<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>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.</p> </abstract>