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On reaction with ‘O’-donors or O2, the synthetic P-450 analogue 2 undergoes O-insertion at a nonactivated C? H bond of the covalently bound substrate. The mechanism of O-insertion with O2 most likely involves homolytic cleavage of the O? O bond followed by O-insertion via radical recombination. 相似文献
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Georgios Papazoglou Jorge Sierra Katharina Homberger Armin Guggisberg Wolf-Dietrich Woggon Manfred Hesse 《Helvetica chimica acta》1991,74(3):565-571
Aphelandrine ( 1 ) is shown to be biosynthesized in the root cells of Aphelandra tetragona (VAHL ) NEES from labelled putrescine ( 4 ), spermidine ( 5 ), and cinnamic acid ( 3 ). Whether spermine ( 6 ) and the (p-hydroxycinnamoyl)spermidine 8 are precursors of 1 is uncertain, since the latter is hydrolysed to a large extent before incorporation, and the former is metabolized to 4 and 5 . Methionine ( 7 ) is the source of the 3-aminopropyl unit of 5 and 6 . 相似文献
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Incubation of the geraniols (R)-(8-2H1)[8-3H1]- 1 and (S)-(8-2H1)[8-3H1]- 1 with microsomal cytochrome P-450Cath. from the subtropical plant Catharanthus roseus (L.)G. DON resulted in the formation of the chiral 8-hydroxygeraniols (S)-(8-2H1)[8-3H1]- 2 and (R)-(8-2H1)[8-3H1]- 2 . Their absolute configuration was assigned on the basis of the 1H-decoupled 3H-NMR Spectra of the corresponding dicamphanates (S)-(8-2H1)[8-3H1]- 9 and (R)-(8-2H1)[8-3H1]- 9 , of which the configurations are established in relation to the synthetic reference samples. The results clearly indicate retention of configuration during the allylic oxidation of 1 . 相似文献
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Oellien F Ihlenfeldt WD Gasteiger J 《Journal of chemical information and modeling》2005,45(5):1456-1467
The tremendous increase of chemical data sets, both in size and number, and the simultaneous desire to speed up the drug discovery process has resulted in an increasing need for a new generation of computational tools that assist in the extraction of information from data and allow for rapid and in-depth data mining. During recent years, visual data mining has become an important tool within the life sciences and drug discovery area with the potential to help avoiding data analysis from turning into a bottleneck. In this paper, we present InfVis, a platform-independent visual data mining tool for chemists, who usually only have little experience with classical data mining tools, for the visualization, exploration, and analysis of multivariate data sets. InfVis represents multidimensional data sets by using intuitive 3D glyph information visualization techniques. Interactive and dynamic tools such as dynamic query devices allow real-time, interactive data set manipulations and support the user in the identification of relationships and patterns. InfVis has been implemented in Java and Java3D and can be run on a broad range of platforms and operating systems. It can also be embedded as an applet in Web-based interfaces. We will present in this paper examples detailing the analysis of a reaction database that demonstrate how InfVis assists chemists in identifying and extracting hidden information. 相似文献
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Martin G. Peter Hans-Rudolf Waespe Wolf-Dietrich Woggon Hans Schmid 《Helvetica chimica acta》1977,60(4):1262-1272
Incorporation experiments with (3H and 14C) doubly labelled farnesols into cantharidin After injection of 11′, 12-[3H]-7-[14C]-farnesol or 11′, 12-[3H]-5,6-[14C]-farnesol, the 3H-label is located specifically in the C(9)-methyl-group of cantharidin, whereas the 14C-labelling pattern follows an incorporation via acetic acid (Scheme 4). C-Atoms 5, 6 and 7 from the middle part of the farnesol molecule are utilized for cantharidin biosynthesis to an extent that is about 2.1–11% of the incorporation rate of the methyl groups C(11′) and C(12), depending on the position of the 14C-label in farnesol. These results confirm our earlier hypothesis [1] that the C10-molecule cantharidin is biosynthesized from the C15-precursor farnesol which is cleaved between C(1)–C(2), C(4)–C(5), and C(7)–C(8). The synthesis of 7-[14C]-farnesol and of 5,6-[14C]-farnesol is described. 相似文献
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The hydroxylation of geraniol ( 8 ) by cytochrome P-450 (P-450Cath.) from the subtropical plant Catharanthus roseus (L.) G. DON was optimised to give 8-hydroxygeraniol ( 9 ) as the single product in 35% yield. Incubations of different 13C- and 2H-labelled geraniols revealed that H-abstraction is completely regioselective in favour of the CH3 group trans to the chain at C(6) of 8 . An intramolecular isotope effect kH/kD = 8.0 was determined, suggesting that H-abstraction is one of the major rate-contributing steps; however, the intermolecular isotope effect was surprisingly inverse at low conversion kH/kD = 0.50, indicating the existence of rate-contributing steps preceding the first irreversible, isotope-sensitive reaction in the sequence. 相似文献
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Hans-Peter Welzel Gerhard Kossmehl Gunnar Engelmann Wolf-Dietrich Hunnius Waldfried Plieth 《Journal of Solid State Electrochemistry》2001,5(2):141-149
Polythiophene films containing ester groups on the surface of electrodes are interesting potential carrier materials for
reagents. Methyl thiophene-3-acetate (3) can be copolymerized with 3-methylthiophene (1) and 3-butylthiophene (2) by means of cyclic voltammetry (CV) at potentials of 0–2.2 V. Higher potentials (0–2.4 V) lead to overoxidation of the copolymers.
The ester groups were confirmed by FTIR spectra. Electrochemical investigations of 2,2′-bithiophene (6) and 3 at equimolar ratios showed no successful copolymerization at potentials of 0–1.3 V. If the copolymerization experiments of
6 with 1 or 3 were carried out at molar ratios of 1:50 at 1.3 V, 6 with its low oxidation potential was polymerized without copolymerization of the other monomers. However, if the oxidation
potential was increased stepwise from 1.3 V, the oxidation of 1 or 3 occurred, forming copolymers containing both monomer components. HPLC investigations of solutions containing mixtures of
6 and 3 and also 6 and 1 in acetonitrile/TEABF4 showed, after exhaustive oxidation at a potential of 1.3 V, the complete absence of 6; 1 and the ester 3 were not oxidized and copolymerized at these potentials. From the results of the copolymerization experiments, as well as
the HPLC investigations, it can be concluded that the dominant mechanism of the electrochemical polymerization is radical
cation dimerization.
Received: 21 August 1998 / Accepted: 11 January 2000 相似文献