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31.
Cyclic (Amino)(aryl)carbenes (CAArCs) as Strong σ‐Donating and π‐Accepting Ligands for Transition Metals 下载免费PDF全文
Bin Rao Huarong Tang Prof. Dr. Xiaoming Zeng Liu Liu Dr. Mohand Melaimi Prof. Dr. Guy Bertrand 《Angewandte Chemie (International ed. in English)》2015,54(49):14915-14919
Cyclic (amino)(aryl)carbenes (CAArCs) result from the replacement of the alkyl substituent of cyclic (alkyl)(amino) carbenes (CAACs) by an aryl group. This structural modification leads to enhanced electrophilicity of the carbene center with retention of the high nucleophilicity of CAACs, and therefore CAArCs feature a small singlet–triplet gap. The isoindolium precursors are readily prepared in good yields, and deprotonation at low temperature, in the presence of [RhCl(cod)]2 and [(Me2S)AuCl] lead to air‐stable rhodium and gold CAArC‐supported complexes, respectively. The rhodium complexes promote the [3+2] cycloaddition of diphenylcyclopropenone with ethyl phenylpropiolate, and induce the addition of 2‐vinylpyridine to alkenes by CH activation. The gold complexes allow for the catalytic three‐component preparation of 1,2‐dihydroquinolines from aniline and phenyl acetylene. These preliminary results illustrate the potential of CAArC ligands in transition‐metal catalysis. 相似文献
32.
We give in this work some results about the existence and uniqueness with optimal regularity for solutions of a parabolic equation in nondivergence form in Lq (0,T;Lp (Omega)) where 1 < p,q < infinity in two cases. We use Lamberton's results (cf. [9]) in the first case and Dore-Venni's results (cf. [6]) in the second case. 相似文献
33.
A new methodology for the synthesis of 1-P-functionalized phosphole-2,5-dicarboxylic acids is described. The carboxylic group is introduced through a two-step sequence which involves a preliminary attack of the phospholide unit onto CO(2) followed by a [1,5]-shift reaction of the CO(2)Li group around the phosphole nucleus. This approach was extended to the preparation of a new type of bidentate ligands. [reaction: see text] 相似文献
34.
Jean-Pierre Monthéard Marcel Camps Mohand Ouali Aït-Yahia 《Tetrahedron letters》1979,20(16):1373-1376
Perchloric acid in acetic acid reacts with phenylacetylene to give acetophenone, α-chloroacetophenone, α,α'-dichloroacetophenone, α-acetoxy α'chloroacetophenone, dichloro-styrène and chlorophenylacetylene. Kinetics of these reactions have been established. 相似文献
35.
Controlled Expansion of a Strong‐Field Iron Nitride Cluster: Multi‐Site Ligand Substitution as a Strategy for Activating Interstitial Nitride Nucleophilicity 下载免费PDF全文
Myles J. Drance Dr. Charles C. Mokhtarzadeh Dr. Mohand Melaimi Dr. Douglas W. Agnew Dr. Curtis E. Moore Prof. Dr. Arnold L. Rheingold Prof. Dr. Joshua S. Figueroa 《Angewandte Chemie (International ed. in English)》2018,57(40):13057-13061
Multimetallic clusters have long been investigated as molecular surrogates for reactive sites on metal surfaces. In the case of the μ4‐nitrido cluster [Fe4(μ4‐N)(CO)12]?, this analogy is limited owing to the electron‐withdrawing effect of carbonyl ligands on the iron nitride core. Described here is the synthesis and reactivity of [Fe4(μ4‐N)(CO)8(CNArMes2)4]?, an electron‐rich analogue of [Fe4(μ4‐N)(CO)12]?, where the interstitial nitride displays significant nucleophilicity. This characteristic enables rational expansion with main‐group and transition‐metal centers to yield unsaturated sites. The resulting clusters display surface‐like reactivity through coordination‐sphere‐dependent atom rearrangement and metal–metal cooperativity. 相似文献
36.
The reaction of benzyl, methyl and phenyl azide, with olefins substituted by three electron-withdrawing groups, has been studied. This reaction gives in certain cases only one triazoline (single orientation of the cycloaddition). In other cases, a mixture of a triazoline and a diazocompound (double orientation of the cycloaddition) is obtained. The structure assignment of the triazolines is confirmed using chemical methods and 13C-NMR. Thermally, diazocompounds rearrange to enaminoesters which cyclise at high temperature to quinolines. 相似文献
37.
38.
Generalization of the Copper to Late‐Transition‐Metal Transmetallation to Carbenes beyond N‐Heterocyclic Carbenes 下载免费PDF全文
Dr. Yannick D. Bidal Orlando Santoro Dr. Mohand Melaimi Dr. David B. Cordes Prof. Alexandra M. Z. Slawin Prof. Guy Bertrand Dr. Catherine S. J. Cazin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(27):9404-9409
Carbene transition‐metal complexes have become a prevalent family of catalysts enabling numerous organic transformations. Their facile synthetic access is a matter of great importance. To this end, the CuI‐NHC transfer methodology has emerged as a powerful alternative presenting attractive advantages over other methods. Herein, we report the remarkable ability of copper to transfer not only NHCs but also other types of carbenes such as abnormal NHCs (aNHCs), cyclic (alkyl)(amino)carbenes (CAACs), and mesoionic carbenes (MICs) to various transition metal precursors. 相似文献
39.
Andjouh Amar Bibi Mohand Ouamer 《Journal of Optimization Theory and Applications》2022,192(1):360-378
Journal of Optimization Theory and Applications - In this paper, we propose a new adaptive method for solving the non-convex quadratic minimization problem subject to box constraints, where the... 相似文献
40.
Methane number and Lower Heating Value (LHV) of natural gas are determined by the online measurement of thermal conductivity at two different temperatures. Natural gas is first considered as a ternary mixture of the most important components. A pseudo-ternary composition can then be calculated, using the thermal conductivity formula for mixtures derived from kinetic theory. A non-linear system is solved numerically using the Newton–Raphson method. A sensor based on thermal conductivity measurement has been developed and tested successfully for many natural gas compositions. To cite this article: C. Rahmouni et al., C. R. Mecanique 331 (2003). 相似文献