- Sonochemical heating profile for solvents and ionic liquid doped solvents, and their application in the N-alkylation of pyrazoles
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The heating profile for 25 solvents was determined in ultrasonic probe equipment at amplitudes of 20%, 25%, and 30%. Each solvent was heated in accordance with its boiling point. The effect of vapor pressure, surface tension, and viscosity of the solvents in dissipated ultrasonic power (Up) was evaluated. Multiple regression analysis of these solvent properties and dissipated Up reveals that solvent viscosity is the property that most strongly affected dissipated Up. Experimentation involving acetonitrile doped with [BMIM][BF4] indicated faster heating than MeCN. Aprotic polar solvents such as DMSO, DMF, and MeCN were tested in the N-alkylation of pyrazoles under ultrasonic conditions. After 5 min at 90 °C, the reactants had been totally converted into product in these solvents. Solvents, with low dissipated Up (e.g., toluene) were tested. Conversions were lower compared to those of aprotic polar solvents. When the reactions were done in hexane, no conversion to product was observed. To check the effect of doping in solvents with low Up, [BMIM][BF4], DMSO, and DMF were selected. The conversions for toluene doped with [BMIM][BF4], DMSO, and DMF were 100%, 59%, and 25%, respectively. These conversions were greater than when done in just toluene (46%). Thus, [BMIM][BF4] was the best polar doping solvent, followed by DMSO. DMF was not considered to be a satisfactory doping solvent. No conversion was observed for reactions in the absence of base performed in DMSO, DMF, and MeCN doped with [BMIM][BF4].
- Frizzo, Clarissa P.,Bacim, Carolini,Moreira, Dayse N.,Rodrigues, Leticia V.,Zimmer, Geórgia C.,Bonacorso, Hélio G.,Zanatta, Nilo,Martins, Marcos A.P.
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- KF/Al2O3-mediated N-alkylation of amines and nitrogen heterocycles and S-alkylation of thiols
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KF/Al2O3 efficiently catalyzes N-alkylation of heterocyclic, primary, and secondary amines and S-alkylation of thiols with a variety of alkyl halides. The N-alkylation and S-alkylation adducts were produced in good to excellent yields and in short times. Copyright Taylor & Francis Group, LLC.
- Moghaddam, Firouz Matloubi,DokhtTaimoory, Seyedeh Maryam,Ismaili, Hossein,Bardajee, Ghasem Rezanejade
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- Enthalpies of formation of N-substituted pyrazoles and imidazoles
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Accurate experimental enthalpies of formation measured using static bomb combustion calorimetry, the "vacuum sublimation" drop calorimetry method, and the Knudsen-effusion method are reported for the first time for four azoles: 1-methylimidazole (1MeIMI), 1-methylpyrazole (1MePYR), 1-benzylimidazole (1BnIMI), and 1-benzylpyrazole (1BnPYR). These values and those corresponding to imidazole (1HIMI), pyrazole (1HPYR), 1-ethylimidazole (1EtIMI), 1-ethylpyrazole (1EtPYR), 1-phenylimidazole (1PhIMI), and 1-phenylpyrazole (1PhPYR) are compared with theoretical values using the G2(MP2) and the B3LYP/6-311*G(3df,2p)//6-31G(d) approaches. In general, there is a very good agreement between calculated and experimental values for the series of N-substituted imidazoles, while the agreement is less good for the series of the N-substituted pyrazoles. Experimentally, the gap between the enthalpies of formation of imidazoles and pyrazoles decreases significantly upon N-substitution, while the theoretical estimates indicate that this decrease is smaller.
- Mo?, Otilia,Ya?n?ez, Manuel,Roux, Mari?a Victoria,Jime?nez, Pilar,Da?valos, Juan Z.,Ribeiro da Silva, Manuel A. V.,Ribeiro da Silva, Maria Das Dores M. C.,Matos, M. Agostinha R.,Amaral, Luisa M. P. F.,Sa?nchez-Migallo?n, Ana,Cabildo, Pilar,Claramunt, Rosa,Elguero, Jose?,Liebman, Joel F.
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- Remarkable fast n-alkylation of azaheterocycles under microwave irradiation in dry media
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Under microwave irradiation a number of azaheterocycles (i.e., pyrrole, imidazole, pyrazole, indole, and carbazole) react remarkably fast with alkyl halides to give exclusively N-alkyl derivatives.
- Bogdal, Dariusz,Pielichowski, Jan,Jaskot, Krzysztof
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Read Online
- A VERSATILE LIGAND FOR PALLADIUM-CATALYZED META-C-H FUNCTIONALIZATIONS
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A class of mono-protected 3-amino-2- hydroxypyridine (MPAHP) ligands that enable the meta- C-H arylation of anilines, phenols, phenylacetic acids, and biologically relevant heterocyclic compounds using norbornene as a transient mediator is disclosed. The applicability of this meta-arylation methodology in the pharmaceutical industry is illustrated for heteroaryl substrates and heteroaryl iodide coupling partners, a feat made possible by using the MPAHP ligand. The enabling nature of MPAHP ligands to achieve other meta-C-H functionalization processes is also illustrated by the development of a meta-C-H amination reaction and a meta-C-H alkynylation reaction.
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Page/Page column 93
(2017/11/15)
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- Synthesizing process of nitrogen-heterocyclic high-selectivity aldehyde
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The invention relates to a synthesizing process of nitrogen-heterocyclic high-selectivity aldehyde. The synthesizing process is characterized in that when nitrogen-heterocyclic nitrogen atoms have hydrogen atoms, pyrrole, piperidine and pyrazole are used as the initial raw materials, and the pyrrole, the piperidine and the pyrazole are allowed to have reaction with piperidine-1-formaldehyde under nitrogen atom protection to obtain required nitrogen-atom ortho-position aldehyde; when nitrogen-heterocyclic nitrogen atoms have no hydrogen atoms, pyridine and pyrimidine are used to have reaction with the piperidine-1-formaldehyde to obtain the required nitrogen-atom ortho-position aldehyde. The synthesizing process is simple to operate, few in steps and high in selectivity and is a universal method using nitrogen heterocycle to synthesize the nitrogen ortho-position aldehyde.
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Paragraph 0014; 0017; 0018; 0030; 0034; 0043; 0046
(2017/09/05)
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- Transition-metal-free hydrogenation of aryl halides: From alcohol to aldehyde
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A transition-metal-and catalyst-free hydrogenation of aryl halides, promoted by bases with either aldehydes or alcohols, is described. One equivalent of benzaldehyde affords an equal yield as that of 0.5 equiv of benzyl alcohol. The kinetic study reveals that the initial rate of PhCHO is much faster than that of BnOH, in the ratio of nearly 4:1. The radical trapping experiments indicate the radical nature of this reaction. Based on the kinetic study, trapping and KIE experiments, and control experiments, a tentative mechanism is proposed. As a consequence, a wide range of (hetero)aryl iodides and bromides were efficiently reduced to their corresponding (hetero)arenes. Thus, for the first time, aldehydes are directly used as hydrogen source instead of other well-established alcohol-hydrogen sources.
- Zheng, Hong-Xing,Shan, Xiang-Huan,Qu, Jian-Ping,Kang, Yan-Biao
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p. 5114 - 5117
(2017/11/07)
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- N-Picolinamides as ligands for Ullmann-type C-N coupling reactions
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The use of N-phenyl-2-pyridincarboxamide-1-oxide as a ligand with Cu2O in Ullmann type C-N bond formations between aryl halides and N-heteroaryls in common solvents, such as MeCN, DMF, and DMSO at 82-120 °C has been successfully demonstrated. The ligand is effective when only 4% equiv is used relative to the substrate. The reaction provided the corresponding products in coupling of electron-rich, electron poor, and ortho-substituted aryl halides, including ortho aryl-chlorides, in good to very good yields. N-arylation is selectively preferred at the benzyl position when ortho-halide benzyl bromide is reacted with one equivalent of pyrazole. However, di-N-arylation is achieved in very high yields when 2.5 equiv of pyrazole is used, providing a stoichiometric control over the coupling reaction.
- Damkaci, Fehmi,Alawaed, Abdulkhaliq,Vik, Erik
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supporting information
p. 2197 - 2200
(2016/05/02)
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- Ligand-Promoted Meta-C-H Arylation of Anilines, Phenols, and Heterocycles
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Here we report the development of a versatile 3-acetylamino-2-hydroxypyridine class of ligands that promote meta-C-H arylation of anilines, heterocyclic aromatic amines, phenols, and 2-benzyl heterocycles using norbornene as a transient mediator. More than 120 examples are presented, demonstrating this ligand scaffold enables a wide substrate and coupling partner scope. Meta-C-H arylation with heterocyclic aryl iodides as coupling partners is also realized for the first time using this ligand. The utility for this transformation for drug discovery is showcased by allowing the meta-C-H arylation of a lenalidomide derivative. The first steps toward a silver-free protocol for this reaction are also demonstrated.
- Wang, Peng,Farmer, Marcus E.,Huo, Xing,Jain, Pankaj,Shen, Peng-Xiang,Ishoey, Mette,Bradner, James E.,Wisniewski, Steven R.,Eastgate, Martin D.,Yu, Jin-Quan
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supporting information
p. 9269 - 9276
(2016/08/05)
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- PYRROLO AND PYRAZOLOPYRIMIDINES AS UBIQUITIN-SPECIFIC PROTEASE 7 INHIBITORS
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The invention relates to inhibitors of USP7 inhibitors useful in the treatment of cancers, neurodegenerative diseases, immunological disorders, inflammatory disorders, cardiovascular diseases, ischemic diseases, viral infections and diseases, and bacterial infections and diseases, having the Formula: where m, n, X1, X2, R1-R5, R5′ and R6 are described herein.
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Paragraph 2118; 2119
(2016/08/03)
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- A 1-alkyl-pyrazol-4-boronic acid frequency method for the synthesis of ester
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The invention belongs to the field of organic chemical synthesis and provides a synthetic method of 1-alkylpyrazole-4-boronic acid pinacol ester. The synthetic method comprises the following three steps: 1. reacting pyrazole with iodine and hydrogen peroxide to generate 4-iodopyrazole A; 2. reacting the 4-iodopyrazole with alkyl halide to obtain an intermediate B; 3. preparing a Grignard reagent of the raw material by using 1-alkyl-4-iodopyrazole as a raw material and adopting an isopropyl Grignard reagent exchange method at 0-30 DEG C, with BE001 as a boron reagent, and reacting to obtain the final product. The technological method is accessible in raw materials, simple and convenient to operate and lower in cost and is a proper method for preparing 1-alkylpyrazole-4-boronic acid pinacol ester compounds.
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Paragraph 0068-0069
(2017/03/14)
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- Radical Hydrodeiodination of Aryl, Alkenyl, Alkynyl, and Alkyl Iodides with an Alcoholate as Organic Chain Reductant through Electron Catalysis
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A simple and efficient method for radical hydrodeiodination is reported. The novel approach uses electron catalysis. In situ generated Na-alcoholates are introduced as radical chain reducing reagents and reactions work with O2as cheap initiator. Hydrodeiodination works on aryl, alkenyl, alkynyl iodides and a tert-alkyl iodide also gets reduced applying the method. Albeit less general, the method is also applicable to the reduction of aryl bromides. The novel reagent is successfully used to conduct typical reductive radical cyclization reactions and mechanistic studies are reported.
- Dewanji, Abhishek,Mück-Lichtenfeld, Christian,Studer, Armido
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supporting information
p. 6749 - 6752
(2016/06/09)
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- Selective palladium-catalyzed direct C-H arylation of unsubstituted N-protected pyrazoles
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A highly selective C-5 arylation of N-dimethylaminosulfamoyl-protected pyrazole with aryl bromides is catalyzed by 2-5 mol% palladium in the presence of triphenylphosphine ligand and carboxylic acid additive. Selectivities up to 45:1 (C-5:C-4) can be achieved by running the reaction in non-polar solvents. A thorough study of scope and limitations shows good general tolerance of aryl bromide substitution. However, limitations on tolerance of ortho-subsitution and protic functional groups were established. Together with a telescoped deprotection step this method presents a viable alternative for the synthesis of C-3 arylated pyrazole building blocks.
- Kumpulainen, Esa T. T.,Pohjakallio, Antti
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supporting information
p. 1555 - 1561
(2014/06/09)
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- N-Alkylation of amines with alcohols over nanosized zeolite beta
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Direct N-alkylation of amines with alcohols was successfully performed by using nanosized zeolite beta, which showed the highest catalytic activity among other conventional zeolites. This method has several advantages, such as eco-friendliness, moderate to high yields, and simple work-up procedure. The catalyst was successfully recovered and reused without significant loss of activity and only water is produced as co-product. In addition, imines were also efficiently prepared from the tandem reactions of amines with 2-, 3- and 4-nitrobenzyl alcohols using nanosized zeolite beta.
- Reddy, Marri Mahender,Kumar, Macharla Arun,Swamy, Peraka,Naresh, Mameda,Srujana, Kodumuri,Satyanarayana, Lanka,Venugopal, Akula,Narender, Nama
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supporting information
p. 3474 - 3483
(2013/12/04)
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- Direct synthesis of pyrazolo[5,1-a]isoindoles via intramolecular palladium-catalyzed C-H bond activation
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An efficient, direct synthesis of pyrazolo-[5,1-a]isoindoles employing a palladium-catalyzed intramolecular C-H bond activation of 1-(2-halobenzyl) pyrazoles has been developed. The use of lithium chloride (LiCl) was found to be essential in these reactions, to suppress further C-H bond activation at the C-3 position of pyrazolo[5,1-a]isoindole, when C-3 is unsubstituted. This protocol can be applied to the synthesis of a pyrazolo[5,1-a]isoquinoline possessing a six-membered central ring system and a fully substituted pyrazolo[5,1-a]isoindole using sequential intra- and intermolecular C-H bond activation.
- Choi, Young Lok,Lee, Hyuk,Kim, Bum Tae,Choi, Kihang,Heo, Jung-Nyoung
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scheme or table
p. 2041 - 2049
(2010/11/19)
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- Reaction of malondialdehyde-DNA adducts with hydrazines - Development of a facile assay for quantification of malondialdehyde equivalents in DNA
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Malondialdehyde is a ubiquitous product of lipid peroxidation that reacts with DNA to form premutagenic lesions. Principal among them is pyrimido-[1,2-α]purin-10(3H)-one (M1G). M1G has recently been found to be a reactive electrophile in DNA that couples with amines at basic pH or hydroxylamines at neutral pH. We explored the reaction of M1G with hydrazines because of the possibility that the latter could act as bifunctional nucleophiles to strip the malondialdehyde equivalent from DNA. Pentafluorophenylhydrazine reacted rapidly with M1G to form a hydrazone conjugate. This hydrazone was stable at room temperature and did not cyclize to form the corresponding pyrazole. In contrast, phenylhydrazine and benzylhydrazine reacted with M1G to form phenylpyrazole and benzylpyrazole, respectively. Pentafluorobenzylhydrazine reacted rapidly with M1G to form pentafluorobenzylpyrazole and dG in near quantitative yield. This reaction formed the basis for a quantitative assay for the presence of M1G or M1G equivalents in DNA or protein that utilized gas chromatography/negative chemical ionization mass spectrometry. The assay was extended to the oxopropenyl donors, M1A, base propenal, and Nε-3-oxopropenyl-lysine. Analysis of DNA treated with bleomycin demonstrated a linear increase in the level of oxopropenyl groups that plateaued at approximately 1 oxopropenyl group/100 bases at a bleomycin concentration of 200 μM. Parallel analysis of M1G in the samples revealed that this adduct represents a small fraction of the total oxopropenyl units generated in DNA by treatment with bleomycin.
- Otteneder, Michael,Plastaras, John P.,Marnett, Lawrence J.
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p. 312 - 318
(2007/10/03)
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- N-Alkylation of anilines, carboxamides and several nitrogen heterocycles using CsF-Celite/alkyl halides/CH3CN combination
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It has been found that the N-alkylation of aniline, carboxamides and heterocyclic compounds bearing an acidic hydrogen atom attached to nitrogen can be accomplished with alkyl halides in acetonitrile and cesium fluoride-celite employed as a solid base. In this manner, pyrrole, indole, pyrazole, imidazole, benzimidazole, carbazole, phthalimide, indazole, indoline, 2-pyrrolidinone, piperidine and 1,2,4-triazole can be successfully alkylated. The procedure is convenient, efficient and generally gives rise to the N-alkylated product exclusively.
- Hayat, Safdar,Atta-Ur-Rahman,Iqbal Choudhary,Khan, Khalid Mohammed,Schumann, Wilhelm,Bayer, Ernst
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p. 9951 - 9957
(2007/10/03)
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- C-pyrazole 2A A receptor agonists
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2-adenosine C-pyrazole compositions having the following formula: and methods for using the compositions as A2A receptor agonists to stimulate mammalian coronary vasodilatation for therapeutic purposes and for purposes of imaging the heart.
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- Quaternization and dequaternization of pyrazoles in solvent- free conditions: Conventional heating versus microwave irradiation
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We report a study on the quaternization and dequaternization of pyrazoles by conventional heating and microwave irradiation in solvent-free conditions. Microwave irradiation produces an acceleration in the quaternization rate and a rapid equilibration between quaternized and non quaternized products. Dequaternization is also more rapid and a change on the selectivity is observed using symmetric pyrazolium salts.
- Diez-Barra, Enrique,De La Hoz, Antonio,Sanchez-Migallon, Ana,Elguero, Jose
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p. 889 - 894
(2007/10/03)
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- Pyrolysis of 1-substituted pyrazoles and chloroform at 550°C: Formation of α-carboline from 1-benzylpyrazoles
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Pyrolysis of 13CH3 labelled 1-methylpyrazole 8 with chloroform at 550°C in a continuous flow reactor yields unlabelled 2-chloropyrimidine 9 and 2-cyanopyrrole 10 labelled at the cyano group. However, pyrolysis of 1-benzylpyrazole 14 with chloroform under similar conditions gives 9,2-phenylpyrimidine 13 and, as the major product, α-carboline 15. Pyrolysis of several substituted 1-(arylmethyl)pyrazoles and the use of 13C and 15N labelled compounds provides direct evidence by which the positions of 7 atoms of 1-benzylpyrazole can be located in the α-carboline. These data support the mechanisms suggested for the formation of 9, 10, and 15.
- Bhatti, Inayat A.,Busby, Reginald E.,Bin Mohamed, Murtedza,Parrick, John,Shaw, C. J. Granville
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p. 3581 - 3585
(2007/10/03)
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- Oxidation potential as a measure of the reactivity of anionic nucleophiles. Behaviour of different classes of nucleophiles
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Anodic peak potentials for 42 anionic nucleophiles are reported along with the rate constants for the reactions of the anions with benzyl chloride.By comparing these rate constants with those of the reactions of outer-sphere electron-transfer reagents (radical anions), it has been demonstrated that the reactions of the anions with benzyl chloride are typical single-step SN2 reactions as opposed to a two-step process comprising dissociative single electron transfer (SET) to benzyl chloride followed by radical combination.The data suggest that very electron-rich nucleophilic anions with potentials of -1.5 to -2.2 V (and more negative) with respect to the ferrocenium/ferrocene couple might participate in a SET reaction.The 42 anions studied included representatives of four classes of nucleophiles, viz. sulfur-, carbon-, oxygen- and nitrogen-centred anions.The previously observed correlation of rate constants and anodic peak potential was again found for these anions with the most reactive species having the most negative peak potentials.Correlations by class indicate that the sensitivity of rate constants to changes in peak potential is greatest (and equivalent) for the sulfur-, carbon- and oxygen-anions and for representatives with the same peak potential, the rate constants by class follow the order sulfur > carbon > oxygen.The nitrogen nucleophiles show a significantly lower sensitivity of rate constant to changes in peak potential than do the other three classes.
- Niyazymbetov, Murat E.,Rongfeng, Zhou,Evans, Dennis H.
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p. 1957 - 1962
(2007/10/03)
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- Deprotonation of 2-Substituted Pyrazole 1-Oxides
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H-3 and H-5 are more acidic in 2-benzylpyrazole 1-oxide than in the parent 1-benzylpyrazole.Deprotonation followed by addition of dimethyl disulfide proceeds with low mono- and regio-selectivity to give a mixture of 3-methylthio-, 5-methylthio- and 3,5-bi
- Almena, Ines,Begtrup, Mikael,Hoz, Antonio de la
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p. 1096 - 1100
(2007/10/02)
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- Synthesis of N-Alkylpyrazoles by Phase Transfer Catalysis without Solvent
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The alkylation of pyrazole is performed by phase transfer catalysis without solvent.High yields of N-alkylpyrazoles are obtained and the principal problems in the alkylation are suitably solved.
- Diez-Barra, E.,Hoz, A. de la,Sanchez-Migallon, A.,Tejeda, J.
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p. 2849 - 2853
(2007/10/02)
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- Alkylation, Acylation and Silylation of Azoles
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Performing alkylation, acylation and silylation reactions in separate deprotonation and nucleophilic displacement steps allows for better control of reaction conditions and facilitates problem handling in these processes.In the alkylation of azoles the alkylating agents and solvents possess individual reaction capabilities which seem to be approximately additive.Monoalkylation occurs if the sum of the normalized reaction potentials is equal or larger than the pKa value of the azole.Dialkylation is avoided by keeping the sum of the normalized reaction potentials below the pKa value of the alkylazole.The applicability of these principles is demonstrated by the development of effective procedures for the methylation, benzylation, acetylation, methoxycarbonylation and trimethylsilylation of azoles.
- Begtrup, Mikael,Larsen, Peter
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p. 1050 - 1057
(2007/10/02)
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- SYNTHESIS BY PHASE TRANSFER CATALYSIS OF N-BENZYL, N-DIPHENYLMETHYL AND N-TRIPHENYLMETHYL AZOLES AND BENZAZOLES: PROTON NMR AND CHROMATOGRAPHIC DATA AS A TOOL FOR IDENTIFICATION
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Pyrazole, imidazole, 1,2,4-triazole, indazole and benzotriazole were alkylated under phase transfer catalysis (PTC) with benzyl-, diphenylmethyl- and trityl chloride.Alkylation occured only at the ring nitrogen atoms of the heterocycle, except for indazole in which substitution took also place at position 3.A systematic study of the N- and C-substituted derivatives by proton NMR and chromatographic techniques has been done.
- Claramunt, Rosa M.,Elguero, Jose,Garceran, Rafael
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p. 2895 - 2906
(2007/10/02)
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- ETUDE DANS LA SERIE DES ORGANOSILYLAZOLES I. ACTION DES HALOGENURES D'ALKYLE, DES CHLORURES D'ACIDE ET DES CETONES HALOGENEES
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The reactivity of organosilylamines of imidazole, pyrazole, 1,2,4-triazole and benzotriazole towards alkyl halides, acidic chlorides and halogenated ketones has been studied.Except for 1-trimethylsilylimidazole, which gives a mixed quaternary salt, reactions with primary halides lead to the corresponding 1-alkylated heterocyclic compounds in high yields; in each case only one isomer is obtained (1-alkyl-1,2,4-triazole and 1-alkylbenzotriazole).Similarly acidic chlorides give 1-acylated derivatives in quantitative yields.Finally α- or β-halogenated ketones show different behaviour and give the addition or substitution products.
- Gasparini, J. P.,Gassend, R.,Maire, J. C.,Elguero, J.
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p. 141 - 150
(2007/10/02)
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