Synthesis of Diiodinated All-Carbon 3,3'-Diphenyl-1,1'-spirobiindene Derivatives via Cascade Enyne Cyclization and Electrophilic Aromatic Substitution.

A synthetic method for the construction of diiodinated all-carbon spirobiindene derivatives has been developed from the reaction of propargyl alcohol-tethered alkylidenecyclopropanes with iodine. The reaction proceeded through an iodination-initiated cascade intramolecular enyne cyclization and electrophilic aromatic substitution reaction process in 1,2-dichloroethane upon heating, giving desired spirocyclic products in moderate to excellent yields. Further transformation of the obtained products has also been presented.