咔唑桥连NCN齿形钯配合物催化的唑类C—H键直接芳基化反应（英文）

基于咔唑的强给电子能力合成了一种对空气稳定的齿形钯配合物催化剂(C1～C6).这种钯催化剂可高效催化唑类和溴代芳烃的直接芳基化反应,在空气条件下,碳酸钾为碱,无需其他添加剂,即取得了较好的催化活性与底物普适性.在相对温和的条件和催化剂用量为0.5mol%时,即可实现噻唑与溴代芳烃直接芳基化反应顺利进行.值得一提的是,这是目前以KOAc为碱的反应体系中,反应活性最高的催化体系.     

低温Suzuki反应合成联苯及三联苯化合物

发展了一个低温下无配体钯催化溴代芳烃与芳基硼酸的Suzuki反应体系。该体系以醋酸钯为催化剂,无水碳酸钾为碱,乙醇水溶液为溶剂,无需加入任何配体,在0oC下即可高效催化溴代芳烃与芳基硼酸的Suzuki反应;反应的底物容忍性好,产品分离收率最高达97%。以溴代芳基N-甲基亚氨基二乙酸硼酸酯为砌块分子,通过调控反应温度,实现了砌块分子选择性Suzuki反应,从而一锅合成了不对称三联苯化合物,产品收率最高为81%。     

无配体、水相中钯催化的卤代芳烃与苯硼酸的Suzuki偶联反应

溴代(碘代)芳烃与苯硼酸在以Li OH为碱、水为反应溶剂、醋酸钯为催化剂、90℃条件下反应24h后,可以较高收率得到二芳基产物。该方法具有收率好,操作方便以及催化体系便宜又简单的优点。     

环钯-[PPh4]Br体系催化氯代芳烃的Heck芳基化反应研究

以氯代芳烃为底物，季鏻盐[PPh4]Br为助催化剂，用于环钯催化的Heek芳基化反应．结果表明，在环钯-[PPh4]Br催化体系中，以Na2CO3作为碱性试剂，使用0．3mol％Pd的环钯催化剂催化氯苯的Heek反应，就可得到比较高的产率（88％）和转化率（90％）．对于大部分卤代芳烃Heck反应而言，环钯-[PPh4]Br是一种有效的催化体系，即使是对含推电子基团的不活泼的氯代芳烃，在此体系中也能获得比较好的结果．此外，文中还探讨了反应温度、[PPh4]Br／Pd比值及催化剂回用对反应活性的影响．     

N,N,N',N'-四[(二苯基膦)甲基]乙二胺钯配合物催化Heck反应研究

以乙二胺为骨架的含氮四膦配体N’NN,N',N'-四[(二苯基膦)甲基]乙二胺和钯组成的催化体系用于丙烯酸酯和芳卤的Heck反应,该催化体系对许多卤代芳烃,尤其含吸电基的溴代芳烃显示了良好的催化活性.对活化底物对溴苯甲醛,即使底物与催化剂的物质的量比达到1000000,其转化率也能达到96％;催化非活化溴代芳烃对溴苯甲醚以及难以反应的氯代芳烃,在Pd含量为0.1 mol％时同样表现出优良催化性能.     

无配体钯催化乙醇水溶液中芳基三氟硼酸钾的Suzuki反应

发展了一个无配体钯催化芳基三氟硼酸钾的Suzuki反应体系.该体系在空气条件下,以醋酸钯为催化剂,1equiv.的无水碳酸钾为碱,在乙醇水溶液中可高效催化卤代芳烃或杂环卤代芳烃与芳基三氟硼酸钾的Suzuki反应,周转频率(TOF)值最高达4656 h~(-1),且该体系还适用于三苯胺衍生物的合成.透射电镜分析结果及汞中毒实验证明该体系的实际催化物质为原位生成的纳米钯粒子.     

硅胶负载钯: 一种新型有效而可循环的Heck反应的催化剂

本文报道了一种新型硅胶负载钯催化剂在Heck 反应中的应用。在硅胶负载钯催化剂,碳酸钾为碱,DMF为溶剂的反应条件下（无膦和无游离胺的存在）,碘代芳烃、溴代芳烃和活泼的氯代芳烃与烯烃发生偶联反应生成高产率相应的偶联产物。而且硅胶负载的钯催化剂经简单处理,可循环使用6次不降低活性。     

碳负载钯催化剂对Heck反应的催化性能

研究了钯碳催化剂对芳基卤和取代芳基卤与丙烯酸和苯乙烯的Heck芳基化反应的催化性能.结果表明:在反应温度为80℃、反应时间为8h、四丁基溴化铵(TBABr)作为溶剂和三丁胺作为碱的条件下,钯碳催化剂对不同取代芳基卤与丙烯酸和苯乙烯的Heck芳基化反应具有良好的催化性能,产物收率在80%以上.     

高活性氨基胍树脂负载Pd(O)配合物的催化性能研究

以氨基碳酸胍改性氯球为载体,与氯化钯溶液反应并还原制备氨基胍树脂负载钯(O)催化剂.对催化剂进行了FT-IR,XRD,BET,TG-DTA表征.研究了该催化剂对各种取代卤代苯与丙烯酸、苯乙烯的Heck芳基化反应催化性能.实验结果表明,该催化剂对活性(吸电子基)溴代苯和碘苯具有良好的催化活性,对含活性吸电子基的溴代苯(4-溴苯甲醛和4-溴硝基苯)于140℃时能在22 min内完成Heck芳基化反应;催化剂具有较好的重复使用性能,在90℃下催化碘苯与丙烯酸的反应循环21次时仍能保持良好的催化活性.反应机理研究表明:催化反应的活性组分是可溶性钯物种;可溶性钯是由卤代苯与催化剂表面上的钯氧化加成所致.     

高活性氨基胍树脂负载Pd(0)配合物的催化性能研究

以氨基碳酸胍改性氯球为载体, 与氯化钯溶液反应并还原制备氨基胍树脂负载钯(0)催化剂. 对催化剂进行了FT-IR, XRD, BET, TG-DTA表征. 研究了该催化剂对各种取代卤代苯与丙烯酸、苯乙烯的Heck芳基化反应催化性能. 实验结果表明, 该催化剂对活性(吸电子基)溴代苯和碘苯具有良好的催化活性, 对含活性吸电子基的溴代苯(4-溴苯甲醛和4-溴硝基苯)于140 ℃时能在22 min内完成Heck 芳基化反应; 催化剂具有较好的重复使用性能, 在90 ℃下催化碘苯与丙烯酸的反应循环21次时仍能保持良好的催化活性. 反应机理研究表明: 催化反应的活性组分是可溶性钯物种; 可溶性钯是由卤代苯与催化剂表面上的钯氧化加成所致.     

Direct Arylation in the Presence of Palladium Pincer Complexes

Direct arylation is an atom-economical alternative to more established procedures such as Stille, Suzuki or Negishi arylation reactions. In comparison with other palladium sources and ligands, the use of palladium pincer complexes as catalysts or pre-catalysts for direct arylation has resulted in improved efficiency, higher reaction yields, and advantageous reaction conditions. In addition to a revision of the literature concerning intra- and intermolecular direct arylation reactions performed in the presence of palladium pincer complexes, the role of these remarkably active catalysts will also be discussed.     

Palladium(II)-N-heterocyclic carbene-catalyzed direct C2- or C5-arylation of thiazoles with aryl bromides

Herein we report, a series of new benzimidazolium chlorides as N-heterocyclic carbene (NHC) ligand and their corresponding palladium(II)-NHC complexes with the general formula [PdCl₂(NHC)₂] were synthesized. All new compounds were characterized by ¹H NMR, ¹³C NMR, IR spectroscopy and elemental analysis techniques. The catalytic activity of palladium(II)-NHC complexes was investigated in the direct C2- or C5-arylation of thiazoles with aryl bromides in presence of palladium(II)-NHC at 150?°C for 1?h. These complexes exhibited the good catalytic performance for the direct arylation of thiazoles. The arylation of thiazoles regioselectively produced C2- or C5-arylated thiazoles in moderate to high yields.     

Palladium(II)‐N‐Heterocyclic Carbene Complexes: Efficient Catalysts for the Direct C‐H Bond Arylation of Furans with Aryl Halides

This paper contains the synthesis and characterization of the seven new benzimidazolium salts and their corresponding new palladium(II)‐NHC complexes with the general formula [PdX₂(NHC)₂], (NHC = N‐heterocyclic carbene, X = Cl or Br), and also their catalytic activity in direct C‐H bond arylation of 2‐substituted furan derivatives with aryl bromides and aryl chlorides. Under the optimal conditions, these palladium(II)‐NHC complexes showed the good catalytic performance for the direct C‐H bond arylation of 2‐substituted furans with (hetero)aryl bromides, and with readily available and inexpensive aryl chlorides. The C‐H bond arylation regioselectively produced C5‐arylated furans by using 1 mol% of the palladium(II)‐NHC catalysts in moderate to high yields.     

Scope of direct arylation of fluorinated aromatics with aryl sulfonates

The scope and limitations of direct arylation of fluorinated aromatics with aryl sulfonates was examined. Pd(OAc)(2), in the presence of MePhos and KOAc in THF, efficiently catalyzed the direct arylation of fluoro aromatics with aryl triflates under ambient conditions. Sterically hindered triflates and heteroaryl triflates gave good to excellent yields of the cross coupled products using a modified catalyst system which involves Pd(OAc)(2)-RuPhos at 100 °C. The direct arylation of electron deficient arenes with aryl mesylates is also established using Pd(OAc)(2)-SPhos as the catalyst in toluene-(t)BuOH at 120 °C.     

Entschuldigung: Readily Removable Directing Group Assisted Chemo‐ and Regioselective C(sp3)?H Activation by Palladium Catalysis

Currently used directing groups for selective aliphatic β‐functionalization of carbonyl compounds show excellent reactivity and selectivity with an amide as a linker. Described herein is 2‐piconimide, used for the first time with commercially available 2‐picolinamide/2‐picolic acid as precursors, to direct C H arylation/alkenylation by palladium catalysis. The directing group is essential for promoting the sequnetial primary and secondary C(sp³) H arylation with different aryl iodides in one substrate. The directing group was easily removed under simple reaction conditions at room temperature.     

Readily Removable Directing Group Assisted Chemo‐ and Regioselective C(sp3)H Activation by Palladium Catalysis

Currently used directing groups for selective aliphatic β‐functionalization of carbonyl compounds show excellent reactivity and selectivity with an amide as a linker. Described herein is 2‐piconimide, used for the first time with commercially available 2‐picolinamide/2‐picolic acid as precursors, to direct C? H arylation/alkenylation by palladium catalysis. The directing group is essential for promoting the sequnetial primary and secondary C(sp³)? H arylation with different aryl iodides in one substrate. The directing group was easily removed under simple reaction conditions at room temperature.     

Phosphine-phosphonium ylides as ligands in palladium-catalysed C2-H arylation of benzoxazoles

As balanced electron-rich P,C-chelating ligands, phosphine-phosphonium-ylides are considered for their ability to in situ promote palladium-catalysed direct C(sp²)-H arylation. Using methyl phosphonium salts of 2,2'-bis(diphenylphosphino)-1,1'-binaphtyl ("methyl-BINAPIUM") as ylide precursors under optimized reaction conditions, arylation of benzoxazole was found to proceed in moderate to high yield to give functional 2-aryl benzoxazoles. A strong anion effect of the non-salt free ylide was evidenced (TfO^- > I^- > PF₆^- ≈ salt-free). This first example of phosphonium ylides as ligands in catalytic C-H activation extends the prospect of their general implementation in homogeneous transition metal catalysis.     

Transition‐Metal‐Catalyzed Direct Arylation of (Hetero)Arenes by C?H Bond Cleavage

The area of transition‐metal‐catalyzed direct arylation through cleavage of C? H bonds has undergone rapid development in recent years, and is becoming an increasingly viable alternative to traditional cross‐coupling reactions with organometallic reagents. In particular, palladium and ruthenium catalysts have been described that enable the direct arylation of (hetero)arenes with challenging coupling partners—including electrophilic aryl chlorides and tosylates as well as simple arenes in cross‐dehydrogenative arylations. Furthermore, less expensive copper, iron, and nickel complexes were recently shown to be effective for economically attractive direct arylations.     

Copper‐Catalyzed Reaction Cascade of Thiophenol Hydroxylation and S‐Arylation through Disulfide‐Directed C−H Activation

Copper‐catalyzed thiophenol C?H activation is described. Through an initial attempt to conduct C‐arylation with arylboronic acid, a rather surprising sequential C?H activation and S‐arylation was discovered. Mechanistic investigation revealed the disulfide intermediate as the key component in directing C?H oxidation. The overall reaction proceeded under mild conditions with molecular oxygen as the oxidant. Discovery of disulfide as the directing group provides a potential new direction for catalytic C?H functionalization under mild conditions.     

<Emphasis Type="Italic">N</Emphasis>-Propylphthalimide-substituted bis-(NHC)PdX<Subscript>2</Subscript> complexes: synthesis,characterization and catalytic activity in direct arylation reactions

Palladium-catalyzed direct arylation of heteroaromatics has become a popular method for producing carbon–carbon bonds via C–H bond activation. A wide diversity of heteroaromatics such as furan, thiophenes and thiazoles can be used for this reaction. This paper reports the synthesis of N-propylphthalimide-substituted bis-(NHC)PdX₂ complexes (NHC = N-heterocyclic carbene), and their catalytic activity in direct arylation reactions. The complexes have been prepared from Ag(I)NHC precursors by transmetallation and characterized by spectroscopy and elemental analysis. The bis-(NHC)PdX₂ complexes show excellent activity as catalysts in the direct arylation reactions of 2-n-butylfuran, 2-n-butylthiophene and 2-isopropylthiazole.