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71.
Renata M. Oballa Rebekah Carson Susan Lait Jay A. Cadieux Joël Robichaud 《Tetrahedron》2005,61(11):2761-2766
Sesquiterpenoids (+)-trans-dracuncuflifoliol (1) and (+)-4-hydroxyoppositan-7-one (2) were prepared stereoselectively from enantiomerically pure (7aR)-7a-methyl-1,2,5,6,7,7a-hexahydro-4H-inden-4-one ((−)-6), whose synthesis was described herein. Conjugate addition of the organocopper (I) reagent 10 to (−)-6, followed by epimerization of the ring junction, generated 3 of the 4 contiguous chiral centers of both natural products. 相似文献
72.
Optically active polymer carbon nanotube composite 总被引:1,自引:0,他引:1
in het Panhuis M Sainz R Innis PC Kane-Maguire LA Benito AM Martínez MT Moulton SE Wallace GG Maser WK 《The journal of physical chemistry. B》2005,109(48):22725-22729
A completely soluble optically active polyaniline-multiwalled carbon nanotube composite was investigated by spectroscopic and microscopic techniques. It was found that the polymer's optical activity was retained in the presence of carbon nanotubes. Solutions were found to be easily processable into thin films, which exhibited dendritic structures only in the presence of nanotubes. 相似文献
73.
Supercritical fluid chromatography (SFC) sometimes exhibits GC-like behavior and sometimes LC-like behavior, depending on conditions. However, it is not always clear whether one of these types of behavior, or a combination, operates for a particular set of conditions for every solute in a mixture. For example, some components may be partitioned mostly by their vapor pressures, while others, in the same mixture, are partitioned predominantly by solvent-like properties of the mobile phase. Plots of retetion (as log of the capacity factor) vs. reciprocal temperature at constant pressure reveal a clear change in the character of the separation of well-behaved solutes. A thermodynamic explanation of the observed behavior is given, based on the assumption that partitioning is controlled by the heats of solution of solute in the mobile and stationary phases. A model of SFC retention as it deviates from pure-GC behavior on the same column is presented. 相似文献
74.
Ashish N. Basuray Dr. Henri‐Pierre Jacquot de Rouville Dr. Karel J. Hartlieb Dr. Takashi Kikuchi Nathan L. Strutt Carson J. Bruns Michael W. Ambrogio Alyssa‐Jennifer Avestro Dr. Severin T. Schneebeli Albert C. Fahrenbach Prof. J. Fraser Stoddart 《Angewandte Chemie (International ed. in English)》2012,51(47):11872-11877
75.
76.
Orawan Winther-Jensen Satyen Desai Roderick L. Shepherd Peter C. Innis Bjorn Winther-Jensen Maria Forsyth Gordon G. Wallace Douglas R. MacFarlane 《Electrochemistry communications》2010,12(11):1505-1508
Conducting polymer based electrochromic devices were assembled with various ionic liquid (IL) based electrolytes to probe the role of the ion structure on electrochromic performance. When the IL contained the same anion as the dopant ion used in the conducting polymers an enhanced electrochromic performance was observed providing high photopic contrast at low applied potential. 相似文献
77.
Fabian Carson Dr. Santosh Agrawal Dr. Mikaela Gustafsson Agnieszka Bartoszewicz Francisca Moraga Prof. Xiaodong Zou Assoc. Prof. Belén Martín‐Matute 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(48):15337-15344
A ruthenium trichloride complex has been loaded into an aluminium metal–organic framework (MOF), MOF‐253, by post‐synthetic modification to give MOF‐253‐Ru. MOF‐253 contains open bipyridine sites that are available to bind with the ruthenium complex. MOF‐253‐Ru was characterised by elemental analysis, N2 sorption and X‐ray powder diffraction. This is the first time that a Ru complex has been coordinated to a MOF through post‐synthetic modification and used as a heterogeneous catalyst. MOF‐253‐Ru catalysed the oxidation of primary and secondary alcohols, including allylic alcohols, with PhI(OAc)2 as the oxidant under very mild reaction conditions (ambient temperature to 40 °C). High conversions (up to >99 %) were achieved in short reaction times (1–3 h) by using low catalyst loadings (0.5 mol % Ru). In addition, high selectivities (>90 %) for aldehydes were obtained at room temperature. MOF‐253‐Ru can be recycled up to six times with only a moderate decrease in substrate conversion. 相似文献
78.
Helio G. Bonacorso Guilherme P. Bortolotto Jussara Navarini Liliane M.F. Porte Carson W. Wiethan Nilo Zanatta Marcos A.P. Martins Alex F.C. Flores 《Journal of fluorine chemistry》2010,131(12):1297-1301
This study describes a simple and efficient procedure to synthesize a novel series of fourteen 4-substituted N-(5-pyridinyl-1H-1,2,4-triazol-3-yl)-6-(trifluoromethyl)pyrimidin-2-amines, where the 4-substituents are H, CH3, C6H5, 4-FC6H4, 4-CH3C6H4, 4-CH3OC6H4 and 2-Furyl; from the cyclocondensation reaction of N-[5-(pyridinyl)-1H-1,2,4-triazol-3-yl]guanidines with 4-alkoxy-4-alkyl(aryl/heteroaryl)-1,1,1-trifluoroalk-3-en-2-ones. The reactions were carried out in ethanol under reflux for 18 h and led to 40-68% yields. N-(Pyridyl-triazolyl)guanidine precursors were further obtained from reactions of cyanoguanidine with nicotinic or isonicotinic acid hydrazides and the halogenated enones from trifluoroacetylation of enolethers or acetals. 相似文献
79.
AC Fahrenbach KJ Hartlieb CH Sue CJ Bruns G Barin S Basu MA Olson YY Botros A Bagabas NH Khdary JF Stoddart 《Chemical communications (Cambridge, England)》2012,48(73):9141-9143
Charged donor-acceptor [2]catenanes containing cyclobis(paraquat-p-phenylene) as the ring component can be synthesised in yields of up to 88% in under one hour by heating two precursors in the presence of macrocyclic polyether templates in N,N-dimethylformamide at 80 °C. 相似文献
80.
Many cell biological pathways exhibit overall polarity (net movement of molecules in one direction) even though individual molecular interactions in the pathway are freely reversible. The A2 RNA trafficking pathway exhibits polarity in moving specific RNA molecules from the nucleus to localization sites in the myelin compartment of oligodendrocytes or dendritic spines in neurons. The A2 pathway is mediated by a ubiquitously expressed trans-acting trafficking factor (hnRNP A2) that interacts with a specific 11 nucleotide cis-acting trafficking sequence termed the A2 response element (A2RE) found in several localized RNAs. Five different molecular partners for hnRNP A2 have been identified in the A2 pathway: hnRNP A2 itself, transportin, A2RE RNA, TOG (tumor overexpressed gene) and hnRNP E1, each playing a key role in one particular step of the A2 pathway. Sequential interactions of hnRNP A2 with different molecular partners at each step mediate directed movement of trafficking intermediates along the pathway. Specific "rules of engagement" (both and, either or, only if) govern sequential interactions of hnRNP A2 with each of its molecular partners. Rules of engagement are defined experimentally using three component binding assays to measure differential binding of hnRNP A2 to one partner in the presence of each of the other partners in the pathway. Here we describe rules of engagement for hnRNP A2 binding to each of its molecular partners and discuss how these rules of engagement promote polarity in the A2 RNA trafficking pathway. For molecules with multiple binding partners, specific rules of engagement govern different molecular interactions. Rules of engagement are ultimately determined by structural relationships between binding sites on individual molecules. In the A2 RNA trafficking pathway rules of engagement governing interactions of hnRNP A2 with different binding partners provide the basis for polarity of movement of intermediates along the pathway. 相似文献