A new octaphenyl[4.4]triphenylparacyclophanediene was readily synthesized in six steps from p-xylene via the installment of bromine atoms, replacement with a vinyl group, carbonylative coupling, intermolecular followed by intramolecular double Grubbs olefin metathesis, Knoevenagel condensation, and Diels-Alder cycloaddition. The belt-shaped structure and trans-stereochemistry of the alkene moieties of the octaphenyl[4.4]triphenylparacyclophane and a synthetic intermediate, 2,21-dioxo-11,30-diene[3.4.3.4]paracyclophane, were determined by X-ray crystallography. The synthetic methodology leading to octaphenyl[4.4]triphenylparacyclophane is applicable for the synthesis of substituted triphenylparacyclophanes and possibly their corresponding bis-hexabenzocoronenylparacyclophanes via a Scholl-Mullen oxidative aryl-aryl coupling reaction.
Keywords: Diels–Alder cycloaddition; Grubbs olefin metathesis; Knoevenagel condensation; belt-shaped molecules; carbonylative coupling; cyclophanes; octaphenyl[4.4]-triphenylparacyclophane.