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21.
Chataigner I Panel C Gérard H Piettre SR 《Chemical communications (Cambridge, England)》2007,(31):3288-3290
Unexpectedly high reactivity of nitrogenated aromatics protected as amides or carbamates, when compared to sulfonamides, can be explained by a decrease of the aromaticity due to a greater ability of the carbon-centered groups to achieve delocalisation of the nitrogen lone pair, resulting in stronger global withdrawing effects. 相似文献
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Chrétien A Chataigner I Piettre SR 《Chemical communications (Cambridge, England)》2005,(10):1351-1353
1-Triflylpyrroles bearing acetyl group(s) on position 3, or 2 and 4, are efficient dienophiles in normal electron demand Diels-Alder reactions activated by high pressures and Lewis acids. 相似文献
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Gautier A Lopin C Garipova G Dubert O Kalinina I Salcedo C Balieu S Glatigny S Valnot JY Gouhier G Piettre SR 《Molecules (Basel, Switzerland)》2005,10(9):1048-1073
Efforts to develop synthetic methodologies allowing the preparation of alpha,alpha- difluorophosphonothioates, alpha,alpha-difluorophosphonodithioates, alpha,alpha-difluorophosphono- trithioates, and alpha,alpha-difluorophosphinates are reviewed in the light of applications in the field of modified oligonucleotides and cyclitol phosphates. Two successful approaches have been developed, based either on the addition of phosphorus-centered radicals onto gem-difluoroalkenes or on a process involving the addition of lithiodifluorophosphono- thioates 91 onto a ketone and the subsequent deoxygenation reaction of the adduct. The radical route successfully developed a practical route to alpha,alpha-difluoro-H-phosphinates which proved to be useful intermediates to a variety of phosphate isosters. The ionic route led to the first preparation of phosphonodifluoromethyl analogues of nucleoside- 3'-phosphates. 相似文献
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Deciphering Ligands’ Interaction with Cu and Cu2O Nanocrystal Surfaces by NMR Solution Tools 下载免费PDF全文
Dr. Arnaud Glaria Jérémy Cure Dr. Kilian Piettre Dr. Yannick Coppel Dr. Cédric‐Olivier Turrin Dr. Bruno Chaudret Dr. Pierre Fau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(3):1169-1178
The hydrogenolysis of [Cu2{(iPrN)2(CCH3)}2] in the presence of hexadecylamine (HDA) or tetradecylphosphonic acid (TDPA) in toluene leads to 6–9 nm copper nanocrystals. Solution NMR spectroscopy has been used to describe the nanoparticle surface chemistry during the dynamic phenomenon of air oxidation. The ligands are organized as multilayered shells around the nanoparticles. The shell of ligands is controlled by both their intermolecular interactions and their bonding strength on the nanocrystals. Under ambient atmosphere, the oxidation rate of colloidal copper nanocrystals closely relies on the chemical nature of the employed ligands (base or acid). Primary amine molecules behave as soft ligands for Cu atoms, but are even more strongly coordinated on surface CuI sites, thus allowing a very efficient corrosion protection of the copper core. On the contrary, the TDPA ligands lead to a rapid oxidation rate of Cu nanoparticles and eventually to the re‐dissolution of CuII species at the expense of the nanocrystals. 相似文献
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Utz A. Lecha-Marzo A. Vila M. Piettre St. Horoszkiewicz H. Marx und M. Piorkowski 《Fresenius' Journal of Analytical Chemistry》1907,46(9):618-620
Ohne Zusammenfassung 相似文献
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Chrystel Lopin Arnaud Gautier Graldine Gouhier Serge R. Piettre 《Tetrahedron letters》2000,41(52):10195-10200
An efficient, three-step preparation of the new 2-phenylselanyl-[1,2,3]-dithiaphosphinane-2-oxide (8) from PCl3 is described. The reagent is shown to behave as a precursor of the corresponding phosphonodithioyl radical, when placed in the presence of tin or silyl radicals. A novel synthesis of S,S-dialkyl phosphonodithioates is described based on these results. Application of this methodology to exocyclic 3-methylene-3-deoxofuranosides leads to the highly diastereoselective formation of 3-phosphonodithiomethyl-3-deoxofuranosides. 相似文献
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[reaction: see text] Selanylated difluoromethylphosphonates and difluoromethylphosphonothioates are good precursors to phosphonodifluoromethyl and phosphonothiodifluoromethyl radicals, respectively. When generated in the presence of alkenes and a hydrogen donor, the corresponding alpha,alpha-difluorinated alkylphosphonates or alkylphosphonothioates are produced in fair to good yields. The use of alkynes results in the formation of alpha,alpha-difluorinated allyl derivatives in useful yields. The presence of the sulfur atom in phosphonothiodifluoromethyl radicals usually translates into higher isolated yields. 相似文献
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The treatment of benzyl dialkyl phosphites and dithiophosphites with benzeneselanyl chloride generates an Arbuzov-type transformation leading to the dialkyl selenophosphates 19a and 19b and to selenophosphorodithioates 21a and 21b. Interaction of these substrates with Lawesson's reagent yields the corresponding selenophosphorothioates 20a and 20b and the selenophosphorotrithioates 22a and 22b. When treated with a radical initiator in the presence of a hydrogen donor and an alkene, all eight phosphorus(V) precursors undergo homolytic cleavage of the P-Se bond to generate the phosphonyl, phosphonothioyl, phosphonodithioyl, or phosphonotrithioyl radicals. Most of these are shown to add onto electron-rich and electron-poor alkenes to deliver the expected adducts in fair to excellent yields. Cyclic precursor 19b displays peculiar behavior and, under the reaction conditions, produces only the corresponding cyclic phosphite. Application of this radical chain process is carried out on furanosyl 3-exo-methylene derivative 37 to diastereoselectively furnish five new 3-phosphonomethyl-, 3-phosphonothiomethyl-, and 3-phosphonodithiomethyl-3-deoxofuranoses 38a-c and 38f,g. The possibility of conducting tandem processes is also discussed through experiments involving (1R)-(+)-alpha-pinene (39) and diallylamine 41. 相似文献