A Modular Synthesis of Substituted Cycloparaphenylenes

Herein, we report a modular synthesis providing access to substituted cycloparaphenylenes (CPPs) of different sizes. A key synthon introducing two geminal ester units was efficiently prepared by [2+2+2] cycloaddition. This building block can be conveniently converted to macrocyclic precursors controlling the ring size of the final CPP. Efficient reductive aromatization through single‐electron transfer provided the substituted nanohoops in a straightforward manner. The tBu ester substitution pattern enables a tube‐like arrangement in the solid‐state governed by van der Waals interactions that exhibits one of the tightest packings of CPPs in tube direction, thus opening new avenues in the crystal design of CPPs.