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排序方式: 共有160条查询结果,搜索用时 31 毫秒
1.
Sandip Halder Theodor Schneller Rainer Waser Florian Thomas 《Journal of Sol-Gel Science and Technology》2007,41(3):203-207
Nickel thin films have been sputtered on standard Si/SiO2 substrates with TiO2 as an adhesive layer. The thermal stability of these substrates was analyzed. SEM images show an increase in grain size with
annealing temperature. They were found to be stable till 800°C, beyond which the nickel layer disintegrated. These substrates
were used for deposition of BaTiO3 and (Ba,Sr)TiO3 dielectric thin films under a reducing atmosphere. The dielectric thin films were processed with various pyrolysis and annealing
temperatures in order to optimize the dielectric properties. Increased pyrolysis temperatures showed an increase in the grain
size. Results on these nickelised substrates were finally compared with dielectric films deposited on platinized silicon substrates
under identical conditions but crystallized in an oxygen atmosphere. 相似文献
2.
The efficient catalytic activation of donor–acceptor aminocyclopropanes lacking the commonly used diester acceptor is reported here in a (3 + 2) dearomative annulation with indoles. Bench-stable tosyl-protected aminocyclopropyl esters were converted into cycloadducts in 46–95% yields and up to 95 : 5 diastereomeric ratio using catalytic amounts of triethylsilyl triflimide. Tricyclic indoline frameworks containing four stereogenic centers including all-carbon quaternary centers were obtained.A catalytic dearomatization of indoles with D–A aminocyclopropane monoesters for the synthesis of highly substituted indolines. 相似文献
3.
Sandip?HalderEmail author Theodor?Schneller Rainer?Waser 《Journal of Sol-Gel Science and Technology》2005,33(3):299-306
A new chemical solution deposition (CSD) route for the fabrication of Ba0.7Sr0.3TiO3 (BST) thin films has been developed which completely prevents the formation of an intermediate oxo-carbonate phase. The latter has been reported previously by several authors to be responsible for increased crystallization temperatures. Barium and strontium diaminoethoxides were synthesized starting from pure barium and strontium metal and aminoethanol. These alkoxides were found to be readily soluble in a wide range of solvents and thus were excellent candidates for the CSD process. To prepare a stable precursor solution the aminoalkoxides were dissolved in 2-butoxyethanol and then used for the deposition of BST thin films. We conclude that the minimum crystallization temperature of 600C to be independent of the formation of the oxo-carbonate phase. DTA-TGA were performed on the precursors and their solutions to study their decomposition behaviour. All films annealed at different temperatures were physically characterized by XRD, IR, and SEM. The films prepared by this route at 650C were found to have high dielectric constant and the leakage currents were comparable to BST films prepared by normal carboxylate based routes at 750C. 相似文献
4.
[reaction: see text] The cobalt-catalyzed hydrohydrazination reaction of dienes and enynes is presented. Allylic and propargylic hydrazines were obtained in synthetically useful yields (allylic amines, 60-90%; propargylic amines, 47-83%) and good chemo- and regioselectivity. 相似文献
5.
Gaetano Riggio Wolfgang Herbert Hopff Alfred Andr Hofmann Peter Gaudenz Waser 《Helvetica chimica acta》1983,66(4):1039-1045
Hydroxyphenyl-1-methylpyridinium-iodide as Potential Reactivators of Acetylcholinesterase Poisoned with Organophosphorus Compounds . It was our aim to reactivate acetylcholinesterase poisoned with sarin. We synthesized 2-(o-hydroxyphenyl)-1-methylpyridinium-iodide ( 9 ), 2-(p-hydroxyphenyl)-1-methylpyridinium-iodide ( 19 ) and 4-(o-hydroxyphenyl)-1-methylpyridinium-iodide ( 14 ) as potential reactivators. All substances showed moderate toxicity against mice; their reactivity potency in vitro and in vivo was negligible. 相似文献
6.
Katharina Zielke Ondřej Kováč Michael Winter Dr. Jiří Pospíšil Prof. Mario Waser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(34):8163-8168
The first highly asymmetric catalytic synthesis of densely functionalized dihydrobenzofurans is reported, which starts from ortho-hydroxy-containing para-quinone methides. The reaction relies on an unprecedented formal [4+1]-annulation of these quinone methides with allenoates in the presence of a commercially available chiral phosphine catalyst. The chiral dihydrobenzofurans were obtained as single diastereomers in yields up to 90 % and with enantiomeric ratios up to 95:5. 相似文献
7.
8.
Guillaume Pisella Alec Gagnebin Prof. Dr. Jérôme Waser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(45):10199-10204
Multicomponent reactions provide efficient means to access molecular complexity. Herein, we report a copper-catalyzed three-component reaction of diazo compounds, alcohols and ethynyl benziodoxole (EBX) reagents for the synthesis of propargyl ethers. Extensive variations of the three partners of the reaction is possible, leading to highly functionalized and structurally diverse products under mild conditions. Alkynylation of a copper ylide intermediate is postulated as key step for this transformation. 相似文献
9.
Dr. Emmanuelle M. D. Allouche Raphaël Simonet-Davin Prof. Dr. Jerome Waser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(17):e202200368
A methodology for the C−H azidation of N-terminal proline-containing peptides was developed employing only commercially available reagents. Peptides bearing a broad range of functionalities and containing up to 6 amino acids were selectively azidated at the carbamate-protected N-terminal residue in presence of the numerous other functional groups present on the molecules. Post-functionalizations of the obtained aminal compounds were achieved: cycloaddition reactions or C−C bond formations via a sequence of imine formation/nucleophilic addition were performed, offering an easy access to diversified peptides. 相似文献
10.
Katharina Röser Bettina Berger Prof. Michael Widhalm Prof. Mario Waser 《ChemistryOpen》2021,10(8):756-759
We herein report an asymmetric protocol to access a series of orthogonally functionalized acyclic chiral target molecules containing a quaternary stereogenic center by carrying out the enantioselective α-alkylation of novel orthogonally functionalized dioxolane-containing cyanoacetates under chiral ammonium salt catalysis. By using just 1 mol % of Maruoka's spirocyclic ammonium salt catalysts enantioselectivities up to e.r.=97.5 : 2.5 could be achieved and further functional group manipulations of the products were carried out as well. 相似文献