The cyperone route to agarofurans: stereoselective introduction of an hydroxy group at C-4

In this paper, the construction of the agarofuran tricyclic ring system bearing an hydroxy group at C-4, with the correct configuration at C-4, is described through the rearrangement of the 4,4a α-epoxy 9-benzoyloxy cyperone derivative 11, readily available from cyperone derivative 5c, under acidic conditions.