共查询到20条相似文献,搜索用时 15 毫秒
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Roberto Ballini Giovanna BosicaDamiana Livi Alessandro PalmieriRaimondo Maggi Giovanni Sartori 《Tetrahedron letters》2003,44(11):2271-2273
The N,N-diethylpropylamine supported on amorphous silica (KG-60-NEt2) catalyses the formation of carboncarbon bonds by nitroalkanes through both the nitroaldol (Henry) and Michael reactions. The catalyst shows general utility with a variety of electrophilic acceptors. Moreover, the catalyst can be reused for two further cycles without loss of the activity. 相似文献
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Chloé Vovard-Le Bray 《Tetrahedron letters》2010,51(34):4555-893
A convenient cyclen-catalyzed Henry reaction of aldehydes with nitroalkanes under mild and neutral conditions is reported. This procedure constitutes the first cyclen-catalyzed synthesis of nitroalcohols and is adapted to the condensation of both aromatic and aliphatic aldehydes with nitromethane in THF at room temperature without addition of stoichiometric amount of the base. A wide range of substrates, β-nitroalcohols, were obtained in moderate to good yields (up to 98%) using this methodology. 相似文献
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Jean-Michel Guenet 《Macromolecular Symposia》2003,203(1):1-12
The relevancy of temperature-composition phase diagrams for the study of polymer-solvent complexes and intercalates is discussed. In particular the use of Tamman's diagrams for determining the stoichiometric composition is evaluated. Examples of the validity of this approach are taken from isotactic or syndiotactic polystyrene compounds. Also, the effect of the path followed for reaching a T, C coordinate is examined. It is shown that cooling hot, homogeneous solutions at composition C or allowing solvent to diffuse in a solid polymer matrix at temperature T yields basically the same thermal behaviour. 相似文献
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不对称催化Henry反应研究进展 总被引:2,自引:0,他引:2
Henry反应是一类重要的有机反应. 按照反应中使用催化剂的种类, 分金属络合物催化、有机小分子催化、酶催化、非均相负载催化四大类, 详细介绍了不对称催化Henry反应的研究进展. 相似文献
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以钛酸四乙酯为催化剂, 芳基乙酮酸乙酯与天然L-薄荷醇进行酯交换, 合成了8个含手性基团的芳基乙酮酸薄荷醇酯; 在手性基团的立体选择性控制下, 芳基乙酮酸薄荷醇酯与硝基甲烷进行不对称Henry反应, 合成了7个(2R)-2-羟基-2-芳基-3-硝基丙酸薄荷醇酯新化合物, 用IR, 1H NMR, 13C NMR, MS和元素分析表征了化合物结构. 用高效液相色谱经手性柱分析了不对称反应效果, 缩合反应的非对映体过量在46.5%~64.2%之间, 表明可以通过立体选择性控制产物构型. 相似文献
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不对称Henry反应的研究进展 总被引:1,自引:1,他引:1
总结了各种能有效催化不对称Henry反应的新方法、新条件和新催化剂,讨论了一类拓展的不对称催化Henry反应。对立体选择性催化Henry反应的催化剂的发展提出了作者的一些看法。参考文献26篇。 相似文献
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Dr. Isaac G. Sonsona Dr. Juan V. Alegre-Requena Dr. Eugenia Marqués-López Prof. Dr. M. Concepción Gimeno Prof. Dr. Raquel P. Herrera 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(24):5469-5478
The first asymmetric catalyzed aza-Henry reaction of hydrazones is presented. In this process, quinine was used as the catalyst to synthesize different alkyl substituted β-nitrohydrazides with ee up to 77 %. This ee was improved up to 94 % by a further recrystallization and the opposite enantiomer can be obtained by using quinidine as the catalyst, opening exciting possibilities in fields in which the control of chirality is vital, such as the pharmaceutical industry. Additionally, experimental and ab initio studies were performed to understand the reaction mechanism. The experimental results revealed an unexpected secondary kinetic isotope effect (KIE) that is explained by the calculated reaction pathway, which shows that the protonation of the initial hydrazone and the C−C bond forming reaction occur during a concerted process. This concerted mechanism makes the catalysis conceptually different to traditional base-promoted Henry and aza-Henry reactions. 相似文献
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CunLiuZHOU YuQingZHOU ZhiYongWANG 《中国化学快报》2003,14(4):355-358
The chemoselective addition of aldehydes in aquoues medium was obtained under mild condition using improved Henry reaction. 相似文献
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I. Iovel L. Golomba J. Popelis A. Gaukhman E. Lukevics 《Chemistry of Heterocyclic Compounds》2000,36(3):264-274
We have studied the reactions of (hetero)aromatic aldehydes with 2-aminopyridines. The results obtained suggest that molecular sieves play a role in these processes not only as a dehydrating agent but also as an acid catalyst. We have synthesized a series of novel heterocyclic azomethines.Dedicated to Professor M. A. Yurovskaya on her Jubilee.Latvian Institute of Organic Synthesis, Riga LV-1006 Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 324–335, March, 2000. 相似文献
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An efficient synthesis of aryliminophosphoranes is described. A mixture of an aromatic amine, diethyl azodicarboxylate and triphenylphosphine undergo a Mitsonobu type reaction at ambient temperature in dry dichloromethane to afford aryliminophosphoranes in excellent yields. 相似文献
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Conclusions In the presence of amines methyl phenylphosphinate reacts to form products only of 1,6 addition to the conjugated system of tetracyclone.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1602–1607, July, 1978. 相似文献
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Akira Ando 《Journal of fluorine chemistry》2003,123(2):283-285
The reaction of halothane, 2-bromo-2-chloro-1,1,1-trifluoroethane (1), with aldehydes and ketones in the presence of bases was found to give 1-alkyl- or 1-aryl-2-bromo-2-chloro-3,3,3-trifluoropropanols (2) or 2-chloro-3,3-difluoro-2-propenols (3) selectively in good to moderate yields depending on the bases and reaction conditions. 相似文献
13.
Tommaso Angelini Eleonora Ballerini Simona Bonollo Massimo Curini 《Green Chemistry Letters and Reviews》2014,7(1):11-17
A new protocol for the Henry addition of nitroalkanes to aryl- and alkyl-aldehydes promoted by PS-BEMP under solvent-free conditions (SolFC) is presented. The corresponding nitroaldol products were obtained in good yields and short times; furthermore minimization of the reaction waste was achieved by reducing the use of organic solvents. Extension of the protocol was obtained by setting up the tandem Michael-Henry reaction of α,β-unsaturated aldehydes and nitroalkane to yield the corresponding dinitro derivatives. 相似文献
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The potential energy surfaces for the transamination reaction catalyzed by SSAO were explored for some of the possible reactants considered in a preliminary investigation (Comput Chem 2000, 24 , 311). The proton transfer to methylamine (as a model of the catalytic base belonging to the enzyme active site)—either from the keto or enol form of the reactant Schiff bases with one of the possible cofactors, pyridoxal phosphate, PLP (using as a model the pyridoxal ring protonated at N)—was investigated. The enol form seems to be preferred in the region of the neutral intermediate, because even the keto form undergoes a spontaneous rearrangement to the enol form once the Cα proton is delivered to methylamine, producing methylammonium. When the proton is returned back to the Schiff base (on C1), the adduct is about 1.4 kcal/mol more stable than the reactants, while a canonical electron distribution is obtainable only for the enol form. The proton transfer to methylamine was also studied in the presence of the other possible cofactor (para or ortho) topaquinone, TQ. A steep uphill pathway, similar to the keto‐pyridoxal Schiff base one, is obtained using the Schiff base with pTQ, which requires a rearrangement to the final intermediate. On the contrary, using the oTQ structures with the quinonoid O on the same side of methylamine, the proton abstracted from the Schiff base goes spontaneously onto the other quinonoid oxygen. The effect on the barrier heights produced by the presence of a variety of functional groups in the vicinity of the pyridoxal ring nitrogen was also examined. © 2001 John Wiley & Sons, Inc. Int J Quant Chem, 2001 相似文献
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Studies on the mechanism and kinetics of the reaction leading to FeVMoO7 have been made using XRD and IR spectroscopy. The activation energy, E = 265 ± 13 kJ/mol has been calculated by the Erofeev model. 相似文献