- Electron Transfer on the Photodehalogenation of 2-(4-chlorophenyl)benzoxazole Assisted by Amines
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The photochemical reactivity of 2-(4-chlorophenyl)benzoxazole in the presence of a series of amines has been investigated.A fluorescence quenching study provides evidence for the formation of an exciplex between the singlet excited state of the benzoxazole derivative and the amine in its ground state.This exciplex gives rise to a charge-transfer complex (CTC).The quenching fluorescence date can be fitted by a Weller-Marcus system, thus leading to large reorganization energies.The measurment of dehalogenation, which is drastically increased in the presence of amines, allowed us to estimate the reactivity of the CTC.In the case of tertiary amines, 1percent of the CTC formed via the singlet state leads to the dehalogenation.For secondary amines a hydrogen transfer between the amine and the excited triplet state of the chloro compound is also postulated.
- Fery-Forgues, Suzanne,Lavabre, Dominique,Paillous, Nicole
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- Isotopic probes for ruthenium-catalyzed olefin metathesis
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Routes are described to previously unreported first- and second-generation Grubbs metathesis catalysts bearing a 13C label at the key benzylidene or methylidene site. Improved syntheses of the 2H-labelled isotopologues are also presented. Labelling at the alkylidene position is important because it provides unique, direct information about changes at the active site of the catalyst, and the fate of the [Ru]CHR ligand during catalyst deactivation. A case study demonstrates the power of 13C-labelling in tracking the methylidene moiety in amine-induced decomposition of the second-generation complex RuCl2(PCy3)(H2IMes)(13CH2). Also reported is the solubility of ethylene in C6D6 and CD2Cl2, measured at 296 ± 1.5 K and 101.0 ± 0.8 kPa. This journal is
- Lummiss, Justin A. M.,Botti, Adrian G. G.,Fogg, Deryn E.
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- SPECIFIC ACID CATALYSIS IN THE DECOMPOSITION OF TRIALKYLTRIAZENES.
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The acid-catalyzed decomposition of 1,3-di-n-butyl-3-methyltriazene (1) in aqueous buffer was investigated. Determination of the kinetics over a pH range of 10. 4 to 12 indicated that the reaction is acid catalyzed. Variation of buffer concentration, at constant ionic strength, produced an insignificant variation in the rate constant. The determination of kinetics of the decomposition of 1 in nine different buffers, ranging in pK//a from 9. 6 to 12. 7, also gave negligible variation in the rate constants. The solvent isotope effect for the reaction, k//H/k//D, was 0. 62. These data strongly support the conclusion that the reaction is specific acid catalyzed. This implies that the reaction involves fast, reversible protonation of the triazene followed by the rate-determining heterolysis of the protonated species to n-butyldiazonium ion and n-butylmethylamine.
- Smith Jr.,Denlinger,Kupper,Koepke,Michejda
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- A Lewis Base Nucleofugality Parameter, NFB, and Its Application in an Analysis of MIDA-Boronate Hydrolysis Kinetics
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The kinetics of quinuclidine displacement of BH3 from a wide range of Lewis base borane adducts have been measured. Parameterization of these rates has enabled the development of a nucleofugality scale (NFB), shown to quantify and predict the leaving group ability of a range of other Lewis bases. Additivity observed across a number of series R′3-nRnX (X = P, N; R′ = aryl, alkyl) has allowed the formulation of related substituent parameters (nfPB, nfAB), providing a means of calculating NFB values for a range of Lewis bases that extends far beyond those experimentally derived. The utility of the nucleofugality parameter is explored by the correlation of the substituent parameter nfPB with the hydrolyses rates of a series of alkyl and aryl MIDA boronates under neutral conditions. This has allowed the identification of MIDA boronates with heteroatoms proximal to the reacting center, showing unusual kinetic lability or stability to hydrolysis.
- García-Domínguez, Andrés,Gonzalez, Jorge A.,Leach, Andrew G.,Lloyd-Jones, Guy C.,Nichol, Gary S.,Taylor, Nicholas P.
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supporting information
(2022/01/04)
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- Photometric Characterization of the Reductive Amination Scope of the Imine Reductases from Streptomyces tsukubaensis and Streptomyces ipomoeae
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Imine reductases (IREDs) have emerged as promising enzymes for the asymmetric synthesis of secondary and tertiary amines starting from carbonyl substrates. Screening the substrate specificity of the reductive amination reaction is usually performed by time-consuming GC analytics. We found two highly active IREDs in our enzyme collection, IR-20 from Streptomyces tsukubaensis and IR-Sip from Streptomyces ipomoeae, that allowed a comprehensive substrate screening with a photometric NADPH assay. We screened 39 carbonyl substrates combined with 17 amines as nucleophiles. Activity data from 663 combinations provided a clear picture about substrate specificity and capabilities in the reductive amination of these enzymes. Besides aliphatic aldehydes, the IREDs accepted various cyclic (C4–C8) and acyclic ketones, preferentially with methylamine. IR-Sip also accepted a range of primary and secondary amines as nucleophiles. In biocatalytic reactions, IR-Sip converted (R)-3-methylcyclohexanone with dimethylamine or pyrrolidine with high diastereoselectivity (>94–96 % de). The nucleophile acceptor spectrum depended on the carbonyl substrate employed. The conversion of well-accepted substrates could also be detected if crude lysates were employed as the enzyme source.
- Matzel, Philipp,Krautschick, Lukas,H?hne, Matthias
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p. 2022 - 2027
(2017/10/07)
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- Copper(II)-Catalyzed Selective Reductive Methylation of Amines with Formic Acid: An Option for Indirect Utilization of CO2
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A copper-catalyzed protocol for reductive methylation of amines and imine with formic acid as a C1 source and phenylsilane as a reductant is reported for the first time, affording the corresponding methylamines in good to excellent yields under mild conditions. This protocol offers an alternative method for indirect utilization of CO2, as formic acid can be readily obtained from hydrogenation of CO2.
- Qiao, Chang,Liu, Xiao-Fang,Liu, Xi,He, Liang-Nian
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supporting information
p. 1490 - 1493
(2017/03/23)
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- N-Methylation of amines with methanol in a hydrogen free system on a combined Al2O3-mordenite catalyst
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N-Methyl amines play a major role in the production of medicines, pesticides, surfactants and dyes. N-Methylation of primary or second amines with methanol is considered to be a green path for the synthesis of N-methyl amines and the catalyst is key. In this article, the combined Al2O3-mordenite catalyst (mass fraction of alumina is 40%) with good activity, selectivity, lifetime and stability was prepared for N-methylation of various amines with methanol in a hydrogen free system in a fixed bed reactor, and characterized by XRD, N2 adsorption and NH3-TPD. Furthermore, the methanol adsorption was investigated by in situ FTIR, and the result indicated that methoxyl species may be the active species for the N-methylation of amines.
- Su, Jiahui,Li, Xungang,Chen, Yunbin,Cui, Yuancun,Xu, Jingwei,Qian, Chao,Chen, Xinzhi
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p. 55643 - 55649
(2016/07/06)
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- Selective N-methylation of aliphatic amines with CO2 and hydrosilanes using nickel-phosphine catalysts
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A method using CO2 and PhSiH3 for the methylation of primary and secondary aliphatic amines catalyzed by Ni (0) complexes was developed, selectively producing the monomethylated products in moderate to good yields. For that purpose, two catalysts were used: [(dippe)Ni(μ-H)]2 and the commercially available Ni(COD)2/dcype, both of which were rather efficient in this process. With a slight experimental modification, the reaction allowed the production of monomethylated ureas in good yields by using low amounts of PhSiH3. On the basis of the experimental results, we propose a possible reaction mechanism for the formation of the new C-N bond.
- Gonzlez-Sebastin, Lucero,Flores-Alamo, Marcos,Garca, Juventino J.
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p. 763 - 769
(2015/05/12)
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- Catalytic hydrogenation of amides to amines under mild conditions
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Under (not so much) pressure: A general method for the hydrogenation of tertiary and secondary amides to amines with excellent selectivity using a bimetallic Pd-Re catalyst has been developed. The reaction proceeds under low pressure and comparatively low temperature. This method provides organic chemists with a simple and reliable tool for the synthesis of amines. Copyright
- Stein, Mario,Breit, Bernhard
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supporting information
p. 2231 - 2234
(2013/03/28)
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- Reactivity of the insecticide fenitrothion toward O and N nucleophiles
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The reactivity of Fenitrothion (1) toward several O- and N-based nucleophiles, including ambident and α-nucleophiles, was investigated in basic media at 25 °C in water containing 2% 1,4-dioxane. In the reactions with HO- and HOO- quantitative formation of 3-methyl-4-nitrophenoxide (2) was observed indicating a SN2(P) pathway. In the reactions with NH2OH, NH2O-, and BuNH2, demethylfenitrothion (4) was formed along with 2, indicating competition between the SN2(P) and SN2(C) pathways; no evidence of a SNAr pathway was observed in any case. The observed rate constants were dissected into the values corresponding to the SN2(P) and SN2(C) pathways. The yield of 4 depends on the nucleophile and on the pH of the reaction, being the main product in the case of BuNH2. With HOO-, NH2OH, and NH 2O- a significant α-effect was observed, confirming the participation of the nucleophile in the rate-limiting step of the reaction.
- Rougier, Natalia M.,Vico, Raquel V.,De Rossi, Rita H.,Bujan, Elba I.
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supporting information; body text
p. 3427 - 3436
(2010/07/05)
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- Synthesis of nonsymmetrical dialkylamines on the basis of diphenylphosphinic amides
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A facile method for the synthesis of nonsymmetrical dialkylamines (C nH2n+1)2NH (n = 1-12) using the Ph 2P(O) protecting group was developed. The method includes successive transformation of monoalkylamines to primary diphenylphosphinic N-alkylamides Ph2P(O)NHR' (R' = CnH2n+1, n = 1-12) by the Todd-Atherton reaction, phase transfer N-alkylation of these compounds, and hydrolysis of the secondary amides Ph2P(O)NR'R″ thus formed. When the (EtO)2P(O) and Bu2P(O) protecting groups are used, N-alkylation of primary amides is accompanied by the formation of Et-O and P-N bond cleavage products, respectively. A study of the stability of the N-alkylamides R2P(O)NHR' (R = Ph, p-MeC6H4, p-CIC6H4, Bu) under strong alkaline conditions used in the phase transfer N-alkylation showed that an increase in the electron-donating ability of substituents at both the nitrogen atom and the phosphorus atom results in a decrease in the degree of P-N bond cleavage. The primary and secondary diphenylphosphinic amides containing a β-hydroxyethyl group at the nitrogen atom are extremely unstable under the alkaline conditions and are converted quantitatively to the diphenylphosphinic acid salt.
- Bondarenko,Kharlamov,Vendilo
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experimental part
p. 1872 - 1885
(2011/01/06)
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- Determination of basic strength of aliphatic amines through ion pair formation in some ionic liquid solutions
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(Chemical Equation Presented) To have an evaluation of the basic strength of aliphatic amines in ionic liquid solution, the stability constants relevant to the formation of amine/p-nitrophenol ion pairs were determined in different ionic liquids at 298 K.
- D'Anna, Francesca,Vitale, Paola,Noto, Renato
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experimental part
p. 6224 - 6230
(2009/12/08)
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- Reductive methylation of primary and secondary amines and amino acids by aqueous formaldehyde and zinc
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Amines can be methylated when treated with formaldehyde and zinc in aqueous medium. Selective mono- or dimethylation can be achieved by proper choice of pH, stoichiometry and reaction time. This method can also be applied for amino acids.
- da Silva, Renato A.,Estevam, Idália H.S.,Bieber, Lothar W.
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p. 7680 - 7682
(2008/03/30)
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- 2,3,4,5-TETRAHYDRO-1H-1,5-BENZODIAZEPINE DERIVATIVE AND MEDICINAL COMPOSITION
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The present invention has its object to provide a 2,3,4,5-tetrahydro-1H-1,5-benzodiazepine derivative represented with the Formula (1) , or the pharmaceutically acceptable salt, which is effective as a therapeutic and prophylactic agent for diabetes, diabetic nephropathy, or glomerulosclerosis.
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- Continuous chemoselective methylation of functionalized amines and diols with supercritical methanol over solid acid and acid-base bifunctional catalysts
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The selective N-methylation of bifunctionalized amines with supercritical methanol (scCH3OH) promoted by the conventional solid acids (H-mordenite, β-zeolite, amorphous silica-alumina) and acid-base bifunctional catalysts (Cs-P-Si mixed oxide and γ-alumina) was investigated in a continuous-flow, fixed-bed reactor. The use of scCH 3OH in the reaction of 2-aminoethanol with methanol (amine/CH 3OH = 1/10.8) over the solid catalysts led to a significant improvement in the chemoselectivity of the N-methylation. Among the catalysts examined, the Cs-P-Si mixed oxide provided the most efficient catalyst performance in terms of selectivity and reactivity at 300 °C and 8.2 MPa; the N-methylation selectivity in the products reaching up to 94% at 86% conversion. The present selective methylation was successfully applied to the synthesis of N-methylated amino alcohols and diamines as well as O-methylated ethylene glycol. Noticeably, ethoxyethylamine was less reactive, suggesting that the hydroxy group of the amino alcohols is a crucial structural factor in determining high reactivity and selectivity, possibly because of the tethering effect of another terminus, a hydroxo group, to the catalyst surface. The magic-angle-spinning NMR spectroscopy and X-ray diffraction analysis of the Cs-P-Si mixed oxide catalyst revealed that the acidic and basic sites originate from P2O5/SiO2 and Cs/SiO2, respectively, and the weak acid-base paired sites are attributed to three kinds of cesium phosphates on SiO2. The weak acid-base sites on the catalyst surface might be responsible for the selective dehydrative methylation.
- Oku, Tomoharu,Arita, Yoshitaka,Tsuneki, Hideaki,Ikariya, Takao
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p. 7368 - 7377
(2007/10/03)
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- Enhanced product selectivity in continuous N-methylation of amino alcohols over solid acid-base catalysts with supercritical methanol
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The unique properties of supercritical fluids can be exploited for fine-tuning product selectivity. Under the conditions listed for the N-methylation of amino alcohols (see scheme) over solid acid-base bifunctional catalysts, the total yield and product selectivity could be improved. Enhanced product selectivity might be attributed to the milder reaction conditions possible with supercritical methanol, as well as the increased concentration of methanol on the catalyst.
- Oku, Tomoharu,Ikariya, Takao
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p. 3476 - 3479
(2007/10/03)
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- Kinetics and mechanism of hydrolysis of phenylureas
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The hydrolysis of phenylureas has been found to be affected by temperature, pH and buffer concentration. Kinetic evidence suggests that the formation of phenylisocyanate, the initial product in the title reaction, occurs via an intermediate zwitterion. Depending on pH and buffer concentrations, the zwitterion can be produced through three parallel routes: at low pH, specific acid-general base catalysis, followed by slow deprotonation of a nitrogen atom by a general base; at high pH, specific basic-general acid catalysis, followed by slow protonation of a N atom by a general acid; at intermediate pH the reaction proceeds through a proton switch promoted by buffers. Bifunctional acid-base buffers such as HCO3-/CO32-, H2PO42- and CH3COOH/CH3COO- are very efficient catalysts. At high buffer concentration, as well as at pH 12, the breakdown of the zwitterion is rate-determining. The results are discussed in relation to recently published papers reporting different pathways.
- Salvestrini, Stefano,Di Cerbo, Paola,Capasso, Sante
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p. 1889 - 1893
(2007/10/03)
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- Process for the preparation of N-methylalkylamines
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A process for the preparation of N-methylalkylamines of the formula CH3 --NH--CH2 --R in which R is an aliphatic radical having 1 to 3 carbon atoms, by reacting an aldehyde of the formula R--CHO with an amine of the formula R'--NH2 to give a Schiff base, removing the water of reaction, and reacting the Schiff base with methylamine and hydrogen in the presence of a hydrogenation catalyst.
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- Preparation of amines
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A process for preparing an amine by catalytic reaction of an olefin with ammonia or a primary or secondary amine by contacting a mixture of the reactants in a reactor at 200° to 400° C. and an elevated pressure up to 700 bar in the presence of a catalyst consisting essentially of an X-ray amorphous (non-crystalline) mesoporous catalyst, some of which may have a microporous non-crystalline content. The catalyst has the composition where Q is at least one of the trivalent elements aluminum, boron, chromium, iron or gallium, and M is at least one of the tetravalent elements silicon, titanium or germanium. The molar ratio of a:b is from 0.5:1 to 1000:1 and the molar ratio of c:b is from 0 to 2:1. As prepared and used in the process, this non-crystalline catalyst has a specific BET surface area of from 200 to 1000 m2 /g.
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- Thermodynamic and nuclear magnetic resonance study of the reactions of α- and β-cyclodextrin with acids, aliphatic amines, and cyclic alcohols
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Titration calorimetry was used to determine equilibrium constants and standard molar enthalpy, Gibbs energy, and entropy changes for the reactions of a series of acids, amines, and cyclic alcohols with α- and β-cyclodextrin. The results have been examined in terms of structural features in the ligands such as the number of alkyl groups, the charge number, the presence of a double bond, branching, and the presence of methyl and methoxy groups. The values of thermodynamic quantities, in particular the standard molar Gibbs energy, correlate well with the structural features in the ligands. These structural correlations can be used for the estimation of thermodynamic quantities for related reactions. Enthalpy-entropy compensation is evident when the individual classes of substances studied herein are considered, but does not hold when these various classes of ligands are considered collectively. The NMR results indicate that the mode of accommodation of the acids and amines in the α-cyclodextrin cavity is very similar, but that the 1-methyl groups in 1-methylhexylamine and in 1-methylheptylamine and the N-methyl group in N-methylhexylamine lie outside the α-cyclodextrin cavity. This latter finding is consistent with the calorimetric results. Many of the thermodynamic and NMR results can be qualitatively understood in terms of van der Waals forces and hydrophobic effects.
- Rekharsky, Mikhail V.,Mayhew, Martin P.,Goldberg, Robert N.,Ross, Philip D.,Yamashoji, Yuko,Inoue, Yoshihisa
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- Synthesis and Hydrolytic Lability of α-Phenoxyacetamides Containing Hydroxy Groups in the N-alkyl Residue
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Secondary and tertiary amides of 3,5-biscarbonyl>phenoxyacetic acid bearing hydroxy groups in positions β (β-OH) and γ (γ-OH) relative to the acetamide nitrogen atom have been synthesized.Such amides easily undergo cleavage of the acetamide bond in water at neutral pH.Hydrolysis rate constant for a series of such amides and protonation constants for the corresponding leaving amines were determined.No simple correlation between the two parameters could be found.A study of the dependence of these parameters on the structural features of the substrates, such as the presence of an N-methyl group and number of β-OH and γ-OH groups, was carried out.All these features lead to enhancement of the amide hydrolysis rate and a synergistic effect is operative when both N-methyl and β-OH groups are contained in the substrate.Presence of a methyl group increases the basicity of amines whereas β-OH and γ-OH groups have the opposite effect.Mechanistic speculations seem to indicate that the abnormal lability of the acetamide bond is due to protic-like catalysis by an intramolecular OH...N hydrogen bond.
- Anelli, Pier Lucio,Brocchetta, Marino,Canipari, Sonia,Losi, Pietro,Manfredi, Giuseppe,et al.
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p. 135 - 142
(2007/10/03)
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- ALKYLATING PROPERTIES OF DIALKYL PHOSPHITES
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When the mixture of amines and dialkyl phosphites is used in the reaction, as for example in the Kabachnik-Fields reaction, all possible N-alkylated products are formed.N-ethylation by diethyl phosphite is much slower than N-methylation by dimethyl phosphite and the latter can be easily formed via transesterification when the methanol is present in the mixture.Key words: Amine alkylation, dialkyl phosphites, Kabachnik-Fields synthesis.
- Gancarz, Roman
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p. 193 - 200
(2007/10/02)
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- ELECTROCHEMICAL REDUCTIVE AMINATION. II. AMINATION OF ALIPHATIC ALDEHYDES WITH PRIMARY AMINES
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The formation of a secondary amine by the electrolysis of an aqueous solution containing an aldehyde and a primary amine was studied.The formation of the secondary amines passes through the intermediate stage of an aldimine.The highest yield of secondary amine is attained at a molar ratio of primary amine to aldehyde of 1.2:1.As electrode material lead, cadmium, zinc, and copper may be used.As supporting electrolyte a phosphate buffer with a pH close to the pKa of the primary amine is recommended.By the method developed 32 amines with various structures were synthesized.
- Smirnov, Yu. D.,Pavlichenko, V. F.,Tomilov, A. P.
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p. 374 - 380
(2007/10/02)
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- 19→nor→steroids
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Novel 19-nor-steroids of the formula STR1 wherein the A and B rings have a structure selected from the group consisting of STR2 having hormonal properties and their preparation and intermediates.
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- PHOSPHONIUM DIAZA-DIYLIDS AND AZA-YLDIID AS NEW AND EFFICIENT REAGENTS FOR PRIMARY AND SECONDARY AMINES SYNTHESIS
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Metallated aminophosphonium ylids, diaza-diylids and aza-yldiid, are investigated as reagents for primary and secondary amines synthesis.
- Cristau, Henri-Jean,Garcia, Chantal,Kadoura, Jumah,Torreilles, Eliane
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p. 151 - 154
(2007/10/02)
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- Aromatic Nucleophilic Substitution Reactions of 1-Dialkylamino-2,4-dinitronaphthalene with Primary or Secondary Amines in Organic Solvents: Facile Amine-Amine Exchange
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The dialkylamino group, (e.g., dimethyl-, diethyl-, and N-n-butyl-N-methylamino, piperidino, and pyrrolidino) of 1-dialkylamino-2,4-dinitronaphthalenes is rapidly replaced by primary amines, particulary in dimethyl sulphoxide; however, substitution does not occur for secondary amines except in the case of pyrrolidine.
- Sekiguchi, Shizen,Horie, Tohru,Suzuki, Tohru
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p. 698 - 700
(2007/10/02)
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- Ion-Dipole Complexes in the Unimolecular Reactions of Isolated Organic Ions. Effect of N-Methylation on Olefin and Amine Loss from Protonated Aliphatic Amines
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The slow unimolecular fragmentation reactions os 18 gaseous protonated aliphatic amines of general formula R1NH(1+)R2R3 (R1=Prn, Pri, Bun, Bui, Bus, or But; R2,R3=H,CH3) are reported and discussed.Two decomposition routes are observed for a metastable ions R1NH(1+)R2R3.The first involves elimination of a neutral amine, R2R3NH, and formation of a carbocation, R1(1+), via a mechanism involving an incipient cation bound to the developing amine by an ion-dipole attraction.Rearrangement of the cation, to give thermodynamically more stable isomers, is feasible in these ion-dipole complexes.Further reorganization of the complexes leads to a species in which an incipient olefin 1-H> and an amine 2R3NH> are co-ordinated to a common proton.Dissociation of these proton-bound complexes, with retention of the proton by the developing amine, results in olefin loss, which is the secondreaction undergone by metastable ions R1NH(1+)R2R3.The relative abundance of amine expulsion is greater for protonated amines containing a primary alkyl group, R1, than is the case for isomeric ions containing secondary or tertiary alkyl groups.Progressive methylation of the nitrogen atom decreases the relative abundance of amine loss from R1NH(1+)R2R3, regardless of the nature of the principal alkyl group.These two trends are explained in terms of the energetics of the intermediates and products involved in the decomposition of the protonated amines.
- Bowen, Richard D.,Harrison, Alex G.,Reiner, Eric J.
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p. 1009 - 1014
(2007/10/02)
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- Mechanism of the Uncatalysed Path of Aromatic Nucleophilic Substitution in Dipolar Aprotic Solvents when Primary and Secondary Amines are the Nucleophiles; a Search for Electrophilic Catalysis of these Reactions
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The kinetics of the reactions of 1-chloro- and 1-fluoro-2,4-dinitrobenzene with morpholine have been studied in dimethyl sulphoxide, dimethylformamide, and nitromethane.The results confirm that the decomposition of the intermediate to products by the uncatalysed path takes place by a unimolecular mechanism.The kinetics of the reactions of 2,4-dinitroanisole with n-butylamine and piperidine in dipolar aprotic solvents have been determined.They show that when primary amines are the nucleophiles, reaction by the uncatalysed path does not occur by the unimolecular mechanism, but by the specific base-general acid (SB-GA) route.The reactions in dimethyl sulphoxide give another example of secondary amines reacting by a base catalysis mechanism whereas the corresponding reaction of a primary amine of the same basicity is not base-catalysed.In a search for electrophilic catalysis the effects of lithium, trialkylammonium, and tetraalkylammonium ions on the reactions of piperidine with 2,4-dinitroanisole and of morpholine with 2,4-dinitrophenyl phenyl ether in dimethyl sulphoxide were investigated.No catalysis was found and a tentative reason is given.When aniline reacts with 2,4,6-trinitrophenyl methyl ether in dimethyl sulphoxide, 82percent of the reaction occurs at the methyl carbon atom, and when the substrate is 2,4,6-trinitrophenyl phenyl ether the reaction is not base-catalysed.The first two observations of the change from base-catalysed to uncatalysed aromatic nucleophilic substitution reactions brought about by a change from protic to dipolar aprotic solvent are recorded.
- Hirst, Jack,Hussain, Ghazanfar,Onyido, Ikenna
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p. 397 - 404
(2007/10/02)
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- Kinetics of Reversible Endothermic Elimination Reactions: β-Amino Carboxylic Esters and Amides
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The kinetics of the elimination reactions of substituted β-amino carboxylic esters and amides, to give amines and the α,β-unsaturated esters and amides, have been studied in several model systems.The reaction was studied by trapping the olefin formed with another nucleophile capable of competing with the amine formed by elimination.The rate constant for elimination of methyl 3-(N-methyl-N-butylamino)propionate, in methanol at room temperature, is 1.8E-6 s-1.The corresponding amide has an elimination rate constant 8.8E-8 s-1.Rate constants for the forward reaction were also measured and combined with the reversion rate constants to yield equilibrium constants for the same two systems.The equilibrium constants for the methyl esters is 2.0E4 L mol-1 and for the amides is 7.3E3 L mol-1.These were confirmed by measurement of the equilibrium concentrations of olefins by 1H NMR spectroscopy.
- Johnson, Mark R.
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p. 833 - 837
(2007/10/02)
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- Competing Hydride Transfer and Ene Reactions in the Aminoalkylation of 1-Alkenes with N,N-Dimethylmethyleniminium Ions. A Literature Correction
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A literature report that N,N-dimethylmethyleniminium ion (2) reacts with propylene and styrene to form unsaturated tertiary amines is shown to be incorrect.The major products are the secondary amines 1-(methylamino)butane and 1-(methylamino)-3-phenylpropane in which N-demethylation has occurred along with the saturation of the alkene.Analogous major products are formed with 1-butene, 1-hexene, 1-octene, 1-dodecene, 1-tetradecene, p-methylstyrene, and m-nitrostyrene as substrates.When the substrates are isobutylene, 2-ethyl-1-hexene, α-methylstyrene, and p-methoxystyrene, the major products are tertiary amines, but the secondary amines are also formed in smaller yields.The small yields of tertiary amines obtained in the cases of styrene and p-methylstyrene were increased by going from solvent acetic acid to acetonitrile and by increasing the branching of the alkyl groups on nitrogen.The internal olefins 5-decene and cyclohexene were far less reactive, giving only 3-4percent of amine products that were mainly tertiary in the former case and secondary in the latter.It is concluded that tertiary amine products are favored by an alkene structure and a solvent that favors the formation of a stable carbenium ion intermediate or a transition state with substantial carbenium ion character upon electrophilic attack of the iminium ion on the alkene.The secondary amine products are favored when a carbenium ion is of low stability and when the β-carbon atom of the olefin and/or the alkyl group attached to nitrogen is sterically unhindered; such hindrance decreases the rate of hydride ion transfer that is believed to occur in the production of secondary amines.
- Cohen, Theodore,Onopchenko, Anatoli
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p. 4531 - 4537
(2007/10/02)
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- THE ELECTROPHILIC AMINATION OF ORGANOLITHIUMS WITH METHYLLITHIUM COMPLEXES OF N-SUBSTITUTED METHOXYAMINES
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Three N-alkyl methoxyamine derivatives are shown to be effective as electrophilic reagents for the conversion of organolithiums to secondary amines.
- Kokko, Bruce J.,Beak, Peter
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p. 561 - 564
(2007/10/02)
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- SELECTIVE CONVERSION OF PRIMARY AMINES INRO N,N-DIMETHYLALKYL- OR N,N-DIALKYLMETHYL-AMINES WITH METHANOL AND RuCl2(Ph3P)3
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N,N-dimethylalkyl- or N,N-dialkylmethyl-amines are selectively obtained from the reaction between aliphatic amines and methanol at 180 deg C for 7 h in the presence of RuCl2(Ph3P)3 catalyst.
- Arcelli, Antonio,Khai, Bui-The,Porzi, Gianni
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- O-Arenesulfonyl-N-alkylhydroxylamines as Aminating Reagents
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O-(p-Toluenesulfonyl)-N-methyl-, -N-ethyl-, and -N-isopropil-hydroxylamines and O-mesitylenesulfonyl-N-methylhydroxylamine were prepared.The N-methyl and N-ethyl derivatives were found to react with tertiary amines and triphenylphosphine to give the corresponding N-(alkylamino)ammonium salts and P-(alkylamino)phosphonium salts, but the N-isopropyl derivative was less reactive, probably due to steric effects.These reagents also reacted with tri-n-butylborane to give the corresponding alkyl-n-butylamines.Keywords-- electrophilic aminating reagent; tert-butoxycarbonylation; di-tert-butyl dicarbonate; N-(methylamino)ammonium salts; P-(methylamino)triphenylphosphonium salt; N-(methylamino)pyridinium salt; secondary amines
- Tamura, Yasumitsu,Ikeda, Hiroyuki,Morita, Iwao,Tsubouchi, Hidetsugu,Ikeda, Masazumi
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p. 1221 - 1224
(2007/10/02)
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- Transition Metal-catalysed N-Alkylation of Amines by Alcohols
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Primary and secondary alcohols effect alkylation of primary and secondary amines in the presence of rhodium, iridium, and ruthenium compounds at = 100 deg C, whereby selective monoalkylation of primary amines can be achieved, and heterocyclic rings can be constructed by both inter- and intra-molecular processes.
- Grigg, R.,Mitchell, T. R. B.,Sutthivaiyakit, S.,Tongpenyai, N.
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p. 611 - 612
(2007/10/02)
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- Reactions of Secondary amines with Their N-(2,4-Dinitro-1-naphthyl)Derivatives To Form Jackson-Meisenheimer Adducts. Substantial Difference in Reaction Rates between Pyrrolidine and Piperidine
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Pyrrolidine, piperidine, and butylmethylamine react with their respective N-(2,4-dinitro-1-naphthyl) derivatives to form ? adducts as through the respective amide ions had attached at the 1 position.These reactions occur in dimethyl sulfoxide solution and proceed to a state of equilibrium.For the pyrrolidine and butylmethylamine reactions, equilibrium constants as well as rate constants both foward and reverse have been measured.Although two amine molecules are required to form the ? adduct, one to supply an amino moiety and the other to receive a proton, the forward reaction is only first order in amine; therefore, amine attack is not base catalyzed.Piperidine reacts so much slower than pyrrolidine, roughly 1/400th as fast, that rate and equilibrium measurements were inconvenient.The low reactivity of the piperidine system is ascribed to stereoelectronic/conformational/steric problems in the piperidino moiety of N-(2,4-dinitro-1-naphthyl)piperidine as it enters the transition state.
- Sekiguchi, Shizen,Bunnett, J. F.
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p. 4871 - 4874
(2007/10/02)
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- Long-range anisotropic effects of long chain amides
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In 1H-NMR spectra of amids with long-chain aliphatic N-substituents one observes - despite of the free mobility of the aliphatic chain - splitting of the signals of the terminal methyl groups which is caused by the hindered rotation of the amide bond. - Keywords: Amides; Hindered rotation; 1H-NMR
- Budzikiewicz, Herbert,Vieth, Peter-Eric,Krueger, Uwe
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p. 825 - 840
(2007/10/02)
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- 1,4-Dithiino[2,3-c; 6,5-c']diisothiazole and related compounds
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The compound 3,7-dicyano-1,4-dithiino[2,3-c; 6,5-c']diisothiazole is prepared by reacting either tetracyano-1,4-dithiin or 4,5-dicyano-1,3-dithiolen-2-one with sulfur in 1,2-dimethoxyethane at a temperature of 50°-280° C in the presence of a basic catalyst. The diisothiazole can be converted to derivatives with various utilities, e.g., as fluorescent brighteners.
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