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11.
Miyoji Hanaoka Hiroshi Yamagishi Mari Marutani Chisato Mukai 《Tetrahedron letters》1984,25(45):5169-5172
Antileukemic benzo[C]phenanthridine alkaloids, fagaronine (1a) and nitidine (1c) were synthesized from the corresponding protoberberines through C6-N bond fission and subsequent cyclization between C6 and C13 position of the protoberberines. 相似文献
12.
Separation of sodium dodecyl sulfate (SDS)-protein complexes is difficult on plastic microchips due to protein adsorption onto the wall. In this paper, we elucidated the reasons for the difficulties in separating SDS-protein complexes on plastic microchips, and we then demonstrated an effective method for separating proteins using polymethyl methacrylate (PMMA) microchips. Separation difficulties were found to be dependent on adsorption of SDS onto the hydrophobic surface of the channel, by which cathodic electroosmotic flow (EOF; reversed flow) was generated. Our developed method effectively utilized the reversed flow from this cathodic EOF as a driving force for sample proteins using permanently uncoated but dynamic SDS-coated PMMA microchips. High-speed (6 s) separation of proteins and peptides up to 116 kDa was successfully achieved using this system. 相似文献
13.
Mária Hvastijová Jiri Kohout Marián Okruhlica Jerzy Mroziński Lothar Jäger 《Transition Metal Chemistry》1993,18(6):579-582
Summary Dicyanamide complexes of CuII, NiII and CoII of the type M[N(CN)2]2L2, where L = benzimidazole, 2-methyl- or 2-ethylbenzimidazole, have been prepared and studied by spectroscopy and magnetochemistry. The complexes, except for Co[N(CN)2]2 (benzimidazole)2, are six-coordinate, involving bidentate bridging dicyanamide groups. While the NiII complexes have practically octahedral structures, the CuII complexes are pseudooctahedral with similar tetragonal distortion. The ligand field strength in these complexes depends mainly on the steric effect of the benzimidazole ligands. The CoII complex of benzimidazole is monomeric tetrahedral, but that of 2-ethylbenzimidazole is tetragonal octahedral. The oridging function of dicyanamide in the six-coordinate complexes is realized either through both cyanide or through amide and cyanide nitrogens. The complex Cu[N(CN)2]2 (2-methylbenzimidazole)2 is a weak antiferromagnet (J = -0.1 cm–1), exhibiting under ca. 15 K a long-range antiferromagnetic ordering. 相似文献
14.
15.
Mari Vellakkaran Taehwan Kim Sungwoo Hong 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2022,134(1):e202113658
The site-selective C?H functionalization of heteroarenes is of considerable importance for streamlining the rapid modification of bioactive molecules. Herein, we report a general strategy for visible-light-induced β-carbonyl alkylation at the C4 position of pyridines with high site selectivity using various cyclopropanols and N-amidopyridinium salts. In this process, hydrogen-atom transfer between the generated sulfonamidyl radicals and O?H bonds of cyclopropanols generates β-carbonyl radicals, providing efficient access to synthetically valuable β-pyridylated (aryl)ketones, aldehydes, and esters with broad functional-group tolerance. In addition, the mild method serves as an effective tool for the site-selective late-stage functionalization of complex and medicinally relevant molecules. 相似文献
16.
Marién Abreu Jan Goedgebeur Domenico Labbate Giuseppe Mazzuoccolo 《Journal of Graph Theory》2019,92(4):415-444
A -bisection of a bridgeless cubic graph is a -colouring of its vertex set such that the colour classes have the same cardinality and all connected components in the two subgraphs induced by the colour classes ( monochromatic components in what follows) have order at most . Ban and Linial Conjectured that every bridgeless cubic graph admits a -bisection except for the Petersen graph. A similar problem for the edge set of cubic graphs has been studied: Wormald conjectured that every cubic graph with has a -edge colouring such that the two monochromatic subgraphs are isomorphic linear forests (ie, a forest whose components are paths). Finally, Ando conjectured that every cubic graph admits a bisection such that the two induced monochromatic subgraphs are isomorphic. In this paper, we provide evidence of a strong relation of the conjectures of Ban-Linial and Wormald with Ando's Conjecture. Furthermore, we also give computational and theoretical evidence in their support. As a result, we pose some open problems stronger than the above-mentioned conjectures. Moreover, we prove Ban-Linial's Conjecture for cubic-cycle permutation graphs. As a by-product of studying -edge colourings of cubic graphs having linear forests as monochromatic components, we also give a negative answer to a problem posed by Jackson and Wormald about certain decompositions of cubic graphs into linear forests. 相似文献
17.
18.
Charles E. McKenna Boris A. Kashemirov Mari Fujimolo 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract Individual E/Z isomers of the C-methyl ester 1 of α-(hydroxyimino)phosphonoacetic acid (“troika acid”) were recently prepared as dicyclohexylammonium salts and found to be stable at neutral pH.1 On alkaline demethylation followed by pH adjustment to 6–7, E?1 and Z?1 stereospecifically undergo P-Cαand Cα-Cβ cleavage, respectively.1 Herein we report synthesis of the corresponding P-methyl ester from trimethyl phos-phonoacetate 2. The product was isolated as its bis-DCHA+ salt E-3, with stereochemistry assigned by NMR.2 相似文献
19.
Boris A. Kashemirov Mari Fujimoto-posner Charles E. McKenna 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract The (E-oxime of phosphonoglyoxylic acid, or (E-troika acid [(E)-l] undergoe: fragmentation leading to phosphorylation of the aqueous solvent at neutral pH and room temperature.[1] In contrast, the corresponding C-methyl ester (a-2 is stable under these mild conditions. Conversion of the unreactive (E)-2 to (E)-1 requires dewthylation a pH 13–14, generating the polyanion of (E-1, which becomes reactive on protonation.[1] 相似文献
20.
Kô Takehara Takao Fujimori Kei Inagi Mari Kajiwara Yoshikazu Harata Kazuhisa Yoshimura 《Electroanalysis》2013,25(2):387-393
A square‐wave voltammetric method for the determination of boric acid in water has been described based on the new understanding of the electrochemical behavior of boric acid‐Azomethine H complexation. Salicylaldehyde and H‐acid were used as the starting materials of boric acid‐Azomethine H complex and their concentrations were optimized for boric acid determination in water. A glassy carbon electrode, instead of a conventional mercury electrode, was used in the measurement. The detection limit of the proposed method was 0.10 mg B dm?3. The proposed method was successfully used for boric acid determination in the water from a seawater desalination RO plant. 相似文献