Targeting cancer cell mitochondria with a multivalent source of singlet oxygen

Naphthalene, anthracene and pyridone endoperoxides are known to thermally release singlet oxygen. However, in the cycloreversion reaction, singlet oxygen is produced stoichiometrically; therefore, multiple singlet oxygen releasing modules are expected to be very useful in inducing apoptosis of cancer cells. Herein, we present a potential therapeutic agent presenting three‐pyridone endoperoxide modules and a mitochondria targeting group. Compared to previously reported pyridone‐based monofunctional endoperoxides, the triple endoperoxide is highly effective as evidenced by assays and fluorescence microscopy.