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  • 1
    Electronic Resource
    Electronic Resource
    Ruthenium(II)-Catalyzed Oppenauer-Type Oxidation of Secondary Alcohols (1996)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 2 (1996), S. 1533-1536 
    Details
    ISSN: 0947-6539
    Keywords: catalysis ; dehydrogenations ; oxidations ; ruthenium complexes ; secondary alcohols ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Highly efficient ruthenium-catalyzed Oppenauer-type oxidations of secondary alcohols to ketones have been developed. The catalytic system consists of [(PPh3)3RuCl2] (1) and K2CO3 or [(C4Ph4COHOCC4Ph4)(μ-H)(CO)4Ru2] (2) in refluxing acetone. The catalytic reaction is of high efficiency and permits a catalyst: substrate ratio of 1:1000 at 56 °C. In some cases the initial turnover rate exceeds 1500 h-1. The reaction was found to be general and compatible with double bonds and oxidation-sensitive aromatics. With some allylic alcohols, isomerization to saturated ketones took place. The reaction proceeds by ruthenium-catalyzed dehydrogenation of the alcohol and subsequent hydrogen transfer to acetone. No primary kinetic isotope effect was observed for the catalytic reaction when α-deuterated 1-phenylethanol was employed as substrate (kH/kD=1.1); this shows that β-hydride elimination from a ruthenium alkoxide intermediate is not the rate-limiting step.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19960021210
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  • 2
    Electronic Resource
    Electronic Resource
    ortho-Chelating Arenethiolatocopper(I) Complexes as Versatile Catalysts in the Regioselective Cross-Coupling of Allylic Derivatives with nBuMgI - An Example of Reversed Reactivity of Leaving Groups (1995)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 1 (1995), S. 351-359 
    Details
    ISSN: 0947-6539
    Keywords: allylic substrates ; carbon-carbon coupling ; catalysis ; copper compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The regioselectivity in the arenethiolatocopper(I)-catalyzed crosscoupling reaction of allylic substrates was studied. It was found that allylic acetates gave highly γ-selective reactions in Et2O at 0°C with slow addition of the Grignard reagent, whereas α-selective reactions were obtained in THF at -30°C with fast addition of the Grignard reagent. It is proposed that the formation of an intermediate in Et2O, in which the allylic acetate coordinates in a bidentate fashion the arenethiolatocopper(I) catalyst, dramatically increases the reactivity of the leaving group and results in excellent γ-selectivity. The remarkable observation that an allylic acetate can be made more reactive than an allylic chloride by using the arenethiolatocopper(I) catalyst 1a supports the theory of a bidentate coordination of the substrate to the catalyst through its double bond and acetate oxygen.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19950010605
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  • 3
    Electronic Resource
    Electronic Resource
    Allylsilanes as Carbon Nucleophiles in the Palladium-Catalyzed 1,4-Oxidation of Conjugated Dienes (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 482-490 
    Details
    ISSN: 0947-6539
    Keywords: allylsilanes ; catalysis ; cyclizations ; oxidations ; palladium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Palladium-catalyzed oxidation of cyclic 1,3-dienes 3, 5, 9, 11, and 13, with an allylsilane group in the side chain, led to an intramolecular 1,4-syn-addition to the conjugated diene through a carbocyclization. Acyclic trienesilanes 7 also underwent analogous 1,4-oxidations. The reaction was carried out in acetone-acetic acid (2:1) with a slight excess of LiCl. p-Benzoquinone was employed as the oxidant and Li2PdCl4 as the catalyst. The reaction proceeds through an intramolecular trans addition of the allylsilane to a (π-diene)palladium complex to produce a bicyclic (π-allyl)palladium intermediate. Subsequent trans attack by chloride at the π-allyl intermediate gives the product. The intermediate (π-allyl)palladium complex was isolated and fully characterized. It was unambiguously demonstrated that the allylsilane had attacked the coordinated double bond trans to palladium (trans-carbopalladation). The use of CuCl2 as the oxidant, instead of p-benzoquinone, gave a less stereoselective addition, but interestingly, with the opposite stereochemistry.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970030320
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