“…The structure of this product was determined to be the exo‐exo adduct by X‐ray analysis and this, in fact, allowed the unambiguous characterization of the aforementioned benzo and naphtho analogues 142 and 176 . Deoxygenation and aromatization by treatment of 219 with HCl in EtOH afforded phenanthro[9,10‐ a ]perylene 220 in very good yield (Scheme ) 71. Surprisingly, although exposure of polyarenes 143 and 177 in solution to ambient air and sunlight caused decomposition by fast photooxidation, compound 220 under similar conditions underwent a rapid and clean photocyclodehydrogenation to afford dibenzo[ cd , n ]naphtho[3,2,1,8‐ pqra ]perylene ( 221 ) quantitatively.…”