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101.
102.
[reaction: see text] The conversion of N-2,2-dichloropropionyl indole methyl ester into a tetracyclic cycloheptannelated indole model compound for the synthesis of dragmacidin E was accomplished in 10 steps. Key reactions include a Witkop cyclization to fashion a C-C bond at C(4) of the indole nucleus and a subsequent Dieckmann cyclization to deliver the desired cycloheptanoid ring. 相似文献
103.
Yang Y Nesterenko DV Trump RP Yamaguchi K Bartlett PA Drueckhammer DG 《Journal of chemical information and modeling》2005,45(6):1820-1823
Three new virtual databases have been developed for use with the bond-orientation-based database searching program CAVEAT. These consist of a database of trisubstituted monocyclic hydrocarbons having ethyl, vinyl, and phenyl substituents; a database of unsubstituted bicyclic hydrocarbons; and a database of core structures from established combinatorial synthetic methods having hydrogen, ethyl, vinyl, and phenyl substituents at the readily varied positions. Each collection of molecules was subjected to a batch conformational search, minimization, and conversion to a vector database for use with CAVEAT. 相似文献
104.
Structural reorientations in metallic fcc nanowires are controlled by a combination of size, thermal energy, and the type of defects formed during inelastic deformation. By utilizing atomistic simulations, we show that certain fcc nanowires can exhibit both shape memory and pseudoelastic behavior. We also show that the formation of defect-free twins, a process related to the material stacking fault energy, nanometer size scale, and surface stresses is the mechanism that controls the ability of fcc nanowires of different materials to show a reversible transition between two crystal orientations during loading and thus shape memory and pseudoelasticity. 相似文献
105.
Sasaki K Sugou K Miyamoto K Hirai J Tsubouchi S Miyasaka H Itaya A Kuroda Y 《Organic & biomolecular chemistry》2004,2(19):2852-2860
The nonameric porphyrin assemblies constructed with the series of free base tetraphenylporphyrins Pn having four pyrazine moieties linked with alkyl chains of different lengths, (CH2)n (n = 1, 5, 9, 17, 30), and dimeric [meso-tetrakis(2-carboxy-4-nonylphenyl)porphyrinato]zinc(II), ZnP2, show the effective light-collection effect and the typical Forster-type energy transfer from ZnP2 to Pn. 相似文献
106.
Terao K Ohsawa A Mori Y Narita T Ichikawa K Dobashi T 《Colloids and surfaces. B, Biointerfaces》2004,37(3-4):129-132
Microcapsules having polyethyleneglycol-grafted poly(ureaurethane) (PUU) membrane and di-2ethylhexyl phthalate core have been prepared, and the structure when they were suspended in dispersing ethanol have been studied by means of single-particle light scattering method. The PUU membrane was synthesized from monomers with aromatic functional groups (microcapsule MC110) and hexamethylene functional groups (microcapsule MC160). Because the outer and inner solvent passed through the membrane easily, the outside and inside of the membrane were the same at the equilibrium state. The thickness of the wall membrane was significantly smaller than that calculated from the overall weight ratio of the wall-forming material and the core solvents. It was attributed to low affinity of PUU membranes and ethanol. 相似文献
107.
Camphor is used as the chiral auxiliary for the enantioselective synthesis of cis linear homoallylic alcohols. A range of catalysts, aldehydes, and solvents were investigated to obtain the optimum yield, enantioselectivity, and cis olefinic geometry. [structure: see text] 相似文献
108.
109.
110.
A Rh(I)/(R)-Tol-BINAP catalyst reacts with a racemic mixture of 4-alkynals to selectively furnish a cyclobutanone from the (R)-substrate and a cyclopentenone from the (S)-substrate. This method is noteworthy from several standpoints, including the scarcity of parallel kinetic resolutions (especially those that are catalyzed or that involve carbon-carbon bond formation) and the dearth of catalytic processes that generate enantioenriched cyclobutanones. 相似文献