How Chemical Environment Activates Anthralin and Molecular Oxygen for Direct Reaction.

The role of the chemical environment in promoting anthralin/O2 reactions was discovered using neat solvents to model the amino acids of a cofactor-independent oxygenase. Experimental and computational results highlight the importance of the substrate-enolate, which is accessed via energetically small, escalating steps in which the ground-state keto-isomer is tautomerized to an enol and then ionized by solvent. The resulting ion-pair is poised for spontaneous electron transfer to O2. Similar activation may be exploited in biological/nonbiological oxidations involving O2.