- Electrophilic ipso-substitution in uracil derivatives
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Treatment of 5-iodo-1,3,6-trimethyluracil with 50% H2SO 4 gives 1,3,6-trimethyluracil; with 5-bromo-1,3,6-trimethyluracil, a mixture of 1,3,6-trimethyluracil and 6-bromomethyl-1,3-dimethyluracil is obtained. 5-Chloro-1,3,6-trimethyluracil remains inert under these conditions. According to the DFT modeling of the reactions of 5-halo-1,3,6-trimethyluracils, a nucleophilic agent can abstract either Hal+ or the methyl proton from the carbocation formed by protonation of the starting halouracil at position 5, which accounts for the formation of two products from the 5-bromo derivative. Under similar conditions, 6-methyluracil dibromohydrin yields N-bromo-5-bromo-6-hydroxymethyluracil. Bromination or chlorination of 5-hydroxymethyl- or 5-formyl-6-methyluracils follows the ipso-substitution scheme leading to 6-methyluracil 5-halo- and 5,5-dihalohydrins.
- Chernikova,Khursan,Spirikhin,Yunusov
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p. 2445 - 2453
(2014/11/07)
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- A remarkably simple one-step procedure for the preparation of α-bromo-α,β-unsaturated carbonyl compounds
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An easy and convenient one-step procedure for the conversion of α,β-unsaturated carbonyl compounds into their corresponding bromo-enones using NBS-Et3N·3HBr in the presence of potassium carbonate in dichloromethane at 0°C to room temperature under very mild conditions in high yields and significantly shorter times, is reported. Georg Thieme Verlag Stuttgart.
- Jyothi, Divya,Hariprasad
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experimental part
p. 2309 - 2311
(2009/12/08)
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- A facile reduction of uracil derivatives by 1,3-propanedithiol
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The in situ 1,3-propanedithiol to 1,2-dithiolane oxidation causes reductive debromination and decyanation of 5-bromo-6-bromo-ethyl-1,3-dimethyluracil and 6-cyano-1,3-dimethyluracil, respectively.But, 1-propanethiol and 1,2-ethanedithiol give the expected substitution products
- Kumar, Subodh,Chimni, Swapandeep Singh
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p. 179 - 181
(2007/10/02)
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- THE SYNTHESIS OF 5-BROMO-1,3-DIMETHYLURACIL AND ITS 6-ALKYL DERIVATIVES
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Bromination of 1,3-dimethyluracil and 6-alkyl-1,3-dimethyluracils with N-bromosuccinimide leads to the corresponding 5-bromo substituted uracils in high yields.
- Celewich, Lech,Koroniak, Henryk
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p. 1001 - 1006
(2007/10/02)
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