Products of Thymine Oxygenation by a Non-heme Oxygenation Model, FeII(MeCN)62+–Ac2O–H2O2, and the Transition State Model between Oxoiron and Thymine

Oxidative thymine damage was investigated using a new non-heme oxygenation model, Fe(MeCN)62+–H2O2–Ac2O, based on high-spin Fe(MeCN)62+ in a non-aqueous solution, Ac2O–MeCN. Thymine and 1,3-dimethylthymine oxidized by the system gave the corresponding trans-thymine glycol derivatives in good yield. Thymineglycol is equivalent to an oxidative product as a measure of oxidative DNA damage in living cells. It is suggested that the activation of Fe(MeCN)62+–H2O2–Ac2O in Ac2O–MeCN forms the oxoiron O=FeIV(AcO)(MeCN)4+ as an active species via a hetelolytic two-electron mechanism, not a Haber–Weiss–Fenton-type reaction with a one-electron process by treatment with a radical scavenger. In addition, we also demonstrated the transition state (TS) for the interaction between thymine and O=FeIV(AcO)(MeCN)4+ in the triplet spin (spin multiplicity; M=3). This model of oxidative thymine damage may provide new insight into the oxidative mechanism of thymine glycol production in non-aqueous reactions of thymine.