Base‐Catalyzed Schmittel Cycloisomerization of o‐Phenylenediyne‐Linked Bis(arenol)s to Indeno[1,2‐c]chromenes.

The present cycloisomerization of (I) to (II) proceeds under transition metal-free basic conditions involving a domino sequence of the prototropic rearrangement into a putative vinylidene o-quinone methide intermediate and subsequent formal inverse-electron-demand hetero Diels—Alder cycloaddition.