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91.
Two‐step Synthesis of New γ‐Lactones via Cyclization of 7‐Chloro‐2‐(methoxycarbonyl)‐4‐6‐dimethylocta‐(2E,4E,6E)‐trienoic acid 下载免费PDF全文
Jean‐Marc Dillenschneider Laurent Dufossé Mireille Fouillaud Nuthathai Sutthiwong Roger Labia Alain Valla 《Journal of heterocyclic chemistry》2016,53(5):1439-1442
A new rapid synthesis of γ‐lactones, cis fused with a cyclopentenic ring by thermal cyclization of 7‐chloro‐2‐(methoxycarbonyl)‐4‐6‐dimethylocta‐7‐phenyl (or methyl) (2E,4E,6E)‐trienoic acids was reported. The key step implicates an intramolecular cyclization to a cyclopentenyl cation, according to an electrocyclic π2s + π2a conrotatory process, published in a recent paper (from the corresponding diacids). We have investigated the thermal behavior of the corresponding half‐esters since; if the cyclization obeys to the proposed mechanism, the diacids, half‐esters must also cyclize in a similar manner. Saponification of these led to γ‐dilactones via intermediary cyclopropanes. Mechanistic pathways were investigated. 相似文献
92.
The response of a membrane electrode is not always identical to that of a redox electrode. Indeed, in the case of membrane electrode the response is not due to a redox equilibrium but to a cross-membrane potential. So, the membrane electrode's response depends mainly on the carrier system and the nature of the membrane. The properties of the membrane can favour several reactions giving rise to different ionic species diffusing in the membrane. The expression of the cross-membrane potential thus depends on the number and quantities of these ionic species. To illustrate this, we established the equations for the case of a two-charge cation detected by a univalent charged carrier. We show that the Nernstian response is not applicable to membrane electrodes. This approach allowed us to interpret results obtained with a cationic gemini surfactant-selective electrode prepared in the laboratory. To prove the well working of this electrode, we determined the critical micelle concentration in water and several NaBr solutions (0.004, 0.006, 0.01 and 0.02 M) from which the counterion binding has been determined. 相似文献
93.
94.
Michle Fontaine Joseph Delhalle Mireille Defranceschi Grard Lcayon 《Journal of Molecular Structure》1995,330(1-3):161-165
The relative modifications induced in the structure of perfluorodiethyl ether (CF3CF2)2O and perfluoroisopropyl methyl ether CF3OCF(CF3)2 by oxygen and fluorine protonation are studied at the RHF level with the 3–21G basis and correlated with their proton affinities and dissociation energies. 相似文献
95.
Mireille Petit Anthony Linden Heinz Heimgartner Grzegorz Mlosto 《Helvetica chimica acta》1994,77(4):1076-1086
Reaction of Phenyldiazomethane with 1,3-Thiazole-5(4H)-thiones: Base-Catalyzed Ring Opening of the Primary Adduct Reaction of 1,3-thiazole-5(4H)-thiones 1 and phenyldiazomethane ( 2a ) in toluene at room temperature yields the thiiranes trans- and cis-1,4-dithia-6-azaspiro[2.4]hept-5-enes (trans- and cis- 4 ; Scheme 2). With Ph3P in THF at 70°, these thiiranes are transformed stereospecifically into (E)- and (Z)-5-benzylidene-4,5-dihydro-1,3-thiazoles 5 , respectively. In the presence of DBU, 1 and 2a react to give 1,3,4-thiadiazole derivatives 6 or 7 via base-catalyzed ring opening of the primary cycloadduct (Scheme 3). In the case of 2-(alkylthio)-substituted 1,3-thiazole-5(4H)-thiones 1c and 1d , this ring opening proceeds by elimination of the corresponding alkylthiolate, yielding isothiocyanate 7 . The structures of (Z)- 5c and 6b have been established by X-ray crystallography. 相似文献
96.
Kelley AM Leng W Blanchard-Desce M 《Journal of the American Chemical Society》2003,125(35):10520-10521
Resonance hyper-Raman spectra have been obtained using 1064 nm excitation for several electron donor-acceptor-substituted, pi-conjugated "push-pull" molecules that have large second harmonic hyperpolarizabilities. The hyper-Raman spectra are nearly identical to the resonance Raman spectra measured with 532 nm excitation. This indicates that both the second harmonic hyperpolarizability and the linear absorption are dominated by the same, single electronic transition that is both one- and two-photon allowed. Comparison of resonance Raman and resonance hyper-Raman spectra is proposed as an experimental test of the common two-electronic-state model for the first hyperpolarizability. 相似文献
97.
98.
99.
Mireille Content François Lemay Pierre Leroux 《Journal of Combinatorial Theory, Series A》1980,28(2):169-190
This paper proposes a general setting for Möbius inversion which includes the cases of locally finite partially ordered sets and monoids with the finite decomposition property (f.d.p.). The unifying concept is that of categories with the f.d.p., called Möbius categories, which we characterize in four different ways. The established theory of incidence algebras, Möbius functions, product formulas, reduced algebras, etc., is carried over. Furthermore, the study of functors between Möbius categories yields results in two directions: firstly, inspired from the substitution of formal power series is the construction of a homomorphism between incidence algebras which allows the transfer of Möbius inversions; secondly, surjective functors often give rise to a reduced incidence algebra, thus shedding new light on many important reduced algebras in combinatorial theory. 相似文献
100.
Mireille Leleyter Pierre Joyes Marie-Claire Cadeville 《Journal of Physics and Chemistry of Solids》1983,44(8):779-787
The intensities of emission of NipCn+(p = 1–3) and NiCn? secondary ions given by two alloys: Ni3C and NiC 5% at. C, show off a saw-toothed behaviour according to the parity of the number n of carbon atoms. Maxima occur when n is odd for NiCn+ ions and when n is even in the other cases (p = 2, 3; negative ions). Besides, the influence of the carbon concentration in the alloy can be observed.The alternations of NiCn+ and Ni2Cn+ ions can be interpreted from Pitzer and Clementi model (the clusters are supposed to be linear). Thus it can be found greater stabilities for NiC2k+1 and Ni2C2k chains than for NiC2k and Ni2C2k+1 chains respectively, which very well agrees with the “correspondence rule” between the emissions of different species of ions and their electronic properties. 相似文献