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在K2CO3-TEBA相转移催化体系中,4位或2位含有—NO2的苯磺酰基乙酸酯与α,β-不饱和酯发生加成-重排反应,制得2-芳基戊二酸酯,其收率较高(73%~87%)。研究了反应物-芳磺酰基乙酸酯苯环上取代基对加成-重排反应的影响,发现只有当芳环上4位或2位有硝基时,在K2CO3-TEBA相转移催化体系中,芳磺酰基乙酸酯与α,β-不饱和酯反应才可发生加成-重排反应,生成2-芳基戊二酸酯,其机理可能是芳磺酰基乙酸酯与α,β-不饱和酯首先发生Michael加成反应,随后加成产物发生分子内的亲核取代,酸化后脱去SO2得2-芳基戊二酸酯。而当芳环上4位或2位含有给电子基团(如,甲基)或弱吸电子基团(如,氯)时,却只能发生正常的Michael加成反应,生成相应的2-芳磺酰基戊二酸酯。 相似文献
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本工作发展了钯催化下芳甲醛对甲苯磺酰腙与膦酰基取代联烯的偶联反应, 顺利地以中等至良好的收率及较高的立体选择性制备了一系列(Z)-[3]戟烯衍生物. 不同于烷基取代的苯磺酰腙与烯烃的简单偶联, 该反应使用芳甲醛对甲苯磺酰腙作为底物, 经由1,3-钯迁移历程成功构筑了两个C=C双键. 在最优反应条件下, 该反应展示了较宽的底物适用范围和较高的立体选择性. 最终以31个反应实例获得一系列(Z)-[3]戟烯衍生物, 最高79%分离产率和>20:1 Z/E选择性, 为(Z)-[3]戟烯衍生物的合成应用提供了简便高效的方法. 相似文献
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2-芳氧基-5-苯基-1,3,4-噁二唑类化合物的合成 总被引:1,自引:0,他引:1
本文通过芳氧基负离子在2—甲磺酰基—苯基—1,3,4—噁二唑环2—位上的亲核取代反应制得9个新的2—芳氧基—5—苯基—l,3,4—噁二唑衍生物。所有化合物的结构经元素分析,IR,~1H NMR和MS确认。初步抗菌实验表明这些化合物具有一定的抑制枯草芽孢杆菌繁殖的活性。 2,5—二取代l,3,4—噁二唑衍生物具有广泛的生物活性,如抗菌,抗黄球菌,除草杀棉花牙虫等。Madhavan等曾通过芳胺在2— 甲磺酰基—5—芳基1,3,4—噁二唑环上的亲核取代反应,制得了2—芳氨基—5—芳基—l,3,4—噁二唑衍生物,我们也曾通过酰肼等亲核试剂在2—甲磺酰基—5—(3,4,5—三甲氧基苯基)—1,3,4—噁二唑环上的亲核取代反应,得到了2—取代酰肼基—5—(3,4,5—三甲氧基苯基)—l,3,4—噁二唑衍生物。在此基础上,我们拟通过Aro在2—甲磺酰基 相似文献
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以取代磺酰肼和糖基异硫氰酸酯反应,生成8种1-取代磺酰基-4-全乙酰糖基氨基硫脲,然后在ClCH2CHO/CH3COONa/DMF条件下关环,区域选择性地合成了一系列新型2-取代磺酰基亚肼基-3-全乙酰糖基-2,3-二氢噻唑.化合物3e的1H-13CHMBC谱图表明1-取代磺酰基-4-全乙酰糖基氨基硫脲与氯乙醛的缩合反应关环位置为氨基硫脲的N-4,而非N-2.所有新化合物的结构均经过1HNMR,13CNMR和元素分析确证,生物活性初步测定结果表明该类二氢噻唑化合物具有一定的除草活性. 相似文献
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在K2CO3-TEBA-DNIF体系中,2-(2-氧-4-硝基苯磺酰基)-1-芳基乙酮与各种烷基化试剂发生烷基化-环化反应,得到一系列3-位取代的1,4-氧硫杂萘4,4-二氧化物,并讨论了反应机理和反应条件. 相似文献
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A highly selective synthesis of 1‐substituted (E)‐buta‐1,3‐dienes with 4,4,5,5‐tetramethyl‐2‐vinyl‐1,3,2‐dioxaborolane as building block
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Justyna Szudkowska‐Frątczak Aline Ryba Adrian Franczyk Jędrzej Walkowiak Maciej Kubicki Piotr Pawluć 《应用有机金属化学》2014,28(3):137-139
Highly selective synthesis of 1‐substituted (E)‐buta‐1,3‐dienes via palladium‐catalyzed Suzuki–Miyaura cross‐coupling of (E)‐alkenyl iodides with 4,4,5,5‐tetramethyl‐2‐vinyl‐1,3,2‐dioxaborolane ( 1 ) is reported. The vinylboronate pinacol ester ( 1 ) acts as a vinyl building block to show high chemoselectivity for the Suzuki–Miyaura pathway versus Heck coupling in the presence of biphasic conditions (Pd(PPh3)4, aqueous K2CO3, toluene and ethanol). Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Stereospecific synthesis of a family of novel (E)‐2‐aryl‐1‐silylalka‐1,4‐dienes or (E)‐4‐aryl‐5‐silylpenta‐1,2,4‐trienes via a cross‐coupling of (Z)‐silyl(stannyl)ethenes with allyl halides or propargyl bromide is described. In the reaction with allyl bromide, either a Pd(dba)2? CuI combination (dba, dibenzylideneacetone) in DMF or copper(I) iodide in DMSO–THF readily catalyzes or mediates the coupling reaction of (Z)‐silyl(stannyl)ethenes at room temperature, producing novel vinylsilanes bearing an allyl group β to silicon with cis ‐disposition in good yields. Allyl chlorides as halides can be used in the CuI‐mediated reaction. CuI alone much more effectively mediates the cross‐coupling reaction with propargyl bromide in DMSO–THF at room temperature compared with a Pd(dba)2? CuI combination catalysis in DMF, providing novel stereodefined vinylsilanes bearing an allenyl group β to silicon with cis ‐disposition in good yields. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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A novel Cu(OAc)2·H2O catalyzed coupling reaction of N‐substituted‐2‐iodobenzamides with malononitrile to afford N‐substituted‐3‐amino‐4‐cyano‐isoquinoline‐1(2H)‐ones is described. The reaction proceeded in DMSO at 90°C for 5 h in nitrogen without external ligands. 相似文献
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Prof. Dr. Masaki Shimizu Yosuke Tomioka Dr. Ikuhiro Nagao Tsugumi Kadowaki Prof. Dr. Tamejiro Hiyama 《化学:亚洲杂志》2012,7(7):1644-1651
(Z)‐1,2‐Diaryl‐1,2‐bis(pinacolatoboryl)ethenes underwent double‐cross‐coupling reactions with 1‐bromo‐2‐[(Z)‐2‐bromoethenyl]arenes in the presence of [Pd(PPh3)4] as a catalyst and 3 M aqueous Cs2CO3 as a base in THF at 80 °C. The double‐coupling reaction gave multisubstituted naphthalenes in good to high yields. Annulation of 1,2‐bis(pinacolatoboryl)arenes with bromo(bromoethenyl)arenes in the presence of a catalyst system that consisted of [Pd2(dba)3] (dba=dibenzylideneacetone) and 2‐dicyclohexylphosphino‐2′,6′‐dimethoxybiphenyl (SPhos) under the same conditions produced fused phenanthrenes in good to high yields. The first annulation coupling occurred regiospecifically at the bromoethenyl moiety. This procedure is applicable to the facile synthesis of polysubstituted anthracenes, benzothiophenes, and dibenzoanthracenes through a double annulation pathway by using the corresponding dibromobis[(Z)‐2‐bromoethenyl]benzenes as diboryl coupling partners. 相似文献
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Dr. Hai‐Tao Zhu Li‐Jing Wang Dr. Ke‐Gong Ji Prof. Dr. Xue‐Yuan Liu Prof. Dr. Yong‐Min Liang 《化学:亚洲杂志》2012,7(8):1862-1866
Functionalized 3,4‐dihalogenated furan‐2(5 H)‐ones can be readily prepared in moderate to good yields by treating 4‐hydroxy‐4‐arylbut‐2‐ynoate derivatives with ICl, IBr, and I2. Both halogen atoms of the electrophile are incorporated in the product. The resulting halides can further afford polycyclic aromatic compounds using known palladium‐catalyzed coupling reactions. 相似文献
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A series of α‐(fluoro‐substituted phenyl)pyridines have been synthesized by means of a palladium‐catalyzed cross‐coupling reaction between fluoro‐substituted phenylboronic acid and 2‐bromopyridine or its derivatives. The reactivities of the phenylboronic acids containing di‐ and tri‐fluoro substituents with α‐pyridyl bromide were investigated in different catalyst systems. Unsuccessful results were observed in the Pd/C and PPh3 catalyst system due to phenylboronic acid containing electron‐withdrawing F atom(s). For the catalyst system of Pd(OAc)2/PPh3, the reactions gave moderate yields of 55% –80%, meanwhile, affording 10% –20% of dimerisation (self‐coupling) by‐products, but trace products were obtained in coupling with 2,4‐difluorophenylboronic acids because of steric hinderance. Pd(PPh3)4 was more reactive for boronic acids with sterically hindering F atom(s), and the coupling reactions gave good yields of 90% and 91% without any self‐coupling by‐product. 相似文献
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The reaction of dialkyl acetylenedicarboxylates 4 with 1‐aryl‐2‐[(3‐arylquinoxalin‐2(1H)‐ylidene)ethanones 3 in the presence of Ph3P leads to dialkyl (2Z)‐2‐[(E)‐1‐aryl‐2‐(3‐arylquinoxalin‐2‐yl)ethenyl]but‐2‐enedioates 1 in good yields. 相似文献
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Novel and Stereospecific Synthesis of (2S)‐3‐(2,4,5‐Trifluorophenyl)propane‐1,2‐diol from D‐Mannitol
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Derya Aktaş Meryem Fıstıkçı Özlem Gündoğdu Hasan Seçen M. Fethi Şahin Ramazan Altundaş Yunus Kara 《Helvetica chimica acta》2015,98(8):1127-1131
A stereospecific synthesis of (2S)‐3‐(2,4,5‐trifluorophenyl)propane‐1,2‐diol from D ‐mannitol has been developed. The reaction of 2,3‐O‐isopropylidene‐D ‐glyceraldehyde with 2,4,5‐trifluorophenylmagnesium bromide gave [(4R)‐2,2‐dimethyl‐1,3‐dioxolan‐4‐yl](2,4,5‐trifluorophenyl)methanol in 65% yield as a mixture of diastereoisomers (1 : 1). The Ph3P catalyzed reaction of the latter with C2Cl6 followed by reduction with Pd/C‐catalyzed hydrogenation gave (2S)‐3‐(2,4,5‐trifluorophenyl)propane‐1,2‐diol with >99% ee and 65% yield. 相似文献
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Hideyuki Higashimura Kiyoshi Fujisawa Shuhei Namekawa Masaaki Kubota Akinobu Shiga Yoshihiko Moro‐Oka Hiroshi Uyama Shiro Kobayashi 《Journal of polymer science. Part A, Polymer chemistry》2000,38(Z1):4792-4804
Various effects on the coupling selectivity of the oxidative polymerization of 4‐phenoxyphenol catalyzed by (1,4,7‐triisopropyl‐1,4,7‐triazacyclononane)copper(II) halogeno complex [Cu(tacn)X2] are described. With respect to the amount of the catalyst and the nature of the halide ion (X) of Cu(tacn)X2, the coupling selectivity hardly changed. The Cu(tacn) catalyst possessed a turnover number greater than 1860. As the temperature of the reaction and the polarity of the reaction solvent were elevated, the C O coupling at the o‐position increased, but the C C coupling was not involved. For the polymerization in toluene at 80 °C, poly(1,4‐phenylene oxide), obtained as a methanol‐insoluble part, showed the highest number‐average molecular weight of 4000 with a melting point (Tm) of 195 °C. Only a slight change in the coupling selectivity was observed in the presence or absence of hindered amines as the base. Surprisingly, however, the C O selectivity decreased from 100 to 24% with less hindered amines, indicating that the selectivity drastically changed from a preference for C O coupling to a preference for C C coupling. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4792–4804, 2000 相似文献
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4‐Halo‐2(5H)‐furanones were prepared by the halolactonization of 2,3‐allenoic acids. The subsequent Suzuki coupling reaction of 4‐halo 2(5H)‐furanones with aryl boronic acids was carried out to produce 4‐aryl‐2(5H)‐furanones in excellent yields. 相似文献