A heavy analogue of the smallest bridgehead alkene stabilized by a base

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34 Citations (Scopus)


Bicyclo[1.1.0]but-1(2)-ene (BBE), one of the smallest bridgehead alkenes and C4H4 isomers, exists theoretically as a reactive intermediate, but has not been observed experimentally. Here we successfully synthesize the silicon analogue of BBE, tetrasilabicyclo[1.1.0]but-1(2)-ene (Si4BBE), in a base-stabilized form. The results of X-ray diffraction analysis and theoretical study indicate that Si4BBE predominantly exists as a zwitterionic structure involving a tetrasilahomocyclopropenylium cation and a silyl anion rather than a bicyclic structure with a localized highly strained double bond. The reaction of base-stabilized Si4BBE with triphenylborane affords the [2+2] cycloadduct of Si4BBE and the dimer of an isomer of Si4BBE, tetrasilabicyclo[1.1.0]butan-2-ylidene (Si4BBY). The facile isomerization between Si4BBE and Si4BBY is supported by theoretical calculations and trapping reactions. Structure and properties of a heavy analogue of the smallest bridgehead alkene are disclosed.

Original languageEnglish
Article number5353
JournalNature communications
Publication statusPublished - 2014 Nov 4

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)


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