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  • Cycloaddition reactions  (3)
  • Hydrogenations  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Carbon=Carbon Hydrogenation of Silicon-Functionalized Silaheterocycles (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1095-1102 
    Details
    ISSN: 1434-1948
    Keywords: Silanorbornenes ; Silanorbornanes ; Silicon-functionalized olefins ; Silacyclobutanes ; Hydrogenations ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Catalytic hydrogenation of olefins containing functionalized silicon groups affords the saturated products in good yields. Chloro and alkoxy substituents at the silicon atom remain unaffected and, in the case of heterocyclic compounds, the cyclic or bicyclic moieties remain intact. The 2-silanorbornanes 4, 5, and 6 were synthesized from the corresponding 2-silanorbornenes 1, 2, and 3, and organosilanes 13 and 14 possessing the cyclopentyl group, were prepared from the cyclopentenyl-substituted precursors 10 and 12. The 3-vinyl-substituted silacyclobutanes 15, 17, and 18 were also hydrogenated in a simple apparatus with diethyl ether or THF as solvent, and Pd/C as a recoverable catalyst system. A basic organosilicon compound, trichloro(vinyl)silane, is hydrogenated in a nearly quantitative yield to form the saturated trichloro(ethyl)silane; this emphasizes the general applicability of this method.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Silaheterocyclen, XXII. Diels-Alder-Reaktionen von Dichlor(neopentyl)silaethen mit Furanen und Umlagerung der erhaltenen Bicyclen zu monocyclischen Si - O-Siebenring-Verbindungen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 575-580 
    Details
    ISSN: 0009-2940
    Keywords: Silaethene derivatives ; Furans ; Cycloaddition reactions ; Rearrangements ; Sila heterocycles ; Diels-Alder reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sila Heterocycles, XXII[1]. - Diels-Alder Reactions of Dichloro(neopentyl)silaethene with Furans and Rearrangement of the Resulting Bicycles into Monocyclic Si - O Seven-Membered Ring compoundsThe reaction of trichloro(vinyl)silane (1) and LitBu (2) initially leads to the α1-lithio adduct Cl3SiCH(Li)CH2tBu (3) which can be trapped by trimethylsilyl triflate yielding the C1-silylated product [Cl3SiCH(SiMe3)CH2tBu (5)]. 1,2-LiCl elimination from 3 gives dichloro(neopentyl)silaethene [Cl2Si=CHCH2tBu (4)] as intermediate. This can be established by insertion of 4 into the Si - O bond of Me3SiOMe to Cl2Si(OMe)CH(SiMe3)CH2tBu (6). 4 is a dienophile of high activity and reacts with the furans 7 - 9 to give the [4 + 2] cycloaddition compounds 10 - 12. These Diels-Alder products are thermally unstable and decompose slowly at room temperature into the starting furans and tetrachlorodisilacyclobutane (15). Under thermolysis conditions (3 d/17°C) they rearrange into the monocyclic Si - O seven-membered ring compounds 16 - 18. A mechanism for the 7-Oxa-2-silabicyclo[2.2.1]hex-5-en → 1-Oxa-2-silacyclohepta-4,6-diene rearrangement is proposed.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260305
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  • 3
    Electronic Resource
    Electronic Resource
    Silaheterocyclen, XXV. (Me3SiO)2Si—CHCH2tBu: Ein Siloxy-funktionalisiertes Syntheseäquivalent für DichlorneopentylsilaethenHerrn Prof. Dr. U. Wannagat zum 70. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2177-2186 
    Details
    ISSN: 0009-2940
    Keywords: Silene, neopentyl- ; Me3SiO substituents ; Cycloaddition reactions ; Silaethene derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Silaheterocycles, XXV[1].  -  (Me3SiO)2Si—CHCH2tBu: A Siloxy-Functionalized Synthetic Equivalent for Dichloroneopentylsilene(Me3SiO)2Si—CHCH2tBu (4) is obtained by the reaction of (Me3SiO)2Si(Cl)CH=CH2 (2) with LitBu. The reaction proceeds via the α-lithiated species 3, which can be intercepted by trimethylsilyl triflate to give 5. Silaethene 4 dimerizes to the E/Z-isomers of disilacyclobutane 7 and adds to Me3SiOMe to give 6. The reactivity of 4 resembles that of Cl2Si—CHCH2tBu (1): A [4 + 2] cycloadduct is obtained from the reaction with anthracene, and with 1,3-cyclohexadiene and 1,3-cycloheptadiene mixtures of monosilacyclobutanes (10 and 12) and bicyclic Diels-Alder adducts (9 and 11) are available. Exclusive [2 + 2] cycloaddition reactions take place with styrene (formation of 13), 2,3-dimethyl-1,3-butadiene (→19), and 1,3-butadiene (→21). With quadricyclane only the product (14) originating from a [2 + 2 + 2] cycloaddition is formed, while with 2,5-norbornadiene the [2 + 2] and [2 + 2 + 2] cycloadducts (14 and 15) are formed. In addition the ene products (16, 18, 20, 22) are isolated in some cases from side reactions.  -  The tendency of 1 and 4 to preferably participate in [2 + 2] cycloaddition reactions is ascribed to the polarity of the Si—C bond and the additional influence of the π donor ligands at silicon. These factors enable a stepwise [2 + 2] reaction in which the primary zwitterionic intermediates B are cyclized to yield the SiC four-membered ring compounds.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261004
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  • 4
    Electronic Resource
    Electronic Resource
    Silaheterocyclen, XXIII. Synthese und Thermolyseverhalten von Si-funktionellen 2-Silaazetidinen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 581-589 
    Details
    ISSN: 0009-2940
    Keywords: Silene, dichloroneopentyl- ; Imines ; Cycloaddition reactions ; 2-Silaazetidines ; Thermolysis reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Silaheterocycles, XXIII[1]. - Synthesis and Thermolysis Reactions of Si-Functionalized 2-SilaazetidinesDichloroneopentylsilene (1) is formed in situ by the reaction of trichlorovinylsilane with LitBu. The [2 + 2] cycloaddition to imines yields Si, Si1-dichloro-functionalized 2-silaazetidines in a preparative scale. With aldimines as trapping agents for 1, the resulting SiN four-membered ring compounds are isolated as syn/anti1-isomers (e.g. syn/anti-15 and -16; syn/anti ≍ 2:1). Silene 1 is not liberated from the silaazetidines on heating, but the Si, Si1-dichloro-substituted silanimine Cl2Si=NtBu (24) is formed. This can be trapped by Me3SiOMe or Ph2C=NtBu to give the addition products 25 and 26, respectively. The pathways are discussed which lead to stereoisomeric SiN ring compounds by a multiple-step mechanism including zwitterionic intermediates (1,4-dipoles). In addition there is strong evidence for the formation of 1, depending on the trapping reagent used. This fact may be explained by donor→silene interactions. The thermolysis products of silaazetidines support the formulation of a stepwise decomposition to an alkene and Cl2Si=NR derivatives.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260306
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