Novel naphthalene diimides as activatable precursors of bisalkylating agents, by reduction and base catalysis

Mild activation of water-soluble naphthalene diimides (NDIs) as bisalkylating agents has been achieved by base catalysis and by chemical and electrochemical reductions. NDI activation by a single electron reduction represents a novelty in the field of activatable electrophiles. Under mild reduction, induced by S2O4(2-) in aqueous solution, the resulting NDI radical anion (NDI*-) undergoes a monomolecular fragmentation to yield a new transient species, where the NDI radical anion is tethered to a quinone methide moiety. The latter still retains electrophilic properties, reacting with amines, thiols, and ethyl vinyl ether. Owing to the NDI recognition properties, these results represent the first step toward selective and bioactivatable cross-linking agents.