A diastereoselective route to the 5,7,5-tricyclic core of the guianolides is presented. This route relies on Cope rearrangement of a divinylcyclopropane prepared by alkenyl Grignard addition to a (pentadienyl)iron(+1) cation, followed by oxidative decomplexation. An additional key reaction involves oxidative rearrangement of a 3,4-epoxy-1,7-diol to generate a γ-lactone. The relative stereochemistry of this product was established by X-ray crystallography.
Gone, Jayapal Reddy; Wallock, Nathaniel J; Lindeman, Sergey; and Donaldson, William, "Synthetic studies directed toward guianolides: an organoiron route to the 5,7,5 tricyclic ring system" (2009). Chemistry Faculty Research and Publications. 44.
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