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O,O-二烷基硫代磷(膦)酸酯(1)与三氯氧磷作用得到S-烷基硫代磷酰氯(2)和O-烷基磷酰二氯(3),此反应包含异构化和氧化两个过程.实验结果表明,1的预期氯化产物O-烷基硫代磷(膦)酰氯酯(5)与三氯氧磷不发生反应,而1的预期异构化产物O,S-二烷基硫代磷(膦)酸酯(6)与三氯氧磷能顺利反应得到2.由此推测,在1的异构化/氯化反应中,异构化很可能发生在氯化之前.根据此结果和三角双锥中间体(TBP)概念,提出了该反应初步的可能机理. 相似文献
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以4-溴儿茶酚和丙烯酸苯乙酯为原料,经过邻二酚羟基的保护、Heck偶联和脱保护3步反应合成了咖啡酸苯乙酯.其中,以乙酰基保护的4-溴儿茶酚在优化的Heck反应条件下,可获得40%收率的咖啡酸苯乙酯.确定的最佳Heck反应条件为:混合溶剂甲苯/二甲基甲酰胺的体积比为4∶1,醋酸钯(0.05 mmol),三苯基膦(0.15 mmol),三乙胺(2 mmol),反应温度90℃,反应时间24 h.该方法具有通用性好、原料易得和操作相对简单的优点. 相似文献
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本文以镁为消耗性电极(阳极), 进行了异硫氰酸酯的电极还原偶联反应的研究, 得到了双分子偶联产物-N, N'-二烃基二硫代草酸胺。 相似文献
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L-孟醇与过量外消旋菊酰氯反应表现出非对映异构体选择性,得到了光学活性菊酸的L-孟醇酯。由外消旋菊酸的L-孟醇酯经异构化反应也得到了光学活性菊酸的L-孟醇酯。 相似文献
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室温下SmI2-HMPA-t-BuOH-THF体系能顺利地将丁烯二酸二酯还原偶联为1, 2, 3, 4-四烷氧基羰基丁烷, 同样条件下, 亚苄基氰乙酸乙酯,α-乙氧羰基肉桂酸乙酯, α-乙酰基肉桂酸乙酯和亚苄基丙二酸亚异丙酯等化合物也发生还原偶联反应得到相应的二聚体。 相似文献
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Zhi Chen Xiao-Xiao Shi Dong-Qin Ge Zhen-Zhen Jiang Qi-Qi Jin Hua-Jiang Jiang Jia-Shou Wu 《中国化学快报》2017,28(2):231-234
The cyclization reaction of 2-ethynyl-N-sulfonylanilides proceeded efficiently in water with the presence of a catalytic amount of K2CO3 under transition metal-free condition to give indoles in high yields. The recovery and reusability of the present catalytic system were investigated. 相似文献
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Sreyashi Jana 《Tetrahedron letters》2009,50(34):4820-585
An efficient palladium(0) immobilized MCM-41 catalytic system for C-C cross-coupling reaction has been developed. Ligand-free Pd(0)-MCM-41 catalyst can be successfully used in coupling reaction between various aryl halides including deactivated chlorobenzene with aryl borane and organotin to give biaryls in excellent yields with high turnover frequency (TOF) (the maximal TOFs are up to 6990 for the reaction of bromobenzene with phenylboronic acid). The catalyst can be recycled and reused without any loss of catalytic activity. 相似文献
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Friedel-Crafts acylation catalyzed by niobium pentachloride with silver salt is described. Aromatic compounds with Ac2O or Bz2O were smoothly converted into the corresponding ketones in good to excellent yields. This system was also applied to the Sakurai-Hosomi reaction using acetals. The reaction proceeded quite rapidly to give the desired products in excellent yields. 相似文献
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近年来,氟烷基碘(1)对烯烃的加成反应得到了广泛的研究。我们已经报道了铜、锌、镁、铁、镍、钯、铂、铱等金属催化下的反应,以及cd型阴离子引发下的加成反 相似文献
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Methylenecyclopropanes react with various arenes to give the Friedel–Crafts reaction products in good yields in the presence of Lewis acid BF3·OEt2. 相似文献
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A series of new carbazole‐based N‐heterocyclic carbene (NHC) ligands have been synthesized in a simple and facile synthetic route and subsequently used in a Pd/carbazole‐based NHC catalytic system, which was found to be effective in catalyzing Heck reactions to provide substituted stilbene derivatives in good yields. Several bioactive stilbenes, including pterostilbene, pinosylvin, trimethoxy resveratrol, and resveratrol, were synthesized in good yields, and a 10 mmol scale‐up was also performed for trimethoxy resveratrol. The synthetic application was also extended by performing a double‐tandem chemoselective Heck reaction followed by Miyaura borylation in a one‐pot procedure to give single‐step access to synthetically useful stilbenyl boronate esters. Similarly, a unique triple‐tandem protocol of a chemoselective Heck reaction/Miyaura borylation/Suzuki–Miyaura coupling reaction sequence was performed for the one‐pot modification of biologically relevant molecules. 相似文献
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Han-Feng Cui 《Tetrahedron letters》2010,51(17):2374-1548
A Lewis acid-catalyzed one-pot sequential transformation of β-keto esters, aromatic aldehydes, and NCS/NBS was reported. The reaction proceeds by way of Knoevenagel condensation/Nazarov cyclization/halogenation to give α-chloro- and α-bromo-β-keto esters in moderate yields with high diastereoselectivities. However, several aromatic aldehydes with electron-withdrawing substituents afforded unexpected α,β′-dichloro-β-keto esters in good to high yields. 相似文献
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The one‐pot four‐component reaction of benzohydrazide, acetylenedicarboxylate, aromatic aldehydes and malononitrile in ethanol with triethylamine as base catalyst afforded functionalized 1‐benzamido‐1,4‐dihydropyridines in satisfactory yields. Under similar conditions, picolinohydrazide or nicotinohydrazide can also be successfully utilized in the reactions to give corresponding functionalized 1,4‐dihydropyridines. 1H NMR data indicated that an equilibrium of cis/trans‐conformations exist in 1‐benzamido‐1,4‐dihydropyridines. 相似文献