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121.
Guillaume Grelaud 《Tetrahedron letters》2010,51(29):3786-3788
The straightforward isolation and characterization of new triphenylphosphines possessing a pendent ethynyl substituent on one or several peripheral aryl ring(s) are reported. The synthesis of this family of compounds is achieved by retro-Favorsky reactions from the corresponding propargylic alcohol derivatives, themselves obtained following a classic Sonogashira-type coupling between the ad hoc bromophenyl phosphines and 2-methylbut-3-yn-2-ol. 相似文献
122.
123.
Delahaye É Eyele-Mezui S Diop M Leuvrey C Rabu P Rogez G 《Dalton transactions (Cambridge, England : 2003)》2010,39(44):10577-10580
Synthesis of new heterometallic layered magnets with controlled chirality have been achieved by insertion of chiral and non-chiral salen-type Ni(II) complexes into copper and cobalt layered simple hydroxides. 相似文献
124.
Haïat G Naili S Ba Vu M Desceliers C Soize C 《The Journal of the Acoustical Society of America》2011,129(4):EL114-EL120
Cortical bone is a viscoelastic heterogeneous medium which may be assessed with axial transmission. This work aims at evaluating the average depth investigated by the lateral wave for radial variations of material properties in relatively thick cortical bone. The equivalent contributing depth (ECD) is derived from the finite element simulation results for spatial variations of a viscoelastic coefficient (η(11)) and of porosity. A value of ECD equal to around 1.6 mm is obtained for a spatial variation of η(11). The method fails to predict accurate values of the ECD for a spatial variation of porosity, because all parameters vary simultaneously. 相似文献
125.
Cribier M Fechner M Lasserre T Letourneau A Lhuillier D Mention G Franco D Kornoukhov V Schönert S 《Physical review letters》2011,107(20):201801
Several observed anomalies in neutrino oscillation data can be explained by a hypothetical fourth neutrino separated from the three standard neutrinos by a squared mass difference of a few eV(2). We show that this hypothesis can be tested with a PBq (ten kilocurie scale) (144)Ce or (106)Ru antineutrino beta source deployed at the center of a large low background liquid scintillator detector. In particular, the compact size of such a source could yield an energy-dependent oscillating pattern in event spatial distribution that would unambiguously determine neutrino mass differences and mixing angles. 相似文献
126.
Gerbaud G Caldarelli S Ziarelli F Gastaldi S 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,210(1):75-81
The intensity of the carbon signal in a CPMAS experiment has been measured for two CH and three CH(2) moieties in four test molecules under different phase-modulated proton decoupling conditions and as a function of the spinning rate. The proton decoupling schemes investigated were the golden standard TPPM and three of the GTn family. Aim of this analysis was to better describe experimentally the impact and limitations of phase-modulated decoupling. Sizeable differences in the response to decoupling were observed in otherwise chemically identical molecular fragments, such as the CHCH(2) found in tyrosine, phenyl-succinic acid or 9-Anthrylmethyl-malonate, probably due to differences in spin-diffusion rates. In keeping with known facts, the efficiency of the decoupling was observed to decrease with the MAS rate, but with somewhat different trends for the tested systems. 相似文献
127.
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129.
Guillaume Maitro Guillaume Prestat David Madec Giovanni Poli 《Tetrahedron: Asymmetry》2010,21(9-10):1075-1084
An escapade in the world of sulfenate anions is described and shows that these nucleophiles, despite being described as unstable species, are mild and efficient sulfinylating agents, allowing access to a variety of allyl and aryl sulfoxides under smooth and operationally very simple conditions. Their use in asymmetric catalysis is also possible allowing the preparation of enantio-enriched sulfoxides. Moreover, such anions have been involved in the development of two new pseudo–domino processes. 相似文献
130.
Guillaume Berionni Bruce Pégot Régis Goumont 《Magnetic resonance in chemistry : MRC》2010,48(2):101-110
The 15N as well as 1H and 13C chemical shifts of nine substituted tetrazolopyridines and their corresponding tetrazolopyridinium salts have been determined by using NMR spectroscopy at the natural abundance level of all nuclei in CD3CN. In this paper, we report, for the first time, the N‐alkylation reaction of electron deficient tetrazolopyridines. The treatment of tetrazolopyridines 5–13 with one equivalent of trialkyloxonium tetrafluoroborate leads to a mixture of two isomers, i.e. N3‐ and N2‐alkyl tetrazolo[1,5‐a]pyridinium salts. It has been observed that the N3‐isomer is always the major isomer, except in the case of the CF3 substituent, where the two isomers are obtained in the same amount. The quaternary tetrazolopyridinium nitrogen N3 is shielded by around 100 ppm (parts per million) with respect to the parent tetrazolopyridine. Experimental data are interpreted by means of density functional theory (DFT) calculations, including solvent‐induced effects, within the conductor‐like polarizable continuum model (CPCM). Good agreements between theoretical and experimental 1H, 13C and 15N NMR were found. The combination of multinuclear magnetic resonance spectroscopy with gauge including atomic orbital (GIAO) DFT calculations is a powerful tool in the structural elucidation for both neutral and cationic heterocycles and in the determination of the orientation of N‐alkylation of tetrazolopyridines. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献