共查询到20条相似文献,搜索用时 62 毫秒
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描述了一种基于二芳炔硫醚(Ar—C≡C—S—C≡C—Ar)底物合成2,6-二芳基-1,4-二噻烯的方法.将二芳炔硫醚和Na2S·9H2O在C2H5OH/C2H5ONa体系中回流反应,以80%~96%的产率合成了一系列2,6-二芳基-1,4-二噻烯化合物.该方法反应条件温和、产率高并且表现出很好的选择性.反应机理涉及硫负离子对底物分子的两个C≡C键的选择性亲核加成,即硫负离子(包括S2-和中间体B硫负离子)总是选择性地加到芳基一侧的炔碳上形成1,4-二噻烯.对化合物1a进行了X线晶体结构解析.分子中的六元杂环呈"船式"构型.C(1)—C(2)和C(1A)—C(2A)具有典型的双键性质,S(1)—C(2)和S(2)—C(1)的键长数则比一般C—S单键稍短,显示硫原子上的孤对电子与C(1)=C(2)双键上的π电子存在一定程度的共轭作用.1a的晶体学参数:属正交晶系,Pnma空间群,a=10.1330(11),b=27.318(3),c=5.5402(6),α=90.00°,β=90.00°,γ=90.00°,V=1533.6(3)3,Z=4,ρcalcd=1.422 g/cm3.最终偏离因子R=0.038,Rw=0.102。 相似文献
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天然产物1,3-二-(2-羟基-4-甲氧基苯基)丙烷和1,3-二-(2,4-二羟基苯基)丙烷的合成 总被引:2,自引:0,他引:2
1,3-二-(2-羟基-4-甲氧基苯基)丙烷(1)和1,3-二-(2,4-二羟基苯基)丙烷(2)是从菊叶薯蓣(Dioscorea composita Hemsl.)分离出来的天然产物, 以间苯二酚为起始原料, 分别经甲酰化和乙酰化得到2,4-二羟基苯甲醛和2,4-二羟基苯乙酮, 然后经选择性地甲基化、甲氧甲基化、羟醛缩合、还原、脱保护等步骤完成了上述两种天然产物的首次全合成. 产物通过1H NMR, IR, MS进行了结构确证. 相似文献
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报道了镁粉(4)促进下,以Weinreb酰胺(1a~1j,1l~1n,1p~1r)、苯乙炔(2)和正丁基溴(3)为原料,"一锅法"合成α,β-炔酮类化合物(5a~5j,5l~5n,5p~5r)的反应。结果表明:在最优反应条件(THF为溶剂,3 1.1 mmol,4 1.25 mmol,混拌2 h;加入2 0.75 mmol,搅拌1 h;加入1 0.5 mmol,于室温反应)下,5a~5j,5l~5n,5p~5r产率45%~86%,其结构经~1H NMR和~(13)C NMR确证。 相似文献
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Dafeng Li 《Tetrahedron letters》2008,49(41):5918-5919
A facile and efficient pathway for CuI/iodine-mediated homocoupling reaction of terminal alkynes to symmetrical 1,4-disubstituted 1,3-diynes in good to excellent yields was reported. 相似文献
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Copper-catalyzed, solvent-free oxidative homocoupling of terminal alkynes can be performed to 1,3-diynes in good to excellent yields in the absence of any additives, using air as environmentally friendly oxidant and the occurrence of water as an exclusive byproduct in the whole process. It is shown that AcO− of copper (II) acetate catalyst may take the role of base and found that the homocoupling cannot occur using weakly basic copper salt catalysts such as CuBr, CuCl, or CuI. Thus, the bases are absolutely necessary in the process of the homocoupling of terminal alkynes. 相似文献
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Amine- and copper salt-free palladium-catalyzed homo-coupling reaction of terminal alkynes proceeded efficiently in the presence of silver(I) oxide, which served as both activator and oxidant, in tetrahydrofuran at 60 °C to achieve satisfactory yields of 1,3-diyne compounds. It was demonstrated for the first time by means of XPS analysis that Pd(0) species can be oxidated to Pd(II) by silver(I) oxide. 相似文献
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《Tetrahedron letters》2019,60(24):1562-1565
A new procedure for the iron-catalyzed synthesis of enamides from ketoximes was developed, and its mechanism was proposed. A unique reduction system, with the concerted use of KI and Na2S2O4, was involved. The reaction exhibited a wide substrate scope and gave good yields in a short reaction time. The procedure is operationally simple and also applicable for the large-scale synthesis. 相似文献
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Amino acids are firstly employed in transition-metal free heterocyclization reaction of 1,3-diynes in the presence of K3PO4 and DMSO at 120 °C. This method produces 2,3,6-trisubstituted pyridines with up to 86% yield. The –CO2H group on the amino acids is crucial for this heterocyclization reaction. The mechanism of such a heterocyclization reaction is discussed, as well. 相似文献
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Luana Bettanin Giancarlo V. Botteselle Marcelo Godoi 《Green Chemistry Letters and Reviews》2014,7(2):105-112
Herein, we report the microwave-assisted synthesis of 1,3-diynes from terminal acetylenes, catalyzed by CuI and tetramethylethylenediamine, in the presence of air as the oxidant, at 100 °C for only 10 min under solvent-free conditions. This efficient methodology allowed the homocoupling of several terminal alkynes in moderate to excellent yields. Moreover, the same protocol was also applicable for the synthesis of some unsymmetrical 1,3-diynes through the cross-coupling reaction. 相似文献
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David Thomae Zhanjie Xu Serge Schneider Gilbert Kirsch Pierre Seck 《Tetrahedron》2009,65(15):2982-9357
In this work, we describe the synthesis of new 2,4,5-trisubstituted-1,3-thiazoles and 1,3-selenazole achieved by an easy one-pot four-step procedure. Expected compounds were obtained in good yield from dimethyl cyanodithioimidocarbonate, which was the common starting material for the preparation of all 1,3-thiazoles and 1,3-selenazoles. Chemical diversity was introduced on thiazole and selenazole rings by varying the amines and the activated halides used. 相似文献
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Sulfamic acid (H2NSO3H) has been proved to be an efficient and green catalyst for liquid Beckmann rearrangement of ketoxime in dried acetonitrile. The use of basic neutralization agent has been avoided in this system due to its intrinsic zwitterionic property. Thus it is a green process for preparation of amide from ketoxime without producing any waste. 相似文献
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J.S. Yadav B.V.S. ReddyK.Bhaskar Reddy K.Uma GayathriA.R. Prasad 《Tetrahedron letters》2003,44(34):6493-6496
Terminal alkynes undergo oxidative-coupling smoothly in the presence of the CuCl-TMEDA catalytic system in hydrophobic [bmim]PF6 ionic liquid under aerobic conditions to produce 1,3-diynes in excellent yields under mild conditions. The substrates, alkynes, show enhanced reactivity and selectivity in ionic liquids (ILs). The recovery of the catalyst is facilitated by the hydrophobic nature of the [bmim]PF6 ionic liquid. 相似文献