Pateamine A is a naturally occurring metabolite extracted from the marine sponge Mycale hentscheli. It exhibits potent cytotoxicity towards cancer cell lines and has been shown to target protein translation initiation via inhibition of the function of eukaryotic initiation factor 4A proteins. We have synthesised a simplified analogue of pateamine A, consisting of the skeletal core of the natural product but with the thiazole heterocycle replaced by a triazole. The convergent design of the synthesis features a base-induced opening of a δ-valerolactone to access the Z,Edienoate moiety, Julia-Kocienski olefination and copper-catalysed azide-alkyne cycloaddition. Bioactivity testing of the simplified pateamine A analogue (3) indicated a significant reduction in cytotoxicity, compared to natural pateamine A. We propose that this reduced activity is due mainly to the substitution of the thiazole for the triazole heterocycle. This supports the hypothesis that the thiazole of pateamine A is important for binding to its biological target.

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<p>Pateamine (1) is a natural product from the marine sponge Mycale hentscheli that exhibits potent anticancer properties, and has potential as an antiviral agent, and in preventing the muscle wasting disorder cachexia. This biological activity of pateamine is due to its ability to inhibit the eukaryotic initiation factor eIF4A, which leads to the formation of stress granules, the inhibition of protein synthesis, and ultimately cell death. Unfortunately, pateamine is obtained in very small amounts from Mycale hentscheli; thus, it is necessary to synthesise pateamine and novel structural analogues in the laboratory. Previously a separate binding and scaffolding domain of pateamine was proposed, which led to the synthesis of a simplified des-methyl des- amino analogue that reduced the number of synthetic steps compared to pateamine while retaining its biological activity. This was followed by the synthesis of a simplified triazole- containing analogue 9 6 ; unfortunately, this exhibited substantially reduced bioactivity compared to pateamine, and it is therefore necessary to determine if the reduction in bioactivity was due to the replacement of the thiazole ring with a triazole ring, or due to the removal of key methyl groups of pateamine. Thus, the thiazole-containing analogue of 96 is deemed to be an important synthetic target.  In this Master’s project a highly simplified side chain-free analogue 130 was synthesised, which laid the groundwork for future synthesis of a thiazole-containing analogue of 96. The synthesis of 130 was achieved through a convergent synthesis with one commercially available and two prepared fragments. Particular attention was paid to the development of an efficient thiazole formation methodology, as well as optimising fragment synthesis and coupling reactions. Determination of the binding of analogue 130 with eIF4A using a competitive bioactivity assay in the presence of pateamine was then undertaken, which showed that either 130 does not bind to eIF4A or that it binds non-covalently and is then displaced by pateamine.</p>