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1.
A wide variety of monobrominated compounds 2a-l have been prepared in good yields from (E)-1-(2′-hydroxy-4′,6′-dimethoxyphenyl)-3-aryl-2-propen-1-ones (1a-l) through regioselective ring bromination using 1.5 equiv of bromodimethylsulfonium bromide (BDMS) at room temperature. Similarly, some of the 2′-hydroxychalcones can be converted directly into tribromides 3 or dibromides 4 by employing 4.0 equiv of BDMS under different reaction conditions which in turn can be transformed into 8-bromoflavones and 7-bromoaurones on treatment with 0.2 M ethanolic KOH solution. Mild reaction conditions, good yields and no chromatographic separation are some of the salient features of the present protocol. 相似文献
2.
A wide variety of unsubstituted β-keto esters can be brominated chemoselectively to the corresponding α-monobromo-β-keto esters by using a combination of vanadium pentoxide, hydrogen peroxide and ammonium bromide in a biphasic system, dichloromethane-water at 0-5 °C. In addition, α-mono substituted β-keto esters, cyclic β-keto-esters and 1,3-diketones can also be brominated selectively using the same protocol. 相似文献
3.
The geometry, frequency and intensity of the vibrational bands of 8-hydroxyquinoline and its 5,7-dichloro, 5,7-dibromo, 5,7-diiodo
and 5,7-dinitro derivatives were obtained by the density functional theory (DFT) calculations with Becke3-Lee-Parr (B3LYP)
functional and 6-31G* basis set. The effects of chloride, bromide, iodide and nitro substituent on the vibrational frequencies
of 8-hydroxyquinoline have been investigated. The assignments have been proposed with aid of the results of normal coordinate
analysis. The observed and calculated spectra are found to be in good agreement.
相似文献
4.
An oxidation method using dilute nitric acid solutions under solvothermal conditions has been developed to synthesise a series of polypyridine-polycarboxylic acids. It has been successfully applied to a range of methyl substituted polypyridines including symmetrical and asymmetrical 2,2′-bipyridines; 2,2′:6′,2″-terpyridines and; 2,2′:6′,2″:6″,2?-tetra-pyridines and yields crystalline polypyridine-polycarboxylic acids in a single step. Simple product recovery through filtration yields a recyclable filtrate. More forcing conditions led to demethylation of the polypyridine ligand most probably via decarboxylation. This simple approach avoids potentially harmful metal-based oxidants and negates any issues associated with the disposal of their resultant (hazardous) waste. 相似文献
5.
Oligonucleotides incorporating the propynyl derivative of 7-deaza-2′-deoxyguanosine (1) were synthesized by solid-phase oligonucleotide synthesis. As building blocks the phosphoramidites 7a,b were prepared. The incorporation of 1 into oligonucleotides exerts a positive effect on the DNA duplex stability. The duplex stabilization by 1 was higher than that of 7-iodo-7-deaza-2′-deoxyguanosine (2b). The stabilizing effect of the 7-propynyl group introduced in the 7-deazapurines is similar to that reported for 8-aza-7-deazapurines. From CD spectra it was deduced that the B-DNA structure is not significantly altered by compound 1. 相似文献
6.
Anhydrous potassium carbonate has been utilized as an inexpensive, safe, and efficient basic catalyst for the synthesis of flavanones starting either from 2′-hydroxychalcones or from 2′-hydroxyacetophenones. In both the cases the favored reaction condition was either refluxing in a solvent with added catalyst or microwave irradiation on the catalyst. 相似文献
7.
D. V. Besedin A. V. Gulevskaya A. F. Pozharskii 《Chemistry of Heterocyclic Compounds》2000,36(10):1213-1218
Heating 6,8-dimethylpyrimido[4,5-c]pyridazine-5,7(6H,8H)-dione N(2)-oxide (2) with piperidine or morpholine gave a moderate yield of 3-piperidino- and 3-morpholino-6,8-dimethylpyrimido[4,5-c]pyridazine-5,7(6H,8H)-diones (3a,b). Reaction of N-oxide (2) with ammonia and alkylamines in the presence of an oxidant led to formation of the 3-amino derivatives of 2 and the corresponding desoxy products 3. The latter were also obtained by an independent method by heating 3-chloro-6,8-dimethylpyrimido[4,5-c]pyridazine-5,7(6H,8H)-dione with alkylamines in butanol. 相似文献
8.
A. V. Gulevskaya V. V. Goryunenko A. F. Pozharskii 《Chemistry of Heterocyclic Compounds》2000,36(8):975-980
6,8-Dimethyl-3-chloropyrimido-[4,5-c]pyridazin-5,7(6H,8H)dione reacts with malonodinitrile, cyanoacetic ester, and nitromethane in the presence of bases to give products of nucleophilic substitution of the chlorine atom. The products containing the cyanoacetic ester and nitromethane residues exist exclusively in the chelated methylidene form in CHCl3 and DMSO solutions. Reactions of pyridazinouracil with methylmagnesium chloride and butyllithium gave products of nucleophilic addition at C(4).For Comuunication 16, see [1].Rostov State University, Rostov-on-Don 344090, Russia Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1113–1118, August, 2000. 相似文献
9.
Oxidative amination of 3-chloro-6,8-dimethylpyrimido[4,5-c]pyridazine-5,7(6H,8H)-dione with primary alkylamines and potassium amide in liquid ammonia gives rise to the corresponding 4-amino derivatives as the major products. The reactions with acyclic secondary amines are accompanied by annelation of the pyrrole moiety to the starting heterosystem to form 1-R-3-R"-6,8-dimethylpyrrolo[2",3";3,4]pyrimido[4,5-c]pyridazine-7,9(6H,8H)-diones. The reaction with piperidine as the aminating agent occurs exclusively as aminodehalogenation. The Sonogashira cross-coupling of 4-amino-3-chloro-6,8-dimethylpyrimido[4,5-c]pyridazine-5,7(6H,8H)-diones with terminal alkynes affords 1-R-2-R"-6,8-dimethylpyrrolo[3",2";3,4]pyrimido[4,5-c]pyridazine-7,9(6H,8H)-diones. 相似文献
10.
Jia-Hua Cui Dagula Hu Xu Zhang Zheng Jing Jing Ding Ru-Bing Wang Shao-Shun Li 《中国化学快报》2013,24(3):215-218
The flavonoids as inhibitors of CYP1Al exhibit chemopreventive effects against certain procarcinogens and have been considered as the promising cancer preventive agents.A series of novel 7,8-dimethoxy-αnaphthoflavones as the substrate analogs were designed and prepared.The enzyme assay suggested that all of these new flavones were stronger inhibitors of CYP1 Al than the lead compoundα-naphthoflavone. Among the tested ones,3h showed the most potent inhibitory effects. 相似文献
11.
Ali Rahmatpour 《应用有机金属化学》2011,25(8):585-590
A new and efficient method for the synthesis of a variety of N‐substituted pyrroles from condensation reactions of 2,5‐hexanedione with amines or diamines using ZrOCl2·8H2O as a water‐tolerant Lewis acid catalyst at room temperature is described.The use of nontoxic, inexpensive, easily available and reusable catalyst under solvent‐free conditions make this protocol practical, environmentally friendly and economically attractive. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
12.
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14.
Arunkumar Natarajan Eugene P. BodenAndrew Burns Patrick J. McCloskeyMichael J. Rishel 《Tetrahedron letters》2014
While exploring water soluble rhodamine based fluorescent polymeric systems for biological imaging applications we came across new rhodamine derivatives that possess interesting optical properties. We report the synthesis of three different 2′,7′-diphenylated rhodamine derivatives (1–3) with distinct photophysical properties. The three rhodamine derivatives differ by the number of methyl groups present on the nitrogens and their absorption maxima are red-shifted on increased methylation. We observed an unusual inertness of these compounds toward traditional DCC–DMAP esterification conditions, which we attribute to the ease of lactonization in the presence of even minute amounts of the nucleophile/base DMAP (pKa = 9.2). Synthesis of acrylate esters was successfully accomplished using MSNT (1-(Mesitylene-2-sulfonyl)-3-nitro-1,2,4-triazole) coupling conditions using a much milder nucleophile/base, for example, N-methyl imidazole (pKa = 6.95). 相似文献
15.
Alexandru Ciocarlan Carolina Edu Andrei Biriiac Lidia Lungu Aculina Aricu Michele D'Ambrosio 《合成通讯》2013,43(22):3020-3033
A series of 15 new polyfunctional drimanic compounds have been obtained by synthesis via dye-sensitized photooxygenation, bromination with N-bromosuccinimide, and electrochemical transformation of drim-7,9(11)-diene 1 and drim-8-en-7-one 2. Three alternative syntheses of 12-acetoxy-drim-7,9(11)-diene 8 and two of 11-bromo-drim-8(9)-en-7-one 10 have been accomplished. For the first time a drimanic compound 12 with an aromatic ring B has been synthesized and the experimental conditions for the selective bromination at C11 and C12 methyl groups of drim-8-en-7-one 2 have been optimized. The synthesized compounds are suitable intermediates for the preparation of natural drimane-type compounds and some of them have shown good antimicrobial and antifungal activities. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.] 相似文献
16.
Palaa Krishna 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):685-690
AbstractA series of new 5-amino-7-bromoquinolin-8-ol sulfonate derivatives 5(a–j) were synthesized from 8-hydroxyquinoline through multi-step process with high yields using mild, efficient and conventional methods. Chemoselectivity was observed during the transformation of 5-amino-7-bromoquinolin-8-ol to 5-amino-7-bromoquinolin-8-ol sulfonate with various sulfonylchlorides exclusively to afford sulfonate derivatives. Also, the products were investigated for their in vitro antimicrobial activities and compared with the standard drugs. Among all the synthesized compounds 5-amino-7-bromoquinolin-8-yl biphenyl-4-sulfonate (5b) and 5-amino-7-bromoquinolin-8-yl 2-hydroxy-5-nitrobenzenesulfonate (5g) have showed potent antibacterial activity, whereas 5-amino-7-bromoquinolin-8-yl biphenyl-4-sulfonate (5b) and 5-amino-7-bromoquinolin-8-yl 2-hydroxy-5-nitrobenzenesulfonate (5g) possessed potent antifungal activities among all the tested pathogens. 相似文献
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18.
B. Madhu Babu G. Santosh KumarPramod B. Thakur Vikas M. BangadeH.M. Meshram 《Tetrahedron letters》2014
A mild and novel approach is described for the synthesis of functionalized fused imidazole analogues in solvent-free and catalyst-free condition in ionic liquid. The short reaction time, good isolated yields, generality and environmentally benign reaction media are the significant features of this protocol. 相似文献
19.
《Magnetic resonance in chemistry : MRC》2003,41(4):301-303
4‐Methyl‐6,8‐dihydroxy‐7H‐benz[de]anthracen‐7‐one was isolated from the sap of Aloe by column chromatography. Its 1H and 13C NMR spectra were completely assigned by utilizing two‐dimensional 1H‐detected heteronuclear one‐bond (HMQC) and multiple‐bond (HMBC) chemical shift correlation experiments together with 1H–1H COSY and DEPT techniques. These techniques were also valuable in assigning the protons and carbons of those benzanthrone compounds which were previously incompletely reported because of the overlap of proton signals. The molecular structure was elucidated by 2D NMR analysis. The spectral properties (MS, IR and UV) are also presented. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
20.
Daniel Długosz Malgorzata Pach Anna Zabrzeńska Monika Zegar Barbara J. Oleksyn Justyna Kalinowska-Tłuścik Katarzyna Ostrowska 《Monatshefte für Chemie / Chemical Monthly》2008,139(5):543-548
Bis(cycloamidine-2-yl)alkanes easily form bromide tribromide salts in the reduction-oxidation processes with bromine. Bis(tetrahydroimidazolium-2-yl)ethane
and bis(hexahydropyrimidinium-2-yl)-ethane bromide tribromides are such new convenient brominating agents for aromatic amides
in chemo- and regioselective electrophilic substitutions and α-bromination reactions.
Correspondence: Katarzyna Ostrowska, Department of Organic Chemistry, Jagiellonian University, R. Ingardena 3, PL-30060 Kraków,
Poland. 相似文献