A small and strained macrocycle containing a 2,2’-alkyne-linked meta-quaterphenyl was discovered to undergo an internal cyclization reaction to form an extended polycyclic aromatic hydrocarbon (PAH). The reaction occurs in solid- and solution-states at elevated temperatures (&gt;220 C) and appears to proceed via a [4+2]-cycloaddition mechanism in which the alkyne reacts with the diene-like portion of the adjacent biphenyl unit, followed by a loss of H<sub>2</sub>. Synthesis of electron-donating and electron-withdrawing derivatives is ongoing, and kinetics experiments are underway and will be presented.

Heat-mediated cyclization of a constrained quaterphenylene ethynylene may proceed through a [4+2]-cycloaddition

ACS Spring 2022

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