- Template-directed synthesis of cucurbituril analogues using propanediurea as a building block
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Two novel cucurbituril-like macrocycles, TD[4] and TD[5], were prepared from the condensation of propanediurea and formaldehyde using CaCl2 and BaCl2 as templates, respectively, featuring convenience and low cost. The two hosts show excellent thermostability and their structures were characterized by 1H NMR, HRMS and single crystal X-ray diffraction.
- Shen, Yenan,Zou, Lei,Wang, Qiaochun
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supporting information
p. 7857 - 7860
(2017/08/15)
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- Discovery of BI 207524, an indole diamide NS5B thumb pocket 1 inhibitor with improved potency for the potential treatment of chronic hepatitis C virus infection
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The development of interferon-free regimens for the treatment of chronic HCV infection constitutes a preferred option that is expected in the future to provide patients with improved efficacy, better tolerability, and reduced risk for emergence of drug-resistant virus. We have pursued non-nucleoside NS5B polymerase allosteric inhibitors as combination partners with other direct acting antivirals (DAAs) having a complementary mechanism of action. Herein, we describe the discovery of a potent follow-up compound (BI 207524, 27) to the first thumb pocket 1 NS5B inhibitor to demonstrate antiviral activity in genotype 1 HCV infected patients, BILB 1941 (1). Cell-based replicon potency was significantly improved through electronic modulation of the pKa of the carboxylic acid function of the lead molecule. Subsequent ADME-PK optimization lead to 27, a predicted low clearance compound in man. The preclinical profile of inhibitor 27 is discussed, as well as the identification of a genotoxic metabolite that led to the discontinuation of the development of this compound.
- Beaulieu, Pierre L.,Anderson, Paul C.,Bethell, Richard,B?s, Michael,Bousquet, Yves,Brochu, Christian,Cordingley, Michael G.,Fazal, Gulrez,Garneau, Michel,Gillard, James R.,Kawai, Stephen,Marquis, Martin,McKercher, Ginette,Poupart, Marc-André,Stammers, Timothy,Thavonekham, Bounkham,Wernic, Dominik,Duan, Jianmin,Kukolj, George
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p. 10130 - 10143
(2015/02/05)
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- Meteorites as catalysts for prebiotic chemistry
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From outer space: Twelve meteorite specimens, representative of their major classes, catalyse the synthesis of nucleobases, carboxylic acids, aminoacids and low-molecular-weight compounds from formamide (see figure). Different chemical pathways are identified, the yields are high for a prebiotic process and the products come in rich and composite panels.
- Saladino, Raffaele,Botta, Giorgia,Delfino, Michela,Di Mauro, Ernesto
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p. 16916 - 16922
(2014/01/06)
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- Synthesis, characterization and pharmacological study of 4,5-dihydropyrazolines carrying pyrimidine moiety
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A series of 5-bromo-2-(3,5-diaryl-4,5-dihydro-1H-pyrazol-1-yl)pyrimidine were prepared under conventional heating as well as microwave reaction condition. The newly synthesized compounds were characterized on the basis of elemental, spectral and single crystal X-ray studies. These new compounds were screened for their antioxidant, anti-inflammatory and analgesic activities. Some of these compounds exhibited potent biological activities compared to the standard drug.
- Adhikari, Adithya,Kalluraya, Balakrishna,Sujith, Kizhakke Veedu,Gouthamchandra, Kuluvar,Jairam, Ravikumar,Mahmood, Riaz,Sankolli, Ravish
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p. 467 - 474
(2012/11/07)
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- Comprehensive investigation of the energetics of pyrimidine nucleoside formation in a model prebiotic reaction
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The problem of β-nucleoside formation under prebiotic conditions represents one of the most significant challenges to the "RNA world" hypothesis. The possibility exists that alternative bases may have come before the contemporary bases (i.e., A, G, C, and
- Sheng, Yinghong,Bean, Heather D.,Mamajanov, Irena,Hud, Nicholas V.,Leszczynski, Jerzy
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body text
p. 16088 - 16095
(2010/02/16)
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- Synthesis and degradation of nucleic acid components by formamide and iron sulfur minerals
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We describe the one-pot synthesis of a large panel of nucleic bases and related compounds from formamide in the presence of iron sulfur and iron-copper sulfur minerals as catalysts. The major products observed are purine, 1H-pyrimidinone, isocytosine, adenine, 2-aminopurine, carbodiimide, urea, and oxalic acid. Isocytosine and 2-aminopurine may recognize natural nucleobases by Watson-Crick and reverse Watson-Crick interactions, thus suggesting novel scenarios for the origin of primordial nucleic acids. Since the major problem in the origin of informational polymers is the instability of their precursors, we also investigate the effects of iron sulfur and iron-copper sulfur minerals on the stability of ribooligonucleotides in formamide and in water. All of the iron sulfur and iron-copper sulfur minerals stimulated degradation of RNA. The relevance of these findings with respect to the origin of informational polymers is discussed.
- Saladino, Raffaele,Neri, Veronica,Crestini, Claudia,Costanzo, Giovanna,Graciotti, Michele,Di Mauro, Ernesto
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experimental part
p. 15512 - 15518
(2009/03/12)
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- VIRAL POLYMERASE INHIBITORS
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The present invention relates to compounds represented by formula (I) wherein A, B, D, E, R2, R3, R4, R5, R6, R9, a, b, d and e are as defined herein, their salt or ester and pharmaceutical compositions thereof useful in the treatment of hepatitis C viral (HCV) infection. Said compounds were found to have inhibitory activity against HCV polymerase, especially as inhibitors of HCV NS5B polymerase
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Page/Page column 54-55
(2010/11/26)
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- VIRAL POLYMERASE INHIBITORS
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A compound, represented by formula (I) or an enantiomer, diastereoisomer or tautomer thereof : wherein either A or B is nitrogen and the other B or A is C, and the radicals R1, R2, R3, R5, R6, R7, R9, and R10 are as defined herein, or a salt, ester or derivative thereof as viral polymerase inhibitors. The compound is used as an inhibitor of RNA dependent RNA polymerases, particulary those viral polymerases within the Flaviviridae family, more particulary to HCV polymerase.
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Page/Page column 64
(2010/02/15)
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- Hydrogen peroxide promoted hydroxylation of haloarenes and heteroarenes
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Addition of aqueous hydrogen peroxide significantly accelerates the substitution reactions of hydroxide salts with haloarenes bearing electron withdrawing substituents. A similar effect is observed in the reactions of hydroxide salts with halogenated heteroarenes. Reactions are carried out in water or water-THF at ambient temperature or at 50-60 °C.
- Cantrell Jr., William R.,Bauta, William E.,Engles, Tracy
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p. 4249 - 4251
(2007/10/03)
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- COMPOUNDS USEFUL AS ANTIPROLIFERATIVE AGENTS AND GARFT INHIBITORS
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The invention relates to compounds, such as compound (1) in equilibrium with its 4-hydroxy tautomer, and its pharmaceutically acceptable salts. Such compounds are useful as inhibitors of glycinamide ribonucleotide formyl transferase (GARFT) or as antiproliferative agents. The invention also pertains to pharmaceutical compositions and methods employing such compounds as GARFT inhibitors or antiproliferative agents. The invention also relates to compounds useful as intermediates for preparing such compounds.
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- Inhibitors of hepatitis C virus NS3 protease
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The present invention relates generally to a novel class of pyrimidinones of Formula (I): that are useful as serine protease inhibitors, and more particularly as Hepatitis C virus NS3 protease inhibitors. This invention also relates to pharmaceutical compositions comprising these compounds and methods of using the same.
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- Bile-acid derived compounds for enhancing oral absorption and systemic bioavailability of drugs
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Disclosed are compounds that exhibit high transport across the intestinal wall of an animal. The compounds may optionally be linked to drugs that are poorly absorbed or poorly transported across the intestinal wall after oral administration to provide for enhanced therapeutic, and optionally prolonged therapeutic, systemic blood concentrations of the drugs upon oral administration of the drug-compound conjugate. Also disclosed are pharmaceutical compositions containing and methods of using such compounds.
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- Angiotensin II receptor antagonistic 1,2,4-triazin-5-one derivatives
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Disclosed are novel 1,2,4-triazin-5-one biphenyl derivatives having structural formula (I) useful as non-peptide antagonists of angiotensin II receptor: where R1 represents alkyl, cycloalkyl, or substituted or unsubstituted aryl; R2 represents alkyl, substituted or unsubstituted aryl, or arylalkyl; A and D independently represent C-R3, N, NH or C=O, wherein when A and D independently denote C-R3 or N, b and c are independently a double bond, and when A and D independently denote NH or C=O, b and c are independently a single bond; provided that b and c are not both double bonds; and R3 is hydrogen, dialkylphosphonate or halogen; and pharmaceutically acceptable salts thereof. Also disclosed is the use of the compounds of formula (I) as non-peptide antagonists of angiotensin II receptor, in the treatment of cardiovascular diseases, in particular hypertension and congestive heart failure.
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- Arylamino fused pyrimidines
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Corticotropin releasing factor (CRF) antagonists of formula I or formula II: and their use in treating anxiety, depression, and other psychiatric and neurological disorders.
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- Alpha-substituted pyrimidine-thioalkyl and alkylether compounds as inhibitors of viral reverse transcriptase
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The subject invention relates to pyrimidine-thioalkyl and alkylether compounds of Formula (I) and pyrimidine-thioalkyl and alkylethers of Formula (IA), namely the compounds of Formula (I) where R 4 is selected from the group consisitng of --H or --NR 15 R 16 where R 15 is --H and R 16 is --H, C 1 -C 6 alkyl, NH 2 or R 15 and R 16 taken together with the --N form 1-pyrrolidino, 1-morpholino or 1-piperidino; and R 6 is selected from the group consisting of --H, or halo (preferably --Cl); with the overall proviso that R 4 and R 6 are not both --H. The compounds of Formula (IA) are useful in the treatment of individuals who are HIV positive being inhibitors of viral reverse transcriptase. STR1
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- Substituted heterocycles
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Compounds of formula I STR1 wherein Q1, Q2, Q3, Q4 and Q5 have any of the meanings given in the specification, their N-oxides, and their pharmacuetically acceptable salts are nonpeptide antagonists NKA, useful for the treatment of asthma, etc. Also disclosed are pharmaceutical compositions, processes for preparing the compounds of formula I and intermediates.
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- Pyrimidine-thioalkyl and alkylether compounds
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The subject invention relates to pyrimidine-thioalkyl and alkylether compounds of Formula (I) and pyrimidine-thioalkyl and alkylethers of Formula (IA), namely the compounds of Formula (I) where R 4 is selected from the group consisting of --H or --NR 15 R 16 where R 15 is --H and R 16 is --H, C 1 -C 6 alkyl, --NH 2 or R 15 and R 16 taken together with the --N form 1-pyrrolidino, 1-morpholino or 1-piperidino; and R 6 is selected from the group consisting of --H, or halo (preferably --Cl); with the overall proviso that R 4 and R 6 are not both --H. The compounds of Formula (IA) are useful in the treatment of individuals who are HIV positive.
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- Ring-Centered Heterocyclic Cations and the Direct Heteroarylation of Aromatic and Heterocyclic Compounds
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(matrix presented) The protonation of heterocyclic diazotates (attachment adjacent to a nitrogen atom) yields ring-centered heterocyclic carbocations that are highly reactive. The carbocations were found to alkylate aromatic and heterocyclic compounds, such as benzene, N-methylpyrrole, and 2-aminopyridine, in reactions that are synthetically useful. This carbocation involvement may serve as a paradigm for the cross-linking of DNA by nitrous acid and the anticancer activity of heterocyclic diazotates.
- Song, Fenhong,St. Hilaire, Valentine R.,White, Emil H.
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p. 1957 - 1959
(2008/02/11)
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- Reaction of pyrimidyl esters of some phosphorus acids with isomeric butyl alcohols
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A series of pyrimidyl esters of some phosphorus acids was prepared with the purpose of investigation of their reaction with isomeric butyl alcohols. According to31P NMR data, the obtained phosphates all are capable of phosphorylating isomeric butyl alcohols. The reactions with diphenyl (4-oxo-3,4-dihydro-2-pyrimidyl) phosphate and diphenyl (2-pyrimidyl) phosphate occur in quantitative yield under mild conditions, and the reactions with diphenyl (4,6-dimethyl-2-pyrimidyl) phosphate and dibutyl (4,6-dimethyl-2-pyrimidyl) phosphate require severe conditions to occur. In the latter two cases, certain reaction selectivity was observed, depending on the nature of the solvent and some other factors. Pyrimidyl esters of sulfur-containing phosphorus acids do not react with isomeric butyl alcohols under the studied conditions.
- Semenov,Akamsin,Enikeev,Reznik
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p. 1386 - 1388
(2007/10/03)
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- Processes for preparing antiproliferative garft-inhibiting compounds
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The invention generally relates to compounds of the formula I, which are in equilibrium with their 4-hydroxy tautomers, and their pharmaceutically acceptable salts: STR1 where n is 0 to 2; A is S, CH2, O, NH or Se, and when n is 0, A is not CH2, and when n is 1, A is not CH2 or NH; X is a substituted or unsubstituted C1 -C3 alkyl, C2 -C3 alkenyl, C2 -C3 alkynyl or amino, or sulfur or oxygen; Ar is a substituted or unsubstituted monocyclic carbocycle or heterocycle, or fused or nonfused polycyclic carbocycle or heterocycle; and R1 and R2 are hydrogen or a moiety that forms together with the attached CO2 a readily hydrolyzable ester group. These compounds and their salts are useful as inhibitors of GARFT or as antiproliferative agents. The invention also pertains to pharmaceutical compositions and methods employing such compounds as GARFT inhibitors or antiproliferative agents. The invention also relates to compounds useful as intermediates for preparing such compounds, and to their synthesis.
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- Piperidine derivatives useful as neurokinin antagonists
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Compounds of formula I STR1 wherein Q1, Q2, Q3, and Q4 have any of the meanings given in the specification, their N-oxides, and their pharmaceutically acceptable salts are nonpeptide antagonists of neurokinin A and useful for the treatment of asthma, etc. Also disclosed are pharmaceutical compositions, processes for preparing the compounds of formula I and intermediates.
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- Process for the manufacture of 2-isopropyl-4-methyl-6-hydroxypyrimine
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Hydroxypyrimidine, a key intermediate in the manufacture of diazinon, is prepared in high yields and high purity by reacting an amidine with methyl-acetoacetate in a dry, i.e. non-aqueous, medium in the presence of a methanolic base in an aliphatic hydrocarbon solvent while azeotropically distilling off water formed during the reaction.
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- Thiapyran formation via an unexpected thioaldehyde intermediate by the thermal decomposition of phenacyl sulfoxides bearing some heterocycles
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Thermolysis of phenacyl sulfoxide bearing some nitrogen-containing heterocycles in the presence of 2,3-dimethyl-2,3-butadiene led to 6-benzoyl-5,6-dihydro-3,4-dimethyl-2H-thiapyran. This product was considered to be formed by the Diels-Alder reaction of the diene with thioaldehyde formed initially by the thermal decomposition of the sulfoxide.
- Morita, Hiroyuki,Takeda, Masahiro,Kamiyama, Hideo,Hashimoto, Tadaaki,Yoshimura, Toshiaki,Shimasaki, Choichiro,Tsukurimichi, Eiichi
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p. 3739 - 3740
(2007/10/03)
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- Platelet aggregation inhibitors
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This invention relates to compounds having the following formula STR1 or a pharmaceutically acceptable salt thereof which are useful in the inhibition of platelet aggregation, to pharmaceutical compositions of such phenylamidines derivatives, and to a method of inhibiting platelet aggregation in mammals by administering such compounds and compositions.
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- ANGIOTENSIN II ANTAGONISTS INCORPORATING A SUBSTITUTED THIOPHENE OR FURAN
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Substituted heterocycles attached through a methylene bridge to novel substituted phenyl thiophene or phenyl furan derivative of the Formula I are useful as angiotensin II antagonists. STR1
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- QUINAZOLINONE, TRIAZOLINONE AND PYRIMIDINONE ANGIOTENSIN II ANTAGONISTS INCORPORATING A SUBSTITUTED BENZYL ELEMENT
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Substituted heterocycles attached through a methylene bridge to novel substituted phenyl derivatives of the Formula I are useful as angiotensin II antagonists. STR1
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- ANGIOTENSIN II ANTAGONISTS INCORPORATING A SUBSTITUTED BENZYL ELEMENT
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Substituted heterocycles attached through a methylene bridge to novel substituted phenyl derivatives of the Formula I are useful as angiotensin II antagonists. STR1
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- Artificial DNA base pair analogues
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The present invention is directed to new artificial base pairs comprising complementary artificial purines and pyrimidines and methods of using artificial complementary base pairs.
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- ANGIOTENSIN II ANTAGONISTS INCORPORATING A SUBSTITUTED INDOLE OR DIHYDROINDOLE
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Substituted heterocycles attached through a methylene bridge to novel substituted indole or dihydroindole derivative of the Formula I are useful as angiotensin II antagonists. STR1
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- Aryl substituted nitrogen heterocyclic antidepressants
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Antidepressant agents having the formula STR1 wherein R1 is a polycycloalkyl group; R2 is methyl or ethyl, X is O; and Y comprises a 5-membered heterocyclic ring having one or two nitrogens.
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- MILD ACID HYDROLYSIS OF 2-PYRIMIDINONE-CONTAINING DNA FRAGMENTS GENERATES APURINIC/APYRIMIDINIC SITES
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Facile glycosidic bond cleavage of 2-pyrimidinone-2'-deoxynucleosides occurs under mildly acidic conditions (pH 3.0) and ambient temperature.When a 2-pyrimidinone nucleoside residue is present in a DNA fragment, hydrolysis results in an apurinic/apyrimidinic (abasic) site.The incorporation of 2-pyrimidinones into chemically synthesized DNA provides a route for the chemical generation of an abasic site at a preselected position in the sequence.
- Iocono, Joseph A.,Gildea, Brian,McLaughlin, Larry W.
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p. 175 - 178
(2007/10/02)
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- 2H-v-triazolo[4-5-d]pyrimidines
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Novel 2H-v-triazolo[4,5-d]pyrimidines of the general formula STR1 where R1 and R2 independently of one another are each alkyl, unsubstituted or substituted phenyl or phenalkyl, or STR2 is a saturated 5-membered or 6-membered heterocyclic ring, X is alkyl, halogen or phenyl n is 0, 1 or 2, and A is STR3 hydrogen, halogen, cyano, thiocyano, alkoxy, alkoxyalkoxy, unsubstituted or substituted phenoxy, phenylalkoxy, alkylthio, phenylthio, --S--(CH2)m --COO-alkyl, where m is from 1 to 4, alkylcarbonyl, benzoyl, carboxyl, carboalkoxy, alkylsulfonyl, phenylsulfonyl, an N-imidazole, benzimidazole, 1,2,3-triazole, benzotriazole, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, 2-mercaptothiazole or 2-mercapto-1,3,4-thiadiazole radical, or a radical of the formula STR4 where R4 is H or C1 -C4 -alkyl, p is from 2 to 5 and R5 and R6 are each C1 -C4 -alkyl, or STR5 is a saturated 5-membered or 6-membered heterocyclic radical which can furthermore contain N, O and/or S as ring members, are useful charge carrier-transporting compounds in electrophotographic recording materials.
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- Herbicidal sulfonamides
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Certain sulfonylurea compounds such as 2-[[[4-methoxy-6-(methylselenylmethyl)pyrimidin-2-yl]aminocarbonyl]aminosulfonyl]benzoic acid, methyl ester and 2-[[[4-methoxy-6-(phenylthiomethyl)pyrimidin-2-yl]-aminocarbonyl]aminosulfonyl]benzoic acid, methyl ester provide herbicidal activity.
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- The Mechanism of Thermal Eliminations. Part 20. The Relative Rates of Pyrolysis of the 2-Ethoxy, 2-Isopropoxy, and 2-t-Butoxy Derivatives of Pyrazine and Pyrimidine to Pyrazine-2-one, pyrimidin-2-one, respectively: Polarity of the Transition States and the Importance of Nucleophilic ...
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We have measured rates of thermal elimination of the title compounds to give the corresponding cyclic amides, between 587.0 and 698.5 K.The relative rates (primary:secondary:tertiary) at 600 K are 1:27.0:3720 for the pyrazines, and 1:26.4:4150 for the pyrimidines.These ratios are somewhat larger than for the corresponding 2-alkoxypyridines and suggest that C-O bond breaking is kinetically more significant in the pyrazines and pyrimidines, leading to a transition state with greater carbocationic character.This is consistent with electron withdrawal provided by the aza 'substituent' facilitating C-O bond cleavage.It does not however lead to a general increase in reactivity (as would be the case for pyrolysis of comparable esters) because this electron withdrawal reduces the nucleophilicity of the nitrogen involved in the elimination.This latter is particularly important for the primary and secondary compounds (which have more Ei-like transition states) than for the tertiary compounds, which therfore show a normal reactivity vs. rate spread pattern.The importance of the nucleophilicity of the nitrogen in the alkoxy-heterocycles, and its ability to be modified, may stem in part from the dual pathway available for transmission of substituent effects in the aromatic ring.
- Al-Awardi, Nouria,Taylor, Roger
-
p. 1585 - 1588
(2007/10/02)
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- The Mechanism of Thermal Eliminations. Part 18. Relative Rates of Pyrolysis of 2-Ethoxypyrazine, 3-Ethoxypyridazine, 2-and 4-Ethoxypyrimidine, 3-Chloro-6-ethoxypyridazine, and 2-Chloro-4-ethoxypyrimidine : the Effect of the Aza 'Substituent' and ?-Bond Order on the Elimination Rate
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A kinetic study has been made of the first-order thermal decomposition of the title compounds into ethylene and the corresponding aza-substituted pyridines, between 650 and 713 K.The relative elimination rates at 650 K are (2-ethoxypyridine = 1): 0.545, 10.0, 1.03, 1.12, 9.68, and 3.28, respectively.The electronic effects of the aza 'substituent' are small, and a more important factor appears to be the C-N ?-bond order; this latter accounts for the high reactivity of the pyridazines.The effects of the chloro substituent and of the aza 'substituent' are explicable in terms of a balance between electron withdrawal from the C-O bond (producing deactivation) and from the nitrogen involved in the cyclic transition state (producing deactivation).The effects of the chloro substituents confirm that the most important step of the reaction is breaking of the C-O bond.The statistically corrected rate (per ring nitrogen) of 2-ethoxypyrimidine is unexpectedly low.This may reflect difficulty in achieving the coplanar transition state in which the lone pairs in the s-orbitals of oxygen and the nitrogen not involved in the elimination are brought into close proximity.
- Al-Awadi, Nouria,Taylor, Roger
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p. 1255 - 1258
(2007/10/02)
-
- Nucleophilic Displacements of N-Aryl and Heteroaryl Groups. Part 4. Pyrylium-mediated Transformations of Heteroarylamines into Pyridinium Salts and their Inter- and Intra-molecular Displacement
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Heteroarylamines and the appropriate pyrylium salts give 1-heteroaryl-2-ethoxycarbonyl-4,6-diphenylpyridinium, and 1-(2-pyridyl)-2,6-diethoxycarbonyl-4-phenylpyridinium salts.Hydrolysis and decarboxylation afford 1-(2-pyridyl)-2,4-diphenyl- and 1-(2-pyridyl)-4-phenyl-pyridinium salts.Neither these, nor their 2,4,6-triphenyl analogues underwent smooth nucleophilic substitution. 1-Pyrimidin-2-yl- and 1-(4,6-dimethylpyrimidin-2-yl)-2-ethoxycarbonyl-4,6-diphenylpyridinium with ethanolic NaOEt smoothly formed the corresponding pyrimidin-2-ones via intramolecular attack.
- Katritzky Alan R.,Agha, Bushra J.,Awartani, Radi,Patel, Ranjan C.
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p. 2617 - 2621
(2007/10/02)
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- Gas Chromatography/Mass Spectrometry Determination of Urea in Plasma and Application to Urea Metabolism Study
-
The study of urea metabolism in human necessitates sensitive methods, so that very low isotopic enrichments of plasma or urinary urea can be measured.A stable derivative of urea, suitable for the measurements of 15N or 13C enrichments of urea using gas chromatography/mass spectrometry, is described.The trimethylsiloxypyrimidine could be used to measure - and urea enrichments as low as 0.5percent with a coefficient of variation below 5percent.Determination of a lower enrichment of urea required the use of 2-trifluoroacetoxypyrimidine, which had a background of0.4 percent at the (M+2) ion.The coefficient of variation in determining the background was 1.6percent; this means a low enrichment, such as 0.1percent, could be determined with confidence.This technique was applied to the study of urea metabolism in humans and dogs.
- Tserng, Kou-Yi,Kalhan, Satish C.
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p. 489 - 491
(2007/10/02)
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- Theoretical Description of Solvent Effects. V. The Medium Influence on the Lactim-Lactam Tautomerism of Hydroxyazines
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Der Loesungsmitteleffekt auf die Tautomeriegleichgewichte der Titelverbindungen wird mit Hilfe klassischer und quantenchemischer Versionen der Solvatonen- und der Reaktionsfeldtheorie berechnet.In Uebereinstimmung mit dem Experiment ergeben alle getesteten Verfahren eine Gleichgewichtsverschiebung zugunsten der Lactamform.Zur quantitativen Beschreibung dieses Effektes ist jedoch das Reaktionsfeldmodell besser geeignet.
- Krebs, C.,Foerster, W.,Weiss, C.,Hofmann, H.-J.
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p. 369 - 378
(2007/10/02)
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- Kinetics and Mechanism of Reaction between 2-Aminopyrimidine and Sodium Hydroxide
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The title reaction has been investigated in strong alkaline medium (1.0 to 3.0 M NaOH solution) at 95 deg.The reaction is pseudo-first order and the rate constants increase with increasing .The dependence of rate on is linear at =1.0 to 2.0 M, thereafter a sharp increase in the reaction rate is observed.A suitable mechanism involving monoanionic and dianionic tetrahedral intermediates is suggested and the following rate equation has been derived.
- Jain, S. K.,Khan, A. Aziz
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p. 397 - 399
(2007/10/02)
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- V-Triazolyl-[4,5-d]-pyrimidines
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v-Triazolyl-[4,5-d]-pyrimidines of the formula STR1 wherein Q is a mono- or disubstituted amino radical, R is an optionally substituted alkyl or aryl group and the benzene ring A can carry one or two substituents. The compounds are suitable as fluorescent whitening agents for organic material of high molecular weight, especially polyamide. The compounds are obtained by starting from a 4-aminopyrimidine which is correspondingly substituted in the 2- and 6-position, coupling it with the diazonium salt of an optionally substituted aniline and oxidising the resultant azo compound to the triazolylpyrimidine.
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- Kinetic Study of the Acid-Promoted Hydrolysis of Some Representative 2-Fluoro Nitrogen Heterocycles
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The acid-promoted hydrolysis of the 2-fluoro derivatives of pyridine, the four isomeric picolines, quinoline, pyrimidine, 4-methylpyrimidine, and 4,6-dimethylpyrimidine have been studied in hydrochloric acid over the concentration range of 0.05-8.0 F HCl.At each acid concentration, the reactions followed pseudo-first-order kinetics, and at low concentrations of acid, the rate of reaction increased linearly with h0.However, at higher acid concentrations negative deviations from linearity were observed for all the substrates and rate maxima for all but the pyrimidines.These results were correlated with the decline in water activity by means of the Bunnett ω and ω* relationships, as well as the Bunnett-Olsen LFER.The slopes of these correlations were suggestive of a proton transfer role for water in the reactions of the less activated 2-fluoropyridines and of 2-fluoroquinoline, while the correlations indicate a nucleophilic role for water in the reactions of the more highly activated pyrimidines.Entropies of activation, calculated both from the pseudo-first-order rate constants, and from the values of k2* obtained from the intercepts of the LFER plot, were significantly more negative for the pyridine and quinoline systems for the pyrimidines.The above results are interpreted as consistent with nucleophilic attack by water in the rate-determining step for the reaction of the pyrimidines, while for the less activated substrates nucleophilic attack may be assisted by proton transfer to additional water molecules.
- Clark, H. R.,Beth, L. D.,Burton, R. M.,Garrett, D. L.,Miller, A. L.,Muscio, O. J.
-
p. 4363 - 4369
(2007/10/02)
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- EQUILIBRE LACTIME-LACTAME DES HYDROXY-PYRIDINES ET DES HYDROXY-PYRIMIDINES (URACILES) EN MILIEU APOLAIRE: ETUDE INFRA-ROUGE
-
In contrast to what observed with mono hydroxy-pyridines and -pyrimidines the lactim-lactam equilibrium of uracils is not found to be markedly influenced by solvent polarity.
- Chevrier, Marianne,Bensaude, Olivier,Guillerez, Jean,Dubois, Jacques-Emile
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p. 3359 - 3362
(2007/10/02)
-
