Merrilactone A (1) was isolated in only 0.004% yield from the methanol extracts of the pericarps of Illicium merrillianum. Structural elucidation of Merrilactone A revealed a compact, cage-like pentacyclic architecture of high molecular complexity, featuring seven stereocentres, five of which as contiguous fully substituted carbon atoms, two γ-lactones and a central oxetane ring. Merrilactone A also exhibits an important neurotrophic activity, significantly promoting neurite outgrowth in the primary cultures of foetal rat cortical neurons at very low concentrations. Structurally, merrilactone A is related to anislactones A and B, a pair of epimeric sesquiterpene dilactones discovered ten years earlier by Kouno and co-workers from the related Illicium anisatum plant. Fukuyama has shown that anislactone B can be converted into merrilactone A using a simple three step sequence, suggesting that the anislactones may be biogenetic precursors to merrilactone A. Described in this thesis are our research efforts directed towards developing a conceptually novel synthetic route enabling regiodivergent total synthesis of both anislactone A / B and merrilactone A. Our synthetic route (around 22 steps) features several key reactions, which include a [2+2] photo-cycloaddition reaction, Tiffeneau-Demjanov ring expansion and titanium(III) mediated radical cyclization.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:563566 |
| Date | January 2011 |
| Creators | Shi, Lei |
| Contributors | Greaney, Mike. : Lusby, Paul |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/5705 |
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