Figure 1.

Organic CO donors capable of CO release under near-physiological conditions without light irradiation. (A) (I) Intermolecular D–A reaction-based CO prodrug; (II) intramolecular D–A reaction-based CO prodrug; (III) elimination-based CO prodrug (LG: leaving group, EWG electro-withdrawing group); (B) oxalic acid-based CO prodrugs using artificial sweeteners as “carriers”; (C) elimination-based CO donors reported by the Larson group; and (D) tautomerization-oxidation-cheletropic reaction-based CO prodrugs described in this work.