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1.
Ordered mesoporous SBA‐15/PrSO3Pd and SBA‐15/PrSO3PdNP as active,reusable and selective phosphine‐free catalysts in CX activation Heck coupling process
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The incorporation of sulfonate into mesoporous SBA‐15 molecular sieves as ligands for palladium ions was used. Then SBA‐15/PrSO3Pd and SBA‐15/PrSO3PdNP were prepared and applied for the Heck arylation reaction of conjugate alkenes with aryl halides, to afford corresponding cross‐coupling products under phosphine‐free aerobic conditions with good to excellent yields. These supported palladium pre‐catalysts could be separated easily from reaction products and reused several times, showing superiority over homogeneous catalysts for industrial and chemical applications. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
2.
研究了无配体、空气下Pd(OAc)2催化的Heck反应. 多种芳基碘化物、芳基溴化物可以与烯丙基醋酸酯、丙烯酸酯和苯乙烯等烯基化合物在Pd(OAc)2催化下发生Heck反应. 该反应不需要配体的加入, 在空气中就可以进行. 讨论了碱、添加剂、溶剂、催化剂等因素对反应产率的影响. 该反应的最优化条件是: Pd(OAc)2 (5 mol%)为催化剂, Ag2CO3 (0.6 equiv.)为添加剂, 以苯或甲苯为溶剂空气中回流12 h, 芳基碘化物、芳基溴化物可以顺利地与烯丙基醋酸酯、丙烯酸酯、苯乙烯等烯基化合物发生Heck反应, 以较高的产率得到目标产物. 相似文献
3.
Jrme Durand Alessandro Scarel Barbara Milani Roberta Seraglia Serafino Gladiali Carla Carfagna Barbara Binotti 《Helvetica chimica acta》2006,89(8):1752-1771
The catalytic behavior of dicationic bis‐chelated PdII complexes, [Pd(N? N)2][PF6]2, in the CO/ethylene/styrene terpolymerization reaction is studied in detail. The bidentate N‐donor ligands were chosen among 2,2′‐bipyridine ( 1 ), 1,10‐phenanthroline ( 3 ), their symmetrically substituted derivatives 2, 4 , and 5 , and 3‐alkyl‐substituted 1,10‐phenanthrolines 6 – 10 . The effect of several parameters (like temperature, CO/ethylene pressure, styrene content, reaction time) was investigated and related to the productivity of the catalytic system, to the relative content of the two olefins in the polymeric chains, and to the molecular mass of the synthesized polyketones. The presence of 1,4‐benzoquinone was necessary to reach productivities as high as 16 kg of terpolymer (TP) per gram of Pd. 13C‐NMR spectroscopy was useful to characterize the distribution of the two repetitive units along the polymer chain. Terpolymers with prevailingly isolated CO/styrene units in CO/ethylene blocks as well as terpolymers with CO/styrene and CO/ethylene blocks were obtained by varying the reaction conditions. Detailed MALDI‐TOF‐MS analysis was performed on the CO/ethylene/styrene terpolymers for the first time, and it allowed us to characterize the end groups of the terpolymer chains. The presence of different chain end groups was found to be related to the initial amount of the two alkenes, thus suggesting that different reactions are involved in the initiation and termination steps of the terpolymerization catalytic cycle. 相似文献
4.
Four types of heterogeneous Pd catalysts (10% Pd/C, 10% Pd/HP20, 0.5% Pd/MS3A, and 0.3% Pd/BN) were applied to the flow hydrogenation to systematically evaluate the appropriate conditions for the reduction of a wide variety of reducible functionalities. The use of 10% Pd/C and 10% Pd/HP20 allowed the hydrogenation of various reducible functionalities by a single-pass of the substrate–MeOH solution through the catalyst cartridge, while 0.5% Pd/MS3A and 0.3% Pd/BN catalyzed a novel chemoselective hydrogenation; only alkene, alkyne, azide, and nitro functionalities could be reduced with other coexisting reducible functionalities intact. 相似文献
5.
高效组合型 Pd/C 催化剂用于 Suzuki 偶联反应 总被引:3,自引:0,他引:3
采用有机金属 Pd2(dba)3 (dba 为二亚苄基丙酮) 还原分解法制得均匀分布的 Pd 纳米颗粒 (粒径为 3~6 nm) 混合液, 并用活性炭直接吸附得到了组合型 Pd/C 纳米催化剂. 采用透射电子显微镜、X 射线光电子能谱和 X 射线衍射等手段测定了催化剂表面 Pd 颗粒大小分布、晶型和化学态等. 将该催化剂用于 Suzuki 碳-碳偶联反应, 其催化活性比浸渍法制备的 Pd/C 催化剂高 2 倍以上. 以溴代芳烃为底物时, 在 80 oC 下 0.5 h 后偶联产物收率可达 98% 以上. 以邻氯硝基苯为底物时, 在 110 oC 下 1 h 后偶联产物收率可达 64%; 延长反应时间, 产物收率可达 90% 以上. 相似文献
6.
The addition reaction between CuBpin and alkenes to give a terminal boron substituted intermediate is usually fast and facile. In this communication, a selectivity-reversed procedure has been designed and established. This selectivity-reversed borocarbonylation reaction is enabled by a cooperative action between palladium and copper catalysts and proceeds with complete regioselectivity. The key to the success of this transformation is the coordination of the amide group and slower CuBpin formation by using KHCO3 as the base. A wide range of β-boryl ketones were produced from terminal unactivated aliphatic alkenes and aryl iodides. Further synthetic transformations of the obtained β-boryl ketones have been developed as well.A selectivity-reversed borocarbonylation reaction has been developed with complete regioselectivity.The catalytic borocarbonylation of alkenes represents a novel synthetic tool for the simultaneous installation of boron and carbonyl groups across alkenes, enabling rapid construction of molecules with high complexity from abundant alkenes. In particular, the obtained organoboron compounds are versatile synthetic intermediates that can be readily converted into a wide range of functional groups with complete stereospecificity.1 Consequently, several catalytic systems have been developed to diversify the molecular frameworks through carbonylative borofunctionalization.2 In general, carbonylative borofunctionalization of alkenes proceeds via an alkyl-copper intermediate, which was produced by the addition of CuBpin to the terminal position of the alkene starting material,3 followed by CO insertion and other related steps. A new C–B bond is formed at the terminal position of the alkene and a carbonyl group has been installed at the β-position simultaneously (Scheme 1a). However, in contrast to the progress in the borocarbonylation, a selectivity-reversed procedure (the boryl group is installed at the internal position) to give β-boryl ketone products is still unprecedented.Open in a separate windowScheme 1Strategies for borocarbonylation of activated alkenes.Recently, several attractive strategies have emerged for the borofunctionalization of unactivated alkenes to give β-boryl products.4–7 In 2015, Fu, Xiao and their co-workers established a copper-catalyzed regiodivergent alkylboration of alkenes.4a In the same year, Miura and Hirano''s group reported a copper-catalyzed aminoboration of terminal alkenes.4b In these two attractive procedures, the regioselectivity was controlled by the ligand applied. More recently, an intermolecular 1,2-alkylborylation of alkenes was described by Ito''s research group.5 A radical-relay strategy was used to achieve the targeted regioselective addition. Furthermore, Engle and co-workers explored a palladium-catalyzed 1,2-carboboration and -silylation reaction of alkenes.6 Stereocontrol can be achieved in this new procedure with the assistance of a chiral auxiliary which is a coordinating group in this case.Inspired by these pioneering studies, we assumed that if the reaction could be initiated by the insertion of an acylpalladium complex into alkenes, followed by transmetalation with CuBpin before reductive elimination, β-boryl ketones can finally be produced (Scheme 1b). However, due to the inherent reactivity of the palladium species toward alkenes, olefin substrates were usually restricted to styrenes and a large excess of them is typically required (>6 equivalents).8,9 Therefore, the critical part of the reaction design is to promote the reaction of the acylpalladium intermediate with alkenes faster than the insertion of CuBpin into olefins. One of the ideas is taking advantage of the coordinating group to transform the reaction from intermolecular to intramolecular. Among the developed directing groups,10 8-aminoquinoline (AQ) is interesting and has been relatively well studied by various groups in a number of novel transformations.11–13 Although the AQ directing group contains a NH group which can participate in intramolecular C–N bond formation,14 we believe that the selectivity-reversed borocarbonylation of alkenes can potentially be achieved through cooperative Pd/Cu catalysis. Then, valuable β-boryl ketones can be produced from readily available substrates directly and effectively.To test the viability of our design on selectivity-reversed borocarbonylation of alkenes, N-(quinolin-8-yl)pent-4-enamide (1a), iodobenzene (2a), and bis(pinacolato)diboron (B2pin2) were chosen as model substrates for systematic studies. As shown in 15 In the testing of palladium precursors, allylpalladium chloride dimer proved to be the best palladium catalyst for this reaction, affording 3a in 41% yield (†) and tend to generate the by-product β-aminoketone. Xantphos was found to be superior to the other tested bidentate ligands ( Entry [Pd] Ligand Cu Base Yield of 3a (%) 1 Pd(TFA)2 L1 IMesCuCl K2CO3 29 2 Pd(OAc)2 L1 IMesCuCl K2CO3 34 3 [Pd(η3-C3H5)Cl]2 L1 IMesCuCl K2CO3 41 4 [Pd(cinnamyl)Cl]2 L1 IMesCuCl K2CO3 36 5 [Pd(η3-C3H5)Cl]2 L1 IPrCuCl K2CO3 0 6 [Pd(η3-C3H5)Cl]2 L1 CuCl K2CO3 33 7 [Pd(η3-C3H5)Cl]2 L1 CuBr K2CO3 41 8 [Pd(η3-C3H5)Cl]2 L1 CuI K2CO3 50 9 [Pd(η3-C3H5)Cl]2 L2 CuI K2CO3 38 10 [Pd(η3-C3H5)Cl]2 L3 CuI K2CO3 47 11 [Pd(η3-C3H5)Cl]2 L4 CuI K2CO3 0 12 [Pd(η3-C3H5)Cl]2 L5 CuI K2CO3 0 13 [Pd(η3-C3H5)Cl]2 L6 CuI K2CO3 <2 14 [Pd(η3-C3H5)Cl]2 L7 CuI K2CO3 10 15 [Pd(η3-C3H5)Cl]2 L8 CuI K2CO3 12 16 [Pd(η3-C3H5)Cl]2 L1 CuI KHCO3 58 (51)b 17 [Pd(η3-C3H5)Cl]2 L1 CuI K2HPO4 26 18 [Pd(η3-C3H5)Cl]2 L1 CuI NaHCO3 0 19 [Pd(η3-C3H5)Cl]2 L1 CuI NaOtBu 11 20c [Pd(η3-C3H5)Cl]2 L1 CuI KHCO3 <5 21 [Pd(η3-C3H5)Cl]2 L7 CuI KHCO3 40