Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/130732
Type: Thesis
Title: Progress Towards the Biomimetic Total Synthesis of Meroterpenoid Natural Products
Author: Sassnink, Stefania Alessandra
Issue Date: 2021
School/Discipline: School of Physical Sciences : Chemistry
Abstract: This thesis outlines synthetic efforts towards three different natural product families. Norascyronones A, B and C are complex polycyclic polyprenylated acylphloroglucinols (PPAPs) isolated from Hypericum ascyron in 2019. A total synthesis of norascyronone C was achieved in 8 steps from commercially available 3-ethoxy-2-cyclohexanone. With norascyronone C in hand, the biosynthetically-inspired radical cascade reaction to norascyronone A was explored. We discovered intriguing reactivity under radical oxidation conditions. A similar synthetic approach was taken in the efforts of synthesising a structurally related (not yet published) natural product. These synthetic efforts led to the synthesis of a precursor which we propose to be an “undiscovered natural product”. Investigation of the key radical cyclisation gave access to several structurally unique side products. The furaquinocin and neomarinone natural product family is a class of meroterpenoid natural products isolated from marine actinomycete bacteria. We proposed that the dihydrobenzofuran motif could be installed by aromatic Claisen rearrangement followed by intramolecular cyclisation of a geranyl or farnesyl side chain. A synthetic model system was developed to investigate this biomimetic theory. Several rearranged intermediates with fascinating structures have been made through three different synthetic routes. Furobinordentatin, furobiclausarin and claudimerines-A and -B are dimeric pyranocoumarin natural products isolated from Citrus plants. We proposed and investigated two possible pathways to access these dimeric natural products from simpler precursor molecules, nordentatin and clausarin. Nordentatin was successfully synthesised in 5 steps from commercially available phloroglucinol. With the synthetic precursor in hand, the oxidative dimerisation was attempted. However, even after an extensive screening of reaction conditions we were unable to access the dimeric natural products.
Advisor: George, Jonathan
Abell, Andrew
Dissertation Note: Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 2021
Keywords: Biomimetic synthesis
total synthesis
meroterpenoid
natural product
Provenance: This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals
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