Thesis

Reactions of a super-electron donor with diarylcyclopropanes and epoxides

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Awarding institution
  • University of Strathclyde
Date of award
  • 2010
Thesis identifier
  • T12709
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Abstract
  • The selective deoxygenation of both cis- and trans-isomers of 2,3-bis(4-fluorophenyl)oxirane, 2,3-bis(4-chlorophenyl)oxirane and 2,3-diphenyloxirane was achieved by the DMAP-derived electron donor 1.57 (Scheme 1). In each case, only the trans-alkene product was isolated. The reaction conditions depend on the energy level of the LUMO of the molecule. The higher the LUMO is, the harsher the conditions are. The use of UV-light was necessary to achieve reductive cleavage of the unsubstituted 2,3-diphenyloxiranes. In the case of 2,3-bis(4- chlorophenyl)oxirane, partial reductive cleavage of the aryl C-Cl bond was also observed. Dichloro- and monochlorostilbenes were isolated. However no monochlorinated oxirane was observed. Scheme 1 - Reactivity of epoxides with electron donor 1.57. The geometric isomerisation of diarylcyclopropanes was also achieved by DMAP-derived electron donor 1.57. Both geometric isomers of 1,2-bis(4-fluorophenyl)cyclopropane and 1,2- diphenylcyclopropane were isomerised when submitted to 1.57 (Scheme 2). However, no complete isomerisation was observed. These reactions required activation by UV-light. However, it has been proved that the isomerisation was not seen in the absence of donor 1.57, even if UV activation was used. Scheme 2 - Reactivity of 1,2-bis(4-fluorophenyl)cyclopropane and 1,2-diphenylcyclopropane with 1.57. N NMe2 N NMe2 1.57 7 A different reactivity was observed when submitting both geometric isomers of 1,2-bis(4- chlorophenyl)cyclopropane to the electron donor 1.57 (Scheme 3). Whereas in this case isomerisation of 1,2-bis(4-chlorophenyl)cyclopropane was mainly due to UV-light, the electron donor 1.57 was responsible for the cleavage of aryl C-Cl bonds giving rise to a complex mixture of both geometric isomers of di-, mono- and non-chlorinated diarylcyclopropanes. Scheme 3 - Reactivity of of 1,2-bis(4-chlorophenyl)cyclopropane with electron donor 1.57.
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Date Created
  • 2010
Former identifier
  • 820307

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