The synthesis of novel polycyclic heterocyclic ring systems via photocyclization. 13 . Dibenzo‐[ f,h ]phenanthro[9′,10′:4,5]thieno[2,3‐ c ]quinoline

The synthesis of a previously unknown polycyclic heterocyclic ring system, dibenzo[ f,h ]phenanthro‐[9′,10′:4,5]thieno[2,3‐ c ]quinoline ( 4 ), was accomplished via photocyclization of the appropriate amide followed by chlorination. Substitution of the chlorine atom with hydrazine followed by removal of the hydrazine moiety with 10% copper sulfate solution afforded the parent ring system 4 . The unequivocal assignment of its highly congested 1 H and 13 C spectra was accomplished by utilizing two‐dimensional nmr methods.