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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1213-1221 
    ISSN: 1434-193X
    Keywords: Diazo compounds ; Carbenes ; Carbenoids ; Silicon ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Copper(I) triflate catalyzes the transformation of α-[(2-alkynyl)oxy]silyl-α-diazoacetates 1a-g into 1,2-bis(2,5-dihydro-1,2-oxasilol-4-yl)ethenes 2 and/or 2H-1,2-oxasilines 3. With rhodium(II) perfluorobutyrate as catalyst, 1a-e furnish only 3 but no 2. Bicyclic 2-methoxyfurans 6 are formed when 1a,c,e (containing terminal alkyne functions) are treated with catalytic amounts of copper(I) chloride. The experimental observations are explained in terms of metal-mediated intramolecular cyclopropenation and subsequent metal-assisted ring-opening of the strained bicyclic cyclopropene leading to vinylcarbene-metal complexes. An unusual autoxidation of 2H-1,2-oxasilines 3a,c,e is also described.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-193X
    Keywords: Diazo compounds ; Carbenes ; Carbenoids ; Silicon ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photolysis of (ethoxy)silyl-, (propyloxy)silyl-, and (isopro-pyloxy)silyl-substituted diazoacetates 1a-c leads to tetrahydro-1,2-oxasiloles 2a-c by intramolecular C-H insertion of a carbene intermediate. Photochemical or catalytic decomposition of (allyloxysilyl)diazoacetates 3a-e results in intramolecular cyclopropanation which provides 3-oxa-2-silabicyclo[3.1.0]hexane systems 5a-e. In contrast, the thermal reaction of 3b-d gives rise to 2,5-dihydro-1,2-oxasiloles 4b-d, which are likely to be formed on a pyrazoline rather than a carbene route. For (3-butenyloxysilyl)diazoacetate 3f, all modes of decomposition generate the 3-oxa-2-silabicyclo[4.1.0]heptane system 7. Fluoride-induced cleavage of the bicyclic systems 5b-d provides trans-2-hydroxyalkyl-1-cyclopropanecarboxylates 9 diastereospecifically.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0009-2940
    Keywords: (1-Diazo-2-oxoalkyl)silanes ; Cyclopropenes ; Cycloaddition ; Silyl shift ; Homopyrazole ; 1,4-Dihydropyridazine isomerization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (1-Diazo-2-oxoalkyl)silanes 1a-h react with cyclopropene 4 to form 2-silyl-2,3-diazabicyclo[3.1.0]hex-3-enes 5 and/or 1-silyll-1,4-dihydropyridazines 6. In most cases, a temperature- and solvent-dependent equilibrium 5 ⇄ 6 maintained by an N →N′ silyl shift exists in solution. With cyclopropene 10, only the 1-silyl-1,4-dihydropyridazines 11 are obtained. None of the 1:1 adducts corresponds to the product expected from a [3 + 2] cycloaddition reaction between the components. Evidence is presented that 1-diazo-2-siloxy-1-alkenes 2 are initially formed from 1 by a 1,3-(C → O) silyl shift and are then trapped by the cyclopropene in a 1,3-dipolar cycloaddition reaction.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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