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.

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All Strychnos and Aspidosperma alkaloids possess a core pyrrolo[2,3-d]carbazole ABCE tetracycle. In order to develop an efficient and divergent methodology for the synthesis of Strychnos alkaloids, a streamlined synthetic sequence to the ABCE tetracycle has been developed. It features a Mitsunobu activation of an N-hydroxyethyl gramine intermediate and subsequent intramolecular aza-Baylis-Hillman reaction. This method was first applied in the total synthesis of (±)-alstolucine B. Additional key steps in the synthesis included (1) chemoselective intermolecular and intramolecular Michael additions and (2) a Swern indoline oxidation. The second application of this method was in the first total synthesis of (-)-melotenine A, a novel rearranged Aspidosperma alkaloid with potent biological activity. Additional key steps in the synthesis included (1) a Piers annulation of a vinyl iodide and a methyl ketone to prepare the D ring and (2) a site-selective intermolecular vinylogous aldol reaction / Chemistry