Synthesis and dimerization of chloro[10]cycloparaphenylene: a directly connected cycloparaphenylene dimer.

The first synthesis and dimerization of monochlorinated [10]cycloparaphenylene (chloro[10]CPP) are described. By assembling a chlorinated 1,4-diborylbenzene unit with brominated and borylated cis-1,4-diphenylcyclohexane units by Suzuki-Miyaura coupling, a triangle-shaped chloro-containing macrocycle was synthesized. The acid-mediated "cyclohexane-to-benzene" aromatization afforded chloro[10]CPP without losing the chloro group. By the action of Ni(0) complex, chloro[10]CPP was converted to a directly connected [10]CPP dimer, which would be an ideal precursor for the "carbon nanobelt".