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Synthesis and properties of some nitrogen-containing bridged systems

posted on 2023-05-26, 21:08 authored by Jaturonrusmee, Wasna
The general aims of this work were to develop routes to new nitrogen-containing bridged systems and to study the properties of these and related known systems. Firstly attention was directed to the synthesis of some new 3-aza-naphthothiadiazolophanes by a ring destruction involving the cyanogen bromideand chloroformate ester-mediated cleavage of a central benzylic carbon-nitrogen bond in cyclic amines containing a reduced isoquinoline moiety, with the concomitant loss of a proton to generate the final aromatic ring system. This type of approach provided a convenient and direct route to 3-aza-naphthothiadiazolophane derivatives as presented in Chapter 2. Secondly, studies on the effects of aromatic ring distortion on the chemical properties of some highly strained 3-aza [5]- and 3-aza [6](1,7)- naphthalenophanes were undertaken as described in Chapter 3. These naphthalenophanes underwent Diels-Alder addition as dienes, and in some cases as dienophiles, to afford a number of new heterocyclic bridged derivatives with a variety of functionality. The addition occurred exclusively on the nonmethoxylated ring under mild conditions for naphthalene derivatives. Very rapid cycloaddition was noted with the most highly distorted 3-aza [51(1,7)- naphthalenophane system. Kinetic studies on the Diels-Alder reaction of the 3- aza [5]- and 3-aza [6](1,7) naphthalenophanes with maleic anhydride were undertaken. These reactions were found to be second order; the rate constants, activation energies, enthalpies and entropies of activation were also determined and found to be consistent with the reaction type proposed. Thirdly, use of the 3-aza( 1,7) naphthalenophane derivatives as precurors for the synthesis of larger bridged systems was investigated (Chapter 4). Studies on the use of a bridged derivative as a potential precursor for a 3- aza [9] metacyclophane derivative by a bromine-induced C-C cleavage reaction are described. The successful synthesis of a 3-aza [9] metacyclophane derivative by oxidative cleavage of a 3-aza [6](1,7) naphthalenophane derivative was achieved. Finally, approaches to the construction of some 3-aza [5] (1,8)- anthracenophane derivatives by ring destruction with cyanogen bromide and methyl chloroformate were investigated. To this end, routes to the synthesis of isoquinoline-fused pentacyclic precursors were studied. Results of these efforts are discussed in Chapter 5. Although the desired precursors were not realized, a number of new synthetic areas have been opened up as a result of the work, involving new 2,8-bridged isoquinoline derivatives and a fused ˜í‚â§- lactam derivative. In all the work, extensive use was made of ¬¨œÄH and ¬¨œÄ¬¨‚â•C n.m.r. spectroscopy in particular, in assigning structures to products. As a result of these studies, a number of new 3-aza-phane derivatives were obtained. The development of synthetic routes to a number of new heterocyclic systems and some interesting chemical properties in strained 3- aza (1,7) naphthalenophane derivatives have also been established. In all, representatives of eighteen new bridged heterocyclic systems have been made, providing a wider basis for future structure-property relationship studies.


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Copyright 1989 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s). Includes bibliographical references. Thesis (Ph.D.)--University of Tasmania, 1991

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