Effect of substituents at 1,4-positions of polycyclic aromatic compounds and preparation of 2,3-difunctionalized pentacenes and naphthacenes

Article abstract of DOI:10.3987/COM-07-S(U)28

Effects of substituents at 1,4-positions of polycyclic aromatic compounds were investigated in the case of reduction of 2,3-bis(alkoxycarbonyl)arenes with the LiAlH₄/AlCI₃ system. 2,3-Bis(alkoxycarbonyl)dihydronaphthacenes and dihydropentacenes 1 were treated with a mixture of LiAlH₄ and AlCl₃. The products were dependent on the substituents at 1,4-positions. Similar type of influence of the substituents at 1,4-positions was observed in the oxidation of diols 2 to dialdehydes 4. Without substituents at 1,4-positions, dialdehydes 4 were conveniently obtained. However, with substituents at 1,4-positions, dialdehydes 4 were not obtained. Instead,1,3-dihydroisobenzofuran-l,3-diol or 1,3-dihydroisobenzofuran-l-ol derivatives 5, 6 were obtained in good yields. Preparation of pentacene imides and pentacene carboxylic acid anhydride was also reported.