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151.
Quentin Ronzon Dr. Wei Zhang Dr. Nicolas Casaretto Dr. Elisabeth Mouray Prof. Dr. Isabelle Florent Dr. Bastien Nay 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(28):7764-7772
The introduction of substituents on bare heterocyclic scaffolds can selectively be achieved by directed C−H functionalization. However, such methods have only occasionally been used, in an iterative manner, to decorate various positions of a medicinal scaffold to build chemical libraries. We herein report the multiple, site selective, metal-catalyzed C−H functionalization of a “programmed” 4-hydroxyquinoline. This medicinally privileged template indeed possesses multiple reactive sites for diversity-oriented functionalization, of which four were targeted. The C-2 and C-8 decorations were directed by an N-oxide, before taking benefit of an O-carbamoyl protection at C-4 to perform a Fries rearrangement and install a carboxamide at C-3. This also released the carbonyl group of 4-quinolones, the ultimate directing group to functionalize position 5. Our study highlights the power of multiple C−H functionalization to generate diversity in a biologically relevant library, after showing its strong antimalarial potential. 相似文献
152.
153.
Gillon B Mathonière C Ruiz E Alvarez S Cousson A Rajendiran TM Kahn O 《Journal of the American Chemical Society》2002,124(48):14433-14441
The spin population distribution in the ferromagnetically coupled hetero-bimetallic chain compound [MnNi(NO(2))(4)(en)(2)] (en = 1,2-ethanediamine) has been investigated by means of polarized neutron diffraction experiments, and the results compared with those from theoretical estimates obtained via calculations based on density functional theory on dinuclear molecular models of the chain. The spin distributions obtained from experiment and from theory are consistent and reflect a larger spin delocalization from the Ni atom due to the more covalent character of the Ni-N bonds compared to the Mn-O ones. Also a nearly isotropic spin distribution is observed for the more ionic d(5) Mn(2+) ion and a clearly anisotropic distribution for the d(8) Ni(2+) ion. The use of dinuclear molecular models for the calculation of the exchange coupling constant between Ni and Mn provide upper and lower limits (+17.6 and -4.2 cm(-)(1)) for the experimentally determined value (+1.3 cm(-)(1)), depending on how the missing part of the chain is simulated, but yield essentially the same spin distribution. The Mn(II)-Ni(II) weak ferromagnetic coupling in the chain is interpreted in a spin delocalization mechanism as resulting from the weakness of the overlap between the magnetic orbitals centered on nickel and those centered on manganese which are only weakly delocalized on the ligands. 相似文献
154.
A density functional study of exchange coupling in halo-bridged dinuclear copper(II) compounds has been carried out. Coupling constants calculated for full unmodeled structures, as determined by X-ray diffraction, are in excellent agreement with experimental data, confirming the ability of the computational strategy used in this work to predict the magnetic behavior of such compounds. Model calculations have been used to examine the influence of several factors on the coupling constant: the nature of the bridging and terminal ligands, the coordination environment around copper atoms, and some structural distortions frequently found in this family of complexes. A ferromagnetic coupling is predicted when N-donor terminal ligands are present, especially for bromo-bridged systems, an interesting synthetic target. 相似文献
155.
Hydrogen bonding between early and late transition metal complexes is proposed as a strategy to obtain ferromagnetic interactions based on a theoretical study using density functional calculations. 相似文献
156.
Fave C Hissler M Sénéchal K Ledoux I Zyss J Réau R 《Chemical communications (Cambridge, England)》2002,(16):1674-1675
In plane parallel arrangement and enhancement of NLO-activity are observed upon coordination of heteroditopic dipoles containing a phosphole ring on square-planar d8-palladium centre. 相似文献
157.
Routaboul C Dumas L Gautier-Luneau I Vergne J Maurel MC Décout JL 《Chemical communications (Cambridge, England)》2002,(10):1114-1115
A remarkable stereoselective reaction of methylglyoxal with 2-aminopyridine, the nucleic base adenine and adenine nucleosides leads in good yield to heterocycles of a new family in water under mild conditions and should be of interest in the understanding of the biological effects of methylglyoxal which is toxic, mutagenic and involved in diabetic complications. 相似文献
158.
Thomas F Gellon G Gautier-Luneau I Saint-Aman E Pierre JL 《Angewandte Chemie (International ed. in English)》2002,41(16):3047-3050
159.
Arbe A Colmenero J Alvarez F Monkenbusch M Richter D Farago B Frick B 《Physical review letters》2002,89(24):245701
We report quasielastic neutron scattering experiments exploring the alpha relaxation in polyisoprene over an unprecedented range in momentum transfer. Corroborating and validating earlier molecular dynamics simulations, the measurements reveal a crossover from a Gaussian regime of sublinear diffusion to a strongly non-Gaussian regime at short distances. We show that a consistent interpretation in terms of a distribution of finite jumps underlying the alpha process is possible. This model leads to a time-dependent non-Gaussian parameter exhibiting all features revealed so far from various simulations. 相似文献
160.
We study the thermal transport properties of several quantum-spin chains and ladders. We find indications for a diverging thermal conductivity at finite temperatures for the models examined. The temperature at which the nondiverging prefactor kappa((th))(T) peaks is, in general, substantially lower than the temperature at which the corresponding specific heat c(V)(T) is maximal. We show that this result of the microscopic approach leads to a substantial reduction for estimates of the magnetic mean-free path lambda extracted by analyzing recent experiments, as compared to similar analyses by phenomenological theories. 相似文献