Halgren, Thomas A. and Firkins, John L. and Fujimoto, T. A. and Suzukawa, H. H. and Roberts, John D. (1971) Evidence for hydrogen abstraction by classical radicals in the norbornenyl-nortricyclyl system. Proceedings of the National Academy of Sciences of the United States of America, 68 (12). pp. 3216-3218. ISSN 0027-8424 http://resolver.caltech.edu/CaltechAUTHORS:HALpnas71
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Studies of product compositions and deuterium-label rearrangements at various concentrations of tri-n-butyltin hydride in the reductions of exo- and endo-5-bromonorbornene and 2-bromonortricyclene to mixtures of norbornene and nortricyclene lead to three main conclusions: (i) at least two radical intermediates contribute to product formation; (ii) each intermediate yields predominantly (80% or more) one product; and (iii) nortricyclene is predominantly derived from a symmetrical intermediate. This constitutes strong evidence for hydrogen abstraction by classical (i.e., single-product) norbornenyl and nortricyclyl radicals. It is argued that the norbornenyl-nortricyclyl system is exceptionally well suited for the generation of a nonclassical (dual-product) radical; hence, the existence of a nonclassical radical in any other system is rather unlikely.
|Additional Information:||© 1971 by the National Academy of Sciences. Contributed by John D. Roberts, September 24, 1971. This work was supported by the National Science Foundation. Contribution no. 4336 from the Gates and Crellin Laboratories of Chemistry.|
|Subject Keywords:||free radical rearrangement; symmetrical intermediates; mechanism|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||31 Jul 2007|
|Last Modified:||26 Dec 2012 09:34|
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