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Pieters G Gaucher A Marrot J Maurel F Naubron JV Jean M Vanthuyne N Crassous J Prim D 《Organic letters》2011,13(16):4450-4453
The synthesis and properties of new chiral polycyclic architectures that display both helicity and a saddle-type shape are described. The enantiomers have been separated, and their absolute configuration was determined by VCD and ECD. The unprecedented molecular architecture is based on a cyclooctatriene core surrounded by an association of benzo[c]fluorene and ortho-phenylene units. 相似文献
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David Gatineau Delphine Moraleda Jean-Valère Naubron Thomas Bürgi Laurent Giordano Gérard Buono 《Tetrahedron: Asymmetry》2009,20(16):1912-1917
Pd(II)-coordinated phosphinous acids catalyzed the formal enantioselective [2+1] cycloaddition of norbornene derivatives with terminal alkynes. The absolute configuration of (+)-3aa was assigned using VCD. 相似文献
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Dr. Amer Baniodeh Danny Wagner Dr. Yan Peng Hagen Kaemmerer Dr. Nicolas Leblanc Prof. Stefan Bräse Dr. Jean-Valére Naubron Dr. Christopher E. Anson Prof. Annie K. Powell 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(61):15103-15109
The {Fe2Dy2} butterfly systems can show single molecule magnet (SMM) behaviour, the nature of which depends on details of the electronic structure, as previously demonstrated for the [Fe2Dy2(μ3-OH)2(Me-teaH)2(O2CPh)6] compound, where the [N,N-bis-(2-hydroxyethyl)-amino]-2-propanol (Me-teaH3) ligand is usually used in its racemic form. Here, we describe the consequences for the SMM properties by using enantiopure versions of this ligand and present the first homochiral 3d/4 f SMM, which could only be obtained for the S enantiomer of the ligand for [Fe2Dy2(μ3-OH)2(Me-teaH)2(O2CPh)6] since the R enantiomer underwent significant racemisation. To investigate this further, we prepared the [Fe2Dy2(μ3-OH)2(Me-teaH)2(O2CPh)4(NO3)2] version, which could be obtained as the RS-, R- and S-compounds. Remarkably, the enantiopure versions show enhanced slow relaxation of magnetisation. The use of the enantiomerically pure ligand suppresses QTM, leading to the conclusion that use of enantiopure ligands is a “gamechanger” by breaking the cluster symmetry and altering the intimate details of the coordination cluster's molecular structure. 相似文献
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Youen Kervella Grégory Germain Benoît Gaurier Jean-Valéry Facq Florence Cayocca Patrick Lesueur 《European Journal of Mechanics - B/Fluids》2010,29(1):32-42
Oyster farming structures are artificial obstacles which disturb tidal flow and wave propagation. These effects can induce modifications of erosion and sedimentation patterns, turbidity changes, local silting up and can be threatening for the shellfish farming itself. The understanding of the impact of these structures in terms of hydrodynamics and sediment dynamics in the far-field, i.e. at the scale of a bay, is a very challenging task.In order to investigate the far-field impact, it is very important to understand in the first place all the changes which occur at a smaller scale, i.e. at the scale of a single table for a farm consisting of oyster tables made of metallic wire structures on which porous bags of oysters are laid. This work is carried out through the idealized representation of the in-situ flow in a free surface flume tank. The flow characteristics around the overall structure are determined from velocity measurements obtained by laser velocimetry. The results highlight an asymmetric development of the boundary layers which suggest the existence of preferential areas for silting up and suspended matter fragmentation under the table. 相似文献
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Jérôme Vachon Steven Harthong Béatrice Dubessy Jean-Pierre Dutasta Nicolas Vanthuyne Christian Roussel Jean-Valère Naubron 《Tetrahedron: Asymmetry》2010,21(11-12):1534-1541
An inherently chiral ABii diphosphonato cavitand (±)-4 bearing a single quinoxaline bridging moiety was synthesized and resolved by chiral HPLC. Its chiroptical properties were investigated and VCD experiments allowed the determination of its absolute configuration. Distinguishable diastereomeric complexes in solution with l-adrenaline were observed by 1H and 31P NMR together with a noticeable enantio-discrimination at 253 K (dr ~2:1) in favor of the dextrorotatory cavitand (+)-4. 相似文献
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Dr. Myriam Roy Dr. Veronika Berezhnaia Dr. Marco Villa Dr. Nicolas Vanthuyne Dr. Michel Giorgi Dr. Jean-Valère Naubron Dr. Salomé Poyer Dr. Valérie Monnier Prof. Dr. Laurence Charles Dr. Yannick Carissan Dr. Denis Hagebaum-Reignier Prof. Dr. Jean Rodriguez Prof. Dr. Marc Gingras Dr. Yoann Coquerel 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(8):3290-3297
We report a molecular design and concept using π-system elongation and steric effects from helicenes surrounding a triphenylene core toward stable chiral polycyclic aromatic hydrocarbons (PAHs) with a maximal π-distortion to tackle their aromaticity, supramolecular and molecular properties. The selective syntheses, and the structural, conformational and chiroptical properties of two diastereomeric large multi-helicenes of formula C90H48 having a triphenylene core and embedding three [5]helicene units on their inner edges and three [7]helicene units at their periphery are reported based on diastereoselective and, when applicable, enantiospecific Yamamoto-type cyclotrimerizations of racemic or enantiopure 9,10-dibromo[7]helicene. Both molecules have an extremely distorted triphenylene core, and one of them exhibits the largest torsion angle recorded so far for a benzene ring (twist=36.9°). 相似文献
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Naubron JV Giordano L Fotiadu F Bürgi T Vanthuyne N Roussel C Buono G 《The Journal of organic chemistry》2006,71(15):5586-5593
The enantiomers of tert-butyl(dimethylamino)phenylphosphine-borane complex 2 have been separated by HPLC using cellulose tris-p-methylbenzoate as chiral stationary phase. The borane protection could be removed without racemization and the P-configuration of the free aminophosphine 1 has shown to be stable in solution. Infrared (IR) and vibrational circular dichroism (VCD) spectra have been measured in CD2Cl2 solution for both enantiomers. B3LYP/6-31+G(d) DFT calculations allowed a prediction that complex (S)-2 exists as three conformers in equilibrium and computed population-weighted IR and VCD spectra. Predicted and experimental IR and VCD spectra compared very well and indicate that enantiomer (+)-2 has the S absolute configuration. This assignment has been confirmed by an X-ray diffraction study on a single crystal of (+)-2. The crystal structure of enantiomerically pure 2 appears to be very close to the most stable computed conformer which proved to be predominant in solution. 相似文献
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Dr. Guillaume Dauvergne Dr. Jean-Valère Naubron Dr. Michel Giorgi Prof. Dr. Xavier Bugaut Prof. Dr. Jean Rodriguez Dr. Yannick Carissan Dr. Yoann Coquerel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(68):e202202473
The synthetic equivalents of the enantiopure binaphthyl bis(aryne) atropisomers derived from BINOL (1,1′-bi-2,2′-naphtol) featuring a stereogenic axis vicinal to the two reactive triple bonds can be generated for the first time in solution in an enantiospecific manner. Using a two-step sequence based on the bidirectional [4+2] cycloaddition of furan derivatives followed by an aromatizative deoxygenation reaction, several 9,9’-bianthracenyl-based atropisomers could be prepared enantiospecifically in high enantiomeric purity. Alternatively, bidirectional reactions with anthracene, 2-bromostyrene, and perylene as the arynophiles afforded very congested bis(benzotriptycene), bis(tetraphene) and bis(anthra[1,2,3,4-ghi]perylene) nanocarbon atropisomers in equally high enantiomeric purity. In complement, cross reactions with two different arynophiles revealed possible. The unusual atropisomer prototypes described in this study open the way to enantiopure nanographene atropisomers designed for functions. 相似文献