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[reaction: see text] Rhodium-catalyzed oxygen transfer was used to generate benzyl 2-silyl-2-oxoacetates in good yields. The hydrogenation of these compounds led to chiral alpha-silyl-substituted alpha-hydroxyacetic acids. Resolution by means of HPLC using a chiral stationary phase afforded an enantiomerically pure representative of this class of compounds, which was successfully applied as a chiral ligand in an asymmetric aldol-type reaction. 相似文献
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Saladin Ducretet Lejeune Henri Moissan Jules Violle Lagrange und Hoho 《Fresenius' Journal of Analytical Chemistry》1895,34(1):176-178
Ohne Zusammenfassung 相似文献
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Lazare Saladin Victor Breton Ophélie Dal Pra Dr. Andrey S. Klymchenko Dr. Lydia Danglot Prof. Pascal Didier Dr. Mayeul Collot 《Angewandte Chemie (International ed. in English)》2023,62(4):e202215085
We herein present a new concept to produce dual-color photoconvertible probes based on a mechanism called Directed Photooxidation Induced Conversion (DPIC). As a support of this mechanism, styryl-coumarins ( SCs ) bearing Aromatic Singlet Oxygen Reactive Moieties (ASORMs) like furan and pyrrole have been synthesized. SCs are bright fluorophores, which undergo a hypsochromic conversion upon visible light irradiation due to directed photooxidation of the ASORM that leads to the disruption of conjugation. SC-P , a yellow emitting probe bearing a pyrrole moiety, converts to a stable blue emitting coumarin with a 68 nm shift allowing the photoconversion and tracking of lipid droplet in live cells. This new approach might pave the way to a new generation of photoconvertible dyes for advanced bioimaging applications. 相似文献
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A system is in a self-organized critical state if the distribution of some measured events obeys a power law. The finite-size scaling of this distribution with the lattice size is usually enough to assume that the system displays self-organized criticality. This approach, however, can be misleading. In this paper we analyze the behavior of the branching rate sigma of the events to establish whether a system is in a critical state. We apply this method to the Olami-Feder-Christensen model to obtain evidence that, in contrast to previous results, the model is critical in the conservative regime only. 相似文献
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Excitation functions at θlab = 130° have been measured for inelastic scattering of 13–24 MeV alpha particles from 186,188,190,192Os. Data have been obtained for 0+, 2+, 4+, 2+' states in 186,188,192Os and for 0+, 2+ states in 190Os. Charge and mass quadrupole deformations, β2c and β2N, were deduced from coupled-channels analysis of the 2+ data. No simple model could provide good fits to the 4+ data over the entire energy range but the very deep interference minima observed establish the charge and mass hexadecapole moments, β4c and β4N, to be negative. The energies of the interference minima for the 4+ states could be reproduced by coupled-channels calculations only if large differences in β4c and β4N were allowed. Data for the (J, K)π = (2, 2)+ states are inconsistent with an asymmetric rotational model. 相似文献
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We numerically investigate the trade-offs between the dispersion properties,coupling efficiency,and geometrical constraints in dual-wire (twin-lead) terahertz (THz) waveguides.In particular,we show that their inherent linearly polarized quasi-transverse electromagnetic (TEM) modes exist for waveguide transverse dimensions comparable with the wavelength,enabling significant end-fire coupling (>10%) for numericalaperture limited Gaussian beams while supporting a relatively low-dispersion propagation of below 0.5 ps 2 /m,as desired for short-pulse time-domain spectroscopy applications.Starting from the dual-wire structure,we also demonstrate that low-dispersion tapers can be designed to improve coupling efficiency. 相似文献
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[reaction: see text] The Rh(II)-catalyzed reaction of benzyl 2-trialkylsilyl-2-diazoacetates with various acyclic and cyclic ketones affords novel dioxolanones via silicon-substituted carbonyl ylides in up to 98% yield. 相似文献