- Preparation and deprotection of aldehyde dimethylhydrazones
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Aldehydes were conveniently protected as dimethylhydrazones by stirring a mixture of the aldehyde, N,N-dimethylhydrazine, anhydrous magnesium sulfate, and dichloromethane at room temperature. Azeotropic removal of water, formed during the course of the reaction, was not required because anhydrous magnesium sulfate functions as a water scavenger. Deprotection of aldehyde dimethylhydrazones was accomplished by stirring a mixture of the aldehyde dimethylhydrazone and aqueous glyoxylic acid at room temperature. The reaction time for the preparation and deprotection of aldehyde dimethylhydrazones varied with the structure of the aldehyde. Copyright Taylor & Francis Group, LLC.
- Petroski, Richard J.
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- Method development for the determination of 1,1-dimethylhydrazine by the high-performance liquid chromatography–mass spectrometry technique
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Unsymmetrical dimethyl hydrazine is highly toxic, carcinogenic compound, widely used for organic synthesis and drug development. Therefore, due to its high reactivity, direct analysis is problematic. Current study proposes to use derivatization reaction t
- Susinskis, Igors,Mekss, Peteris,Hmelnickis, Juris
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- An alternative channel of reductive condensation of trichloromethylarenes with hydrazines
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The reductive condensation of trichloromethylarenes with hydrazines can proceed without intermediate formation of pyridinium salts and without participation of pyridine in the reduction act. Variants of reductive condensation using hydrazines as reducting agents and α-chlorobenzylhydrazines and hydrazonoyl chlorides, nitrite imines, or hydrazonoylpyridinium salts as intermediates are considered. α-Chlorobenzylhydrazines and hydrazonoyl chlorides are shown to be the most probable intermediates.
- Belen'kii,Luiksaar,Chuvylkin,Krayushkin
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- Design, synthesis, and evaluation of analogues of 3,3,3-trifluoro-2-hydroxy-2-phenyl-propionamide as orally available general anesthetics
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We have recently discovered a novel class of compounds that have oral general anesthetic activity, potent anticonvulsant activity, and minimal hemodynamic effects. The 3,3,3-trifluoro-2-hydroxy-2-phenyl-propionamide (1) demonstrated potent ability to reduce the minimum alveolar concentration (MAC) of isoflurane, with no effects on heart rate or blood pressure at therapeutic concentrations. Analogue 1 also had potent oral anticonvulsant activity against maximal electroshock (MES) and subcutaneous metrazol (scMET) models with a therapeutic index of 10 for MES activity. In this study, we further synthesized nine new racemic analogues and evaluated these compounds for effects on isoflurane MAC reduction and blood pressure. Preliminary data demonstrate potent reduction in the isoflurane MAC for two new compounds. Current mechanistic studies were unrevealing for effects on voltage-gated ion channels as a putative mechanism. Liposomal partitioning studies using 19F NMR reveal that the aromatic region partitions into the core of the lipid. This partitioning correlated with general anesthetic activity of this class of compounds. Further, compound 1 was used at a concentration of 1 mM and slightly enhanced GABAA current in hippocampal neurons at 10 μM. Altogether, 3,3,3-trifluoro-2-hydroxy-2-phenyl-propionamide exhibited excellent oral general anesthetic activity and appears devoid of significant side effects (i.e., alterations in blood pressure or heart rate).
- Choudhury-Mukherjee, Indrani,Schenck, Hilary A.,Cechova, Sylvia,Pajewski, Thomas N.,Kapur, Jaideep,Ellena, Jeffrey,Cafiso, David S.,Brown, Milton L.
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- Transient imine as a directing group for the metal-free o-C-H borylation of benzaldehydes
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Organoboron reagents are important synthetic intermediates and have wide applications in synthetic organic chemistry. The selective borylation strategies that are currently in use largely rely on the use of transition-metal catalysts. Hence, identifying much milder conditions for transition-metal-free borylation would be highly desirable. We herein present a unified strategy for the selective C-H borylation of electron-deficient benzaldehyde derivatives using a simple metal-free approach, utilizing an imine transient directing group. The strategy covers a wide spectrum of reactions and (i) even highly sterically hindered C-H bonds can be borylated smoothly, (ii) despite the presence of other potential directing groups, the reaction selectively occurs at the o-C-H bond of the benzaldehyde moiety, and (iii) natural products appended to benzaldehyde derivatives can also give the appropriate borylated products. Moreover, the efficacy of the protocol was confirmed by the fact that the reaction proceeds even in the presence of a series of external impurities.
- Rej, Supriya,Chatani, Naoto
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supporting information
p. 2920 - 2929
(2021/03/01)
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- Efficient reductions of dimethylhydrazones using preformed primary amine boranes
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A convenient method for the reduction of N,N-dimethylhydrazones using amine borane complexes generated in situ is described. It was found that primary amine borane complexes performed exceedingly well at reducing N,N-dimethylhydrazones in as little as 1.1 equivalents, furnishing the corresponding air-sensitive hydrazine products in excellent yields.
- Frabitore, Christian,Lépeule, Jérome,Livinghouse, Tom,Robinson, William C.,Towey, Bradley
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supporting information
(2021/12/21)
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- AROMATIC COMPOUNDS FROM FURANICS
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Described are methods for preparing phenols, benzene carboxylic acids, esters and anhydrides thereof from furanic compounds by reaction with a dienophile, wherein the furanic compounds are reacted with a hydrazine and/or oxime and then reacted with a dienophile.
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Page/Page column 34
(2017/09/21)
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- Perfluoroalkylation of Aryl-N,N-dimethyl Hydrazones Using Hypervalent Iodine(III) Reagents or Perfluoroalkyl Iodides
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Radical trifluoromethylation of aryl N,N-dimethyl hydrazones using TBAI as an initiator and Togni's reagent as a trifluoromethyl radical source is described. Cascades proceed via electron-catalysis; this approach is generally more applicable to hydrazone perfluoroalkylation using perfluoroalkyl iodides as the radical precursors in combination with a base under visible-light initiation.
- Janhsen, Benjamin,Studer, Armido
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p. 11703 - 11710
(2017/11/24)
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- Modular construction of quaternary hemiaminal-based inhibitor candidates and their in cellulo assessment with HIV-1 protease
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Non-peptidomimetic drug-like protease inhibitors have potential for circumventing drug resistance. We developed a much-improved synthetic route to our previously reported inhibitor candidate displaying an unusual quaternized hemi-aminal. This functional group forms from a linear precursor upon passage into physiological media. Seven variants were prepared and tested in cellulo with our HIV-1 fusion-protein technology that result in an eGFP-based fluorescent readout. Three candidates showed inhibition potency above 20 μM and toxicity at higher concentrations, making them attractive targets for further refinement. Importantly, our class of original inhibitor candidates is not recognized by two major multidrug resistance pumps, quite in contrast to most clinically applied HIV-1 protease inhibitors.
- Gros, Guillaume,Martinez, Lorena,Gimenez, Anna Servat,Adler, Paula,Maurin, Philippe,Wolkowicz, Roland,Falson, Pierre,Hasserodt, Jens
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supporting information
p. 5407 - 5413
(2013/09/02)
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- New types of reactivity of α,β-unsaturated N,N- dimethylhydrazones: Chemodivergent diastereoselective synthesis of functionalized tetrahydroquinolines and hexahydropyrrolo[3,2-b]indoles
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The indium trichloride-catalyzed reaction between aromatic imines and α,β-unsaturated N,N-dimethylhydrazones in acetonitrile afforded 1,2,3,4-tetrahydroquinolines bearing a hydrazone function at C4 through a one-pot diastereoselective domino process that involves the formation of two C-C bonds and the controlled generation of two stereocenters, one of which is quaternary. This reaction constitutes the first example of an α,β-unsaturated dimethylhydrazone that behaves as a dienophile in a hetero Diels-Alder reaction. The related reaction between anilines, aromatic aldehydes, and methacrolein dimethylhydrazone in CHCl3 with BF 3·Et2O as catalyst afforded polysubstituted 1,2,3,3a,4,8b-hexahydropyrrolo[3,2-b]indoles as major products through a fully diastereoselective ABB′C four-component domino process that generates two cycles, three stereocenters, two C-C bonds, and two C-N bonds in a single operation. Copyright
- Sridharan, Vellaisamy,Ribelles, Pascual,Estevez, Veronica,Villacampa, Mercedes,Ramos, M. Teresa,Perumal, Paramasivan T.,Menendez, J. Carlos
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p. 5056 - 5063
(2012/05/20)
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- Hydrazone as the directing group for Ir-catalyzed arene diborylations and sequential functionalizations
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The use of hemilabile pyridine-hydrazone N,N-ligands allows the highly selective Ir-catalyzed ortho,ortho'-directed diborylation of aromatic N,N-dimethylhydrazones in near-quantitative yields. One-pot sequential Suzuki-Miyaura cross-coupling with different aryl bromides provides a short entry to unsymmetrically substituted 2,6-diarylbenzaldehyde derivatives.
- Ros, Abel,Lopez-Rodriguez, Rocio,Estepa, Beatriz,Alvarez, Eleuterio,Fernandez, Rosario,Lassaletta, Jose M.
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supporting information; experimental part
p. 4573 - 4576
(2012/04/23)
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- Synthesis of o -(dimethylamino)aryl ketones, acridones, acridinium salts, and 1 H -indazoles by the reaction of hydrazones and arynes
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A novel, efficient route to biologically and pharmaceutically important o-(dimethylamino)aryl ketones, acridones, acridinium salts, and 1H-indazoles has been developed starting from readily available hydrazones of aldehydes and o-(trimethylsilyl)aryl triflates. The reaction proceeds through arynes under mild conditions, tolerates a wide range of functional groups, and provides the final products in good to excellent yields.
- Dubrovskiy, Anton V.,Larock, Richard C.
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p. 11232 - 11256
(2013/02/23)
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- Use of hemilabile N,N ligands in nitrogen-directed iridium-catalyzed borylations of arenes
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The hemilabile character of 2-pyridyl carbaldehyde hydrazones as N,N bidentate ligands is key to performing regioselective IrIII-catalyzed ortho borylations of 2-aryl pyridines(isoquinolines) and aromatic N,N-dimethylhydrazones (see scheme; pin=pinacol, Bn=benzyl). Internal "ate" complexes or products free from N-B interactions are formed depending on the steric properties of the substrates. Copyright
- Ros, Abel,Estepa, Beatriz,Lopez-Rodriguez, Rocio,Alvarez, Eleuterio,Fernandez, Rosario,Lassaletta, Jose M.
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supporting information; experimental part
p. 11724 - 11728
(2012/02/14)
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- Synthesis of o -(dimethylamino)aryl ketones and acridones by the reaction of 1,1-dialkylhydrazones and arynes
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A novel, efficient route to biologically and pharmaceutically important o-(dimethylamino)aryl ketones and acridones has been developed starting from readily available 1,1-dimethylhydrazones of aldehydes and o-(trimethylsilyl)aryl triflates. The reaction proceeds under mild conditions, tolerates a wide range of functional groups, and provides the final products in good to excellent yields.
- Dubrovskiy, Anton V.,Larock, Richard C.
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supporting information; experimental part
p. 4136 - 4139
(2011/10/12)
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- From aldehydes to nitriles, a general and high yielding transformation using HOF·CH3CN complex
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N,N-Dimethylhydrazones of aldehydes undergo a rapid oxidative cleavage to form nitriles in very high yields on reaction with HOF·CH3CN under mild conditions. The reaction is chemoselective and proceeds rapidly without racemization. The nitriles were resistant to further oxidation, even when a large excess of the reagent was employed.
- Carmeli, Mira,Shefer, Neta,Rozen, Shlomo
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p. 8969 - 8972
(2007/10/03)
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- A novel, one-pot synthesis of α-C-cyanohydrazines in the presence of lithium perchlorate/diethylether solution (5.0 M)
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Condensation of N,N-dimethylhydrazine, an aldehyde in lithium perchlorate/diethylether solution (5.0 M) gave N,N-dimethylhydrazone, which were treated with trimethylsilylcyanide to afford α-C-cyanohydrazine. These compounds are important precursors of nitrogen-substituted reagents.
- Heydari, Akbar,Baharfar, Robabe,Rezaie, Mohsen,Aslanzadeh, Saied M.
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p. 368 - 369
(2007/10/03)
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- A 'one-pot' procedure for the oxidative conversion of alkyl halides and tosylates to N,N-dimethylhydrazones
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The treatment of a solution of an alkyl halide with sodium azide results in the formation of a solution of the alkyl azide, which upon filtration to remove the sodium halide, is treated with N,N-dimethyl hydrazine and catalytic FeCl3.6H2O under refluxing conditions. The result is a one pot conversion of an alkyl halide to an N,N-dimethyl hydrazone, a net oxidation of the halogen-bearing carbon.
- Barrett,Kerr
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p. 1673 - 1675
(2007/10/03)
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- Reaction of 1,1-dimethylhydrazones with propargyl bromide and 1,3-dibromopropyne
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Quaternary salts of 1,1-dimethyl-1-(2-propynyl)hydrazones of acetaldehyde, benzaldehyde, 4-nitrobenzaldehyde, 2-thiophenealdehyde, 4-pyridinecarboxaldehyde and quaternary salts of 1,1-dimethyl-1-(3-bromo-2-propynyl)hydrazones of acetaldehyde and benzaldehyde were synthesized from the corresponding hydrazones, propargyl bromide, and 1,3-dibromopropyne at 20°C or at heating, with no solvent or in ether, acetonitrile, benzene.
- Yelokhina,Nakhmanovich,Karnaukhova,Larina,Lopyrev
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p. 479 - 481
(2007/10/03)
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- A facile synthesis of 3-alkoxy and 3-amino pyrroles
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N-Amino-3-methoxy-3-pyrrolines 2 obtained from the reaction of 1-lithio methoxyallene with arylhydrazones may be converted to either 3-methoxy pyrroles 6 or 3-amino pyrroles 7 by treatment with m-chloroperbenzoic acid or 0.25 M HCl, respectively.
- Breuil-Desvergnes, Valerie,Compain, Philippe,Vatele, Jean-Michel,Gore, Jacques
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p. 8789 - 8792
(2007/10/03)
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- Planar boron heterocycles with nucleic acid-like hydrogen-bonding motifs
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To promote the development of boron-containing purine analogues that exist in planar, non-zwitterionic dominant structural form. in aqueous solution, rigorous solution and solid state structural analyses of 1-hydroxy-1H-2,3,1-benzoxazaborine (1), 1,2-dihydro-1-hydroxy-2,3,1-benzodiazabo (2), and related 2,3,1-benzodiheteraborines were undertaken. With the aid of isotope-enriched compounds, a multisolvent 1H, 13C, 11B, and 15N NMR spectroscopic analysis of 1 and 2 was conducted, providing structurally-diagnostic chemical shift data for all non-oxygen atoms that constitute their heterocyclic peripheries. In addition, single-crystal X-ray diffraction analyses of 1 and 2 were performed. In stark contrast to their 2,4,1 isomeric counterparts, the 2,3,1-benzoxaza- and benzodiazaborines exist in planar structural form in protic solution and in the solid state and display proton dissociative and associative tendencies reflective of the predominant Bronsted, yet still Lewis acidic-capable character of the B-OH group together with the basic one at the C4-N3 imine group. In the solid state, 1 and 2 display intermolecular hydrogen-bonding patterns not too dissimilar from the motifs of certain natural nucleic acid bases. Diazaborine 2 was shown by VT-NMR to undergo a triple hydrogen-bonding solution association with a 2',3',5'-tri-O-protected cytidine in a demonstration of one biomimetic potential held by a 1-hydroxy-2,3,1-diheteraborine periphery. In general, 1, 2, and related 1-hydroxy-2,3,1-benzodiheteraborine heterocycles were found to be characterized by an environment-dependent O1 → N3 Bronsted prototropy and B-OH group Bronsted/Lewis acid ambidency so sensitive and subtle that certain past difficulties encountered in attempts to delineate their physicochemical properties now become readily appreciated.
- Groziak, Michael P.,Chen, Liya,Yi, Lin,Robinson, Paul D.
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p. 7817 - 7826
(2007/10/03)
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- α-Alkylation of α,β-Unsaturated Aldehyde Dimethylhydrazones Accompanied with the Double Bond Migration to β,γ
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Lithiated α,β-unsaturated aldehyde N,N-dimethylhydrazones reacted with alkyl halides accompanied by double bond migration to give α-alkylated β,γ-unsaturated aldehyde N,N-dimethylhydrazones in satisfactory yields.This reaction was found to be caused at the first step by deprotonation from a γ-carbon atom by lithium diisopropylamide.In the case of hydrazones with two kinds of γ-protons, deprotonation from the less hindered γ-carbon occurred selectively.Using this reaction, a novel sesquiterpene, 2,5,9-trimethyl-2-vinyl-4,8-decadienal, which has a vinyl group at the α-position, was synthesized in a good yield.
- Yamashita, Masakazu,Matsumiya, Kaoru,Nakano, Ken-ichi
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p. 1759 - 1763
(2007/10/02)
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- Synthesis of β-lactams via cycloaddition of hydrazones with phenoxyketene
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Phenoxyketene is capable of annelating the disubstituted hydrazones to afford stereoselectivity cis-monocyclic β-lactams with a 1-amino functionality. The ease of cycloaddition is governed by substitutents on the azomethine carbon as well as on the hydraz
- Sharma,Pandhi
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p. 2196 - 2200
(2007/10/02)
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- Aza-enamines, VIII. - Electrophilic Substitution reactions at the Azomethine C-Atom of Aldehyde Dialkylhydrazones: Vilsmeier Formylation and Consecutive Reactions
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The reaction of hydrazones 1 with the Vilsmeier reagent yields 3-phenyl-1,4,5-triaza-1,3-pentadienium salts according to their aza-enamine character.Hydrolysis of 2 gives 1-phenylglyoxal 1-dialkylhydrazones 3, which rearrange in acidic media to 1-phenylglyoxal 2-dialkylhydrazones 4.Compound 3h forms the dihydropyrroloimidazole 5 in boiling ethanol.Pyrrolotriazinium salt 6 is obtained by the reaction of 1b with the isolated Vilsmeier reagent from dimethylformamide/oxalyl chloride.
- Brehme, Rainer
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p. 2039 - 2046
(2007/10/02)
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- Elimination Reactions of Hydrazonium Salts: Experimental and Theoretical Evidence for a Large Stereoelectronic Effect of Nitrogen
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Elimination of trimethylamine from hydrazonium salts (8, R = Me) is promoted by base (methoxide ion in methanol).The mechanism is characterized as E2 as shown by substituent effects (ρ = +2.57), Broensted coefficients, a primary kinetic isotope effect (kH/kD = 2.10), and solvent effects.Variation in the leaving group (8, R = arylmethyl) shows that N-N bond cleavage is less well advanced in the transition state than C-H bond breaking.The elimination to give the nitrile is syn-periplanar and, using the phthalazinium salt 4 as a model for the anti elimination, an anti/syn ratio of ca. 102 is found.The reactions have been modelled using ab initio methods with the transition structures located at the HF/3-21G level and relative energies computed using the MP2/6-31G* method.Using both H2O and NH3 as model bases to induce elimination on +, the calculated energy for anti elimination is lower (in the range 11-13 kcal mol-1) than that for syn elimination.The implications of the results for the ease of formation of nitriles from aldehydes via the hydrazonium salt route are discussed.
- Nguyen, Minh Tho,Clarke, Leo F.,Hegarty, Anthony F.
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p. 6177 - 6183
(2007/10/02)
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- 3-Acryl-7-chloro-3,4-dihydro-1,9(2H, 19H) acridinedione, 1-hydrazones as potent antimalarial agents (1,2)
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A series of 3-aryl-7-dihydro-1,9(2H, 10H)-acridinedione, 1-hydrazones was prepared from the corresponding acridinediones, and examined for antimalarial activity. Potent antimalarial activity against Plasmodium berghei infections in mice was found with aliphatic substituted hydrazones. Among the substituents on the phenyl ring at the 3 position of the acridine moiety particularly high activity was associated with the 4-(trifluoromethyl)phenyl group and the 2,4-dichlorophenyl group. Moreover the ring N-OH function was shown to be necessary for good biological activity. Additional structure activity relationships are also discussed.
- Werbel,Hung,McNamara,Ortwine
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p. 363 - 370
(2007/10/02)
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