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Thermolysis of unsymmetrically substituted vinylcyclopropane systems : site-selectivity in homo-[1,5]-sigmatropic hydrogen migrations

This thesis describes the preparation and thermal rearrangement,
via homo-[l,5]-hydrogen migration, of a series of unsymmetrically substituted bicyclic and tricyclic vinylcyclo-propanes (65a)-(67a), (68b), (69), (70), (71a), (72a), (74)-(76) and (77a). In each of these compounds two hydrogen atoms one (H[sub=C]) adjacent to the substituent and the other (H[sub=J]) more distant from it - are suitably disposed to undergo homo-[1,5]-hydrogen migration.
It was found that an oxygen substituent retarded the rate of homo-[l,5]-migration of the hydrogen atom (H[sub=C]) adjacent to it relative to that of the other more remote hydrogen atom (H[sub=J]) The retarding effect appeared to be dependent on the structure of the oxy-substituted vinylcyclopropane as well as on the nature
of the oxygen substituent. A methyl substituent exerted a negligible, retarding effect on the rate of migration of while phenyl and trimethylsilyl groups accelerated the rate of migration of H[sub=C] relative to that of H[sub=J].
The results are consistent with the proposal that in the transition state for the homo-[1,5]-hydrogen migration the carbon
centre bearing the migrating hydrogen atom develops a partial
negative charge. / Science, Faculty of / Chemistry, Department of / Graduate

Identiferoai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/24328
Date January 1983
CreatorsMaxwell, Anderson Richard
PublisherUniversity of British Columbia
Source SetsUniversity of British Columbia
LanguageEnglish
Detected LanguageEnglish
TypeText, Thesis/Dissertation
RightsFor non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.

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