When anthracene is added to the reaction of chlorobenzene with concentrated NaOH at 350 C, an interesting

Question:

When anthracene is added to the reaction of chlorobenzene with concentrated NaOH at 350 °C, an interesting Diels-Alder adduct of formula C20H14 results. The proton NMR spectrum of the product shows a singlet of area 2 around ( 3 and a broad singlet of area 12 around ( 3 Propose a structure for the product, and explain why one of the aromatic rings of anthracene reacted as a diene.