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1.
I. B. Chernikova S. L. Khursan L. V. Spirikhin M. S. Yunusov 《Russian Chemical Bulletin》2013,62(11):2445-2453
Treatment of 5-iodo-1,3,6-trimethyluracil with 50% H2SO4 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. 相似文献
2.
Wojciech Zielenkiewicz Anna Zielenkiewicz Jean-Pierre E. Grolier Alain H. Roux Geneviève Roux-Desgranges 《Journal of solution chemistry》1992,21(1):1-13
Densities and apparent molar heat capacities of some alkylated derivatives of uracil and adenine: 1-methyluracil, 1,3-dimethyluracil, 1,3-diethylthymine, 5,6-trimethylene-1,3-dimethyluracil, 5,6-tetramethylene-1,3-dimethyluracil, 5,6-pentamethylene-1,3-dimethyluracil, 2,9-dimethyladenine, 2-ethyl-9-methyladenine, 2-propyl-9-methyladenine, 8-ethyl-9-methyladenine, 6,8,9-trimethyladenine and 8-ethyl-6,9-dimethyladenine were determined using flow calorimetry and flow densimetry at 25°C. It was found that the partial molar volumes and heat capacities correlate linearly with the number of substituted methylene groups-CH
2
-as well as to the number of hydrogen atoms, n
H
, belonging to the skeleton of the molecule. In the case of alkylated uracils a difference was observed in the values at infinite dilution V
2
o
and C
p2
o
, depending on the substitution of alkyl and cyclooligomethylene groups. 相似文献
3.
The gas phase acidities of a series of uracil derivatives (1-methyluracil, 3-methyluracil, 6-methyluracil, 5,6-dimethyluracil, and 1,3-dimethyluracil) have been bracketed to provide an understanding of the intrinsic reactivity of uracil. The experiments indicate that in the gas phase, uracil has four sites more acidic than water. Among the uracil analogs, the N1-H sites have deltaH(acid) values of 331-333 kcal mol(-1); the acidity of the N3 sites fall between 347-352 kcal mol(-1). The vinylic C6 in 1-methyluracil and 3-methyluracil brackets to 363 kcal mol(-1), and 369 kcal mol(-1) in 1,3-dimethyluracil; the C5 of 1,3-dimethyluracil brackets to 384 kcal mol(-1). Calculations conducted at B3LYP/6-31+G* are in agreement with the experimental values. The bracketing of several of these sites involved utilization of an FTMS protocol to measure the less acidic site in a molecule that has more than one acidic site, establishing the generality of this method. In molecules with multiple acidic sites, only the two most acidic sites were bracketable, which is attributable to a kinetic effect. The measured acidities are in direct contrast to in solution, where the two most acidic sites of uracil (N1 and N3) are indifferentiable. The vinylic C6 site is also particularly acidic, compared to acrolein and pyridine. The biological implications of these results, particularly with respect to enzymes for which uracil is a substrate, are discussed. 相似文献
4.
Condensation of aromatic (heteroaromatic) aldehydes with 1,3-dicarbonyl compounds under the 1-butyl-3-methylimidazolium tetrafluoroborate
([Bmim][BF4]) ionic liquid-piperidinium acetate catalytic system (0.2 equiv. of each component) in the absence of a solvent affords,
depending on the structures of the reagents, 2-arylidene derivatives of methyl acetoacetate and acetylacetone, diethyl 2,4-bis(trifluoroacetyl)-3-phenylpentanedioate,
or dimethyl 2-aryl-4-hydroxy-6-oxocyclohexane-1,3-dicarboxylates. The reactions of the resulting 2-arylidene derivatives with
O-methylisourea in the [Bmim][BF4] ionic liquid produced methyl 2-methoxy-4-methyl-6-aryldihydropyrimidine-5-carboxylates and 1-(2-methoxy-4-methyl-6-phenyldihydropyrimidin-5-yl)ethanone
(mixtures of 3,6- and 1,6-dihydro isomers), which were transformed into the corresponding 3,4-dihydropyrimidin-2(1H)-one derivatives.
Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1199–1204, May, 2005. 相似文献
5.
Compounds consisting of two or three uracil fragments were synthesized by reaction of methyl-substituted uracil sodium salts with 1-(6-bromohexyl)-3,6-dimethyluracil or 1,6-dibromohexane. Treatment of these compounds with paraformaldehyde gave the corresponding pyrimidinophanes and acyclic compounds in which the uracil fragments are linked through methylene bridges. Uracil derivatives having no substituent on N3 were synthesized by reactions of silylated uracils with 1,3-bis(6-bromohexyl)uracil or 4,4′-(6-bromohexyloxy)diphenylmethane. The acyclic compound was converted into pyrimidinophane containing uracil fragments with N3H groups. A trinucleotide analog including uracil and two adenine fragments was synthesized from 1,3-bis(6-bromohexyl)uracil. 相似文献
6.
The reaction of 4-chloro-2-ethylthio-6-methylpyrimidine with 30% H2O2 in ethanol with heating forms 5-chloro-6-methyluracil instead of the expected 4-chloro-2-hydroxy-6-methylpyrimidine. Under similar conditions but in the presence of HC1, 6-methyluracil and 2-ethylthio-4-hydroxy-6-methylpyrimidine are also converted into 5-chloro-6-methyluracil.For part IV, see [10]. 相似文献
7.
W. Zielenkiewicz A. Zielenkiewicz K. L. Wierzchowski 《Journal of solution chemistry》1993,22(11):975-981
Enthalpies of solution in water H
sol
o
and enthalpies of sublimation H
sub
o
were determined for a number of crystalline derivatives of uracil: 1,6-dimethyluracil (m
2
1,6
Ura), 1,3,6-trimethyluracil (m
3
1,3,6
Ura), 6-ethyl-1,3-dimethyluracil (e6m
2
1,3
Ura), 6-propyl-1,3-dimethyluracil (pr6m
2
1,3
Ura) and 6-butyl-1,3-dimethyluracil (but6m
2
1,3
Ura). Standard enthalpies of hydration H
hydr
o
and standard enthalpies of interaction H
int
o
of the solutes with their hydration shells were calculated. The data obtained show that dependence of H
int
o
on the number of-CH2- groups of n-alkyl chain added upon substitution of diketopyrimidine ring is nonlinear. This finding is discussed in connection with results of X-ray diffraction structure determinations for the crystalline compounds. 相似文献
8.
V. P. Krivonogov V. A. Myshkin G. G. Kozlova Yu. N. Chernyshenko A. I. Savlukov V. V. Plechev R. B. Ibatullina I. B. Abdrakhmanov L. V. Spirikhin 《Russian Journal of Organic Chemistry》2006,42(11):1711-1714
Alkylation of 6-methyluracil, 5-fluorouracil, uracil-5-ammonium sulfate, 5-hydroxyuracil, 5-hydroxy-6-methyluracil, 3,6-dimethyl-5-hydroxyuracil, and 1,3,6-trimethyl-5-hydroxyuracil with ethylene chlorohydrin in water-alcohol medium in the presence of KOH was investigated. 相似文献
9.
Isao Saito Satoru Ito Hiroshi Sugiyama Munetaka Akita Teruo Matsuura 《Tetrahedron letters》1979,20(42):4065-4066
Photolysis of 1,3,7-trimethyl-8-azaxanthine in the presence of primary and secondary alkylamines gave 6-alkylamino-5-methylamino-1,3-dimethyluracils , whereas irradiation of in methanol yielded 5-hydroxy-6-methoxy-1,3-dimethyluracil . 相似文献
10.
The reduction of 1-methyl-, 3-methyl- and 1,3-dimethyl-5-nitrouracil (Ia-c) to the corresponding 5-aminouracils (IIa-c) is described. Diazotization of 5-amino-1-methyluracil (IIa) and 5-amino-1,3-dimethyluracil (IIc) gave 5-diazouracils which were characterized as thermally stable C6 covalent hydrates (III and XIII). Diazotization of 5-amino-3-methyluracil (IIb) gave anhydro 5-diazo-3-methyluracil (X) which underwent covalent methanolation and thermally reversible covalent hydration. Treatment of III and XIII with hot methanol resulted in solvent exchange of the C6 hydroxyl groups by a mechanism which may involve initial formation of diazoethers. Treatment of the methanolates (IV, XI and XIV) with dimethylamine resulted in coupling at the diazo group with a concomitant expulsion of the C6 methoxyl groups to give 5-(3,3-dimethyl-1-triazeno)uracils (XVa-c). 相似文献
11.
Melting of a mixture of 5-substituted 2,4-dimethyl-1,6-dihydropyrimidin-6-ones with cinnamic aldehyde, 1-methylindoline-2,3-dione and 6-methoxy-2-chloroquinoline-3-carbaldehyde in the presence of ZnCl2 led to the formation of substituted pyrimidines with conjugated bonds in the position 2. The structure of synthesized compounds as 2-isomers was confirmed by 2D 1H NMR NOESY data. 相似文献
12.
13.
V. N. Yuskovets B. A. Ivin E. N. Kirillova 《Russian Journal of General Chemistry》2007,77(12):2150-2161
Readily accessible 5-acetyl-4-hydroxy-3,6-dihydro-2H-1,3-thiazine-2,6-dione reacts with substituted hydrazines and carboxylic acid hydrazides under mild conditions to give the corresponding hydrazones. Under severe conditions (heating in boiling dimethylformamide) the reaction is accompanied by extrusion of COS with formation of substituted 1-amino-6-methyluracils. Reactions of 5-acetyl-4-hydroxy-3,6-dihydro-2H-1,3-thiazine-2,6-dione with monosubstituted alkyl-and arylhydrazines take different pathways, depending on the conditions. Heating of equimolar mixtures of the reactants in ethanol or propan-1-ol leads to the formation of 2-substituted 5-methyl-3-oxo-2,3-dihydro-1H-pyrazole-4-carboxamides rather than 1-amino-6-methyluracil derivatives. 相似文献
14.
Abstract— Photoexcited 1,3-dimethyluracil (DMU) reacts with methanol to give 1,3-dimethyl-6-hydroxymethyl-5-hydrouracil ( 1 a) in addition to cyclobutane type dimers and 1,3-dimethyl-6-methoxy-5-hydrouracil ( 2 a). Free radical induced reaction, initiated by photodecomposition of di- t -butyl peroxide with light of wavelength greater than 290nm, leads to 1 a, 5,6-dihydroxymethyl-5,6-dihydro-1,3-dimethyl-uracil ( 1 d) and 6-hydroxymethyl-1,3-dimethyluracil as the products. 相似文献
15.
Di-uracil substituted cyclen derivatives were prepared by the reaction of cyclen with 6-chloro-1-methyluracil or 6-chloro-1,3-dimethyluracil. The reaction of cyclam with 6-chloro-1,3-dimethyluracil gave a similar di-uracil substituted cyclam. The 1,7-di-uracil substituted cyclen was converted to the tricyclic guanidinium salt and acylurea upon heating in DMSO in the presence of weak acid. The 1,8-di-uracil substituted cyclam gave a tricyclic dihydroimidazolium salt under the same conditions. These reactions can be explained by an intramolecular uracil ring-breaking reaction mechanism. 相似文献
16.
The mechanism of base catalyzed proton exchange at the 5-position of uracil and its N-methylated derivatives has been studied. These reactions proceed by addition — elimination across the 5,6-double bond when the 1-nitrogen is substituted with a methyl group, or with anchimeric assistance of the N-1 anion if the 1-position is unsubstituted. The base catalyzed hydrolyses of 1,3-dimethyluracil and 3-methyluracil also appear to proceed through hydrated intermediates. A facile method for an acid catalyzed preparation of 5-deuterated uracils is described as well as a simple and accurate method for analysis of deuterium content. 相似文献
17.
《Journal of Molecular Structure》1997,435(2):133-141
The crystal and molecular structures of 5,6-diamino-1-methyluracil and 5,6-diamino-1,3-dimethyluracil monohydrate have been determined from X-ray diffraction. Both compounds are planar and the two amino groups have two different conformations. The substituent at the 5 position seems to be a true primary amino group with a strongly sp3 nitrogen, whereas the one at the 6 position is nearly coplanar with the uracil ring, displaying a predominant sp2 character.Semiempirical calculations were made on 5,6-diaminouracil, 5,6-diamino-2-thiouracil and their endocyclic N-methylated derivatives using the AM1 and PM3 hamiltonians. These indicate that the stability decreases on increasing methylation, the 2-thio compounds always being less stable than the 2-oxo ones. 相似文献
18.
Yu. K. Voronina L. F. Saifina E. S. Romanova O. A. Lodochnikova I. A. Litvinov 《Journal of Structural Chemistry》2009,50(3):588-591
Single crystal XRD is used to study the crystal structure of 1-(4-bromobutyl)-3,6-dimethyluracil and 1,3-dimethyl-5-(5-bromopentyl)-isocyanurate
in comparison with structurally similar compounds studied previously. It is shown that unlike macrocyclic compound, for which
the crystal structure is determined by the presence of the stacking effect, in the crystals of their artificial precursors
stacking interactions are not observed. For 1-(4-bromobutyl)-3,6-dimethyluracil, C-H...O interactions and C=O...Br interactions
for 1,3-dimethyl-5-(5-bromopentyl)-isocyanurate are found.
Original Russian Text Copyright ? 2009 by Yu. K. Voronina, L. F. Saifina, E. S. Romanova, O. A. Lodochnikova, and I. A. Litvinov
__________
Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 3, pp. 608–611, May–June, 2009. 相似文献
19.
Andrea Preuß Sebastian Notz Eduard Kovalski Dr. Marcus Korb Dr. Thomas Blaudeck Dr. Xiao Hu Dr. Jörg Schuster Dr. Dominique Miesel Dr. Tobias Rüffer Dr. Alexander Hildebrandt Dr. Katja Schreiter Prof. Dr. Stefan Spange Prof. Dr. Stefan E. Schulz Prof. Dr. Heinrich Lang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(12):2635-2652
The synthesis of 1-Fc- ( 3 ), 1-Br-6-Fc- ( 5 a ), 2-Br-7-Fc- ( 7 a ), 1,6-Fc2- ( 5 b ), 2,7-Fc2-pyrene ( 7 b ), 3,6-Fc2-9,10-phenanthrenedione ( 10 ), and 3,6-Fc2-9,10-dimethoxyphenanthrene ( 12 ; Fc=Fe(η5-C5H4)(η5-C5H5)) is discussed. Of these compounds, 10 and 12 form 1D or 2D coordination polymers in the solid state. (Spectro)Electrochemical studies confirmed reversible Fc/Fc+ redox events between −130 and 160 mV. 1,6- and 2,7-Substitution in 5 a (E°′=−130 mV) and 7 a (E°′=50 mV) influences the redox potentials, whereas the ones of 5 b and 7 b (E°′=20 mV) are independent. Compounds 5 b , 7 b , 10 , and 12 show single Fc oxidation processes with redox splittings between 70 and 100 mV. UV/Vis/NIR spectroelectrochemistry confirmed a weak electron transfer between FeII/FeIII in mixed-valent [ 5 b ]+ and [ 12 ]+. DFT calculations showed that 5 b non-covalently interacts with the single-walled carbon nanotube (SWCNT) sidewalls as proven by, for example, disentangling experiments. In addition, CV studies of the as-obtained dispersions confirmed exohedral attachment of 5 b at the SWCNTs. 相似文献
20.
Asymmetric Diels-Alder Reaction of 1-Methoxybuta-1,3-diene with (2R)-N-Glyoxyloylbornane-10,2-sultam
Tomasz Bauer Christian Chapuis Janusz Kozak Janusz Jurczak 《Helvetica chimica acta》1989,72(3):482-486
Starting from sultam 1 , the chiral dienophile (2R)-N-glyoxyloylbornane-10,2-sultam ( 4 ) was readily prepared. Non-catalyzed atmospheric- and high-pressure as well as [Eu(fod)3]-promoted [4 + 2] cycloadditions of 1-methoxy-buta-1,3-diene ( 5 ) to chiral dienophile 4 , leading with high asymmetric induction to 6-methoxy-3,6-dihydro-2H-pyran-2-yl derivatives 6 – 9 , are described. The extent and direction of asymmetric induction in these reactions were established by 1H-NMR analysis and chemical correlation, respectively. Stereochemical models for both non-catalyzed and [Eu(fod)3]-promoted reactions are proposed. 相似文献