En Route to Furan-Fused Naphthopyrones: Formal Synthesis of the (+)-Lasionectrin and Its C12-Epimer

Despite the vast presence of the furan-fused naphthopyrone (FFN) skeleton in many bioactive natural products, such as lasionectrin, at present, a general approach to FFNs has not been developed yet. For that reason, a simple and straightforward synthetic approach consisting of a sequential procedure of a Diels-Alder reaction between 1,3-dimethoxy-benzocyclobutenol I and furan-fused-α,β-unsaturated-δ-lactones II (via an ο-quinodimethane intermediate III) followed by an oxidative aromatization of the corresponding Diels-Alder adduct IV is reported. Subsequently, the formal synthesis of the (+)-lasionectrin and its C12-epimer was achieved, the latter in only six steps.