- Observations on some Pd((0)) catalysed intermolecular reaction of electron deficient alkylidene cyclopropanes with olefins: A novel route to highly functionalised skipped diene units
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Methylene cyclopropanes 1 bearing an electron withdrawing group react under palladium (0) catalysis with electron poor olefins to give skipped dienes 2. This reaction, which is believed to proceed via hydride transfer, highlights the fact that the reactivity of methylene cyclopropanes can be dramatically influenced by the nature of ring substituents.
- Corlay, Herve,Fouquet, Eric,Motherwell, William B.
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p. 5983 - 5986
(2007/10/03)
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- 213. Synthesis of Triafulvene-Precursors from Trisubstituted Cyclopropanes
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Trisubstituted cyclopropanes 5a-f are prepared by carbene addition to the appropriate olefins.While 5a (Y = OAc) and 5c (Y = Cl) rearrange in the presence of BuLi, 5d (Y = SPh) is stable enough to allow the envisaged sequence for triafulvene (Scheme 2); halogen-Li exchange, followed by methylation of 6d, gives 7d in a 93percent yield; after base-induced elimination of HBr from 7d, the key precursor 1-methylene-2-(phenylthio)cyclopropane (9, 70percent yield) is isolated.Compound 9 is transformed into the corresponding sulfoxide 10 (83percent), sulfone 11 (80percent), and sulfonium fluoroborate 12 (95percent yield) by subsequent oxidation and methylation, respectively.Some 1H NMR results of cyclopropanes 5a-f and 7d as well as of methylidene-cyclopropanes 9-11 are discussed.
- Weber, Andreas,Sabbioni, Gabriele,Galli, Roberto,Staempfli, Urs,Neuenschwander, Markus
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p. 2026 - 2033
(2007/10/02)
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