Rearrangement of a trishomocubane derivative to a tetracyclo[6.3.0.02,6.03,10]undec-4-ene |
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| Authors: | Alexander M Aleksandrov Mariusz Krawiec Tonis J Pehk Alexander Petrenko William H Watson |
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| Institution: | (1) Institute of Bioorganic Chemistry, Ukrainian Academy of Sciences, Kiev, Ukraine;(2) Institute of Chemical and Biological Physics, Estonian Academy of Sciences, Tallinn, Estonia;(3) Department of Chemistry, Texas Christian University, 76129 Fort Worth, Texas |
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| Abstract: | Reaction of 8,8,11,11-tetrafluoropentacyclo5.4.0.02,6.03,10.05,9]undecane with idio trimethylsilane leads to the expectedd
3-trishomocubane derivative, but reaction with the more electrophilic boron tribromide yields a tetracyclo6.3.0.02,6.03,10]undec-4-ene derivative which was characterized by X-ray diffraction. The most easily visualized pathway for this transformation would be an initial rearrangement of the starting material to ad
3-trishomocubane followed by additional bond breaking to form the undec-4-ene compound. Molecular mechanics calculations indicate the brominatedd
3-trishomocubane is about 4 kcal/mol more stable than the brominated undec-4-ene molecule and the associated carbonium ions show the same ordering. These data would indicate an alternate reaction pathway must be operative; however, semiempirical calculations predict the reverse ordering of the above energies. |
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| Keywords: | Tetracycloundecane d
3-trishomocubane" target="_blank">d
3-trishomocubane tetracycloundec-4-ene molecular mechanics semiempirical calculations X-ray analysis carbonium ion rearrangements |
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