Selective synthesis of [7]- and [8]cycloparaphenylenes.

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.