Syntheses and Structures of Functionalized [9]Cyclo­para­phenylenes as Carbon Nanohoops Bearing Carbo­methoxy and N‑Phenyl­phthalimido Groups

Functionalized [9]­cyclo­para­phenylenes ([9]­CPPs) bearing nine aromatic units in the macrocyclic structures were synthesized. The macrocyclic structures were substituted with carbomethoxy or N-phenyl­phthalimido groups. The Diels–Alder reaction of (E,E)-1,4-bis­(4-bromophenyl)-1,3-butadiene or a related diene with dimethyl acetylene­dicarboxylate followed by the nickel-mediated homocoupling reactions and oxidative aromatization produced the functionalized [9]­CPPs. Treatment of a resultant [9]­CPP with aniline or 1,4-diamino­benzene gave the corresponding N-phenyl­phthalimides. The X-ray structure of a [9]­CPP bearing six carbomethoxy groups was obtained.