Naphthoquinone (14) reacted with the o-quinodimethanes, which were generated from the benzocyclobutenes (9, 10 and 11), o-xylyl dibromide (12) and N-aminodihydroisoindole (13), to give the naphthacene-5, 12-quinones (15, 16, 17 and 18), respectively.