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Title: Total synthesis of rubriflordilactone A
Author: Goh, Simin Shermin
ISNI:       0000 0004 6061 4039
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2015
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Rubriflordilactones A and B are highly oxygenated nortriterpenoid natural products isolated from Schisandra rubriflora. The latter is of particular biological interest as it shows significant anti-HIV activity. Two transition metal-catalysed cascade cyclisation approaches for the formation of the CDE rings of the rubriflordilactones were developed. Palladium-catalysed cyclisation of bromoenediynes and cobalt-catalysed triyne cyclotrimerisation both transform acyclic precursors into 7,6,5-bisannelated arenes in a single step. Two enantioselective syntheses of the AB ring fragment common to both rubriflordilactones, with bromoene or alkyne functional groups required for the respective cyclisation methods, are described; along with the refinement of a route to the CDE diyne fragment of rubriflordilactone A. From these fully functionalised bromoenediyne and triyne substrates, both metal-catalysed cyclisation methods were successful; these strategies converged on a late-stage intermediate bearing the ABCDE ring system of rubriflordilactone A. Construction of the F ring, followed by attachment of the G ring by an intriguing oxo-carbenium ion addition reaction completed two enantioselective total syntheses of (+)-rubriflordilactone A.
Supervisor: Anderson, Edward Sponsor: Agency for Science, Technology and Research (A*STAR)
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: organic synthesis ; total synthesis ; Schisandra natural products