- Synthesis of multi-substituted 1,2,4-triazoles utilising the ambiphilic reactivity of hydrazones
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The synthesis of N-alkyl-1H-1,2,4-triazoles from N,N-dialkylhydrazones and nitriles via formal [3+2] cycloaddition including the C-chlorination/nucleophilic addition/cyclisation/dealkylation sequence was developed. This sequential reaction utilising the in situ generation of hydrazonoyl chloride based on the ambiphilic reactivity of hydrazones afforded a variety of multi-substituted N-alkyl-triazoles in high yields. The synthetic utility of multi-substituted triazoles was also demonstrated by further transformations.
- Matsuzaki, Haruo,Takeda, Norihiko,Yasui, Motohiro,Okazaki, Mayuko,Suzuki, Seishin,Ueda, Masafumi
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supporting information
p. 12187 - 12190
(2021/11/30)
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- Kinetic studies of hydrazine and 2-hydroxyethylhydrazine alkylation by 2-chloroethanol: influence of a strong base in the medium
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To optimize yields, the study of reaction kinetics related to the synthesis of 2-hydroxyethylhydrazine (HEH) obtained from the alkylation of N 2H4 by 2-chloroethanol (CletOH) was carried out with and without sodium hydroxide. In both cases, the main reaction of HEH formation was followed by a consecutive, parallel reaction of HEH alkylation (or dialkylation of N2H4), leading to the formation of two isomers: 1,1-di(hydroxyethyl)hydrazine and 1,2-di(hydroxyethyl)hydrazine. In this study, hydrazine and hydroxyalkylhydrazine alkylations followed SN2 reactions triggered directly by CletOH or indirectly in the presence of a strong base by ethylene oxide, an intermediate compound. The kinetics was studied in diluted mediums by quantifying HEH and CletOH by gas chromatography and gas chromatography coupled with mass spectrometry (GC-MS). The activation parameters of each reaction and the influence of a strong base present in the medium on the reaction mechanisms were established. A global mathematical treatment was applied for each alternative. It allowed modeling the reactions as a function of reagent concentrations and temperature. In the case of direct alkylation by CletOH, simulation was established for semi-batch and batch syntheses and was confirmed in experiments for concentrated mediums (1.0 M≤[CletOH]0 ≤3.2 M and 15.7 M≤[N2H4]0 ≤18.8 M). Simulation therefore permits the prediction of the instantaneous concentration of reagents and products, in particular ethylene oxide concentration in the case of indirect alkylation, which must be as weak as possible.
- Goutelle,Pasquet,Stephan,Bougrine,Delalu
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experimental part
p. 382 - 393
(2009/11/30)
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- Hydrogen bonding of 2-tetrazenes, 2. Synthesis and structural studies of hydroxyalkyl-substituted 2-tetrazenes
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Five hydroxyethyl-2-tetrazenes (1 - 5) and their methyl ethers (6 - 10) have been synthesized and hydrogen bonding in these compounds has been investigated by theoretical and spectroscopic (IR, 1H NMR, 15N NMR) methods. The structure of 1,1,4,4-tetrakis(2-hydroxyethyl)-2-tetrazene (4) was determined by X-ray diffraction analysis. Several conformations with intramolecular hydrogen bonds were investigated by ab initio B3LYP as well as semiempirical SCF calculations. In all cases, conformers with OH---N hydrogen bonds with azo nitrogen atoms as acceptors (conformers A, B, C) are found as most stable. In compounds with small or flexible N1- and N4- substituents R besides the hydroxyethyl group (3, 4), hydrogen bonds forming six-membered rings, with the R groups taking syn positions at the N1-N2 and N3-N4 bonds (conformer A), are preferred over those with seven-membered rings and R taking anti positions (conformer B). Steric interaction in the other compounds (1, 2, 5) leads to destabilization of conformers A and conformers B become more stable. A special case is presented by compound 4 which has only hydroxyethyl substituents on the 2-tetrazene unit. In the most stable conformer (4C) there are two OH---O and one OH---N hydrogen bonds. By IR solution measurements intra- and intermolecular hydrogen bonds could be distinguished. Association shifts Δδ measured by 1H NMR spectroscopy, indicate that the investigated compounds exhibit comparable association properties with intermolecular association clearly prevailing. 15N NMR spectra of compounds 1 - 10 in two solvents have been measured if solubility was sufficient. The data indicate that all nitrogen atoms of 1 - 5 participate in H bonding. In the crystalline state, molecules 4 adopt a conformation without intramolecular H bonds (4D) and are associated by intermolecular OH---O hydrogen bonds that form a three-dimensional network. An untypical decomposition pattern was discovered for benzyl derivatives 5 and 10.
- Porath, Bernd,Rademacher, Paul,Boese, Roland,Bl?ser, Dieter
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p. 365 - 376
(2007/10/03)
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- ACYLATION OF HYDROXYETHYLHYDRAZINES BY DICARBOXYLIC ACID ANHYDRIDES
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The reaction of 2-hydroxyethylhydrazine with maleic and phthalic anhydrides leads to the formation of the corresponding 6-pyridazinone derivatives.The reaction with succinic anhydride proceeds at the β-nitrogen atom to form a linear compound.Acylation of unsymmetrical di(2-hydroxyethyl)hydrazine by these anhydrides gives the corresponding substituted monohydrazides of dicarboxylic acids.
- Shevchenko, V. V.,Vasil'evskaya, G. A.,Klimenko, N. S.,Loshkareva, S. N.,Khramova, T. S.
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p. 636 - 639
(2007/10/02)
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