Cycloparaphenylenes (CPPs) are a remarkable class of hoop-shaped conjugated macrocycles with inimitable properties. Herein we describe a divergent synthesis of [7]CPP and [8]CPP. Furthermore we present the first crystal structure of [7]CPP. Thus, we have now established the size-selective synthesis of [n]CPP (n = 7-16) in a uniformed cyclohexane-based method.
A palladium-free, short-step synthesis of [101cycloparaphenylene ([101CPP) 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. (C) 2015 Published by Elsevier Ltd.