Chapter 5
Perfluorinated Alkenes and Dienes in a Diverse Chemistry R. D. Chambers, S. L. Jones, S. J . Mullins, A. Swales, P. Telford, and M . L. H. West
Downloaded by CORNELL UNIV on August 23, 2016 | http://pubs.acs.org Publication Date: February 22, 1991 | doi: 10.1021/bk-1991-0456.ch005
Department of Chemistry, University of Durham, South Road, Durham DH1 3LE, United Kingdom
Model compound studies reveal factors which influence free—radical additions of ethers, polyethers, and crown—polyethers, to fluorinated alkenes. Stereo-electronic effects significantly affect relative reactivities of cyclic amines. Novel dienes are obtained by reactions of some oligomers of fluorinated alkenes with sodium amalgam and some reactions of these systems with nucleophiles are described. This presentation is deliberately general, i.e. derived from the work of a range of co-workers and their names appear at points in the text corresponding to their work. We are attempting to give aflavourof some of our work, that relates to structure and reactivity, and which illustrates general principles. Two types of process will be included for discussion because they illustrate a number of fundamentals: 1. 2.
Free—radical additions tofluorinatedalkenes, (B. Grievson, A.P. Swales, P. Telford, S.L. Jones, A. Joel, R.W. Fuss) Nucleophilic substitutions withfluorinateddienes, (M. Briscoe, M.P. GreenhaH, S. Mullins, T. Nakamura)
Reactions with Ethers Essentially, we are addressing the general problem of use of the carbonhydrogen bond as a functional group, in the synthesis of fluorine-containing systems and are particularly concerned withfree—radicaladditions of functional compounds tofluorinatedalkenes. In principle, therefore, this is an attractive route to various fluorinated derivatives and a considerable amount of earlier work has taken place in this area (see e.g. 1—3). Indeed, a study of structure and reactivity in free-radical chemistry is of interest in its own right because our understanding of such free-radical processes falls far short of our general knowledge of many ionic processes. Fluorinated alkenes are particularly reactive towards ethers in freeradical processes; why should this be so? Stabilisation of a radical centre by adjacent oxygen is, of course, well known but if we represent this in
0097-6156/91/0456-0068$06.00/0 © 1991 American Chemical Society
Welch; Selective Fluorination in Organic and Bioorganic Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1991.
5. CHAMBERS ET AL.
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Perfluorinated Alkenes and Dienes
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• x-i-JJr III I Chain Transfer
Downloaded by CORNELL UNIV on August 23, 2016 | http://pubs.acs.org Publication Date: February 22, 1991 | doi: 10.1021/bk-1991-0456.ch005
x-i- + x-i-i-c-H I III valence—bond terms, then we see why electron—withdrawal may be offset by involvement of the electron pair.
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