- 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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- Mechanism and Stereochemistry of the luorination of Uracil and Cytosine Using Fluorine and Acetyl Hypofluorite
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The products of the reaction of CH3COOF and F2 with uracil and cytosine dissolved in acetic acid and water were studied by using 18F as a tracer.Apart from 5-fluorouracil (2) and the 5,5-difluoro adducts 5a and 5b, the 1H NMR spectra of the crude reaction mixture showed the presence of two geometric isomers of both 5- fluoro-6-acetoxy-5,6-dihydrouracil (3a, 4a) and 5-fluoro-6-hydroxy-5,6-dihydrouracil (3b, 4b).In the fluorination of cytosine, corresponding products were observed with the exception of the acetoxy adducts.For both reagents and for both substrates a radical-cation mechanism is proposed.The observed conversions of the acetoxy adducts of uracil are explained by an acylimine (iii) as an intermediary.
- Visser, Gerard W. M.,Boele, Saskia,Halteren, Bert W. v.,Knops, Gertrudis H. J. N.,Herscheid, Jacobus D. M.,et al.
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p. 1466 - 1471
(2007/10/02)
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