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Three-component condensation of 6-aminoquinoline with formaldehyde and cyclic β-diketones (cyclohexane-1,3-dione and dimedone) gave new partially hydrogenated benzo[b][4,7]phenanthroline derivatives. An analogous reaction with indan-1,3-dione gave indeno[2,1-b][4,7]phenanthroline derivatives. The products were subjected to oxidative dehydrogenation. 相似文献
3.
W. B. Kang Seiko Nan'Ya Yasushi Yamaguchi Etur
Maekawa Yoshio Ueno 《Journal of heterocyclic chemistry》1987,24(1):91-94
The 2,6-disubstituted-, 3,6-disubstituted-5H-benzo[a]phenothiazin-5-one derivatives and 7-substituted-benzo[a] [1,4]benzothiazino[3,2-a]phenothiazine derivatives were prepared by the condensation of 2,3,6-trisubstituted-1,4-naphthoquinones with 2-aminothiophenol. The resulting compounds were subjected to reduction, dehalogenation and condensation with aniline. Some of the condensation intermediates were isolated and the reaction mechanism was also investigated. 相似文献
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The most important industrial process for the synthesis of vanillin is performed in two steps involving an condensation reaction of glyoxalic acid with guaiacol followed by an oxidative decarboxylation of the intermediary 3-methoxy-4-hydroxymandelic acid (MHPA) formed, thereby producing not only vanillin, but also byproducts, which have to be eliminated. In the present study, we focused our efforts on the first step of vanillin synthesis, namely, the condensation reaction governing the yield of vanillin. The factors influencing the stability of glyoxalic acid were preliminarily evaluated to provide significant referential value for suppressing the dismutation of glyoxalic acid in the condensation reaction, and the results indicate that the stability of glyoxalic acid largely depends on the pH, temperature, and holding time of the feed solution. Then the process of the condensation reaction was optimized under the factors affecting the stability of glyoxalic acid, as well as the molar ratio of guaiacol to glyoxalic acid. Under the optimized conditions, the maximum yield of the condensation reaction can reach to 88%. 相似文献
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AbstractMethyl-2-(3-oxo-3-aryl) benzoates derived from acid catalyzed air oxidative fragmentation of 2-aryl-1-tetralones were efficiently undergone intramolecular-Claisen condensation in the presence of potassium tertiary butoxide. The resulting 2-benzoyl-1-indanones formed in two-step ring contractions were further subjected to indium triflate mediated retro-Claisen condensation to get 1-indanones. 相似文献
7.
研究了腰果酚在无光引发剂条件下的紫外光固化反应,并用IR、UV、元素分析、GPC等分析手段分析了腰果酚的紫外光固化机理及其固化膜性能。结果表明:在紫外光辐照下,腰果酚通过侧链发生氧化聚合反应,和酚羟基的邻对位失去质子形成的自由基引起的苯环缩合反应,最终形成体型高聚物。腰果酚的紫外光固化膜的常规物理机械性能、抗溶剂性、耐化学介质腐蚀性、热稳定性和抗紫外线性能均优于腰果酚醛缩聚物(PC)涂膜。 相似文献
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I. G. Danilova E. A. Paukshtis A. V. Kalinkin A. L. Chuvilin G. S. Litvak A. A. Altynnikov V. F. Anufrienko 《Kinetics and Catalysis》2002,43(5):698-710
The effect of the deposition of oxidative condensation products in the reaction of oxidative propane dehydrogenation in the presence of SO2 on the catalytic, acid–base, and texture characteristics of silica was studied. It was found that the oxidative condensation products exhibited high catalytic activity in this reaction. The carbonization of silica from 0 to 40 wt % was accompanied by an increase in the yield of propylene from 3.4 to 46 mol % (640°C; a C3H8/SO2/He + N2 mixture, 10 : 10 : 80 vol %). Further accumulation of condensation products resulted in a considerable decrease in the pore volume and radius; this imposed diffusion limitations on both propane conversion and selectivity to propane conversion products. The nature of active and deactivated condensation products was studied by DRIFT spectroscopy, diffuse-reflectance UV–VIS spectroscopy, EPR spectroscopy, XPS, thermal analysis, and electron microscopy. 相似文献
9.
The oxidative dehydrogenation of alcohols to aldehydes catalyzed by Ag nanoparticles supported on Al_2O_3 was studied.The catalyst promoted the direct formation of imines by tandem oxidative dehydrogenation and condensation of alcohols and amines.The reactions were performed under mild conditions and afforded the imines in high yield(up to 99%) without any byproducts other than H_2O.The highest activity was obtained over 5 wt%Ag/Al_2O_3 in toluene with air as oxidant.The reactions were also performed under oxidant-free conditions where the reaction was driven to the product side by the production of H_2 in the gas phase.The use of an efficient and selective Ag catalyst for the oxidative dehydrogenation of alcohol in the presence of amines gives a new green reaction protocol for imine synthesis. 相似文献
10.
Convenient preparation of novel 9,11-dimethylbenzocyclohepta[6,7-b]pyrimido[5,4-d]furan-10(9H),12(11H)-dionylium tetrafluoroborate 11*BF4- consisted of a condensation reaction of benzo[d]tropone with dimethylbarbituric acid and following oxidative cyclization reaction by using DDQ-Sc(OTf)3 or photoirradiation under aerobic conditions. Alternative synthesis of 11*BF4- was also accomplished by a condensation reaction of 2-methoxybenzo[d]tropone with dimethylbarbituric acid and a subsequent cyclization reaction by using 42% aq HBF4. The X-ray crystal analysis and MO calculation were carried out to clarify the structural characteristics. Properties of the cation 11 were studied by the pKR+ value (4.7) and reduction potentials (-0.46 and -1.07 V vs Ag/AgNO3) as well as the reaction with some nucleophiles. The oxidizing ability of 11*BF4- toward alcohols in the autorecycling process was demonstrated as well. 相似文献
11.
Daniel Obrecht Christine Abrecht Alfred Grieder Jos M. Villalgordo 《Helvetica chimica acta》1997,80(1):65-72
We describe a versatile novel approach for the synthesis of 2, 4, 6-trisubstituted pyrimidines on solid support. Thus, polymer-boun J thiouronium salt 2 reacted in high yield in a cyclocondensation reaction with the acetylenic ketones 3 to form, after tert-butyl-ester cleavage, the polymer-bound carboxylic acids 4 , which were cleaved by oxidation with 3-chloroperbenzoic acid and pyrrolidine to form the 2-pyrrolidinylpyrimidine-4-carboxylic acids 6a-c in high yields and purities without further purification (Scheme 1). Alternatively, acid 4a was subjected to an Ugi four-component condensation which gave the polymer-bound Ugi products 9a-e in good yields (Scheme 2). Multidirectional cleavage reaction of sulfone 8a with different nucleophiles resulted in the clean formation of pyrimidine-4-carboxamides 10–13 (Scheme 3). This strategy combines efficiently solid-phase chemistry with a multicomponent reaction and a multidirectional cleavage step to form highly diverse pyrimidines in a parallel array. 相似文献
12.
A. T. Soldatenkov K. B. Polyanskii A. V. Temesgen N. D. Sergeeva V. V. Vysotskaya B. B. Averkiev M. Yu. Antipin N. N. Lobanov 《Chemistry of Heterocyclic Compounds》2004,40(5):641-649
New derivatives of piperidino[4,5-d]dioxane and 3-oxa-7-bicyclo[3.3.1]nonane were obtained by the oxidatively catalysed condensation of 4-aryl-1,2,3,6-tetrahydropyridines with formaldehyde. The direction of this reaction is sharply altered in the presence of manganese dioxide to give 6-oxa-2-azabicylo[3.2.1]octan-4-one — the product of the oxidative condensation of a new type. 相似文献
13.
Chiral Phosphoric Acid Catalyzed Kinetic Resolution of Indolines Based on a Self‐Redox Reaction 下载免费PDF全文
Dr. Kodai Saito Prof. Dr. Takahiko Akiyama 《Angewandte Chemie (International ed. in English)》2016,55(9):3148-3152
A strategy for oxidative kinetic resolution of racemic indolines was developed, employing salicylaldehyde derivative as the pre‐resolving reagent and chiral phosphoric acid as the catalyst. The iminium intermediate, formed by the condensation reaction of an enantiomer of indoline with salicylaldehyde derivative, was hydrogenated by the same enantiomer of indoline to afford another enantiomer of indoline by a self‐redox mechanism. The oxidative kinetic resolution of 2‐aryl‐substituted indolines proceeded to give enantiomers in good yields with excellent enantioselectivities. 相似文献
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David Jirovsky Petr Bedná? Renáta Myjavcová Zdenka Barto?ová Jana Skopalová Michaela Tvrdoňová Karel Lemr 《Monatshefte für Chemie / Chemical Monthly》2011,378(4):1211-1217
Abstract
Electrochemistry coupled with mass spectrometry (EC–MS) is a promising analytical tool for the online study of oxidation processes of anthocyanins. Two cyanidin glycosides, cyanidin-3-galactoside (ideain) and cyanidin-3,5-diglucoside (cyanin), were subjected to electrochemical oxidation and subsequent online mass spectrometric identification of the formed products. Application of relatively low working potentials (around 100 mV vs. Pd/H2) using a porous graphite coulometric electrode yielded detectable oxidation products. As determined by hydrodynamic voltammetry, the monoglycosylated analogue undergoes anodic oxidation easier than the diglycosylated one. As a first step of the electrochemically induced oxidation, incorporation of a hydroxyl group was observed for both glycosides. Besides, an oxidative condensation of two anthocyanin molecules was observed. The proposed oxidative condensation was further confirmed by consecutive fragmentation (i.e., collection of MS2, MS3, and MS4 spectra) in which corresponding subsequent losses of the sugar moiety were observed. 相似文献15.
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Jiyun Sun Huaibin Ge Xiaohua Zhen Xuechan An Guangtao Zhang Daisy Zhang-Negrerie Yunfei Du Kang Zhao 《Tetrahedron》2018,74(17):2107-2114
A new oxidative system of tert-butyl hydroperoxide (TBHP)/azodiisobutyronitrile (AIBN) has been used for the first time for a convenient, metal-free synthesis of substituted 2-aminothioazoles from active methylene ketone derivatives and thiourea. The reaction is postulated to proceed via an oxidative cyclization initiated by a radical process and followed by a condensation reaction. 相似文献
17.
[reaction: see text] A two-step method for the synthesis of 9-aryl-6-hydroxy-3H-xanthen-3-one fluorophores involving condensation of aryl aldehydes and fluororesorcinol is shown to proceed through a triarylmethane intermediate. The condensation is complicated by retro-Friedel-Crafts reactions which can be minimized by controlling the amount of acid. The xanthenone ring system is prepared by a final oxidative cyclization with DDQ. 相似文献
18.
The pyranocoumaronochromone lupinalbin H was synthesized in three major steps, which involved preparation of 2′-hydroxygenistein by the Suzuki-Miyaura reaction, followed by oxidative cyclodehydrogenation into lupinalbin A. The final step was the regiospecific introduction of the dimethylpyran moiety to ring A of lupinalbin A via an aldol-type condensation with 3-methyl-2-butenal and 6π-electrocyclization. 相似文献
19.
A single-step synthesis for ring-fluorinated 4H-1,4-benzothiazines is reported by the condensation and oxidative cyclization of β-diketones with 2-amino-5-fluorobenzenethiol. The reaction is believed to proceed via an enaminoketone system. 相似文献
20.
Shuntaro Mataka Kazufumi Takahashi Masashi Tashiro 《Journal of heterocyclic chemistry》1983,20(4):971-974
Di- and triphenyldibenzoylpyridines ( 1 ) were prepared by the condensation reaction of 3, 4-dibenzoyl-2, 5-diphenylthiophene ( 2 ) with methylamine derivatives 3 and by the subsequent oxidative ring cleavage of the resultant thieno[3, 4-c]pyridines 4 . The reaction of 1 with 3 afforded polyphenyl-2, 6- ( 5 ) and -2, 7-naphthyridines ( 6 ). 相似文献