Accessing extended and partially fused hexabenzocoronenes using a benzannulation-cyclodehydrogenation approach

A rapid and efficient approach to prepare extended or partially fused hexabenzocoronene derivatives is described. The method is based on the sequential benzannulation and cyclodehydrogenation (Scholl oxidation) of simple diaryl alkynes. The benzannulation reaction proceeds efficiently on highly congested substrates and with complete regioselectivity. Scholl oxidation of the resulting oligo(arylene)s proceeds without rearrangements and provides either fully fused or specific partially fused polycyclic aromatic hydrocarbon products. The partially fused derivatives are a new class of contorted aromatic systems with high solubility, enhanced visible absorption, and reversible redox processes. The efficiency and specificity of the benzannulation and oxidation reactions are promising for accessing new classes of organic semiconductors and carbon nanostructures.