Toward the Synthesis of Rimarikiamide A

Rimarikiamide A is a linear diterpenoid marine natural product featuring an unusual taurine structural moiety. Rimarikiamide A was isolated from the sea sponge Latrunculia brevis found in the Rimariki Islands in northern New Zealand, and was shown to elicit low μM cytotoxicity against HL-60 cells. Unfortunately, only 400 μg of rimarikiamide A was isolated from 700 g of sea sponge, making the characterisation of the two chiral centres impossible by spectroscopic means. To explore the full potential of rimarikiamide A as a therapeutic agent, the molecule must be synthesised in a stereoselective manner or from a starting material of known stereochemistry, fully characterised, and tested for biological activity. A Barbier coupling of two terpene units is required early in the proposed synthesis of Rimarikiamide A, and previous attempts have failed to generate the desired linear product. In this work, the suitability of a titanium-mediated Barbier coupling was investigated, and proved successful for the generation of the desired linear product.