Bromination of cytosine derivatives

Haloperoxidase-catalyzed halogenation of nitrogen-containing aromatic heterocycles represented by nucleic bases

“…Scheme I Substitutions of hydrogen at the 5-position of uracil and cytosine at the 4-position of pyrazole by halogen are likely, because of the general resonance. Bromination of cytosine and uracil by bromine in an aqueous solution was examined in detail by Taguchi and Wang (1979) and Tee and Berks (1980), respectively. The first step in the bromination reaction is the formation of unstable bromohydrin derivatives, which are subsequently converted to 5-bromocytosine or 5-bromouracil derivatives.…”

New Insights into the Structure and Reactivity of Uracil Derivatives in Different Solvents—A Computational Study

“…We have extensive experience with the kinetics and thermodynamic studies of the bromination reactions of organic molecules such as ethene, propene, isobutene, flouroethene, chloroethene, ( E )-1,2-difluoroethene, ( E )-1,2-dichloroethene, and adamantylideneadamantane. − Note that no computational studies have been reported for the potential energy surface for the bromination of cytosine, 1-methyl cytosine, and cytidine. Taguchi et al have shown that the reaction of cytosine and 1-methyl cytosine with Br 2 in aqueous and methanolic solutions produces multiple intermediates via several intermediate steps, ultimately producing the final product of 5-bromocytosine and 5-bromo-1-methyl cytosine, respectively. In this study, we investigated a pathway that leads to the formation of trans -dibromo adduct via a one-step pathway, which would provide important insights as to how the uracil derivatives in different solvents may behave during a reaction.…”

Synthesis and Reaction of Pyrimidine Nucleosides

“…4-Methylpyrimidin-2-one riboside(172) is converted to the 4aldoxime derivative (173) on treatment of(172) with nitrous acid.t 371 ) Compound(173) was then converted to the 4-cyano derivative(174) and subsequently to uridine. The methyl group of 6-methyluridine(175) was oxidized to the 6-formyl derivative (176) by treatment with selenium dioxide. This aldehyde underwent the Wittig reaction with ethoxycarbonylmethylenetriphenylphosphorane to give trans-3-( uridinyl )acrylic acid ester(177) (357).…”