共查询到20条相似文献,搜索用时 62 毫秒
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γ-羟基丁烯羟酸内酯类内皮激素拮抗剂的比较分子场分析 总被引:1,自引:0,他引:1
采用比较分子场分析方法(CoMFA)分析了一组γ-羟基丁烯羟酸内酯类内皮激素拮抗剂的活性与结构的关系。在计算中,除了考察立体场和静电场,还引入了氢键场,结果表明,引入氢键场可以明显改善计算的结果。所得模型不仅能够很好地预测训练集中的分子,而且还可准确地预测测试集中的化合物。通过分析分子场等值面图在空间的分布,可以观察到叠合分子周围的立体、静电以及氢键特征对化合物活性的影响。 相似文献
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以生物质来源的对甲氧基苯甲醛(大茴香醛)为原料,经还原反应制备得到对甲氧基苄醇,经氯代反应制备得到对甲氧基氯苄,再与乙酰乙酸乙酯经取代反应制备得到2-乙酰基-3-(4-甲氧基苯基)丙酸乙酯,再经串联的水解、脱羧反应制备得到4-(4-甲氧基苯基)-2-丁酮,最后经脱甲基反应制备得到4-对羟基苯基-2-丁酮,总收率为60.7%。具有路线简捷、易于操作、环境友好、收率高等优点。 相似文献
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羟基酸引发ε-己内酯开环聚合的研究 总被引:5,自引:0,他引:5
研究了水、醇、羧酸存在下ε-己内酯开环聚合的情况 ,发现在适当温度下 (80℃ ) ,羧基并不引发ε-己内酯的开环聚合 ,但对羟基引发ε-己内酯开环聚合起加速作用 ,而且催化能力与酸度有关 .进而又对羟基酸(乙醇酸、DL 苹果酸、柠檬酸 )引发ε-己内酯开环聚合做了研究 ,合成了一系列含不同数目遥爪羧基的α-羟基-ω-羧基(1,2 ,3)己内酯低聚物 (HCPCL) ,并对其结构做了酸值滴定、羟值滴定、UV、FTIR与1H NMR分析 .对羧基催化羟基引发ε-己内酯开环聚合的机理做了分析. 相似文献
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Jacek Mlynarski 《Tetrahedron letters》2004,45(41):7549-7552
A number of combinations of Lewis acids and chiral ligands has been screened for the enantioselective direct tandem aldol condensation--Evans-Tishchenko reduction of aldehydes and ketones. Chiral ytterbium complexes were found to catalyze the condensation of aromatic aldehydes with 3-pentanone (and other ketones) giving rise to the anti-1,3-diol monoesters in good yield, and with high diastereocontrol and moderate levels of enantioselectivity. Three adjacent stereogenic centers are created in one reaction sequence in acyclic systems. 相似文献
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Milandip Karak Luiz C.A. Barbosa Celia R.A. Maltha Thiago M. Silva John Boukouvalas 《Tetrahedron letters》2017,58(29):2830-2834
Several α-unsubstituted β-arylbutenolides have been prepared in 69–92% yield by reductive dehalogenation of α-halo-β-arylbutenolides. The latter were assembled in a single-step from α,β-dihalobutenolides, which are accessible on a large-scale from biomass-derived furfural. Our dehalogenation protocol is illustrated by a new synthesis of the marine antibiotics rubrolide E and F, and 3″-bromorubrolide F. 相似文献
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Synthesis of light alkenes on manganese promoted iron and iron-cobalt Fischer-Tropsch catalysts 总被引:1,自引:0,他引:1
Sergio L. González-Cortés Serbia M. A Rodulfo-Baechler Alberto Oliveros José Orozco Bernardo Fontal Asiloé J. Mora Gerzon Delgado 《Reaction Kinetics and Catalysis Letters》2002,75(1):3-12
The Perkin reaction is accompanied by competitive transformations of the intermediate carbanions. These transformations are found to be inhibited by the reacting aldehydes. The limiting stage of the Perkin reaction is NACC attack (nucleophilic attack at carbonyl carbon) of amines on the anhydride. 相似文献
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A catalytic process for the synthesis of optically active C4-substituted tetrahydroindandiones using an asymmetric intramolecular aldol condensation reaction was developed. When 30 mol% of phenylalanine and 50 mol% of pyridinium p-toluenesulfonate were used under highly concentrated conditions, a variety of C4-substituted tetrahydroindandiones and octahydronaphthalenediones were obtained in high yield (up to 89% yield) and high enantiomeric excess (up to 94% ee). One of the products was successfully transformed into the key intermediate for the synthesis of the phosphatidylinositol 3-kinase inhibitor wortmannin, achieving formal total synthesis of (+)-wortmannin. 相似文献
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三羟甲基烷烃是用于醇酸树脂、聚氨酯树脂、表面活性剂、合成润滑油等的原料[1-3].三羟甲基十一烷(化学结构见图1)作为三羟甲基烷烃中直碳链最长的一员,不仅具有亲水性(分子中含三个亲水基),而且具有疏水性(含一个长直碳链亲油基),因此可用作表面活性剂.不仅如此,与同样用作乳化剂的一般高级脂肪醇(如十六烷醇)相比,可以在化妆品用的乳液中加入三羟甲基十一烷作乳化剂,以降低乳液的黏度,防止乳液中由于大量加入高级脂肪醇而导致产品黏度过高以至不能在皮肤上被充分涂抹开的状况发生[4].为制备智能芳香缓释型聚氨酯微胶囊壳材[5],需要设计聚氨酯的分子结构中含有能与相变石腊和油溶性香料有良好相容性的疏水链(三羟甲基十一烷与六亚甲基二异氰酸酯的加成物).因此,本文合成并表征了三羟甲基十一烷. 相似文献
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《中国化学》2017,35(7):1185-1194
In continuation/checking of a previous synthesis directed toward the literature structure of stereocalpin A it was found that the data for a substantial part of the intermediates reported before were incorrect. Some of the transformations were not successfully reproduced and the failures were shown to be consequences of the presence of the N‐Me and the particular location of the ester linkage. The origins of the “extra/minor” signals in the NMR for most of the intermediates, which tend to be mistaken as signs for the presence of impurity/isomers, are also discussed. 相似文献
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介绍了一个国外的本科生实验,通过简单的羟醛缩合反应制备四苯基环戊二烯酮。在介绍羟醛缩合反应的同时探讨了这类不具有手性原子的分子的手性问题。 相似文献
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Some synthetic efforts directed to the proposed structure of stereocalpin A are disclosed. The stereogenic centers in the aldol unit were installed using the method of Evans and the intermediates obtained through a reliable route helped to reveal that the spectroscopic data reported earlier in the literature for the same structures were either erroneous or irrelevant. 相似文献
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Alessandro Marrone Dr. Andrea Renzetti Dr. Paolo De Maria Prof. Stéphane Gérard Dr. Janos Sapi Prof. Antonella Fontana Prof. Nazzareno Re Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(43):11537-11550
The condensation of dialkyl β‐diesters with various aldehydes promoted by TiCl4 has been studied by DFT approaches and experimental methods, including NMR, IR and UV/Vis spectroscopy. Various possible reaction pathways have been investigated and their energy profiles evaluated to find out a plausible mechanism of the reaction. Theoretical results and experimental evidence point to a three‐step mechanism: 1) Ti‐induced formation of the enolate ion; 2) aldol reaction between the enolate ion and the aldehyde, both coordinated to titanium; and 3) intramolecular elimination that leads to a titanyl complex. The presented mechanistic hypothesis allows one to better understand the pivotal role of titanium(IV) in the reaction. 相似文献