \lambda '\sum\limits_{j = 1}^N {A_j^{ * 2} A_j^2 + \mu \sum\limits_{j = 1}^N {A_j^ * A_j + i\lambda \sum\limits_{j = 1}^N {A_j^ * (A_j + A_j^ * )A_j } } } \hfill \\ + \alpha \sum\limits_{j = 1}^{N - 1} {(A_{j + 1}^ * A_j + A_j^ * A_{j + 1} ),} \hfill \\ \end{gathered}$$ whereA* j andA j ,j∈[1,N] are the creation and annihilation operators. In the third section, we restrict our study to the case of nul transverse dimension (N=1). Following the study done in [1], we consider the operator: $$H_{\lambda ',\mu ,\lambda } = \lambda 'A^{ * 2} A^2 + \mu A^ * A + i\lambda A^ * (A + A^ * )A,$$ whereA* andA are the creation and annihilation operators. For λ′>0 and λ′2≦μλ′+λ2. We prove that the solutions of the equationu′(t)+H λ′, μ,λ u(t)=0 are expandable in series of the eigenvectors ofH λ′,μ,λ fort>0. In the last section, we show that the smallest eigenvalue σ(α) of the operatorH λ′,μ,λ,α is analytic in α, and thus admits an expansion: σ(α)=σ0+ασ1+α2σ2+..., where σ0 is the smallest eigenvalue of the operatorH λ′,μ,λ,0. 相似文献
64.
Mohamed F. M. Abdelkader Mohamed H. Mahmoud Loay A. A. Mohamed A. Abdein Khaled Metwally Shinya Ikeno Samar M. A. Doklega 《Molecules (Basel, Switzerland)》2022,27(12)
In the present study, an experiment was carried out on the postharvest of cucumber fruit during a 14-day shelf life. The aim was to assess the impact of calcium nanoparticles (CaNPs) blended with different concentrations of salicylic acid (SA) on the shelf life of cucumbers during the seasons of 2018 and 2019. The investigation further monitored the influences of CaNPs-SA on some physical properties of cucumber, including the percentage weight loss, color, and fruit firmness. In addition, chemical properties, such as total soluble solids (SSC%), total acidity (TA%), total soluble sugars, and chlorophyll pigmentation of the fruit skin, were assessed during a 14-day shelf lifeCell wall degradation enzymes (CWEAs) such as polygalacturonase (PG), cel-lulase (CEL), xylanase (XYL), and pectinase (PT) were also researched. In addition, the generation rates of H2O2 and O2•− were calculated, as well as the reduction of DPPH. The lipid peroxidation (malondialdehyde, MDA) and cell membrane permeability (IL%) of cell wall composites were also determined. CaNPs-SA at 2 mM suppressed CWEAs, preserved fruit quality, reduced weight loss throughout the shelf-life period, and reduced the percent leakage value. At this concentration, we also found the lowest levels of MDA and the highest levels of DPPH. 相似文献
65.
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67.
Cycloaddition reactions are an integral and weighty part of organic chemistry in pedagogy and research as well. The wealthy literature on cycloaddition reactions from their birth up to now, unequivocally witnesses to their leading chemistry. The so-called “conventional solvents” are organic solvents that have indubitably promoted their success. Yet, the toxicity facet of these solvents impedes their use freely and with no fear. Not only is the operating chemist uncomfortable while experimenting, but also the environment is equally threatened. Working out the cycloaddition reactions and other organic ones in aqueous systems would certainly bring some relief to the chemist and to the environment as well. Unusual outcomes in terms of yield, reactivity and selectivity compared to those performed in organic solvents were commonly observed, and have overwhelmed the chemists with surprise indeed. In this review, homo Diels–Alder reactions in aqueous media include those involving the following dienophiles: maleimides, α,β-unsaturated esters, p-benzoquinones, vinyl ketones, phenyl-1-(2-pyridyl)-2-propen-1-one, α,β-unsaturated esters. A special case is the organocatalysis of Diels–Alder cycloaddition of α,β-unsaturated ketones (aldehydes). Of no less importance, some hetero Diels–Alder cycloaddition reactions in water systems are delineated. The impact of additives (salts, organic and inorganic chemicals), micellar catalysis and Lewis/Brønstëd acid catalysis on outcomes of such cycloaddition reactions is discussed. The 1,3-dipolar cycloaddition methodology applied to aqueous media has brought forth a number of heterocyclic compounds, usually with a regio- and stereoselectivity pecularity. These heterocycles include triazoles, tetrazoles, pyrazoles, isoxazoles, isoxazolidines, pyrroles and pyrrolidines. The superiority of copper(I) catalysis in the azide-alkyne cycloaddition (Huisgen cycloaddition) in water is endorsed by a number of examples. 相似文献
68.
Awad A. H. Abdel-Ghany Ahmed W. Abd El-Wahab Ayman A. El-Gamasy Ramadan Abdellatif Mohamed Hazem 《Journal of Thermal Analysis and Calorimetry》2020,140(6):2615-2623
Journal of Thermal Analysis and Calorimetry - The purpose of this work is to investigate the opportunity of re-using M&G wastes to get novel PP composites. Recycling of marble and granite... 相似文献
69.
70.
Benyoub Nassima Barça Abdelhafid Selâdji Fawzia Benhamou Abdellah Debab Abdelkader 《Research on Chemical Intermediates》2021,47(10):4311-4331
Research on Chemical Intermediates - The single and binary adsorption of two anionic dyes Acid Yellow 17 (AY17) and Naphtol Green B (NGB) onto N–N–Dimethyl-n-octylamine (DMOA) modified... 相似文献