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A search for shorter, more convergent routes to enantiopure naphthopyrans related to the aphid insect pigments

McManus, Joshua David (2007) A search for shorter, more convergent routes to enantiopure naphthopyrans related to the aphid insect pigments. PhD thesis, Murdoch University.

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The naphtho[2,3-c]pyran ring system is generally found amongst natural products as the 5,10- or 6,9-quinones. These compounds display a wide range of biological activities, and as such, have been synthesised by various research groups. The synthetic work described in this thesis is directed towards finding shorter, more convergent routes to enantiopure quinone A 10, quinone A' 11 and quinone-pm 13, three derivatives of the aphid insect pigments protoaphin-fb 6, protoaphin-sl 7 and protoaphin-pm 9, respectively.

The first chapter describes the previous syntheses of some naphtho[2,3-c]pyrans including those relating to the aphid insect pigment derivatives. Also detailed is the ability of these naphthopyranquinones to act as potential bioreductive alkylating and dialkylating agents. The latter part of the chapter records some of the previously achieved assemblies of quinones A 10 and A' 11 in both racemic and enantiopure form, as well as the only synthesis of enantiopure quinone-pm 13.

Chapter 2 involves the preparation of regioselectively halogenated aryldioxolanes starting with the allylation of brominated and chlorinated phenols. The isomerisation of these dioxolanes into the corresponding halogenated 2-benzopyrans is then investigated.

Chapter 3 examines the regioselectivity of the Diels-Alder reaction between protected benzopyranquinones and the substituted diene 1-methoxy-1,3-bis(trimethylsilyloxy)-buta-1,3-diene 80. Such protection involves preparing the acetates and methoxymethyl ethers of the benzopyranquinones. The latter part of the chapter describes the direct bromination of benzopyranquinones.

Chapter 4 reports on the stereoselective reaction between metal phenolates and the chiral aldehyde 108 to subsequently afford naphthyldioxolanes 264, 291, 292 and 295. The rearrangement reaction of the derived naphthyldioxolane 295 is then investigated.

Item Type: Thesis (PhD)
Murdoch Affiliation(s): School of Biological Sciences and Biotechnology
Supervisor(s): Giles, Robin
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