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491.
492.
François C Boddaert T Durandetti M Querolle O Van Hijfte L Meerpoel L Angibaud P Maddaluno J 《Organic letters》2012,14(8):2074-2077
A series of new silylated heterocycles has been efficiently prepared using an intramolecular silicon version of the Matteson rearrangement, providing two isomers of binuclear heterocycles. This method applies to a large variety of substrates, a direct relationship between the Hammett constants of the aromatic substituents and the isomer ratio being observed. Complementary experiments suggest that a common pentaorganosilicate species is involved. 相似文献
493.
André C Legrand B Deng C Didierjean C Pickaert G Martinez J Averlant-Petit MC Amblard M Calmes M 《Organic letters》2012,14(4):960-963
In order to investigate the ability of the (S)-aminobicyclo[2.2.2]octane-2-carboxylic acid 1 (H-(S)-ABOC-OH) to induce reverse turns into peptides, two model tripeptides, in which this bicyclic unit was incorporated into the second position, were synthesized and analyzed by FT-IR, CD, NMR, and X-ray studies. 相似文献
494.
Dr. Redouane Beniazza Dr. Valérie Desvergnes Dr. Emeline Girard Dr. Brice Kauffmann Dr. Muriel Berlande Prof. Dr. Yannick Landais 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(38):11976-11986
7‐Silyl‐ and 7‐silylmethylcycloheptatrienes were shown to react with acylnitroso reagents at room temperature, through their norcaradiene forms, to generate the corresponding cycloadducts 5 a – b and 6 a – b as single diastereomers. The course of the reaction was dramatically modified by changing the reaction conditions. Using a polar medium, functionalized cyclohexa‐1,3‐dienes 7 a – b and bicyclic compounds 13 a – b were instead generated, incorporating one or two amino groups. Similar behavior was observed by using other dienophiles, including triazolinedione, but also activated aldehydes and ketones. A tentative mechanism has been proposed to rationalize the formation of both classes of products that relies on a domino process involving four consecutive elementary steps, in this order: 1) electrocyclic process, 2) hetero‐Diels–Alder reaction, 3) cyclopropane ring opening, and 4) hetero‐Diels–Alder reaction. Trapping of the cationic intermediate and isolation of the primary cycloadduct provide support for this hypothesis. An enantioselective version of the cascade using cycloheptatriene 4 b and aldehydes and ketones, under copper(II) catalysis was also carried out, leading to cyclohexa‐1,3‐dienes 21 , 28 , and 30 with enantioselectivities up to 93 % ee. Finally, elaboration of the intermediates above has been carried out, opening a straightforward access to sugar mimics 42 – 43 and complex polycyclic systems 36 and 39 . 相似文献
495.
Bouit PA Escande A Szűcs R Szieberth D Lescop C Nyulászi L Hissler M Réau R 《Journal of the American Chemical Society》2012,134(15):6524-6527
A synthetic route to planar P-modified polycylic aromatic hydrocarbons (PAHs) is described. The presence of a reactive σ(3),λ(3)-P moiety within the sp(2)-carbon scaffold allows the preparation of a new family of PAHs displaying tunable optical and redox properties. Their frontier molecular orbitals (MOs) are derived from the corresponding phosphole MOs and show extended conjugation with the entire π framework. The coordination ability of the P center allows the coordination-driven assembly of two molecular PAHs onto a Au(I) ion. 相似文献
496.
The synthesis, characterization and singlet oxygen quantum yield of novel unsymmetrical dendrons containing photosensitizing units at their periphery is reported. Boc-protected 2,2′-(ethylenedioxy)-bis-ethylamine reacted with methyl acrylate and ethylene diamine to give half-dendrimers 4 and 5 with 2 and 4 end groups, respectively. Amine-tethered porphyrins and compounds 4 and 5 were efficiently coupled in DMF at 100 °C to give the functionalized dendrons. UV-visible and fluorescence emission spectra showed that the photophysical properties of the porphyrins were retained in the dendrimers. 相似文献
497.
Barsu C Fortrie R Nowika K Baldeck PL Vial JC Barsella A Fort A Hissler M Bretonnière Y Maury O Andraud C 《Chemical communications (Cambridge, England)》2006,(45):4744-4746
The design of new chromophores presenting simultaneous SHG and TPEF properties is reported. 相似文献
498.
Su HC Fadhel O Yang CJ Cho TY Fave C Hissler M Wu CC Réau R 《Journal of the American Chemical Society》2006,128(3):983-995
The photophysical, electrochemical, and optoelectronic properties of conjugated systems incorporating dibenzophosphole or phosphole moieties are described. Dibenzophosphole derivatives are not suitable materials for OLEDs due to their weak photoluminescence (PL) in the solid state and the instability of the devices. Variation of the substitution pattern of phospholes and chemical modification of their P atoms afford thermally stable derivatives, which are photo- and electroluminescent. Comparison of the optical properties of solution and thin film of thioxophospholes shows that these compounds do not form aggregates in the solid state. This property, which is also supported by an X-ray diffraction study of three novel derivatives, results in an enhancement of the fluorescence quantum yields in the solid state. In contrast, (phosphole)gold(I) complexes exhibit a broad emission in thin film, which is due to the formation of aggregates. Single- and multilayer OLEDs using these P derivatives as the emissive layer have been fabricated. The emission color of these devices and their performances vary with the nature of the P material. Interestingly, di(2-thienyl)thiooxophosphole is an efficient host for the red dopant DCJTB, and devices using the gold complexes have broad emission spectra. 相似文献
499.
500.
Wouter G. Reyntjens Laura E. Jonckheere Eric J. Goethals 《Macromolecular rapid communications》2002,23(4):282-285
Segmented polymer networks containing poly(methyl vinyl ether) (PMVE) segments were prepared by free‐radical‐initiated copolymerization of PMVE‐α,ω‐dimethacrylate with styrene or 2‐hydroxyethyl methacrylate (HEMA). These networks were evaluated as thermo‐responsive solid‐phase extraction materials. Suspension‐derived polymer networks consisting of 80% of PMVE and 20% of HEMA adsorb toluene from an aqueous solution at 40°C and release the adsorbed toluene quantitatively at 20°C. 相似文献