C–H Nucleophilic Substitution for the Diversity-Oriented Modification of Polycyclic Aromatic Hydrocarbons

Conventional strategies for modifying organic π-systems, such as polycyclic aromatic hydrocarbons (PAHs), rely heavily on aromatic electrophilic substitution or transition-metal-catalyzed cross-couplings. These target-oriented approaches are sometimes hampered by limitations, such as poor regioselectivity, harsh reagents, mandatory prehalogenations, and stepwise syntheses. To overcome these constraints, we herein develop an innovative C–H nucleophilic substitution strategy for the diversity-oriented functionalization of π-systems, leveraging their accessible and stable cationic radicals. This methodology stands in stark contrast to prior studies, which predominantly focused on investigating their physical properties; our work marks their application as key intermediates in organic synthesis. This novel protocol, characterized by its mild (majority take place at room temperature) and rapid (typically complete within 1 h) reaction profile, not only significantly improves the yields for functionalizing the challenging bay regions of cornerstone molecules like perylene and perylene diimide, but also enables efficient access to a wide range of previously inaccessible architectures. Furthermore, it accommodates an expansive nucleophile scope, several of which are employed for the first time in C–H substitution reactions. Mechanistic studies provide a rationale for the observed reactivity and regioselectivity. From the resulting library of novel compounds with diverse properties, we identified promising candidates for phototheranostic applications. In summary, this strategy represents a paradigm shift in the diversity-oriented editing of π-systems.