Synthesis of Dibenzopyrenes and Pyrenes via Photolytic Sulfur Extrusion and Intramolecular Cross-Coupling Reactions of Dithia[3.3](1,3)naphthalenophanes and Dithia[3.3]metacyclophanes

The syntheses of several substituted dithia[3.3]metacyclophanes and dithia[3.3](1,3)naphthalenophanes are reported and their photolyses in triethyl or trimethyl phosphite are described. Under these conditions, the corresponding tetrahydrodibenzopyrenes and tetrahydropyrenes are produced in a one-pot procedure when the precursor dithianaphthalenophanes and dithiacyclophanes possess at least one intraannular methoxyl group. A mechanism with supporting evidence is proposed to account for these results. Structural determinations of the four isomeric 11,22-dimethoxy-2,13-dithia[3.3](1,3)naphthalenophanes by NMR and X-ray single-crystal diffraction studies are also described. The syntheses of the novel anti - transoid - and anti - cisoid -[2.2](1,3)naphthalenophanes are also described.