排序方式: 共有114条查询结果,搜索用时 0 毫秒
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Ajellal N Lyubov DM Sinenkov MA Fukin GK Cherkasov AV Thomas CM Carpentier JF Trifonov AA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(18):5440-5448
A series of new bis(guanidinate) alkoxide Group 3 metal complexes [Ln((Me3Si)2NC(NiPr)2)2(OR)] (R=OtBu, Ln=Y, Nd, Sm, Lu; R=OiPr, Ln=Y, Nd, Lu) has been synthesized. X-ray structural determinations revealed that bis(guanidinate) tert-butoxides are monomeric complexes. The isopropoxide complex [Y((Me3Si)2NC(NiPr)2)2(OiPr)] undergoes slow decomposition in solution, to afford the unusual dimeric amido complex [(Y((Me3Si)2NC(NiPr)2)2(mu-N(iPr)C triple chemical bond N))2]. Complexes [Ln((Me3Si)2NC(NiPr)2)2(OR)] (R=OtBu, Ln=Y, Nd, Sm, Lu; R=OiPr, Ln=Y, Nd, Lu) are active catalysts/initiators for the ROP of rac-lactide and rac-beta-butyrolactone under mild conditions. Most of those polymerizations proceed with a significant degree of control. Bis(guanidinate) alkoxides appear to be well suited for achieving immortal polymerization of lactide, through the introduction of large amounts of isopropanol as a chain-transfer agent. The synthesized complexes are able to promote the stereoselective ROP of rac-beta-butyrolactone to afford syndiotactic poly(hydrobutyrate) through a chain-end control mechanism, while they are surprisingly non-stereoselective for the ROP of lactide under strictly similar conditions. 相似文献
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Trofimov BA Ivanov AV Ushakov IA Schmidt EY Sobenina LN Vasil'tsov AM Mikhaleva AI 《Dalton transactions (Cambridge, England : 2003)》2012,41(18):5512-5516
N-Vinylpyrroles and -indoles bearing electron-withdrawing substituents at the pyrrole ring are mercurated, with 1 equivalent of Hg(OAc)(2) in dry MeCN (20-80 °C), regioselectively at the vinyl group (yields are almost quantitative), while their congeners without electron-withdrawing functions are mercurated both at the N-vinyl group and the pyrrole ring. 相似文献
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AA Yurkova EA Khakina SI Troyanov A Chernyak L Shmygleva AS Peregudov VM Martynenko YA Dobrovolskiy PA Troshin 《Chemical communications (Cambridge, England)》2012,48(71):8916-8918
We report Arbuzov-type reactions of chlorofullerene C(60)Cl(6) with trialkyl phosphites producing highly functionalized fullerene derivatives C(60)[P(O)(OR)(2)](5)H with high yields. The designed family of [60]fullerene phosphonic acids and their esters showed unusual properties which might find valuable material science applications. 相似文献
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Wu J Shih HP Vigont V Hrdlicka L Diggins L Singh C Mahoney M Chesworth R Shapiro G Zimina O Chen X Wu Q Glushankova L Ahlijanian M Koenig G Mozhayeva GN Kaznacheyeva E Bezprozvanny I 《Chemistry & biology》2011,18(6):777-793
Huntington's disease (HD) is a neurodegenerative disorder caused by a polyglutamine expansion within Huntingtin (Htt) protein. In the phenotypic screen we identified a class of quinazoline-derived compounds that delayed a progression of a motor phenotype in transgenic Drosophila HD flies. We found that the store-operated calcium (Ca(2+)) entry (SOC) pathway activity is enhanced in neuronal cells expressing mutant Htt and that the identified compounds inhibit SOC pathway in HD neurons. The same compounds exerted neuroprotective effects in glutamate-toxicity assays with YAC128 medium spiny neurons primary cultures. We demonstrated a key role of TRPC1 channels in supporting SOC pathway in HD neurons. We concluded that the TRPC1-mediated neuronal SOC pathway constitutes a novel target for HD treatment and that the identified compounds represent a novel class of therapeutic agents for treatment of HD and possibly other neurodegenerative disorders. 相似文献
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Lyubov N. SobeninaZinaida V. Stepanova Igor’ A. UshakovAl’bina I. Mikhaleva Denis N. TomilinOl’ga N. Kazheva Grigorii G. AlexandrovOleg A. Dyachenko Boris A. Trofimov 《Tetrahedron》2011,67(26):4832-4837
Ethyl 3-(4,5,6,7-tetrahydroindol-2-yl)propynoate, readily available from 4,5,6,7-tetrahydroindole and ethyl bromopropynoate, when treated with dichlorodicyanobenzoquinone (DDQ) in methanol affords furan-2-one-4,5,6,7-tetrahydroindole-cyclobutene sequence in a 52% yield. As kinetic and minor products, a furan-2-one isomer along with bicycloheptadienone have been either isolated or identified. The reaction has been shown to proceed via the isolable intermediate the [2+2]-cycloadduct of ethyl 3-(4,5,6,7-tetrahydroindol-2-yl)propynoate with DDQ. Other alcohols react with the [2+2]-cycloadduct in a similar way. The effect of the alcohol structure on the products ratio has been analyzed. All the intermediates and products are formed as single diastereomer, thus indicating a concerted character of the rearrangement. 相似文献
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Rafael A. Cherkasov Ilyas S. Nizamov Yevgeniy M. Martianov Lyubov A. Almetkina Yevgeniy N. Nikitin Radik R. Shamilov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):24-26
Abstract Novel organyldithiophosphonic and bis(aryldithiophosphonic) acids were obtained by the reaction of 2,4-diorganyl 1,3,2,4-dithiadiphosphetane-2,4-disulfides with paracetamol, 4-(1H-pyrrol-1-yl)phenol, ethambutol dihydrochloride, vitamin B6, and its acetonide derivatives. 相似文献
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Venkatesh AK Zhang AX Mansour J Kubatina L Oh CH Blasche G Selim Unlü M Balamore D Jolesz FA Goldberg BB Albert MS 《Magnetic resonance imaging》2003,21(7):773-776
In hyperpolarized (HP) noble-gas magnetic resonance imaging, large nuclear spin polarizations, about 100,000 times that ordinarily obtainable at thermal equilibrium, are created in 3He and 129Xe. The enhanced signal that results can be employed in high-resolution MRI studies of void spaces such as in the lungs. In HP gas MRI the signal-to-noise ratio (SNR) depends only weakly on the static magnetic field (B(0)), making very low-field (VLF) MRI possible; indeed, it is possible to contemplate portable MRI using light-weight solenoids or permanent magnets. This article reports the first in vivo VLF MR images of the lungs in humans and in rats, obtained at a field of only 15 millitesla (150 Gauss). 相似文献