共查询到20条相似文献,搜索用时 11 毫秒
1.
L. Rastyanite G. K. Kupyatis A. Matiyeshka O. Eicher-Lorka 《Chemistry of Heterocyclic Compounds》2002,38(11):1363-1367
When 1,2-dihydropyridazine-3,6-, 2,3-dihydrophthalazine-1,4-, 1-phenyl-1,2-dihydropyridazine-3,6-, and 2-phenyl-2,3-dihydrophthalazine-1,4-diones react with 1,3-propanesultone and bromoalkanesulfonates, depending on the nature of the sulfoalkylating agent in the case of 1,2-dihydropyridazine-3,6- and 2,3-dihydrophthalazine-1,4-diones, either N,O- or O,O1-disulfoalkylated compounds may be formed, while O-monosulfoalkylated reaction products may be formed in the case of the N-phenyl-substituted derivatives of the above-indicated azinediones. 相似文献
2.
Alberto Moscatelli M.Francesca Ottaviani Waldemar Adam Anatoly Buchachenko Steffen Jockusch NicholasJ. Turro 《Helvetica chimica acta》2006,89(10):2441-2449
At high concentrations of oxygen, the EPR spectrum of the nitroxide radical 4‐oxo‐TEMPO (= 4‐oxo‐2,2,6,6‐tetramethylpiperidin‐1‐yloxy) is found to broaden significantly. In addition to the expected broadening, double integration of the EPR signals indicates that a significant fraction of the nitroxide spins has ‘disappeared’. In perfluoro(2‐butyltetrahydrofuran) at 273 K, the extent of diminution of the EPR signal intensity is ca. 20%. The results are analyzed in terms of collision and supramolecular complexes between oxygen and 4‐oxo‐TEMPO. It is concluded that a supramolecular complex is responsible for the observed phenomenon. 相似文献
3.
The tunable three-component reactions of enals, electron deficient alkynes, and primary amines have been achieved for selective synthesis of 1,4- and 1,2-dihydropyridines. The selectivity has been found to be in close relation to the property of the amine component. 相似文献
4.
Marek Burian Ladislav Omelka Oldřich Farsa Silvia Hrubanová 《Monatshefte für Chemie / Chemical Monthly》2006,137(9):1169-1175
Summary. The synthesis and reaction with two oxidation agents is described for N-phenyl-1-(2-oxo-1-azacycloalkyl)methanesulfonamides. Their oxidation was carried out using
radicals and 3-chloroperbenzoic acid. In both cases, the EPR spectra of corresponding aminoxyl radicals were recorded. Their
simulation confirmed that the –SO2– group in the neighbourhood of the –
– fragment does not prevent the interaction of the unpaired electron with the methylene protons and the nitrogen atom of the
heterocyclic ring. 相似文献
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7.
Lukas Werner 《Tetrahedron》2010,66(21):3761-3928
Conjugated dienes were converted to 1,2-oxazines by reaction with an acyl nitroso dienophile. The oxazines were reduced to 1,4-N-acetylamino alcohols, which were rearranged to the corresponding oxazolines upon treatment with methanesulfonyl chloride or anhydride. The oxazolines yielded 1,2-N-acetylamino alcohols upon hydrolysis. Thus either 1,4- or 1,2-N-acetylamino alcohols are available from 1,3-dienes via this methodology. Experimental and spectral data are provided for all new compounds. 相似文献
8.
N. A. Keiko E. A. Funtikova L. G. Stepanova Yu. A. Chuvashev L. I. Larina 《Chemistry of Heterocyclic Compounds》2002,38(4):390-395
The reaction of 2-alkoxypropenals with ethane-1,2-dithiols and propane-1,3-dithiols under various conditions was studied by 1H NMR and chromato-mass spectrometry. Under kinetically controlled conditions at 20° in the absence of catalysts the addition of dithiols takes place according to the Markovnikov rule. The primary adducts are unstable and are quickly converted into the corresponding substituted 1,4-dithiacycloheptane or 1,4-dithiane. The latter in turn can be converted under the reaction conditions or at high temperature into a thiolane derivative. The reaction of 2-ethoxypropenal with a twofold excess of ethane-1,2-dithiol at 60°C in the presence of p-toluenesulfonic acid leads to 2-methyl-2,2'-bi(dithiolane) 相似文献
9.
In this paper, detailed comparisons of the driving force in thermodynamics and intrinsic force in the kinetics of 1,2-dihydropyridine and 1,4-dihydropyridine isomers of PNAH, HEH, and PYH in hydride transfer reactions are made. For 1,2-PNAH and 1,4-PNAH, the values of the thermodynamic driving forces, kinetic intrinsic barriers, and thermo-kinetic parameters are 60.50 and 61.90 kcal/mol, 27.92 and 26.34 kcal/mol, and 44.21 and 44.12 kcal/mol, respectively. For 1,2-HEH and 1,4-HEH, the values of the thermodynamic driving forces, kinetic intrinsic barriers, and thermo-kinetic parameters are 63.40 and 65.00 kcal/mol, 31.68 and 34.96 kcal/mol, and 47.54 and 49.98 kcal/mol, respectively. For 1,2-PYH and 1,4-PYH, the order of thermodynamic driving forces, kinetic intrinsic barriers, and thermo-kinetic parameters are 69.90 and 72.60 kcal/mol, 33.06 and 25.74 kcal/mol, and 51.48 and 49.17 kcal/mol, respectively. It is not difficult to find that thermodynamically favorable structures are not necessarily kinetically favorable. In addition, according to the analysis of thermo-kinetic parameters, 1,4-PNAH, 1,2-HEH, and 1,4-PYH have a strong hydride-donating ability in actual chemical reactions. 相似文献
10.
Luana Cardinale Dr. Mikhail O. Konev Prof. Dr. Axel Jacobi von Wangelin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(37):8239-8243
Functionalization with C1-building blocks are key synthetic methods in organic synthesis. The low reactivity of the most abundant C1-molecule, carbon dioxide, makes alternative carboxylation reactions with CO2-surrogates especially important. We report a photoredox-catalyzed protocol for alkene carbamoylations. Readily accessible 4-carboxamido-Hantzsch esters serve as convenient starting materials that generate carbamoyl radicals upon visible light-mediated single-electron transfer. Addition to various alkenes proceeded with high levels of regio- and chemoselectivity. 相似文献
11.
G Venkat Reddy 《Journal of fluorine chemistry》2003,124(2):203-209
Unsymmetrical 1,2-phenylenediamine on reaction with various ketones resulted in a number of fluorinated heterocycles such as benzimidazoles, quinoxalines and spiro benzimidazoles in high yields. The role of substituents in diamine in its reaction with various ketones and on the nature of product formation has been studied in detail. 相似文献
12.
Man LU Jian Guo FANG Zhong Li LIU Long Min WU* National Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou 《中国化学快报》2002,13(10)
Nitroxides have been found to be the intermediate in the in vivo metabolism of hydroxamic acid, a well-known biological molecule1. Structural modification of some antitumor drugs by introducing nitroxides can lower toxicity remarkably with retention or even increase of the antitumor activity2. Furthermore, the use of nitroxides as spin probes makes it possible to get information regarding the microenvironment of the reaction. 4-Substituted Hantzsch 1,4-dihydropyridines (DHP) are analogs … 相似文献
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Ladislav Omelka Silvie Ondrášová Lothar Dunsch Andreas Petr Andrej Staško 《Monatshefte für Chemie / Chemical Monthly》2001,132(5):597-606
Summary. The oxidation of aniline and some derivatives of 1,2-phenylenediamine was performed by the system Pb(CH3COO)4—CF3COOH—CH2Cl2. An ESR investigation of the oxidized aniline confirmed the presence of secondary cation radical. Its structure was determined
by comparison of its ESR spectrum with those of cation radicals prepared from derivatives of 1,4-phenylenediamine. The oxidation
of 1,2-phenylenediamine and its derivatives leads to the formation of either primary or secondary cation radicals, the latter
having the character of substituted dihydrophenazinium cation radicals.
Received August 17, 2000. Accepted (revised) October 16, 2000 相似文献
15.
Lidia S. Konstantinova 《Tetrahedron letters》2007,48(33):5851-5854
Reaction of 4-isopropylamino-5-chloro-1,2-dithiole-3-ones 3 and S2Cl2 in acetonitrile gave selectively 3-oxo-bis[1,2]dithiolo[1,4]thiazine-5-thiones 1 by the addition of triethylamine and bis[1,2]dithiolo[1,4]thiazine-3,5-diones 5 under the action of formic acid. 3,5-Diones 5 were also obtained by intramolecular cyclization of N,N-bis(5-chloro-3-oxo[1,2]dithiol-4-yl)amines 6 with S2Cl2 in the presence of Et3N. 相似文献
16.
An efficient and simple approach of the synthesis of some spiro indeno[1,2-b]quinoxalines via a one-pot three-component reaction of 11H-indeno[1,2-b]quinoxalin-11-one, pyrazolone, and malononitrile in the presence of Na2CO3 at 70 °C is reported. This reaction has shown to have high atom economy. 相似文献
17.
1,2-Carboboration of Arylallenes by In Situ Generated Alkenylboranes for the Synthesis of 1,4-Dienes
Arthur Averdunk Max Hasenbeck Tizian Müller Dr. Jonathan Becker Dr. Urs Gellrich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(32):e202200470
We herein report a novel method for the coupling of unactivated alkynes and arylallenes, which relies on an unprecedented and regioselective 1,2-carboboration of the allene by an alkenylborane. The alkenylborane is conveniently prepared in situ by hydroboration of an alkyne with Piers’ borane, i. e., HB(C6F5)2. The boryl-substituted 1,4-dienes that are formed by this carboboration are well-suited for a subsequent Suzuki-Miyaura coupling with aryl iodides. This allowed us to develop a three-step, one-pot protocol for the synthesis of aryl-substituted 1,4-dienes. The generality of the reaction was demonstrated by the synthesis of twenty dienes with modular variations of all three reaction partners. The mechanism of the new 1,2-carboboration was investigated using dispersion corrected double-hybrid DFT computations that allowed us to rationalize the chemo- and regioselectivity of this key step. 相似文献
18.
《合成通讯》2013,43(5):851-862
Abstract 1-(2-Nitrophenyl)indole-2-carboxylates 5, obtained by the N-arylation of indole-2-carboxylates 4, on catalytic reductive cyclization afford indolo[1,2-a]quinoxalino-6(5H)-ones 6. These compounds on reduction with LAH in ether/THF yielded indolo[1,2-a]quinoxalines 7. 相似文献
19.
Summary. Electron donor-acceptor (EDA) complexes of several substituted anilines with the -acceptor 2,3-dichloro-1,4-naphthoquinone (DClNQ) in chloroform, dichloromethane, and 1,2-dichloroethane were studied by a spectrophotometric method. Experimental data has been shown to confirm the 1:2 stoichiometry of the acceptor-donor in spite of the apparent linearity of the Benesi-Hildebrand plot for a 1:1 complex. The calculated values of oscillator strengths, transition moments, and thermodynamic parameters confirms the 1:2 (A:D) stoichiometry of the complexes. The formation constants and molar absorptivities for these AD2 complexes have been evaluated. The stoichiometry was unaffected by the variation of the temperature over a small interval and also by the change in polarity of the solvent. The order of the donor strength followed the sequence: N-benzylaniline>p-chloroaniline>m-chloroaniline>o-chloroaniline.Present address: Materials Research Centre, Indian Institute of Science, Bangalore-12, India 相似文献
20.
Dr. Fabian Hecker Lisa Fries Dr. Markus Hiller Prof. Dr. Mario Chiesa Prof. Dr. Marina Bennati 《Angewandte Chemie (International ed. in English)》2023,62(4):e202213700
The hydration structure of nitroxide radicals in aqueous solutions is elucidated by advanced 17O hyperfine (hf) spectroscopy with support of quantum chemical calculations and MD simulations. A piperidine and a pyrrolidine-based nitroxide radical are compared and show clear differences in the preferred directionality of H-bond formation. We demonstrate that these scenarios are best represented in 17O hf spectra, where in-plane coordination over -type H-bonding leads to little spin density transfer on the water oxygen and small hf couplings, whereas -type perpendicular coordination generates much larger hf couplings. Quantitative analysis of the spectra based on MD simulations and DFT predicted hf parameters is consistent with a distribution of close solvating water molecules, in which directionality is influenced by subtle steric effects of the ring and the methyl group substituents. 相似文献