Synthesis and structure of a polyphenylene macrocycle related to "cubic graphite"

[structure: see text] Palladium-catalyzed coupling of 1,2-bis(4-bromophenyl)-3,4,5,6-tetraphenylbenzene and the corresponding hexaphenylbenzene bis(boronic acid) gave a mixture of linear and cyclic oligomers of hexaphenylbenzene. An X-ray crystal structure of the tetrameric oligomer showed it to be the polyphenylene macrocycle 4 (C(168)H(112)). The roughly D(2) symmetric macrocycle contains a large central cavity, and it is one of the channel substructures of "phenylogous cubic graphite".