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1.
Methylenecyclobutanes undergo a lithiation reaction in the presence of n-BuLi or n-BuLi/KOtBu from −78 °C to room temperature or to 40 °C in THF within 3 h and then quenching with a variety of electrophiles to give the corresponding addition products (alcohols) in moderate to good yields within 2 h. The alcohols can be easily oxidized to the ketones, which can be transformed to the substituted cyclopentenes in the presence of AlCl3 within short reaction time. 相似文献
2.
Radhakrishnan Subashini Fazlur-Rahman Nawaz Khan 《Monatshefte für Chemie / Chemical Monthly》2012,20(9):485-489
Abstract
Solvent-free, microwave-induced condensation of 2-aminoaryl alkyl ketones and ethyl 3-oxobutanoate in the presence of amberlite Na sr1L gave quinolinones in high yield when compared to other catalysts. Further, N-alkylation of the quinolinones was carried out effectively with various halides using amberlite Na sr1L. An N-alkylated quinolinone exhibited enhanced activities against B. subtilis, E. coli, and P. aeruginosa, similar to standard drug ampicillin. Two compounds showed effective activity against S. aureus, and one resulted in moderate activity against E. coli. 相似文献3.
Liqiang Wu Chunguang Yang Binxuan Niu Fulin Yan 《Monatshefte für Chemie / Chemical Monthly》2009,26(3):1195-1198
Abstract
A simple and efficient one-pot synthesis of 6-chloroquinolines was achieved in good yields via the three-component reaction of 2-aminoaryl ketones, α-methylene carbonyl compounds, and BTMA ICl4 in AcOH. 相似文献4.
Abstract
Several achiral and chiral basic ionic liquids (ILs) were prepared and tested as the medium for Ru-catalyzed hydrogen-transfer reduction of different aromatic ketones. Hydrogen-transfer reduction of ketones proceeded well in achiral basic ILs using chiral catalysts. The interesting observation was made that raising the reaction temperature did not have a negative effect on enantioselectivity of the reaction. On the other hand no reaction was observed in chiral ILs. 相似文献5.
Pramod Kulkarni Balaji Totawar Pudukulathan K. Zubaidha 《Monatshefte für Chemie / Chemical Monthly》2012,141(10):625-629
Abstract
Various β-aminoketones were synthesized in a three-component reaction of ketones, aldehydes, and amines in the presence of calcium chloride as catalyst in ethanol in high yields as compared to other synthetic methods. The advantages of this new method are a short reaction time (2 h), high yields, easy workup, convenience, low cost, and eco-friendly protocol. 相似文献6.
Quang Huy To Yong Rok Lee Sung Hong Kim 《Monatshefte für Chemie / Chemical Monthly》2012,14(2):1421-1426
Abstract
A simple and efficient method to synthesize a variety of tetrahydroquinolinones was successfully achieved by reacting various β-enaminones with several α,β-unsaturated aldehydes. This strategy can be viewed as a Br?nsted acid-mediated formal [3+3] cycloaddition. 相似文献7.
Abolghasem Davoodnia Majid M. Heravi Leila Rezaei-Daghigh Niloofar Tavakoli-Hoseini 《Monatshefte für Chemie / Chemical Monthly》2009,13(3):1499-1502
Abstract
Efficient and convenient synthesis of β-acetamido ketones has been achieved by one-pot reaction of acetophenone, aryl aldehydes, acetyl chloride, and acetonitrile in the presence of 3-methyl-1-(4-sulfonylbutyl)imidazolium hydrogensulfate [HO3S(CH2)4MIM][HSO4], a Br?nsted-acidic ionic liquid, as a green and reusable catalyst in solvent-free media at room temperature. The catalyst could be recycled and reused without noticeable decrease in catalytic activity. 相似文献8.
Michal Paták Old?ich Pytela Filip Bure? 《Monatshefte für Chemie / Chemical Monthly》2011,14(3):1131-1136
Abstract
Overall, six tartrate- and imidazole-derived ketones and diols were synthesized in a stepwise manner as model compounds for the coordination of Cu2+ ions. The stability constants of copper(II) complexes were studied spectrophotometrically. It was found that the two model structures coordinate Cu2+ ions differentially. 相似文献9.
Abstract
Arylaminotetrazoles were efficiently synthesized from secondary arylcyanamides by application of ZnCl2/AlCl3/silica as a reusable heterogeneous Lewis acid catalyst. 5-Arylamino-1H-tetrazoles can be obtained from arylcyanamides carrying electron-withdrawing substituents on the aryl ring, while with electron-releasing groups 1-aryl-5-amino-1H-tetrazoles will be produced. The former isomer is also produced within longer reaction times (~20 h) even with electron-releasing groups. 相似文献10.
Abdelwareth A. O. Sarhan Mohammed S. Ibrahim Mostafa M. Kamal Kaiko Mitobe Taeko Izumi 《Monatshefte für Chemie / Chemical Monthly》2009,9(11):315-323
Abstract
New ferrocenyl ketones were obtained as precursors of novel π-conjugated ferrocene-dithiafulvalene (Fc-DTF) and π-extended-ferrocenedithia-fulvalenes (π-exFc-DTF) as electron-donor conducting materials from ferrocene by a direct aroylation process using the Friedel–Crafts reaction. Novel Fc-DTF conjugates were synthesized using the Wittig–Horner reaction and their structures were determined. The redox behavior of the ferrocenyl carbonyl compounds Fc-DTF and Fc-π-exDTF was investigated in comparison to the parent ferrocene by means of cyclic voltammetry. A one-electron redox behavior was observed for carbonylferrocenes as one wave potential, while a two-electron process was observed as two oxidation waves for the conjugates. Introduction of electron-withdrawing groups led to increasing E pa values and decreasing ΔE p values. The UV–Vis spectra of some compounds were studied in comparison with ferrocene. The absorption spectra showed a red-shift with a slight increase in the absorption intensities. 相似文献11.
Abstract
Chiral α-ethylphenylamine tartaric acid salts were synthesized from α-ethylphenylamine by direct reaction with chiral tartaric acid. The crystal structure of S-(−)-α-ethylphenylamine-(2R,3R)-(−)-dihydroxybutanedioic acid was determined. The crystal is monoclinic, of space group P21/n , with a = 6.331(5) ?, b = 14.209(11) ?, c = 7.495(6) ?, α = 90.00o, β = 107.000(13)o, γ = 90.00o, λ = 0.7103 Ǻ, V = 644.7(9), Z = 2, D c = 1.397 g/cm3, M r = 271.27 and F(000) = 288, R = 0.0477, and ωR = 0.0838 for 1388 observed reflections with I > 2σ(I). We then used the chiral α-ethylphenylamine tartaric acid salts as catalysts in the cyanosilylation of prochiral ketones, and moderate conversions were obtained. 相似文献12.
Abstract
An efficient, facile, and mild oxidation of alcohols to the corresponding aldehydes or ketones with potassium peroxodisulfate and 2,2,6,6-tetramethylpiperidinyl-1-oxy in the presence of a catalytic amount of iodobenzene is reported. The oxidation proceeded in a mixed solvent to afford carbonyl compounds in moderate to excellent yields. A possible mechanism for the oxidation is proposed. 相似文献13.
1. | A series of C-functional derivatives of (3)-1,2-dicarbaundecaborate was synthesized and some of their properties were studied. |
2. | Apparent ionization constants of acids of the (3)-1,2-dicarbaundecaborate series were measured and it was found that they are very weak carboxylic acids. |
3. | Upon reaction with excess LiA1H4, under mild conditions the carbonyl, *20c \CH(OH) / \begin{array}{*{20}c} \backslash \\ {CH(OH)} \\ / \\ \end{array} , and CH2OH groups of dicarbaundecaborate ketones and alcohols are reduced to CH2 and CH3 groups, respectively. |
4. | The effect of Grignard reagent on ketones and esters of the dicarbaundecarbprate series was studied and it was established that the composition of reaction products depends both on the steric hindrance of the carbonyl group and on the electron-donating effect of the (3)-1,2-dicarbaundecaborate substituent. |
14.
Someshwar D. Dindulkar Paramasivam Parthiban Yeon Tae Jeong 《Monatshefte für Chemie / Chemical Monthly》2012,21(3):113-118
Abstract
A range of Lewis acid catalysts were used for a series of one-pot multi-component reactions. Of them, silica-supported boron trifluoride (BF3·SiO2) was found to be an effective catalyst for the promotion of the modified Mannich condensation of ketones, aldehydes, and ammonium acetate in 1:2:1 molar ratio to afford 3,5-dialkyl-2,6-diarylpiperidin-4-ones in high yields of 80–92%. Also this simple, easily prepared, and reusable catalyst executed the condensation very effectively in a significantly shorter reaction duration (about 1–4 h) than the conventional method, which requires 1 day or more and involves a tedious work-up procedure. Further, this protocol ensures the stereospecificity; accordingly, all the synthesized piperidones adopted a chair conformation with an equatorial orientation of all substituents at C-2, C-3, C-5, and C-6. 相似文献15.
Rahman Hosseinzadeh Mahmood Tajbakhsh Maryam Mohadjerani Zahra Lasemi 《Monatshefte für Chemie / Chemical Monthly》2009,42(12):57-60
Abstract
Ethylenebis(N-methylimidazolium) ditribromide, a stable crystalline solid, is easily prepared by reaction of the corresponding dibromide salt with bromine in n-hexane. 1,3-Diketones and β-ketoesters can be brominated chemoselectively to the corresponding α-monobrominated products by using this reagent at 0–5 °C. Under the same reaction conditions, diethyl malonate, ethyl cyanoacetate, and malonitrile were monobrominated at moderate yield. 相似文献16.
Nadya G Gurskaya Alexander P Savitsky Yurii G Yanushevich Sergey A Lukyanov Konstantin A Lukyanov 《BMC biochemistry》2001,2(1):6-7
Background
Green Fluorescent Protein (GFP) cloned from jellyfish Aequorea victoria and its homologs from corals Anthozoa have a great practical significance as in vivo markers of gene expression. Also, they are an interesting puzzle of protein science due to an unusual mechanism of chromophore formation and diversity of fluorescent colors. Fluorescent proteins can be subdivided into cyan (~ 485 nm), green (~ 505 nm), yellow (~ 540 nm), and red (>580 nm) emitters. 相似文献17.
Samiullah Khan Tania Pozzo Márton Megyeri Sofia Lindahl Anders Sundin Charlotta Turner Eva Nordberg Karlsson 《BMC biochemistry》2011,12(1):11
Background
The thermostable β-glucosidase (TnBgl1A) from Thermotoga neapolitana is a promising biocatalyst for hydrolysis of glucosylated flavonoids and can be coupled to extraction methods using pressurized hot water. Hydrolysis has however been shown to be dependent on the position of the glucosylation on the flavonoid, and e.g. quercetin-3-glucoside (Q3) was hydrolysed slowly. A set of mutants of TnBgl1A were thus created to analyse the influence on the kinetic parameters using the model substrate para-nitrophenyl-β-D-glucopyranoside (pNPGlc), and screened for hydrolysis of Q3. 相似文献18.
Ben-Mei Wei Zhi-Yong Zhang Zhi-Qun Dai Kai-Cheng Zhang 《Monatshefte für Chemie / Chemical Monthly》2011,57(1):1029-1033
Abstract
Dealkylation of esters to carboxylic acids was performed using chloroaluminate ionic liquids (PyHBr/AlCl3, PyHCl/AlCl3, Me3NHCl/AlCl3, Et3NHCl/AlCl3) as catalyst and medium. The catalytic activity of PyHBr/AlCl3 (X(AlCl3) = 0.67) proved to be superior to the other three ionic liquids for the dealkylation of methyl benzoate with a conversion of 97% after 3 h at 140 °C. After easy separation from the products the ionic liquid PyHBr/AlCl3 could be reused six times without loss of its activity. 相似文献19.
L. Kh. Freidlin L. I. Gvinter V. A. Zamureenko L. N. Suvorova 《Russian Chemical Bulletin》1976,25(4):795-797
1. | Intermediate enol formation has been registered by deuterium exchange in the hydrogenation products of, -unsaturated ketones on Co/C and Rh/C, indicating 1,4 addition of hydrogen to the enone system. |
2. | The presence of 1,4 hydrogen addition to,-unsaturated ketones is determined by the nature of the catalyst; Pd/C does not catalyze this process route. |
3. | Modification of Pd catalysts with cadmium changes their orienting action and selectivity in favor of 1,4 hydrogen addition with intermediate enol formation. |
20.