36799-17-4Relevant articles and documents
Unusual Competition between Nitrogen and Carbon Methylation of Nucleosides by Methyl Radical in Various Aqueous Media
Zady, Mona F.,Wong, John L.
, p. 2373 - 2377 (1980)
Five nucleosides, adenosine, guanosine, cytidine, thymidine, and uridine, were allowed to react with methyl radical produced by homolysis of tert-butyl peracetate.The extent and sites of reaction exhibited a marked dependence on the pH of the aqueous medium.In the region of pH 1-4, the major products arose from C-methylation of the nucleosides.The purines were more reactive than the pyrimidines under these acidic conditions.In the pH range of 4-10, the extent of C-methylation decreased steadily with increasing pH while N-methylated products arising from methylationof the ring nitrogen and/or exocyclic amino groups predominated.In this pH range, the pyrimidine nucleosides were the more reactive.Beyond pH 10, the extent of methylation diminished in all cases as decomposition of tert-butyl peracetate became rampant.The C-methylation occurs by way of an addition mechanism while N-methylation appears to proceed via radical abstraction of a hydrogen from the N-H group followed by combination with methyl radical.The implications of these reactivity and methylation patterns in radical carcinogenesis are discussed.
