Synthesis of cyclododeciptycene quinones.

Cycloiptycenes are elusive and synthetically challenging molecules. We report the first synthesis of two substituted cyclododeciptycene tetraquinones via a sequence of intermolecular and intramolecular Diels-Alder reactions from cis,cis-heptiptycene tetraquinone 2 and substituted 7,16-dihydro-7,16-(o-benzeno)heptacenes 3. Heptiptycene tetraquinone 2 was made from triptycene bisquinone 4 and 1,4-dimethoxyanthracene in three steps, and 6,8,15,17-tetramethoxy-7,16-dihydro-7,16-(o-benzeno)heptacene (3a) was synthesized from triptycene bisquinone 4 and 1,4-dihydro-2,3-benzoxathiin-3-oxide in four steps. The structure of a cyclododeciptycene, 1a, was determined by a single-crystal X-ray analysis. The synthetic sequence is general and should allow the incorporation of various alkoxy and acetoxy substituents appended to the cycloiptycene framework.