Lewis Acid Promoted [2 + 2] Cycloaddition of Allylsilanes and Unsaturated Esters: A Novel Method for Cyclobutane Construction

Authors

  • Prof. Dr. Hans-Joachim Knölker,

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    1. Institut für Organische Chemie der Universität, Richard-Willstätter-Allee, D-76131 Karlsruhe (FRG), Telefax: Int. code +(721)698-529
    • Institut für Organische Chemie der Universität, Richard-Willstätter-Allee, D-76131 Karlsruhe (FRG), Telefax: Int. code +(721)698-529
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  • Gerhard Baum,

    1. Institut für Anorganische Chemie der Universität Karlsruhe (FRG)
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  • Dipl.-Chem. Regina Graf

    1. Institut für Organische Chemie der Universität, Richard-Willstätter-Allee, D-76131 Karlsruhe (FRG), Telefax: Int. code +(721)698-529
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  • Cycloadditions of Allylsilanes, Part 6. This work was supported by the Deutsche Forschungsgemeinschaft (Gerhard-Hess-Förderpreis) and the Fonds der Chemischen Industrie. Part 5: [13].

Abstract

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A third mode of reactivity for allylsilanes in their reactions with α,β-unsaturated carbonyl compounds has been found in addition to the Sakurai reaction and the [3 + 2] cycloaddition. Silylmethyl-cyclobutanes are formed regioselectively via a siliranium ion intermediate (1). The reaction with methyl propynoate provides bicyclo[2.2.0]hexanes in a one-pot conversion.

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