Gold(I)-catalyzed cycloisomerization of β,β-diaryl-o-(alkynyl)-
styrenes at 80 °C selectively yields dihydroindeno[2,1-a]indenes in a
transformation that encompasses a formal [4 + 1] cycloaddition and takes
place through a cascade 5-endo-cyclization−diene activation−iso-Nazarov
cyclization. In addition, by performing the reaction at 0 °C, the same
substrates exclusively give rise to benzofulvene derivatives, which have also been shown to be intermediates in the formation of
the tetracyclics.
