(PPh_3)_2Pd(Ar)Br在Suzuki偶联反应中的应用

芳基钯(Ⅱ)化合物(PPh3)2Pd(Ar)Br(1a~1e)与苯硼酸(2)经Suzuki偶联反应定量合成了一系列取代联苯(3a~3e),其结构经1H NMR确证。考察了辅助膦配体、反应温度、反应溶剂、反应时间、原料配比及芳环上取代基对偶联反应的影响。实验结果表明,在最佳反应条件[1 1 mmol,n(1)/n(2)=1/1,不加膦配体,甲苯/水为溶剂,于60℃~90℃反应3 h~24 h]下,可定量生成3;过量辅助膦配体和低反应温度不利于偶联反应中金属转移和还原消除的顺利进行,收率较低;芳环上带有吸电子基团时则有利于金属转移和还原消除,收率较高。     

1-苯基-3-甲基-4-苯甲酰基吡唑啉酮/PdCl2在温和条件下催化Suzuki偶联反应的研究

考察了商品化的简单非膦配体1-苯基-3-甲基-4-苯甲酰基吡唑啉酮在有氧温和条件下的Suzuki偶联反应活性,探讨了反应温度、反应时间、溶剂以及碱对反应的影响。结果表明,该配体在优化的反应条件下能高效催化不同溴代反应物和氯代反应物与苯硼酸的交叉偶联反应;提高反应温度、延长反应时间和引入质子性极性有机/水混合溶剂有利于偶联反应的进行。     

羟基磷灰石负载锰催化溴苯的Suzuki反应

以羟基磷灰石(HAP)负载Mn作为催化剂(MnHAP)催化溴苯与苯硼酸的Suzuki交叉偶联反应.以氟离子交换羟基磷灰石的羟基(MnFAP)后,催化剂的活性显著提高,在优化的反应条件下能得到约70%的产率.进一步考察了溶剂和不同取代基的影响.结果表明,MnFAP作用下溶剂极性对反应有很大影响,当溶剂DMF/H2O比例为1/3时产率最高.对于不同取代基取代的溴代芳烃或苯硼酸,可以得到中等产率(18%~46%)的偶联产物.     

新型含咔唑双膦配体-钯催化 Suzuki 反应

 以 3-溴苯甲醚为原料合成了新型双膦配体 6,6′-二甲氧基-2,2′-二 (二-N-咔唑基膦)-1,1′联苯, 并将该配体与钯组成的配合物用于对溴苯甲醚和苯硼酸的 Suzuki 偶联反应, 考察了溶剂、碱、底物/催化剂摩尔比、膦/钯摩尔比对偶联反应的影响. 结果表明, 该催化体系在 1,4-二氧六环中催化对溴苯甲醚和苯硼酸的 Suzuki 偶联反应得到 99% 的分离产率. 同时, 该催化体系用于其它芳基溴和苯硼酸的 Suzuki 偶联反应也表现出很好的催化性能, 即使芳基溴有较大的空间位阻或具有取代基也能获得很好的结果.     

壳聚糖席夫碱钯配合物催化碘代苯与苯乙烯交叉偶联反应的研究

水杨醛与壳聚糖反应制得壳聚糖席夫碱配体,此配体与钯盐反应得到壳聚糖席夫碱钯催化剂.研究了该催化剂对碘代苯(PhI)与苯乙烯偶联生成反式-二苯乙烯的催化性能.考察了不同反应因素(原料比、缚酸剂种类及其用量、反应温度、溶剂、催化剂用量、反应时间)对该反应的影响,由此确定了该催化反应的最佳反应条件.该催化剂经过滤分离、溶剂洗涤,循环使用6次仍有较高的催化活性,该催化剂对取代碘苯与苯乙烯的反应也有较高的催化活性.     

糖基配体促进的铜催化水相Ullmann型C—N偶联反应

开发了一种用于实现水相中的铜催化Ullmann型C—N偶联反应的绿色且高效的催化体系.以Cu I为催化剂、N-(2-羟乙基)-β-D-吡喃葡萄糖胺为配体,芳基碘化物、芳基溴化物与N-亲核试剂都能在水中实现偶联反应,芳基碘化物的吸电子取代和供电子取代效应影响较小.偶联产物的收率良好(61%~96%).该催化体系也成功扩展到各种吲哚与4-碘苯甲醚的水相偶联反应中.绿色且可降解的配体、温和的反应条件、绿色的水溶剂和广泛的底物适用性,使得该水相偶联策略具有重要的意义.     

吸电子基团对席夫碱及其钯配合物在抑菌及催化活性方面的影响

报道了2,6-二异丙基苯胺缩苯甲醛或2,4-二氯苯甲醛席夫碱(L1和L2)及其钯配合物(1和2)的合成,并通过元素分析、红外光谱、X-射线单晶衍射等方法对席夫碱配体及配合物进行了表征。通过与已报道的席夫碱L1及其钯配合物1结构相比较,发现引入吸电子取代基合成的一个新的席夫碱及其钯配合物(L2和2)对抑菌及催化活性有较大影响。抑菌活性试验表明,配体及配合物均具有良好的抑菌活性,配合物相对于配体具有更好的抑菌效果,配体苯环上的吸电子取代基能有效提高抑菌活性。研究了两组配合物(1和2)对溴代苯和丙烯酸Heck交叉偶联生成苯丙烯酸的催化性能,考察了不同反应因素(缚酸剂种类、反应温度及溶剂)对该反应的影响,确定了反应的最佳条件;催化实验结果显示吸电子基团的引入增加了钯配合物的空间位阻效应进而降低其催化活性。     

吸电子基团对席夫碱及其钯配合在抑菌及催化活性方面的影响

报道了2, 6-二异丙基苯胺缩苯甲醛或2, 4-二氯苯甲醛席夫碱(L1和L2)及其钯配合物(1和2)的合成, 并通过元素分析、红外光谱、X-射线单晶衍射等方法对席夫碱配体及配合物进行了表征。通过与已报道的席夫碱L1及其钯配合物1结构相比较, 发现引入吸电子取代基合成的一个新的席夫碱及其钯配合(L2和2)对抑菌及催化活性有较大影响。抑菌活性试验表明, 配体及配合物均具有良好的抑菌活性, 配合物相对于配体具有更好的抑菌效果, 配体苯环上的吸电子取代基能有效提高抑菌活性。研究了两组配合物(1和2)对溴代苯和丙烯酸Heck交叉偶联生成苯丙烯酸的催化性能, 考察了不同反应因素(缚酸剂种类、反应温度及溶剂)对该反应的影响, 确定了反应的最佳条件;催化实验结果显示吸电子基团的引入增加了钯配合物的空间位阻效应进而降低其催化活性。     

氟喹诺酮作为钯催化Heck反应有效配体的研究

研究了氟喹诺酮作为钯催化Heck反应的有效配体. 碘苯、溴苯和其它芳基卤衍生物与丙烯酸丁酯、苯乙烯等取代乙烯类化合物在钯和氟喹诺酮的催化下发生Heck反应. 讨论了配体、催化剂用量、碱和溶剂对Heck反应产率的影响. 该反应的最优化条件是: 钯源为Pd(OAc)2 (0.1 mol%), 诺氟沙星作为配体(0.2 mol%), K2CO3作为碱, DMA作为溶剂, 取代碘苯及溴苯和它们的衍生物与丙烯酸丁酯、苯乙烯等乙烯基化合物的反应均可以得到高收率的目标偶联产物.     

双氮席夫碱配体对甲基三氧化铼催化烯烃环氧化反应的影响

 利用 2-吡啶甲醛、6-甲基-2-吡啶甲醛或 6-异丙基-2-吡啶甲醛与对甲基苯胺缩合制得双氮席夫碱配体, 考察了席夫碱配体以及溶剂和温度对甲基三氧化铼 (MTO) 催化不同结构烯烃环氧化反应的影响. 结果表明, 这些席夫碱配体与 MTO 构成的催化剂体系在甲醇溶剂中的催化性能最好, 双氮配体能显著提高环氧化反应的选择性. 当以甲醇为溶剂, 环己烯为底物, 在 –10 oC 反应 12 h 时, 环己烯转化率和环氧化物选择性均可达 100%. 席夫碱的配位能力越强, 越有利于提高环氧化物选择性, 而其配位能力取决于吡啶环中 6-位取代基的电子和立体结构. 给电子能力较强和空间位阻较小的烷基对应的配体的配位能力较强.     

OCCURRENCE OF LIGAND COUPLING IN THE REACTIONS OF VARIOUS SULFOXIDES WITH GRIGNARD REAGENTS

Abstract

Ligand coupling reactions take place not only between benzyl and 2-pyridyl groups and two 2-pyridyl groups in the treatment of benzyl, alkyl and aryl 2-pyridyl sulfoxides with Grignard reagents, but also between such groups as p-benzenesulfonylphenyl, 4-pyridyl, 2-quinolyl and 2-pyrimidyl, and the benzyl group. There are cases in which ligand exchange precedes ligand coupling, especially with 2-heteroaryl groups. In addition, even some alkyl groups were found to couple with the 2-pyridyl group. The ease of coupling seems to be associated with the electronegativity of the coupling carbon atom of the ligand, when one compares the ¹³C NMR chemical shifts.     

Dumbbell-Shaped 2,2’-Bipyridines: Controlled Metal Monochelation and Application to Ni-Catalyzed Cross-Couplings

2,2’-Bipyridine ligands (dsbpys) with dumbbell-like shapes and differently substituted triarylmethyl groups at the C5 and C5’ positions showed high ligand performance in the Ni-catalyzed cross-electrophile coupling and the Ni/photoredox-synergistically catalyzed decarboxylative coupling reactions. The superior ligand effects of dsbpys compared to the conventional bpy ligands were attributed to the monochelating nature of dsbpys.     

Biscyclometalated ruthenium complexes bridged by 3,3',5,5'-tetrakis(N-methylbenzimidazol-2-yl)biphenyl: synthesis and spectroscopic and electronic coupling studies

A series of biscyclometalated ruthenium complexes bridged by the title ligand were prepared by either an oxidative dimerization of corresponding monometallic complexes or treatment of the bridging ligand with Ru(L)Cl(3) (L = capping ligand). The electronic properties of these complexes were examined by electrochemical and spectroscopic analysis and DFT/TDDFT calculations. The degree of metal-metal electronic coupling of these complexes was estimated on the basis of intervalence charge-transfer transition analysis of corresponding mixed-valent complexes. These studies indicated that the electronic coupling was strongly dependent on the electronic nature of the terminal ligands. A hole-transfer superexchange mechanism was used to understand the underlying electron-transfer processes.     

Surface-modified membranes as a matrix for protein purification.

Recently introduced membrane-based chromatographic supports for protein separation are available either with a coupled ligand, e.g., protein A, protein G or ion-exchange groups, or as activated matrices for coupling a desired ligand. The coupling conditions for protein A and immunoglobulin G to an epoxy-activated membrane were determined. The performance of the prepared affinity membranes was investigated using pure rabbit immunoglobulin G and protein A as a model system. For practical application monoclonal antibodies from cell culture supernatant were purified with a prepared protein A membrane and for comparison with a sulphonic acid ion exchange membrane.     

Asymmetric synthesis of an axially chiral antimitotic biaryl via an atropo-enantioselective Suzuki cross-coupling

A catalytic asymmetric synthesis of the axially chiral bridged biaryl (-)-2, a structural analogue of natural (-)-rhazinilam possessing original antimitotic properties, is described. The key step is an intermolecular asymmetric Suzuki coupling, furnishing the nonbridged biaryl (-)-6, precursor of (-)-2, with up to 40% ee using binaphthyl ligand 7a. Various known or new binaphthyl and ferrocenyl phosphines as well as phosphetanes were screened as ligands in this reaction, the conditions of which were optimized. The comparison with another Suzuki coupling system showed that 7a is the most versatile ligand described to date for this type of transformation. This work gives the first application of the asymmetric Suzuki coupling to a biologically relevant target.     

In flow activation of diol-silica with cyanogen bromide and triethylamine for preparing high-performance affinity chromatographic columns

A new coupling strategy using pre-packed diol-silica supports to obtain affinity columns for high-performance affinity chromatography (HPAC) is described. These columns were prepared by "in flow" activation in which solutions containing anhydrous solutions of CNBr and triethylamine are separately pumped to a mixer and then onto a pre-packed diol-silica column. Recycling the amino ligand to be coupled several times over the activated silica diol columns results in ligand immobilization. DNA (the Op 1 lac operator), 6-aminohexyl-Cibacron and a peptide (melittin) were all successfully "in flow" coupled to freshly activated columns. Methods for CNBr activation of pre-packed diol-silica column were developed for one, two or three pump HPLC systems. The supports were successfully used for the HPAC purification of a Lac repressor-beta-galactosidase fusion protein, alcohol dehydrogenase, and calmodulin. Columns prepared by in flow activation/coupling procedures were shown to be stable for at least 14 months. Also, in flow activated silica columns could be stored in anhydrous acetone for at least 3 months prior to coupling. Our experiments with these affinity ligand columns (DNA-silica, aminohexyl-Cibacron F3GA-silica, and melittin-silica), suggests that this is a very successful coupling protocol for producing a variety of HPAC columns.     

Catalysis of copper(II) chelate-amine complexes in the oxidative coupling of 2,6-dialkylphenols

The oxidative coupling reaction of 2,6-dimethylphenol and 2,6-di-tert-butylphenol with molecular oxygen was performed by using a series of copper(II) chelate complexes as a catalyst, derived from copper(II), β-diketone, and some Shiff bases. Under the applied reaction conditions, the reaction products of 2,6-dimethylphenol were poly(2,6-dimethyl-1,4-phenylene oxide) (C? O coupling product) and 3,3′,5-5′-tetramethyl-4,4′-diphenoquinone (C? C coupling product), and that of 2,6-di-tert-butylphenol oxidation was only 3,3′,5-5′-tetra-tert-butyl-4,4′-diphenoquinone (C? C coupling product). The catalytic activity has been shown to be dependent on the properties of the copper(II) chelates used as catalysts and the mole ratios of amine ligand to copper(II) chelate (ligand ratio). The basicity and the steric bulkiness of the amine used as a ligand for copper(II) β-diketonato catalysts were found to be two of the main factors that govern the oxidative coupling mode (C? O and/or C? C coupling) of 2,6-dimethylphenol. The oxidative coupling activity of 2,6-dialkylphenol is discussed in terms of both the stabilities of the copper(II) chelates and of the copper(II) chelate-amine adducts. The rate of oxygen absorption for 2,6-dimethylphenol catalyzed by the copper(II) acetylacetonato-piperidine system is first order in oxygen partial pressure and zero order in 2,6-dimethylphenol concentration, respectively. A Cu(II)-oxygen, as an intermediate is suggested on the basis of the results obtained.     

Reaction of triphenylsulfonium salt with organolithium reagents

The reaction of triphenylsufonium trifluoromethanesulfonate with various nucleophilic, organolithium reagents gave ligand coupling products and the corresponding diaryl or di-heteroaryl sulfides. Moreover, ligand exchange reaction did not give any noticeable product in each reaction. Therefore, it was found that only the ligand coupling reaction proceeds in this reaction system.Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1053–1058,. August, 1995. Original article submitted August 19, 1995.     

Copper(I) Oxide Catalyzed Formation of C?S Bond Mediated by N,N′‐Type Ligand

1,10‐Phenanthroline, a simple and cheap N,N′‐type ligand, was found to work well as the ligand of C? S coupling catalyzed by Cu₂O. The corresponding coupling products were synthesized in good to excellent yields (75%–99%) in DMSO at 80°C. A variety of aryl halides and thiols were investigated and satisfactory results were obtained.     

A new recyclable/reusable ionic liquid/LiCl system for Suzuki–Miyaura cross coupling reactions

Suzuki–Miyaura cross coupling reactions of aryl halides with aryl boronic acids were carried out in basic ionic liquids in the presence of lithium chloride as a promoter. The coupling reactions, carried out in the absence of base and ligand, proceed in good to excellent yields with easy product isolation and catalyst recycle.