Browsing by Author "Giles, R G F"

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    Novel naphthoquinones and their derivatives
    (1972) Green, Ivan Robert; Giles, R G F
    This dissertation deals with some novel routes investigated towards the synthesis of 1H-benz[f]indene-4,9-dione.
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    Novel quinone syntheses
    (1976) Roos, Gregory Harold Pelteret; Giles, R G F
    As indicated by the title, this dissertation deals with the investigation of the syntheses of a number of novel quinones. Chapter I deals with the syntheses of quinonoid derivatives of the compounds isobenzofuran and isoindole. These are the parent species of that series of heterocyclic compounds which contain a single heteroatom and are isoelectronic with naphthalene. They have been of considerable interest to workers in recent years, but have proved to be relatively unstable. We have therefore set out to prepare stable quinonoid derivatives of these. In Chapter II we have sought to develop, via regiospecific Diels-Alder additions, simple syntheses of some synthetically useful napthaquinonoid systems. The formation of many of these, required in the past as intermediates for the syntheses of a number of naturally occurring quinones, has previously proved tedious. Tae study of these addition reactions has afforded a direct route for the synthesis of the natural quinone, droserone. Finally, in Chapter III, some of the napthaquinones produced in Chapter II have been employed as intermediates in the syntheses of certain naturally occurring quinonoid species. These include a caryopterone and model compounds for the proposed syntheses of the anti biotics, Juglomycins A and B.
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    Some aspects of quinonoid chemistry
    (1979) Mitchell, Peter Robert King; Giles, R G F
    The first part of this thesis deals with the attempts made to synthesise 4 - hydroxypiloquinone. The proposed synthesis involved the making of two correctly substituted aromatic moieties that could be joined together to give a stilbene, which on irradiation would give a phenanthrene, that could be further elaborated to give a suitable precursor to 4 - hydroxypiloquinone. All attempts to convert the precursor to the required quinone were unsuccessful. In the second part of this thesis, a number of 2 - acetyl - 3 -alkylamino - 6 - anilino - 1,4 - benzoquinones were prepared by the reaction of 2 - acetyl - 3,6 - dianilino - 1,4 - benzoquinone with alkylamines in chloroform. Irradiation of these alkylamino - p -benzoquinones with ultra-violet light gave benzoxazoles where an á -hydrogen atom was present in the alkylamino substituent, except for the cyclohexylamino - and s - butylamino - benzoquinones which gave an unstable photo-product. With t - butylamino - benzoquinone no photoreaction was observed.
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    Syntheses related to some naturally occurring naphthopyranquinones
    (1986) Hugo, Victor Ignatius; Giles, R G F
    The naphtho[2,3-c]pyran ring system occurs not infrequently in Nature as derivatives of the 5,10-quinone. Examples include the eleutherins, the nanaomycins and the protoaphins some of which have been shown to possess antibiotic activity. The synthesis of these natural products requires appropriate regiospecific aromatic oxygenation of 2- acetylnaphthoquinone. Syntheses of 3-acetyl-5-methoxy-1, 4- naphthoquinone and the corresponding 5,7-dimethoxy analogue are described and the use of these in the syntheses of several naturally occurring pyranquinones or their derivatives, has been investigated. In the course of this work, an unusual Fries rearrangement and a novel baseinduced cyclisation were discovered - the latter affording several naphtho[2,3-c]pyrans in high yield. Previous routes to (±)-isoeleutherin and (±)-deoxyquinone A dimethyl ether have been recorded, but they give rise to a mixture of eleutherin and isoeleutherin in the first case, and a mixture of deoxyquinone A dimethyl ether and its cisdimethyl isomer. The synthetic routes to isoeleutherin and deoxyquinone A dimethyl ether developed during this investigation are highly stereoselective. The formation of the dimethyl ethers of quinones A and A', which is also highly stereoselective represents the first reported synthesis of the degradation products of the aphid pigments, protoaphin-fb and protoaphin-s1. The synthesis of 7-methoxyeleutherin is also described. The reaction of trifluoroacetic anhydride with various naphthalene derivatives is described and the potential of some of these acylated naphthalenes to be employed in the syntheses of naphtho[2, 3-c]pyrans and naturally occurring quinones has been investigated.