2140-69-4Relevant articles and documents
Noncanonical RNA Nucleosides as Molecular Fossils of an Early Earth—Generation by Prebiotic Methylations and Carbamoylations
Schneider, Christina,Becker, Sidney,Okamura, Hidenori,Crisp, Antony,Amatov, Tynchtyk,Stadlmeier, Michael,Carell, Thomas
supporting information, p. 5943 - 5946 (2018/04/30)
The RNA-world hypothesis assumes that life on Earth started with small RNA molecules that catalyzed their own formation. Vital to this hypothesis is the need for prebiotic routes towards RNA. Contemporary RNA, however, is not only constructed from the four canonical nucleobases (A, C, G, and U), it also contains many chemically modified (noncanonical) bases. A still open question is whether these noncanonical bases were formed in parallel to the canonical bases (chemical origin) or later, when life demanded higher functional diversity (biological origin). Here we show that isocyanates in combination with sodium nitrite establish methylating and carbamoylating reactivity compatible with early Earth conditions. These reactions lead to the formation of methylated and amino acid modified nucleosides that are still extant. Our data provide a plausible scenario for the chemical origin of certain noncanonical bases, which suggests that they are fossils of an early Earth.
Micellar Methylating Agents: (Long-chain-alkyl)dimethylsulphonium Iodides
Yamauchi, Kiyoshi,Hisanaga, Yorisato,Kinoshita, Masayoshi
, p. 1941 - 1942 (2007/10/02)
Dodecyl-, hexadecyl-, and octadecyl-dimethylsulphonium iodide were found to methylate efficiently various nucleosides, hydroxy aromatic compounds, and thiols at pH 8-11 and 50 - 70 deg C.The optimum conditions and the mechanism of the reaction are discussed briefly in relation to the micellar reaction characteristics.
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 (2007/10/02)
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.
