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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Asymmetric synthesis of substituted 2-aminotetralins

Aaseng, Jon Erik January 2010 (has links)
Presented in this thesis are the results obtained from the project: Asymmetric synthesis of substituted 2-aminotetralins. The initial goal was to establish new or improved routes to enantiopure 2-aminotetralin (2-AT) derivatives. The motivation for this project was based on the diverse applications various 2-ATs represent as biologically active compounds. Despite the role of 2-aminotetralins as interesting target molecules, reflected by the massive research activity in the field, no general and cost efficient route has really been established. Chapter 1 in this thesis gives an introduction to 2-ATs as biologically active compounds, as well as a brief survey of the concepts of chirality and asymmetric synthesis. Aziridines are also presented, given their role as key intermediates in our developed strategies (chapters 2-4). In chapter 2, a total synthesis of substituted (S)-2-ATs is presented, starting from natural L-aspartic acid. Two 2-AT derivatives were successfully synthesised, but especially one step (ring-closing to tetralones) proved difficult, providing up to 41% yield only. Chapter 3 is directly based on the experiences we made in the former chapter, and presents an improved route from the same starting point (chiral pool strategy utilising L-aspartic acid). Again we struggled with one specific cyclisation reaction (up to 36% yield), but the remaining steps provided overall good yields. In Chapter 4, a different approach has been targeted, i.e. asymmetric aziridination of 1,2-dihydronaphthalenes. Here, various copper, rhodium and ruthenium catalytic systems were tested with alternative nitrogen sources. While we were able to achieve quite good results for non-substituted 1,2-dihydronaphthalene, substituted substrates provided only mediocre yields and enantioselectivity. Aziridines were selectively ring-opened by catalytic hydrogenation to their respective N-protected 2-ATs in good yields.

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