Synthesis and properties of butterfly-shaped expanded naphthofuran derivatives.

The construction of dinaphtho[2,1-b;2',3'-d]furan-6-ol was developed via a dehydration reaction involving two molecules of 2,3-dihydroxynaphthalene in the presence of a strong acid. Starting from the dinaphthofuran, a variety of butterfly shaped derivatives were synthesized. The optical properties of these compounds were investigated with special attention to the dihedral angle formed by adjacent dinaphthofuran rings and/or the sizes of the fused aromatic rings.