Synthesis and reinvestigation of tetrazocines
Healy, Cathal (2004) Synthesis and reinvestigation of tetrazocines. PhD thesis, Dublin City University.
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This thesis is concerned with the study of tetrazocines. These rare, eight-membered ring systems containing four nitrogen atoms are in the infancy of their development. Little is known of their potential application, properties and generation. It was endeavoured to learn more about this compound class by examining what has been presented in the literature (chapter 1), generating novel tetrazocines (chapter 3 and 4) and finally substantiating existing syntheses, which were viewed as unlikely or doubtful by this research group (chapter 2).
Previous work from this research group involving the photolytic ring expansion of hexahydropyrrolotriazoles led to a novel 1,2,3,5-tetrazocine system. Hexahydropyrrolotriazoles are cycloaddition products from the reaction of a 1,3- dipole with various activated dipolarophiles. This thesis was concerned with accelerating this reaction, manipulating functionality post cycloaddition and optimising the photochemical ring opening process leading ultimately to tetrazocines. In particular, the cycloaddition product of our standard 1,3-dipole with benzyne furnished a 1,3-diphenylindazole thermally and a tetrazocine photochemically. Other analogues of this tetrazocine have previously been postulated as being only intermediate.
In another area, four previously reported syntheses of tetrazocines were re-examined and found not to correlate with our observed results. This work was undertaken based on the relative instabilities of this compound class.
Finally, the proposed synthesis of the only second entry into the rare 1,2,4,7-tetrazocine ring system is described but has yet to be conclusively verified.
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