Homolytic Reactions of Homocubane and Basketane: Rearrangement of the 9-Basketyl Radical by Multiple β-Scissions

Gavin T. Binmore, John C. Walton, Ernest W. Delia, Gordon M. Elsey, Nicholas J. Head

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

Methods are described for the synthesis of 9-hydroxy-and 9-bromopentacyclo[4.3.0.02, 5.03, 8.04, 7]nonane (homocubane derivatives) and for the same derivatives of pentacyclo[4.3.0.02, 5.03, 8.04, 7]decane (basketane). The 9-homocubyl and 9-basketyl radicals generated from these precursors were observed by EPR spectroscopy. In spite of their very large strain energies, both radicals rearranged extremely slowly, and unrearranged products were obtained from homolytic reactions in solution at temperatures below 150 °C. At higher temperatures the 9-basketyl radical rearranged by a cascade of three β-scissions, the ultimate product being 1 -(4-cyclobut-2-enyl)cyclohexa-2, 4-diene. The Arrhenius parameters for the rearrangement were found to be log(Ar/s-1) = 13.6, Er= 13.5 kcal mob-1. The 9-homocubyl radical did not rearrange even at 220 °C. An explanation as to why these cage radicals rearrange at least 6 orders of magnitude more slowly than the related cubylcarbinyl radical is presented, and semiempirical SCF-MO calculations are reported.

Original languageEnglish
Pages (from-to)2759-2766
Number of pages8
JournalJournal of the American Chemical Society
Volume116
Issue number7
DOIs
Publication statusPublished - 1 Apr 1994

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