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 <i>bay</i> 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.