Organic largely conjugated molecules, characterized by their delocalized π-electron systems, exhibit significant and broad application potential in fields such as materials chemistry, medicinal chemistry, and chemical biology. Functionalizing these conjugated systems to modulate their properties has become a major focus in chemical research. However, current methods for late-stage modification of extended conjugated molecules remain limited, primarily relying on conventional strategies such as electrophilic aromatic substitution and transition-metal-catalyzed coupling reactions. This review systematically summarizes recent advances in unique C-H nucleophilic substitution reactions on extended conjugated molecules, covering classical systems such as porphyrins, BODIPYs, azulene, and some other large conjugated molecules. Studies have demonstrated that by optimizing reaction conditions, selecting suitable nucleophiles, and employing directing groups, efficient functionalization of specific C-H bonds can be achieved, enabling the construction of compounds with tailored structures and functions. This review not only deepens the understanding of nucleophilic substitution mechanisms but also opens new avenues for designing π-conjugated systems with unique functionalities.

Key words: largely conjugated systems, π-electron system, nucleophilic substitutions, C-H functionalization