Elaboration of Diaryl Ketones into Naphthalenes Fused on Two or Four Sides: A Naphthoannulation Procedure

Transition metal-catalyzed double ring closures of 1,1-diaryl-2,2-diethynylethylenes yield polycyclic
aromatic hydrocarbons and heterocycles that contain a newly formed naphthalene ring system embedded
in a larger polycyclic network. The diynes required for this procedure are readily synthesized from diaryl
ketones by the Corey−Fuchs olefination and subsequent Sonogashira coupling with trimethylsilylacetylene
followed by desilylation. This procedure provides easy access to new compounds such as 3,11-di-tert-butyl[4]helicene and 1,8,9-perinaphthothioxanthene. Double naphthoannulation of 9,10-anthraquinone by
this procedure closes four new benzene rings in a single operation to give coronene, although the yield in
this case is presently low.