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101.
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This review presents the structure, biological activity, biosynthetic studies and, where applicable, references to syntheses of 81 marine alkaloids containing either tetra-, hexa- or octa-hydrogenated variants of pyrrolo[4,3,2-de]quinoline, pyrrolo[4,3,2-de]pyrrolo[2,3-h]quinoline and pyrido[2,3-h]pyrrolo[4,3,2-de]quinoline core skeletons. The literature describing the isolation of pyrroloiminoquinones, and related metabolites, from marine sponges is littered with taxonomic inconsistencies and recent efforts to clarify the taxonomy of the sponges that produce this group of metabolites are discussed. 相似文献
103.
Edith Sylla 《Historia Mathematica》1981,8(3):364-367
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Shao H Wang Z Lacroix E Wu SH Jennings HJ Zou W 《Journal of the American Chemical Society》2002,124(10):2130-2131
2'-Aldehydes and 2'-ketones of alpha-C-glycosides, including the gluco-, galacto-, and manno- series, were epimerized exclusively to their beta-anomers in good-to-excellent yields under basic conditions and in the presence of zinc acetate. The beta-stereoselectivity is independent of the neighboring group at 2-O-substitution of sugar substrates. Therefore, this provides a particularly useful method for the preparation of manno-beta-C-glycosides. The epimerization is likely initiated by the formation of Zn-enolate that is stabilized by intramolecular chelation to the pyranose ring-oxygen to form a syn chair-boat structure. Due to the activation generated by the Zn-O coordination, fission of the C1-O bond occurs, leading to opening of the pyranose ring, which is spontaneously followed by a change in conformation. The more stable anti chair-boat transition state is favored, and the subsequent hetero-intramolecular Michael addition results in the formation of beta-C-glycoside in a ring-closure step. 相似文献
107.
Stephan Felder Dr. Sandra Dreisigacker Dr. Stefan Kehraus Edith Neu Prof. Dr. Gabriele Bierbaum Patrick R. Wright Prof. Dr. Dirk Menche Dr. Till F. Schäberle Prof. Dr. Gabriele M. König 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(28):9319-9324
Marine myxobacteria (Enhygromyxa, Plesiocystis, Pseudoenhygromyxa, Haliangium) are phylogenetically distant from their terrestrial counterparts. Salimabromide is the first natural product from the Plesiocystis/Enhygromyxa clade of obligatory marine myxobacteria. Salimabromide has a new tetracyclic carbon skeleton, comprising a brominated benzene ring, a furano lactone residue, and a cyclohexane ring, bridged by a seven‐membered cyclic moiety. The absolute configuration was deduced from experimental and calculated CD data. Salimabromide revealed antibiotic activity towards Arthrobacter cristallopoietes. 相似文献
108.
Denise Langheinrich Edith Yslas Martín Broglia Viviana Rivarola Diego Acevedo Andrés Lasagni 《Journal of Polymer Science.Polymer Physics》2012,50(6):415-422
In this work, we describe a laser‐assisted microstructuring technique called Direct Laser Interference Patterning to produce topographical cues for tumor cells in a one‐step process. Line‐like patterns with spatial periods ranging from 500 nm to 10 μm are fabricated on polyimide (PI) films. The resulting structures exhibit a well‐defined shape and quality even for patterns with small periodic distances. Subsequently, the behavior of mouse mammary adenocarcinoma cells over those structures is evaluated. The results show that cell growth is well aligned to the direction of the patterns (over 60% lying within 0° to 15° to either side of the surface lines) for all evaluated structure sizes. Moreover, cells grown on patterns with 500 nm spatial period are the most narrowly aligned (up to 80% found between 0° and 15°), showing the potential of the technique. The fabrication process of the PI patterns is supported by a mathematical model of the underlying photo‐chemical ablation process. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
109.
Juan C. Marrero David Martínez Torres Edith Padrón 《Annals of Global Analysis and Geometry》2011,40(3):311-337
We obtain universal models for several types of locally conformal symplectic manifolds via pullback or reduction. The relation with recent embedding results for locally conformal Kähler manifolds is discussed. 相似文献
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