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141.
Arnaud Tatibouët Patrick Rollin Olivier R. Martin 《Journal of carbohydrate chemistry》2013,32(4-5):641-645
Within the frame of an ongoing project on glycosidase inhibitors, we have been interested in the synthesis of “heteroglycals”, namely, glycal analogues with sulfur or nitrogen in the ring. Glycals2 are well known for their applications in sugar chemistry in particular for glycosyl transfer.3 They are also known as glycosidase inhibitors through a slow chemical reaction with the enzyme. Recently exo-glycals emerged as a new class of glycals4 which showed interesting features as glycosidase inhibitors but also as precursors of glycomimetics such as C-glycosides.5 We have undertaken investigations on related heteroglycals: such compounds are of interest because they combine a planar geometry at the anomeric center and a possible charge site - both elements known to be important to mimic the transition state of the enzymatic glycoside hydrolysis process.6 相似文献
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143.
Raman Tandon Teresa Unzner Dr. Tobias A. Nigst Dr. Nicolas De Rycke Dr. Peter Mayer Dr. Bernd Wendt Dr. Olivier R. P. David Prof. Dr. Hendrik Zipse 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(20):6435-6442
New heterocyclic derivatives of 9‐azajulolidine have been synthesized and characterized with respect to their nucleophilicity and Lewis basicity. The Lewis basicity of these bases as quantified through their theoretically calculated methyl‐cation affinities correlate well with the experimentally measured reaction rates for addition to benzhydryl cations. All newly synthesized pyridines show exceptional catalytic activities in benchmark acylation reactions, which correlate only poorly with Lewis basicity or nucleophilicity parameters. A combination of Lewis basicity with charge and geometric parameters in the framework of a three‐component quantitative structure–activity relationship (QSAR) model is, however, highly predictive. 相似文献
144.
Dr. Antoine Demont Dr. Carmelo Prestipino Dr. Olivier Hernandez Dr. Erik Elkaïm Serge Paofai Prof. Nikolaï Naumov Dr. Bruno Fontaine Prof. Régis Gautier Dr. Stéphane Cordier 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(38):12711-12719
The crystal structure of Cs2BaTa6Br15O3 has been elucidated by using synchrotron X‐ray powder diffraction and absorption experiments. It is built from edge‐bridged octahedral [(Ta6${{\rm Br}{{{\rm i}\hfill \atop 9\hfill}}}$ ${{\rm O}{{{\rm i}\hfill \atop 3\hfill}}}$ )${{\rm Br}{{{\rm a}\hfill \atop 6\hfill}}}$ ]4? cluster units with a singular poor metallic electron (ME) count equal to thirteen. This leads to a paramagnetic behaviour related to one unpaired electron. The arrangement of the Ta6 clusters is similar to that of Cs2LaTa6Br15O3 exhibiting 14‐MEs per [(Ta6${{\rm Br}{{{\rm i}\hfill \atop 9\hfill}}}$ ${{\rm O}{{{\rm i}\hfill \atop 3\hfill}}}$ )${{\rm Br}{{{\rm a}\hfill \atop 6\hfill}}}$ ]5? motif. The poorer electron‐count cluster presents longer metal–metal distances as foreseen according to the electronic structure of edge‐bridged hexanuclear cluster. Density functional theory (DFT) calculations on molecular models were used to rationalise the structural properties of 13‐ and 14‐ME clusters. Periodic DFT calculations demonstrate that the electronic structure of these solid‐state compounds is related to those of the discrete octahedral units. Oxygen–barium interactions seem to prevent the geometry of the octahedral cluster to strongly distort, allowing stabilisation of this unprecedented electron‐poor Ta6 cluster in the solid state. 相似文献
145.
Azetidinium triflates were reacted in a one-pot two-steps sequence involving, generation of an azetidinium ylide, its alkylation with an halide, and final regioselective Hofmann elimination of the produced alkylated azetidinium ion to yield substituted α,β-unsaturated nitriles bearing an aminoethyl side-chain. The scope of this sequence was examined, and was found to depend both on the steric hindrance around the reactive center in the starting azetidinium salt, and on the nature of the reacting halide. Produced acrylonitriles were further used in DBU-catalyzed conjugate addition of amines, to yield 4-amino-2-aminomethyl-butyronitriles with fair diastereoselectivity, or, alternatively, to give C2 symmetrical cyclopropanes. 相似文献
146.
Ming Xu Sandrine Frelon Olivier Simon Ryszard Lobinski Sandra Mounicou 《Analytical and bioanalytical chemistry》2014,406(4):1063-1072
A non-denaturating isoelectric focusing (ND-IEF) gel electrophoresis protocol has been developed to study and identify uranium (U)–protein complexes with laser ablation–inductively coupled plasma mass spectrometry (LA-ICP MS) and electrospray ionization mass spectrometry (ESI-MS). The ND-IEF-LA-ICP MS methodology set-up was initiated using in vitro U–protein complex standards (i.e., U–bovine serum albumin and U–transferrin) allowing the assessment of U recovery to 64.4?±?0.4 %. This methodology enabled the quantification of U–protein complexes at 9.03?±?0.23, 15.27?±?0.36, and 177.31?±?25.51 nmol U L?1 in digestive gland cytosols of the crayfish, Procambarus clarkii, exposed respectively to 0, 0.12, and 2.5 μmol of waterborne depleted U L?1 during 10 days. ND-IEF-LA-ICP MS limit of detection was 19.3 pmol U L?1. Elemental ICP MS signals obtained both in ND-IEF electropherograms and in size exclusion chromatograms of in vivo U–protein complexes revealed interactions between U- and Fe- and Cu-proteins. Moreover, three proteins (hemocyanin, pseudohemocyanin-2, and arginine kinase) out of 42 were identified as potential uranium targets in waterborne-exposed crayfish cytosols by microbore reversed phase chromatography coupled to molecular mass spectrometry (µRPC-ESI-MS/MS) after ND-IEF separation. Figure
The paper presents the development of a non-denaturating protocol for the separation of uranium-protein complexes by isoelectric focusing gel electrophoresis (ND-IEF) before their quantitative detection by Laser Ablation coupled to Inductively Coupled Plasma Mass Spectrometry. Potential protein targets of uranium are subsequently identified by liquid chromatography - electrospray mass spectrometry 相似文献
147.
Dr. Qaisar Nadeem Dr. Federica Battistin Dr. Olivier Blacque Prof. Dr. Roger Alberto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(5):e202103566
Bis-arene sandwich complexes are generally prepared by the Fischer-Hafner reaction, which conditions are incompatible with most O- and N- functional groups. We report a new way for the synthesis of sandwich type complexes [Re(η6-arene)2]+ and [Re(η6-arene)(η6-benzene)]+ from [Re(η6-napht)2]+ and [Re(η6-napht)(η6-benzene)]+, with functionalized arenes and pharmaceuticals. N-methylpyrrolidine (NMP) facilitates the substitution of naphthalene with the incoming arene. A series of fully characterized rhenium sandwich complexes with simple arenes, such as aniline, as well as with active compounds like lidocaine and melatonin are presented. With these rhenium compounds in hand, the radioactive sandwich complexes [99mTc(η6-pharm)2]+ (pharm=pharmaceutical) can be unambiguously confirmed. The direct labelling of pharmaceuticals with 99mTc through η6-coordination to phenyl rings and the confirmation of the structures with the rhenium homologues opens a path into molecular theranostics. 相似文献
148.
149.
Dr. Maria Petrosino Dr. Francesco Stellato Prof. Roberta Chiaraluce Prof. Valerio Consalvi Dr. Giovanni La Penna Dr. Alessandra Pasquo Dr. Olivier Proux Prof. Giancarlo Rossi Prof. Silvia Morante 《ChemistryOpen》2021,10(11):1133-1141
We present in this work a first X-ray Absorption Spectroscopy study of the interactions of Zn with human BST2/tetherin and SARS-CoV-2 orf7a proteins as well as with some of their complexes. The analysis of the XANES region of the measured spectra shows that Zn binds to BST2, as well as to orf7a, thus resulting in the formation of BST2-orf7a complexes. This structural information confirms the the conjecture, recently put forward by some of the present Authors, according to which the accessory orf7a (and possibly also orf8) viral protein are capable of interfering with the BST2 antiviral activity. Our explanation for this behavior is that, when BST2 gets in contact with Zn bound to the orf7a Cys15 ligand, it has the ability of displacing the metal owing to the creation of a new disulfide bridge across the two proteins. The formation of this BST2-orf7a complex destabilizes BST2 dimerization, thus impairing the antiviral activity of the latter. 相似文献
150.
Florian Venel Dr. Hiroki Nagashima Dr. Andrew G. M. Rankin Christelle Anquetil Dr. Vytautas Klimavicius Dr. Torsten Gutmann Prof. Gerd Buntkowsky Dr. Sylvie Derenne Prof. Olivier Lafon Dr. Arnaud Huguet Dr. Frédérique Pourpoint 《Chemphyschem》2021,22(18):1907-1913
Estuaries are key ecosystems with unique biodiversity and are of high economic importance. Along the estuaries, variations in environmental parameters, such as salinity and light penetration, can modify the characteristics of dissolved organic matter (DOM). Nevertheless, there is still limited information about the atomic-level transformations of DOM in this ecosystem. Solid-state NMR spectroscopy provides unique insights into the nature of functional groups in DOM. A major limitation of this technique is its lack of sensivity, which results in experimental time of tens of hours for the acquisition of 13C NMR spectra and generally precludes the observation of 15N nuclei for DOM. We show here how the sensitivity of solid-state NMR experiments on DOM of Seine estuary can be enhanced using dynamic nuclear polarization (DNP) under magic-angle spinning. This technique allows the acquisition of 13C NMR spectra of these samples in few minutes, instead of hours for conventional solid-state NMR. Both conventional and DNP-enhanced 13C NMR spectra indicate that the 13C local environments in DOM are not strongly modified along the Seine estuary. Furthermore, the sensitivity gain provided by the DNP allows the detection of 15N NMR signal of DOM, in spite of the low nitrogen content. These spectra reveal that the majority of nitrogen is in the amide form in these DOM samples and show an increased disorder around these amide groups near the mouth of the Seine. 相似文献