排序方式: 共有56条查询结果,搜索用时 296 毫秒
31.
Palucki M Um JM Yasuda N Conlon DA Tsay FR Hartner FW Hsiao Y Marcune B Karady S Hughes DL Dormer PG Reider PJ 《The Journal of organic chemistry》2002,67(16):5508-5516
An efficient and practical asymmetric synthesis of (+)-trans-3-hydroxymethyl-4-(3-fluorophenyl)cyclopentanone (1) is described. An asymmetric Mo-catalyzed alkylation reaction was used to establish the first stereocenter and a Cu-catalyzed intramolecular diastereoselective cyclopropanation reaction was used to set the second stereocenter. The last step involved a one-pot ring-opening/deprotection/hydrolysis/decarboxylation sequence that furnished the desired product in good yield. 相似文献
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John Y.L. Chung Frederick W. Hartner Raymond J. Cvetovich 《Tetrahedron letters》2008,49(42):6095-6100
With the goal of improving the synthetic efficiency, the development of a convergent synthesis of a minocycline derivative PTK0796 via an intermolecular acyliminium Friedel-Crafts reaction (Tscherniac-Einhorn reaction) is described. The entire C9 neopentylaminomethyl side chain was installed in one step using an electronically optimized chloromethylacyliminium precursor in 83% yield. Deprotection and re-equilibration to the C4 α-epimer in the presence of CaCl2 and ethanolamine or NaOH afforded the target aminomethylcycline antibiotic. The corresponding crystalline tosylate salt was found to exhibit improved solid state stability. 相似文献
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Gerhard Bringmann Robert-Michael Pfeifer Kristina Hartner Reto Brun Eva-Maria Peters 《Tetrahedron》2004,60(30):6335-6344
A broad variety of enantiopure axially chiral 2-aminomethyl-1-(2-oxyphenyl)naphthalenes were prepared via short and efficient synthetic pathways by using the ‘lactone method’ for the regio- and stereoselective construction of the biaryl axis. Their in vitro activity against Trypanosoma cruzi, the causative agent of Chagas' disease, was evaluated. In particular, the M-configured atropisomers, with the 2-oxy function equipped with an O-triflate group, were found to exhibit good antitrypanosomal activities (down to IC50=1.6 μg/mL), combined with low levels of cytotoxicity. 相似文献
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Anjos JC Appel JA Bean A Bracker SB Browder TE Cremaldi LM Elliott JR Escobar CO Estabrooks P Gibney MC Hartner GF Karchin PE Kumar BR Losty MJ Luste GJ Mantsch PM Martin JF McHugh S Menary SR Morrison RJ Nash T Nauenberg U Ong P Pinfold J Punkar G Purohit MV Raab JR Santoro AF Sidhu JS Sliwa K Sokoloff MD Souza MH Spalding WJ Streetman ME Stundia AB Witherell MS 《Physical review letters》1988,60(13):1239-1242
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Anjos JC Appel JA Bean A Bracker SB Browder TE Cremaldi LM Elliott JR Escobar CO Estabrooks P Gibney MC Hartner GF Karchin PE Kumar BR Losty MJ Luste GJ Mantsch PM Martin JF McHugh S Menary SR Morrison RJ Nash T Nauenberg U Ong P Pinfold J Punkar G Purohit MV Raab JR Santoro AF Sidhu JS Sliwa K Sokoloff MD Souza MH Spalding WJ Streetman ME Stundia AB Witherell MS 《Physical review letters》1988,60(10):897-900
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Anjos JC Appel JA Bean A Bracker SB Browder TE Cremaldi LM Duboscq JE Elliott JR Escobar CO Gibney MC Hartner GF Karchin PE Kumar BR Losty MJ Luste GJ Mantsch PM Martin JF McHugh S Menary SR Morrison RJ Nash T Pinfold J Punkar G Purohit MV Ross WR Santoro AF Schmidt DM Shoup AL Sliwa K Sokoloff MD Souza MH Sperka D Spalding WJ Streetman ME Stundia AB Witherell MS 《Physical review letters》1991,67(12):1507-1510
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W. Hartner P. Bosk G. Schindler H. Bachhofer M. Mört H. Wendt T. Mikolajick C. Dehm H. Schroeder R. Waser 《Applied Physics A: Materials Science & Processing》2003,77(3-4):571-579
The effects of annealing in forming gas 5% hydrogen, 95% nitrogen; FGA) are studied on spin-coated SrBi2Ta2O9 (SBT) thin films. SBT films on a platinum bottom electrode are characterized with and without a platinum top electrode. Films are characterized by residual stress measurements, scanning electron microscopy (SEM), Auger electron spectroscopy (AES), high-temperature X-ray diffraction (HT-XRD) and secondary ion mass spectrometry (SIMS). To determine the degree of strain, lattice constants of Pt are measured by X-ray diffraction (XRD). HT-XRD of blanket SBT/Pt/Ti films in forming gas revealed that the bismuth-layered perovskite structure of SBT is stable up to approximately 500 °C. After formation of an intermediate phase between 550 °C and 700 °C, SBT changes its structure to an amorphous phase. SIMS analysis of Pt/SBT/Pt samples annealed in deuterated forming gas (5% D2, 95% N2) showed that hydrogen accumulates in the SBT layer and at the platinum interfaces next to the SBT. After FGA of blanket SBT films, tall platinum–bismuth whiskers are seen on the SBT surface. It is confirmed that these whiskers originate from the platinum bottom electrode and grow through the SBT layer. FGA of the entire Pt/SBT/Pt/Ti stack shows two different results. For the samples with a high-temperature annealing (HTA) step in oxygen after top electrode patterning, peeling of the top electrode is observed after FGA. For the samples without a HTA step, no peeling is observed after FGA. The residual stress at room temperature is measured for blanket platinum wafers deposited at different temperatures. It is found that an increase in tensile stress caused by the HTA step in oxygen is followed by a decrease in stress caused by the hydrogen in the forming gas. Without HTA, however, an increase of stress is observed after FGA. PACS 77.84.-s; 81.40.-z; 77.55.+f 相似文献