A facile and efficient synthesis of 3‐cyanoindoles by a simple palladium(II)‐catalyzed C─H activation of indoles

An efficient trans ‐PdCl₂(NH₂CH₂COOH)₂‐catalyzed direct C3‐cyanation of indole C─H bonds is described. Notably, free (N─H)‐indoles reacted smoothly using the procedure, and the desired product 3‐cyanoindoles were obtained in good to excellent yields.     

4-戊基(4′-丙基环己基)三联苯液晶的合成

在相转移催化剂十六烷基三甲基溴化铵的助催化作用下,用PdCl2催化芳基硼酸与溴代芳烃偶联反应合成了液晶化合物4－戊基（4′－丙基环己基）三联苯,反应转化率达到93％,反式产物选择性86％。结构经IR,^1H NMR和MS确证,并用DSC测定了此液晶的相变数据。考察了加料顺序和相转移催化剂对偶联反应的影响。提出了相转移条件下可能的催化循环机理,认为芳基硼酸是以ArB(OH)3^-离子形式参与偶联反应的。     

Periodic mesoporous organosilica grafted palladium organometallic complex: efficient heterogeneous catalyst for water‐medium organic reactions

Water‐medium organic reactions were studied over periodic mesoporous silica (PMO) containing Pd(II) organometallic complex. This heterogeneous catalyst was achieved by Pd(II) compound coordinated with the PPh₂‐ligand onto the pore surface of phenylene‐bridged PMO support. This catalyst displayed ordered mesoporous channels, which ensured the high dispersion of Pd(II) active sites and the convenient diffusion of reactant molecules into the pore channels. Meanwhile, the phenyl group in the pore wall of PMO could enhance the surface hydrophobicity which promoted the adsorption of organic reactant molecules on the catalyst in aqueous environment. As a result, this elaborated catalyst exhibited comparable activity and selectivity with the corresponding PdCl₂(PPh₃)₂ homogeneous catalyst in the water‐medium organic reactions, and could be used repeatedly, showing a good potential in industrial applications. Copyright © 2010 John Wiley & Sons, Ltd.     

钯-三苯膦催化体系选择氢化顺酐制备琥珀酸酐

开发了一种由顺酐直接加氢高选择性及高转化率制备琥珀酸酐的新方法,研究结果表明：钯三苯基膦催化体系对顺酐加氢具有较高的反应活性．在所考察的反应条件下,此催化剂体系对琥珀酸酐的选择性为１００％,无其他副产物生成．并考察了三苯基膦／钯摩尔比,反应温度,氢气压力,催化剂和顺酐浓度对顺酐催化加氢生成琥珀酸酐的影响．在反应条件为ＰｄＣｌ２＝１２５×１０－３ｍｏｌ／Ｌ,ｎ（顺酐）／ｎ（Ｐｄ）≤２０００,ｎ（三苯基膦）／ｎ（Ｐｄ）＝４,Ｔ＝３７３～３９３Ｋ,２５ＭＰａ的氢压下于乙二醇二甲醚溶剂中反应１ｈ以上,可使顺酐的转化率大于９０％．     

PdCl_2-catalyzed heterocyclotrimerization in MeOH/scCO_2:A versatile approach to dimethyl pyridine-3,5-dicarboxylate from methyl acrylate and urea

A novel and green method for the synthesis of dimethyl pyridine-3,5-dicarboxylate has been developed. It is PdCl2-catalyzed heterocyclotrimerization of methyl acrylate with urea in methanol/supercritical carbon dioxide. The target compound was obtained with a 75% isolated yield under the optimized con-ditions.     

Formal total synthesis of (−)-hamigeran B from a chemo-enzymatically prepared building block with quaternary chiral center

A formal total synthesis of (?)-hamigeran B was achieved in 17 steps from commercially available ethyl 2-oxocyclopentanecarboxylate. Carbonyl reductase-catalyzed asymmetric reduction and the subsequent chemical transformations furnished an enantiomerically pure synthetic intermediate, (R)-5-formyl-2-isopropyl-5-methylcyclopent-1-en-1-yl trifluoromethylsulfonate. Suzuki-Miyaura coupling with Gao's arylboronate [2-(2-formyl-3-methoxy-5-methylphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane], under PdCl₂(dppf)?CH₂Cl₂ catalysis, and the subsequent cyclization by way of intramolecular reductive SmI₂-mediated 1,2-diol formation provided a tricyclic skeleton with a tetrasubstituted double bond between C-1 and C-9b. Upon hydrogenation of this double bond, the proper stereochemistry of the remaining chiral centers was established. Exclusive addition of the hydrogen atom from the β-face occurred, owing to the shielding of the α-face with a bulky TBS protective group on the C-4 alcohol. The hydrogenation products were transformed into Clive's synthetic precursor for (?)-hamigeran B.     

PdCl_2－CuCl_2－PPh_3催化剂立体选择催化烯烃氢酯基化反应

研究了以ＰｄＣｌ２－ＣｕＣｌ２－ＰＰｈ３为催化剂体系，甲基乙基酮、乙二醇二甲醚为溶剂，苯乙烯与一氧化碳及甲醇立体选择生成２－苯基丙酸甲酯的反应．对不同的催化剂前体催化烯烃氢酯基化反应进行了研究，得知ＣｕＣｌ２在此催化反应中起着立体控制作用．同时考察了影响反应的各种因素如溶剂、反应温度、反应压力、不同的膦配体等．实验结果表明，该反应的最佳条件是：反应温度８０℃，反应压力４．０—６．０ＭＰａ，反应时间２４ｈ，最好的溶剂是乙二醇二甲醚及甲基乙基酮．利用该催化剂体系对不同结构的烯烃催化反应进行了研究，发现该体系仅仅对苯乙烯类有较高的立体选择催化活性     

三氟甲基磺酸盐在氯化钯催化苯乙烯与CO共聚中的助催化作用

苯乙烯／CO共聚所选用的催化体系主要由弱酸钯盐、N配体、pKa〈2的酸所组成，在催化共聚反应中表现出了较高的活性．而将PdCl2代替上述催化体系中的Pd（OAc）2直接将其用于烯烃／CO共聚活性很差．我们通过实验发现：在三氟甲基磺酸盐M（OTf）。的助催化作用下，PdCl2在催化烯烃与CO共聚反应中表现出较好的活性，其中以Cu（OTf）2助催化作用最为显著．     

脒基配体/PdCl2催化Suzuki偶联反应研究

合成和表征了一系列具有不同位阻和电子效应取代基的脒基配体.研究表明,脒基配体在有氧条件下,与氯化钯原位作用能有效地催化不同溴代反应物与苯硼酸的Suzuki偶联反应.考察了配体结构、反应温度和溶剂对反应的影响,结果表明,脒基配体上具有大体积和推电子取代基有利于偶联反应的进行;提高反应温度和引入质子性极性溶剂也是提高偶联反...     

Kryptofix 5 as an inexpensive and efficient ligand for the palladium‐catalyzed Mizoroki‐Heck reaction

A novel complex of PdCl₂ with a multidentate cryptand ligand, Kryptofix 5, has been prepared and characterized by various techniques including ¹H‐ and ¹³C NMR spectroscopy, Fourier transform infrared (FT‐IR), Raman, ultraviolet and visible (UV‐VIS) spectroscopy, inductively coupled plasma (ICP), CHN elemental and energy dispersive X‐ray analysis (EDX). This heat‐ and air‐stable complex was utilized as a highly active catalyst for the Mizoroki‐Heck reaction of aryl halides with various olefins. Interestingly, it was found that aryl bromides as well as aryl iodides were efficiently cross‐coupled with terminal alkenes at 130 °C in 10 min. Furthermore, the least reactive aryl chlorides reacted with styrene to obtain the desired products in acceptable yields.