Yasutomo Segawa, Petr Šenel, Sanae Matsuura, Haruka Omachi, and Kenichiro Itami

Chem. Lett. 2011, 40, 423–425. DOI: 10.1246/cl.2011.423 Selected as “Editor’s Choice”

Nickel-mediated synthesis of [9]cycloparaphenylene ([9]CPP) is described. L-shaped diphenylcyclohexane monomers underwent cyclotrimerization under the influence of Ni(cod)2/bipy. X-ray crystal structure analysis and VT NMR analysis of the thus-formed cyclic trimer confirmed its triangle structure and interesting cyclohexane-flipping behavior in solution. Cyclic trimer was converted to [9]CPP by acid-mediated aromatization. The first X-ray crystal structure of [9]CPP is also mentioned.