Palladium-free synthesis of [10]cycloparaphenylene

Abstract A palladium-free, short-step synthesis of [10]cycloparaphenylene ([10]CPP) has been developed. The key macrocyclization step was performed by a nickel-mediated homocoupling of a newly designed U-shaped unit 2 . Surprisingly, the rectangular macrocycle 3 was obtained in high yield compared with previous macrocyclization reactions in CPP syntheses. X-ray crystallography as well as DFT calculation revealed unstrained structure of the macrocycle 3 .