OXIDATION OF 1,3-DIMETHYLTHYMINE WITH OXONE CATALYZED BY (4N-METHYLPYRIDINIUMYL)PORPHYRINATOMANGANESE-(III) PENTAACETATE

The reaction of 1,3-dimethylthymine 2 with KHSO5 (oxone) catalyzed by 5, 10, 15, rakis-(4N-methylpyridiniumyl)porphyrinatomanganese (III) pe ntaacetate 1 [T4MPyPMn (III) (OAc)(5)] in phosphate buffer gives 1,3-d imethyl-5-hydroxymethyluracil 3, 1,3-dimethyl-5-formyluracil 4, 1,3-di methyruracil-5-carboxylic acid 5, cis-1,3-dimethylthymine-5,6-glycol 6 and 1,3,5-trimethyl-5-hydroxybarbituric acid 8 in different yields de pending on the pH of the reaction medium. Oxidation of the S-methyl gr oup of 1,3-dimethylthymine to 1,3-dimethyl-5-hydroxymethyluracil 3, 1, 3-dimethyl-5-formyluracil 4 and the corresponding acid 5 with oxone ca talyzed by T4MPyPMn (III) (OAc)(5) may be explained by hydrogen abstra ction and recombination mechanism, whereas oxidation of 5,6-double bon d of thymine to cis-1,3-dimethylthymine-5,6-glycol 6 and 1,3,5-trimeth yl-5-hydroxybarbituric acid 8 may be explained either by electron tran sfer followed by oxygen atom transfer or by the involvement of hydroxy radicals.