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1.
The conjugate bases of camphor oxime and 2-nitro-bornane, possessing a π array, accept elements of H+ and Br+ selectively from the “crowded” exo side. The present work adds another facet towards the understanding of stereochemical controls inherent in the bornane framework, the other two related being the endo addition of nucleophiles to camphor and the exo electrophile acceptance by camphor enolates. The present work describes, inter alia, a practical route to 2-endo nitrobornane and the novel 2,2-dinitrobornane. 相似文献
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The synchronized self-motion of a camphor fragment and a mobile boundary on a water surface depending on the initial conditions and the asymmetry of the boundary was investigated. When a camphor fragment, which showed unidirectional rotation, was surrounded by a circular ring as a symmetric mobile boundary on a water surface, the circular ring also rotated but in the direction opposite to that of the camphor fragment. The velocity of the rotation of the mobile ring varied depending on the anisotropy of the shape of the ring. When a camphor fragment was placed on the inside of a circular ring floating on the water surface, the ring and camphor fragment exhibited translational motion without rotation. These characteristics of synchronized self-motion are discussed in relation to the surface tension as the driving force and convective flow due to the gradient of the surface-active camphor layer. 相似文献
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We describe a novel plastic material composed of camphene, camphor, and polypropylene that seems perfectly suited for studies on self-propelled objects on the water surface. Self-motion is one of the attributes of life, and chemically propelled objects show numerous similarities with animated motion. One of important questions is the relationship between the object shape and its motility. In our paper published in 2019, we presented a novel hybrid material, obtained from the solution of camphor in camphene, that allowed making objects of various shapes. This hybrid material has wax-like mechanical properties, but it has a very high tackiness. Here, we report that a small amount of polypropylene removed this undesirable feature. We investigated the properties of camphor–camphene–polypropylene plastic by performing the statistical analysis of a pill trajectory inside a Petri dish and compared them with those of camphor-camphene wax. The plastic showed the stable character of motion for over an hour-long experiment. The surface activity of objects made of plastic did not significantly depend on the weight ratios of the compounds. Such a significant increase in usefulness came from the polypropylene, which controlled the dissipation of camphor and camphene molecules. 相似文献
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Pravin V. ShindeAmol H. Kategaonkar Bapurao B. ShingateMurlidhar S. Shingare 《Tetrahedron letters》2011,52(22):2889-2892
In the present work, successful implementation of ultrasound irradiation for the rapid synthesis of α-hydroxy and α-amino phosphonates under solvent-free conditions is demonstrated. Use of a novel catalyst (i.e., camphor sulfonic acid) in combination with ultrasound technique is reported for the first time. Comparative study for the synthesis of α-hydroxy and α-amino phosphonates using conventional as well as ultrasonication method is discussed. 相似文献
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Ghattas G Chen D Pan F Klankermayer J 《Dalton transactions (Cambridge, England : 2003)》2012,41(30):9026-9028
A camphor based chiral phosphonium hydrido borate zwitterion was synthesised and successfully applied in the enantioselective hydrogenation of imines with selectivities up to 76% ee. The high stability of the novel chiral FLP-system enables effective recycling of the metal-free catalyst. 相似文献
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The orientation of the substrate camphor in the active site of reduced CO-bound cytochrome P450cam (CYP101) as a function of reduced putidaredoxin (Pdxr) addition has been examined by NMR using perdeuterated CYP101 and perdeuterated Pdx as well as isotopically labeled d-camphor. This permits the 1H resonances of CYP101-bound camphor to be observed without interference from the signals of CYP101 or Pdx and confirms assignments of the methyl signals of camphor in the bound form. The Cys4Fe2S2 ferredoxin Pdx is the physiological redox partner and effector of CYP101. The addition of Pdx to the reduced CYP101-camphor-CO complex results in a conformational selection that is slow on the chemical shift time scale with spectral effects observed primarily at the 8-CH3 group of the camphor. The camphor signals are ring current shifted by the heme, and for the 9- and 10-CH3 resonances, these shifts are reasonably well predicted by ring current calculations from the crystal structure of CO-bound CYP101. However, in the absence of Pdx, the 8-CH3 resonance of CYP101-bound camphor is observed at considerably higher field than predicted. Dynamic simulations using ring current shift restraints generated a structure with low chemical shift violations in which the hydrogen bond between the camphor carbonyl oxygen and the OH of Tyr96 is lost, and an expansion of the active site takes place that permits reorientation of the camphor within the active site. 相似文献
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Antonio García Martínez Enrique Teso Vilar Florencio Moreno Jimnez Ana María lvarez García Patricia Pinilla Rodríguez 《Tetrahedron: Asymmetry》2002,13(24):2635-2639
An easy three-step route for the enantiospecific synthesis of novel 1-norbornyl thioethers and thiocyanates from readily available natural fenchone and camphor is described. The key step of the synthetic route is the nucleophilic substitution over the sulfenyl sulfur atom of the intermediate thiotriflates by the corresponding C-nucleophiles. 相似文献
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Summary In this paper an application is presented of the median molecule workflow to the de novo design of novel molecular entities with a property profile of interest. Median molecules are structures that are optimised to be similar to a set of existing molecules of interest as an approach for lead exploration and hopping. An overview of this workflow is provided together with an example of an instance using the similarity to camphor and menthol as objectives. The methodology of the experiments is defined and the workflow is applied to designing novel molecules for two physical property datasets: mean molecular polarisability and aqueous solubility. This paper concludes with a discussion of the characteristics of this method. 相似文献
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《Tetrahedron: Asymmetry》2006,17(21):2970-2975
An easy two-step route for the stereoselective synthesis of novel bridgehead-fused norbornanethiazolines from readily available natural camphor and fenchone is described. The key step of the synthetic route is the highly stereoselective trapping of 1-(trifluoromethylsulfonylthio)-2-norbornyl cations by nitriles followed by intramolecular cyclization, which constitutes a new modification of the Ritter reaction. 相似文献
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The determination of the freezing point depression of organic solutions with camphor as solvent was performed by means of DTA. Amounts of 50–100μg substance and 1–2 mg camphor were weighed on a platinum wire, the camphor being pressed to a pellet by a glass press. The temperature difference between the glass tubes with pure camphor and with solution was recorded versus temperature, while the samples were cooled in a previously heated aluminium block. The difference between the recorded deviations from a straight line was found to be a measure of the freezing point depression. Errors less than 5 % were computed for various samples. 相似文献
13.
以3-乙酰基樟脑作为辅助配体的环金属铱配合物的合成及光电性能研究 总被引:2,自引:0,他引:2
以立体位阻3-乙酰基樟脑为辅助配体合成了系列新型的环金属铱配合物3-乙酰基樟脑-2-(2,4-二氟)苯基吡啶环金属铱配合物[(46dfppy)2Ir(acam)], 3-乙酰基樟脑-2-苯基吡啶环金属铱配合物[(ppy)2Ir(acam)], 3-乙酰基樟脑-2-苯并噻吩吡啶环金属铱配合物[(btp)2Ir(acam)]. 将配合物的吸收光谱、光致发光光谱以及光致发光效率与辅助配体为乙酰丙酮(acac)的对应配合物进行了比较, 发现在配合物中引入具有大空间位阻的3-乙酰基樟脑使配合物的光致发光效率均有所提高. 并将(ppy)2Ir(acam)用于有机电致发光器件, 电致发光光谱在516 nm 处有一最大强度峰, 驱动电压为12 V 时最大亮度为10930 cd/m2, 最大亮度效率达到14.6 cd/A, 电压为10.7 V 时最大功率为4.23 lm/W, 亮度为698 cd/m2. 相似文献
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《Tetrahedron: Asymmetry》2004,15(2):293-298
A short and convenient procedure for the stereoselective synthesis of novel optically active 2-hydroxy-1-norbornanesulfonamides starting from commercially available natural camphor and fenchone is reported. The synthetic route involves a nucleophilic substitution at the sulfenyl sulfur atom of 2-methylene-1-norbornylthiotriflates followed by oxidation of the intermediate sulfenamides and highly diastereoselective reduction of the carbonyl group of the parent 2-oxo-1-norbornanesulfonamides. 相似文献
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Several novel ligands that are based on the camphor skeleton or contain the O‐sulfonyl group were synthesized and used in the asymmetric addition of phenylacetylene to aldehydes. This enantioselective reaction afforded chiral propargylic alcohols in high yields and with good to excellent levels of enantiopurity (up to 99% enantiomeric excess). Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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The first two stable enantiomerically pure chiral N-H oxaziridines, derived from camphor and fenchone, are shown to act as electrophilic sources of nitrogen upon reaction with various carbon nucleophiles. Nitrogen is transferred, together with the camphor/fenchone unit, when deprotonated esters, malonates, and nitriles are used as nucleophiles. One of the ester or nitrile units in the substrate usually undergoes hydrolysis; a cyclic mechanism is proposed to account for this observation. 相似文献
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Chelucci G 《Chemical Society reviews》2006,35(12):1230-1243
This tutorial review deals with the synthesis and application in asymmetric catalysis of camphor-based pyridine ligands. These ligands can be roughly divided into two groups: those in which the camphor is annulated in the 2,3-positions to the beta-face of the pyridine ring and those in which the pyridine is contained as a pendant on the C2 or C3 of the camphor framework. Camphor-based pyridine ligands can also contain other donor centers located on the pyridine ring or camphor skeleton. Some of these ligands have provided interesting enantioselectivities in several asymmetric reactions, such as S(N)2' reactions, allylic oxidations, carbonyl additions with organozinc reagents and hydrogenations. This review contains a lot of chemistry on ligand synthesis and readers will find it of value and also perhaps an inspiration for the development of more active and improved versions. 相似文献
20.
Diamines are useful as additional ligands in enantioselective hydrogenations. A new route for synthesizing such a rigid diamine from naturally available camphor via camphor oxime/camphor furoxan/deoxygenation in large scale was developed. The resulting dinitriles were subjected to hydrogenation with Raney Ni or other heterogenous catalysts. In most cases, the reduction resulted in complex mixtures. The best results were obtained with Raney Ni in THF/H2O in strongly basic media (NaOH), which affords compound 5b only in good yield. Homogenous catalyst like Grubbs 2nd generation reduced only the less hindered CN group to yield an amino nitrile. 相似文献