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  • 4-Methylenespiro[2.4]heptane derivatives  (1)
  • Bicyclo[1.1.1]pentane  (1)
  • 1
    ISSN: 1434-193X
    Keywords: Bicyclo[1.1.1]pentane ; Haloarenes, cross-coupling of ; Propellanes ; Palladium ; Catalysis ; Small-ring systems ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Radical addition reactions of organyl iodides 7a-s onto [1.1.1]propellane (2) followed by halogen-lithium exchange and transmetallation with zinc chloride, as well as additions of Grignard reagents to 2, have furnished a variety of 3-substituted bicyclo[1.1.1]pentyl-1-magnesium (14) and -zinc (19) derivatives. The latter have been coupled with various alkenyl, aryl, and biaryl halides and triflates under NiCl2dppe, Pd(PPh3)4, or PdCl2(dppf) catalysis to give a number of 1,3-disubstituted bicyclo[1.1.1]pentyl derivatives 17, 20, and 23, several of which exhibit liquid crystalline properties, in moderate to very good yields. The coupling products 20ca, 23ab, 23ae, 23ff, and 23fg have been further transformed to yield bicyclo[1.1.1]pentyl derivatives 32, 24ab, 24ae, 27ff, and 27fg, respectively, bearing alkynyl, cyano, and/or alkenyl groups.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-193X
    Keywords: Bicyclopropylidene ; [3 + 2] Co-cyclization ; Nickel(0) catalysis ; Palladium(0) catalysis ; 4-Methylenespiro[2.4]heptane derivatives ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bicyclopropylidene (1) readily undergoes a palladium(0)-catalyzed [3 + 2] co-cyclization with electron deficient alkenes (methyl acrylate, methyl trans-crotonate, methyl cinnamate and diethyl fumarate) as well as with some strained alkenes (norbornene, norbornadiene) by distal ring cleavage of one of the three-membered rings of 1. All these co-cyclizations are regioselective with respect to 1 as well as regio- and stereoselective with respect to the alkenes to give the corresponding 4-methylenespiro[2.4]heptane-trans-6-carboxylates 2a-5 with the electron deficient alkenes and the cycloadducts 6 and 7 with the strained alkenes in acceptable to good yields (56 to 83%). In contrast to palladium(0) catalysts nickel(0) complexes catalyze both distal ring opening of 1 and oxidative coupling of the two double bonds when 1 is reacted with e.g. diethyl fumarate. The result is a mixture of the methylenecyclopentane derivative 5 with the [2 + 2] cycloadduct 8 and the cotrimer 9.
    Type of Medium: Electronic Resource
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