Complex sentence: The dienylketene then undergoes a six-electron electrocyclization to give a hexadienone intermiediate which rapidly tautomerizes to yield a highly substituted phenol or naphthol structures.
Split into simpler sentences: The dienylketene then undergoes a six-electron electrocyclization to give a hexadienone. This final intermediate tautomerizes to yield a highly substituted phenol or naphthol structures.