Catalytic [2 + 2 + 2] cycloaddition of benzothiophene dioxides with α,ω-diynes for the synthesis of condensed polycyclic compounds

A Rh-catalyzed intermolecular [2 + 2 + 2] cycloaddition of the 2,3-double bond of benzothiophene dioxides with α,ω-diynes gave sulfone-containing cycloadducts in high yields. This is the first example of a catalytic [2 + 2 + 2] cycloaddition that uses the 2,3-double bond of a heterole as an ene moiety. The consecutive reaction of benzodithiophene tetraoxide with 2,3-naphthylene-tethered 1,7-diyne gave an 11-ring condensed polycyclic compound in one pot.