- Effect of the structure of 1- and 3-methyl-5-fluoropyrimidin-4-ones on H-D exchange in position 6 under conditions of base catalysis
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Hydrogen atom in position 6 of 5-fluoro-1-methylpyrimidin-4(1H)-one and its 2-methylsulfan-yl, 2-methoxy and 2-butylamino derivatives is readily replaced by deuterium in 90% methanol-d4 at ~20εC under conditions of base catalysis. The rate of H
- Kheifets,Gindin,Moskvin
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- Effect of the structure of 1- and 3-methylpyrimidin-4-ones on the rate of nucleophilic substitution of the 2-methylsylfanyl group
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Rate constants for substitution of the 2-methylsulfanyl group in 1- and 3-methyl-2-methylsulfanyl-pyrimidin-4-ones and their 5-fluoro analogs were measured in the reaction with butylamine, alkaline hydrolysis, and methanolysis. The rate of substitution in 1-methyl isomers having a zwitterionic structure is greater by a factor of ~2 than the rate of substitution in 3-methyl isomers with conjugated double bonds in the ring. The presence of a fluorine atom in position 5 accelerates nucleophilic substitution in 1-methyl isomers, while 5-fluoro-3-methyl-2-methylsulfanylpyrimidin-4-ones react at a lower rate than their 5-unsubstituted analogs. According to the NMR data, the reactions involve formation of a tetrahedral intermediate. Anchimeric effect of the methyl group on N1 hampers attack by basic reagent on the C6 atom.
- Kheifets,Gindin,Nikolova
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p. 104 - 113
(2007/10/03)
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- The photocycloaddition reactions of uridine and related compounds with 2,3-dimethyl-2-butene
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The photochemical reactions of uracil and 5-fluorouracil derivatives with simple alkenes have been investigated. Photocycloaddition of uracil or 5-fluorouracil derivatives and 2,3-dimethyl-2-butene in acetone gave an enantiomeric mixture of cross cycloadducts (4, 7) in moderate yields. Under similar conditions, diastereomers of 4-substituted 7,7,8,8-tetramethyl-cis-2,4-diazabicyclo[4.2.0]octane-3,5-dione nucleosides (14-17) were formed from uridine or 5-fluorouridine derivatives in good yields. The structures and stereochemistry of these cycloadducts of the nucleoside series were elucidated on the basis of the proton nuclear magnetic resonance spectra and X-ray crystallographic analysis.
- Ishikawa,Itoh,Takayanagi,Oshima,Kawahara,Mizuno,Ogura
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p. 1922 - 1930
(2007/10/02)
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- Application of the Benzyloxycarbonyloxymethyl Moiety to a Protective Group of 5-Fluoroacil. Selective Alkylation of Amide Nitrogen of the Uracil Ring
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Selective alkylation of 5-fluorouracil using the benzoyloxycarbonyloxymethyl moiety as a protective group of amide nitrogen of the uracil ring is described.Protection, alkylation and deprotection were carried out in high yields.
- Nagase, Toshio,Seike, Kanzo,Shiraishi, Kazuto,Yamada, Yutaka,Ozaki, Shoichiro
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p. 1381 - 1384
(2007/10/02)
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- Glorination of Pyrimidines. Part 2. Mechanistic Aspects of the Reaction of Acetyl Hypofluorite with Uracil and Cytosine Derivatives
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The reaction of acetyl hypofluorite (AcOF) with uracil, cytosine, and some N-1-substituted derivatives dissolved in either acetic acid or water has been investigated.Analysis by radio-h.p.l.c., using (18)f as a tracer, and by (1)H n.m.r. revealed that a substituent at N-1 of uracil has a remarkable effect on the stability of the intermediate 6-acetoxy-5-fluoro-5,6-dihydrouracils.In addition, it was found that these cytosine adducts rapidly deaminate in water yielding their corresponding uracil analogues.
- Visser, W. M. Gerard,Herder, E. Renella,Kanter, Frans J. J. de,Herscheid D. M. Jacobus
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p. 1203 - 1208
(2007/10/02)
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