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71.
Sophia S. Michaelidou 《Tetrahedron》2010,66(3):685-3845
Anthranilonitrile 3a, 4,5-dimethoxyanthranilonitrile 3b and 5-nitroanthranilonitrile 3c, react with paraformaldehyde, KCN and ZnCl2 in acetic acid under acid catalysis (H2SO4) in a sealed tube at ca. 55 °C to give the corresponding 2-(cyanomethylamino)benzonitriles 4a-c in 96, 86 and 57% yields, respectively. Thorpe-Ziegler cyclisation of the N-unprotected 2-(cyanomethylamino)benzonitriles 4a-c with K2CO3 in EtOH at elevated temperatures and pressures using either microwave heating or conventional heating in a sealed tube gives 3-amino, 3-amino-5,6-dimethoxy, and 3-amino-5-nitroindole-2-carbonitriles 2a-c in moderate to good yields. All new compounds are fully characterised. 相似文献
72.
The Bowman-Birk inhibitors (BBIs) are a family of proteins that share a canonical loop structure whose presence in a conserved conformation is linked to their inhibitory activity. We study the conformational properties of the canonical loop using a graph theoretical approach as implemented in the floppy inclusions and rigid substructure topography (FIRST). We find that the canonical loop is an independent rigid cluster in the natural inhibitors. We have further used this technique to identify residues that play an important role in the structural rigidity of the protein by quantifying their contribution to the overall rigidity of the inhibitor. We find that the conserved elements among the natural and synthetic peptides are the ones that contribute the most to rigidity, even if they are located far from the active site, as rigidity effects are nonlinear and hence nonlocal. The results help to elucidate why certain mutations in the loop of the BBI produce peptides that fail to have the designed inhibitory activity. 相似文献
73.
Gullick J Taylor S Ryan D McMorn P Coogan M Bethell D Bulman Page PC Hancock FE King F Hutchings GJ 《Chemical communications (Cambridge, England)》2003,(22):2808-2809
During the aziridination of styrene using copper bis(oxazoline) complexes the ee increases with conversion due to further reactions of the product. 相似文献
74.
Sankar Muniappan Sophia Liptsman Israel Goldberg 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(4):m140-m143
Tetrakis(4‐methoxycarbonylphenyl)porphyrin, or tetramethyl 4,4′,4′′,4′′′‐porphyrin‐5,10,15,20‐tetrabenzoate, crystallizes as a nitrobenzene 1.9‐solvate, C52H38N4O8·1.9C6H5NO2, (I). The solvent molecules are contained in extended channels which propagate through the host lattice between parallel screw/glide‐related columns of offset‐stacked porphyrin entities. Side packing of these columns involves π–π interactions between the methoxycarbonylphenyl residues. Molecules of the porphyrin host lie on crystallographic inversion centres. The zinc(II)–pyridine derivative pyridine(tetramethyl 4,4′,4′′,4′′′‐porphyrin‐5,10,15,20‐tetrabenzoato)zinc(II), [Zn(C52H36N4O8)(C5H5N)], (II), is a square‐pyramidal five‐coordinate complex with pyridine as an apical ligand, which crystallizes as a chloroform–pyridine solvate. The metalloporphyrin–pyridine units form an open layered arrangement, occluding the non‐coordinated solvent moieties within the intralayer interporphyrin voids. Within such arrays, the host porphyrin molecules are in contact with one another through the peripheral methoxycarbonyl substituents. The crystal packing consists of a bilayered arrangement of inversion‐related porphyrin layers, with the axial ligands mutually penetrating into the voids of neighbouring arrays and tight offset stacking of these bilayers. 相似文献
75.
John Erik Fornæ ss Nils Ø vrelid Sophia Vassiliadou 《Proceedings of the American Mathematical Society》2005,133(8):2377-2386
We obtain some -results for the operator on forms that vanish to high order on the singular set of a complex space.
76.
Sophia Th.?Kyritsi Nikolaos S.?PapageorgiouEmail author 《Annali di Matematica Pura ed Applicata》2005,184(4):449-472
In this paper we examine a nonlinear elliptic problem driven by the p-Laplacian differential operator and with a potential function which is only locally Lipschitz, not necessarily C1 (hemivariational inequality). Using the nonsmooth critical point theory of Chang, we obtain two strictly positive solutions.
One solution is obtained by minimization of a suitable modification of the energy functional. The second solution is obtained
by generalizing a result of Brezis-Nirenberg about the local C10-minimizers versus the local H10-minimizers of a C1-functional.
Mathematics Subject Classification (2000) 35J50, 35J85, 35R70 相似文献
77.
Sophia?Th?Kyritsi Nikolaos?S.?PapageorgiouEmail author 《Calculus of Variations and Partial Differential Equations》2004,20(1):1-24
In this paper we study a class of nonlinear elliptic eigenvalue problems driven by the p-Laplacian and having a nonsmooth locally Lipschitz potential. We show that as the parameter
approaches
(= the principal eigenvalue of
) from the right, the problem has three nontrivial solutions of constant sign. Our approach is variational based on the nonsmooth critical point theory for locally Lipschitz functions. In the process of the proof we also establish a generalization of a recent result of Brezis and Nirenberg for C01 versus W01,p minimizers of a locally Lipschitz functional. In addition we prove a result of independent interest on the existence of an additional critical point in the presence of a local minimizer of constant sign. Finally by restricting further the asymptotic behavior of the potential at infinity, we show that for all
the problem has two solutions one strictly positive and the other strictly negative.Received: 7 January 2003, Accepted: 12 May 2003, Published online: 4 September 2003Mathematics Subject Classification (2000):
35J20, 35J85, 35R70 相似文献
78.
Time periodic solutions for the hyperbolic gauged Ginzburg–Landau system, with spatial domain the unit disc, are shown to exist. Time periodic solutions representing bound states of vortices rotating about one another have been previously obtained in the near self-dual limit, using perturbative techniques. In contrast, we here take a variational approach, the solutions being obtained as critical points of an indefinite functional. We consider a special class of solutions which map out, uniformly in time, an orbit of the rotation group SO(2). It is shown that in the limit of large coupling constant the solutions have nontrivial time dependence or, as is shown to be equivalent, are not radially symmetric in any gauge. 相似文献
79.
Sophia Demoulini David M. A. Stuart Athanasios E. Tzavaras 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2000,17(6):711
It is shown that the variational approximation scheme for one-dimensional elastodynamics given by time discretisation converges, subsequentially, weakly and a.e. to a weak solution which satisfies the entropy inequalities. We also prove convergence under the restriction of positive spatial derivative (for longitudinal motions). 相似文献