Extraction of the aerial part of the Korean plant Aruncus dioicus var. kamtschaticus enabled the isolation of the previously unknown cytotoxic (against Jurkat T cells) monoterpenoid product aruncin B (1), first reported in 2011. Spectroscopic analysis suggested a structurally unique dihydropyran core, containing an exocyclic enol ether, cross-conjugated with a carboxylic acid, together with a potentially acid-labile tertiary allylic ether. In this poster, I will present the synthesis of the Na-Salts of the Z- and E- isomers of the postulated structure of aruncin B, together with another regioisomeric isomer (ethoxy group in C3). These Na-Salts were obtained using a divergent ring-closing metathesis (RCM)-ethoxyselenation-elimination strategy. Acidification of these salts only resulted in rapid and total decomposition of the material, even using mild acidification methods. This acid unstability, together with inconsistencies in the NMR data, led us to consider significant structural revision. The synthesis of the correct structure has been achieved, and will be also presented. Optimisation of this sequence, work towards an enantioselective synthesis of the natural product and biological evaluation are in progress.

Total synthesis and structural revision of aruncin B

252nd National Meeting (2016)

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