共查询到20条相似文献,搜索用时 15 毫秒
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Juan I. Sarmiento-Sánchez Adrián Ochoa-Terán Lorenzo A. Picos-Corrales Lorenzo U. Osuna-Martínez Julio Montes-Ávila Pedro Bastidas-Bastidas 《Green Chemistry Letters and Reviews》2016,9(4):196-202
Benzoxazinediones exhibit potential as versatile synthons in the synthesis of wide variety of heterocyclic compounds with biological activity. In this work, an efficient and eco-friendly one-step synthesis of benzoxazine-2,4-diones from phthalic anhydrides derivatives and trimethylsilyl azide using the microwave technique was developed and compared with conventional heating. Microwave irradiation plays a critical role in driving the reaction and providing access to products and/or regioisomers not available from conventional heating. Thus, the regioselectivity of the reaction may be modulated by the irradiation time. Depending on the method employed the benzoxazinediones were isolated with yields in the range of 30–90%. 相似文献
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The one-pot, three-component condensation of benzil, benzonitrile derivatives and primary amines on the surface of silica gel under solvent-free conditions and microwave irradiation provided tetrasubstituted imidazoles in high yields. 相似文献
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According to popular belief, oxygen and water are the natural enemies of organometallic reactions and therefore must be excluded rigorously from the reaction vessel. This belief is founded in the case of the highly reactive nucleophilic metal alkylidene complexes that were used in early catalytic olefin metathesis. However, owing to the high stability of the ruthenium carbene complexes introduced by Grubbs, metathesis in water has become reality. 相似文献
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M. Gopalakrishnan P. Sureshkumar V. Kanagarajan J. Thanusu 《Research on Chemical Intermediates》2007,33(6):541-548
Condensation of structurally diverse aldehydes including heterocyclic aldehydes, like furfural, with various amines in the
presence of calcium oxide affording the corresponding imines in solvent-free conditions in good to excellent yields under
microwave irradiation is described. A comparative study has been done under thermal conditions. The synergy between dry media
and microwave irradiation in this reaction is evaluated by condensing less electrophilic aldehydes with poorly nucleophilic
amines. The main advantages of this environmentally friendly protocol are the use of the non-toxic and inexpensive reagent
calcium oxide and the considerable rate enhancement in comparison with a thermal reaction. 相似文献
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Javad Safari Sayed Hossein Banitaba Shiva Dehghan Khalili 《Arabian Journal of Chemistry》2011,4(1):11-15
Silica sulfuric acid was found to be an efficient, reusable and environment-friendly catalyst for fast hydrolysis of various isobenzofuranone to corresponding 2-ketomethylquinoline derivatives in a high yield under solvent-free using microwave irradiation. As the activator of silica sulfuric acid the wet SiO2 was chosen. The reactions in conventional conditions were compared with the microwave assisted reactions. This approach can prove beneficial since the recovery of solvents from conventional reaction systems always results in some losses. 相似文献
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Clavier H Grela K Kirschning A Mauduit M Nolan SP 《Angewandte Chemie (International ed. in English)》2007,46(36):6786-6801
Ruthenium-catalyzed olefin metathesis reactions represent an attractive and powerful transformation for the formation of new carbon-carbon double bonds. This area is now quite familiar to most chemists as numerous catalysts are available that enable a plethora of olefin metathesis reactions. Nevertheless, with the exception of uses in polymerization reactions, only a limited number of industrial processes use olefin metathesis. This is mainly due to difficulties associated with removing ruthenium from the final products. In this context, a number of studies have been carried out to develop procedures for the removal of the catalyst or the products of catalyst decomposition, however, none are universally attractive so far. This situation has resulted in tremendous activity in the area dealing with supported or tagged versions of homogeneous catalysts. This Review summarizes the numerous studies focused on developing cleaner ruthenium-catalyzed metathesis processes. 相似文献
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Hajime IwamotoKoji Itoh Hiroyuki NagamiyaYoshimasa Fukazawa 《Tetrahedron letters》2003,44(31):5773-5776
[3]Catenane 5a and 5b were synthesized conveniently by olefin metathesis dimerization of pseudorotaxanes 3a and 3b. The yields of 5a and 5b were influenced by concentrations of 3a and 3b, and a ring size of a center wheel of [3]catenane. 相似文献
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Ruthenium- and rhodium-based catalysts can be designed and finely tuned to some extent so as to mediate either carbene transfer
to olefins (e.g., olefin cyclopropanation) or olefin metathesis. The different outcome of the reactions can be quite simply predicted based
on either the ability or the absence of ability of the metal center to coordinate both the carbene and the olefin. Several
available coordination sites at the metal center are favorable for metathesis to the prejudice of olefin cyclopropanation.
Based on the report presented at the conference “Organometallic Chemistry on the Eve of the 21st Century,” May 19–23, 1998,
Moscow.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1219–1224, July, 1999. 相似文献
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Yu Xie Ye Yuan Bibimaryam Mousavi Yuan Cai Cheng Kai Yin Lu Mehman Yusubov Francis Verpoort 《应用有机金属化学》2015,29(9):573-579
Olefin metathesis is a transition metal‐mediated transformation that rearranges the carbon atoms of the carbon–carbon double bond of olefins. This reaction has become one of the most important and powerful reactions. Therefore development of new, well‐defined, highly active and selective catalysts is very desirable and a valuable goal. This mini‐review mainly introduces the development of ruthenium catalysts in olefin metathesis highlighting oxygen‐chelated indenylidene ruthenium catalysts. Applying an alkoxyl group on the indenylidene ligand fragment can generate the Ru ? O chelating bond. Additionally, various modifications of the ligand as well as the catalytic activity for ring‐closing metathesis reaction and selectivity of cross metathesis reaction are overviewed. Finally, the perspectives on the development of new catalysts are summarized. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Qing Han Li 《中国化学快报》2009,20(7):793-796
Six new asymmetric thiocarbonohydrazones 3a-3f were synthesized from following steps:firstly hydrazine hydrate reacted with carbon disulfide to form thiocarbonohydrazide(1) under microwave irradiation.Then compound(1) reacted with ketone and different aldehydes step by step to give 3a-3f with excellent yields under solvent-free conditions using microwave irradiation.Their structures have been determined by elemental analysis,IR,MS and ~1H NMR data. 相似文献
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Julian P. Edwards William J. Wolf Robert H. Grubbs 《Journal of polymer science. Part A, Polymer chemistry》2019,57(3):228-242
Cyclic polymers have drawn considerable interest for their peculiar physical properties in comparison to linear polymers, despite their equivalent compositions. Synthetically, cyclic polymers can be accessed through either macrocyclic ring‐closure or by ring‐expansion polymerization, but the main challenge with either method is the production of highly pure cyclic polymer samples. This highlight describes advances in the area of cyclic polymer synthesis, with a particular focus on ring‐expansion metathesis polymerization. Methods for characterizing cyclic polymers and assessing their purity are also discussed in order to emphasize the need for additional robust and reliable methods for synthesizing and studying topologically complex macromolecules. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 228–242 相似文献
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N. B. Bespalova M. A. Bovina M. B. Sergeeva V. G. Zaikin 《Russian Chemical Bulletin》1994,43(8):1425-1426
Olefin metathesis of diallylacetic acid esters is proposed for the synthesis of 3-cyclopentenecarboxylic acid esters. WCl6-organosilicon compounds are used as homogeneous catalysts.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1503–1504, August, 1994. 相似文献
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Plant oils are attractive substrates for the chemical industry. Their scope for the production of chemicals can be expanded by sophisticated catalytic conversions. Olefin metathesis is an example, which also illustrates generic issues of "biorefining" to chemicals. Utilization on a large scale requires high catalyst activities, which influences the choice of the metathesis reaction. The mixture of different fatty acids composing a technical-grade plant oil substrate gives rise to a range of products. This decisively determines possible process schemes, and potentially provides novel chemicals and intermediates not employed to date. 相似文献
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Fournier PA Savoie J Stenne B Bédard M Grandbois A Collins SK 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(28):8690-8695
In asymmetric olefin metathesis reactions, the addition of halide additives is often required to augment enantioselectivities, despite the fact that the additives result in catalysts with diminished reactivities. The preparation of new chiral Ru-based catalysts was accomplished by exploiting previously reported mechanistic studies. The catalysts possess a high level of reactivity and successfully induce high levels of asymmetry in desymmetrization reactions without the use of halide additives. 相似文献
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《Green Chemistry Letters and Reviews》2013,6(1):97-100
Abstract An efficient one-pot condensation has been developed for the synthesis of polyhydroquinolines via a four component coupling reaction of aldehyde, dimedone, ethyl acetoacetate, and ammonium acetate under catalyst and solvent-free conditions. Non-hazardous experiment procedure, operational simplicity, mild reaction conditions, and the compatibility with various functional groups represent the advantages of the present method. 相似文献