Total Synthesis of (+)-Strongylin A, a Rearranged Sesquiterpenoid Hydroquinone from a Marine Sponge

A biologically attractive and structurally unique marine natural product, (+)-strongylin A (1), was synthesized for the first time by starting from a known trans-decalone derivative (19% overall yield in 11 steps). The synthetic method involved the following key steps: (i) stereocontrolled hydrogenation of an exo-olefinic decalin to install the C8 stereogenic centre present in the required decalin segment; (ii) coupling of the decalin segment with an aromatic moiety to assemble the desired carbon skeleton; and (iii) sequential BF3Et2O-induced dehydroxylation/rearrangement/cyclization of a decalin tertiary alcohol to directly produce target compound 1. This total synthesis has established the absolute configuration of the natural product.