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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

Synthesis of Alkynes from Bi-3H-diazirin-3-yls: Trapping of Strained Cycloalkynes

Al-Omari, Mohammad Hasan 30 January 2004 (has links)
Abstract Al-Omari, Mohammad Synthesis of Alkynes from Bi-3H-diazirin-3-yls: Trapping of Strained Cycloalkynes Chemnitz Technical University, Fakulty of Science Dissertation 2003, 76 pages. In this study, we have succeeded in synthesis of alkynes by a new method using bidiazirines as precursors. Different bidiazirinyl systems, such as acyclic, cyclic, and bicyclic systems, were investigated to show if they could serve as appropriate precursors for cycloalkynes. It has been shown that alkynes of no strain (e.g. 2-butyne) as well as extremely strained cycloalkynes (e.g. norbornyne) could be generated utilizing this method. This new method represents a simple, clean, and very efficient route to alkynes. That the strained cycloalkynes had actually been generated was shown by different trapping experiments. In these experiments, the thermal or photoextrusion of nitrogen atoms of the bidiaziridine moieties will certainly leads to the formation of a C,C triple bond, most probably through carbene intermediate. In terms of their reactions with the trapping dienes reagents, the generated cycloalkynes should be considered as normal, yet strained alkynes. In turn, bidiazirines were easily synthesized by oxidative dehydrogenation of their corresponding bidiaziridines. Bidiaziridines, which were the key step in the whole process, were successfully synthesized from bisdiimine precursors. It has been shown, that bisdiimines were the only suitable starting materials for the synthesis of bidiaziridines. Neither the diketones, nor the iminoketone derivatives proved to serve as appropriate starting materials. keywords: 1,2-diketon, 1,2-diimines, bidiaziridin, bidiazirin, strained cycloalkynes, Norbornyne, trapping agents, cycloaddition. / Bibliographische Beschreibung und Referat Al-Omari, Mohammad Synthesis of Alkynes from Bi-3H-diazirin-3-yls: Trapping of Strained Cycloalkynes Technische Universität Chemnitz, Fakultät für Naturwissenschaften Dissertation 2003, 76 Seiten. In der vorliegenden Arbeit wird eine neue Methode zur Synthese von Alkinen beschrieben. Ausgehend von acyclischen, mono- und bicyclischen 1,2-difunktionalisierten Vorläufern wurden Bidiazirine synthetisiert und deren Eignung als Precursoren für Alkine untersucht. Dabei musste festgestellt werden, dass sich weder von 1,2-Diketonen noch von Iminoketonen die als Zwischenprodukte benötigten Bidiaziridine direkt darstellen ließen. Der einzige erfolgreiche Syntheseweg führte über die 1,2-Diimine zu Diastereomeren-Gemischen der gewünschten Bidiaziridine. Die Oxidation der Bidiaziridine lieferte die Bidiazirine, welche als Vorstufen für die Synthese von Alkinen dienten. So konnten auf diesem Wege sowohl spannungsfreie lineare Alkine wie 2-Butin als auch extrem gespannte Cycloalkine wie Cyclohexin oder Norbornin synthetisiert werden. Der spektroskopische Nachweis der Alkine erfolgte dabei direkt bzw. über verschiedene Abfangprodukte. Stichworte: 1,2-Diketon, 1,2-Diimine, Bidiaziridin, Bidiazirin, gespannte Cycloalkine, Norbornin, Abfangreagentien, Cycloaddition.

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