氨基酸促进的Ullamann反应

芳基胺、二芳基醚、N-烯基酰胺类骨架广泛存在于具有重要生理活性的天然产物和人造分子中。合成这三类化合物的方法很多,其中铜催化的U ll-m ann类型的偶联反应是最重要的方法之一。铜促进的U llm ann类型的C-N,C-O偶联反应自从其报道以来已经有了近100年的历史,在实验室和工业     

钯催化一锅法合成2-碘联芳烃的研究

Suzuki偶联反应是构建分子碳骨架的有效手段之一,因而被广泛应用于联芳烃化合物的合成,长期以来受到化学家们的广泛关注。本文通过两步一锅法钯催化芳基硼酸与2-碘苯胺发生Suzuki偶联反应,生成的2-氨基联苯不用分离发生重氮化反应直接转化为2-碘联芳烃化合物。该方法无需磷配体的参与,催化剂的用量较低,合成产率进一步提高,操作更加简单易行。     

新型邻位烷基取代联芳基膦配体在Suzuki偶联中的应用

联芳基骨架广泛存在于天然产物,药物中,合成这类分子具有重要的价值。Suzuki偶联的发展为其提供了一种重要的合成方法,在此我们测试了一种新型邻位烷基化的联芳基膦在钯催化Suzuki偶联合成联芳基化合物中活性应用,能以最低0.01 mol%的钯用量以很高的产率进行反应,为合成联芳基化合物降低了成本。邻位烷基的引入有利于机理中氧化加成,还原消除步骤,与商业化膦配体对比也表现出较高的反应活性。     

芳香酰氯和芳基硼酸的Suzuki-Miyaura偶联反应研究进展

芳香酰氯具有较高的反应活性,易于和芳基硼酸反应生成工业上应用广泛的芳基酮。概述了应用各种钯催化剂,在条件温和、低毒的情况下进行芳香酰氯和芳基硼酸的Suzuki-Miyaura偶联反应,并就各类反应的优点进行了详细阐述。     

碳-碳偶联反应在含氟芳香单体制备中的应用

介绍了过渡金属催化的碳-碳偶联反应在含氟芳香单体制备中的应用。主要是在α-氟代苯乙烯、β-氟代苯乙烯、α,β-二氟代苯乙烯、β,β-二氟代苯乙烯和三氟乙烯基芳基醚制备中的应用。详细综述了α,β,β-三氟代苯乙烯(TFS)的制备工艺及其应用前景。与其他方法相比,偶联工艺具有反应条件温和、步骤少、转化率高和选择性高等优点。随着含氟芳香聚合物的发展,偶联反应在其单体制备中的应用会不断增多。     

二茂铁烯丙基钯卡宾络合物的合成及其催化性能

采用"一锅法"用1, 3-双(2, 6-二异丙基苯基)氯化咪唑对二茂铁烯丙基钯二聚体Ⅰ在室温下进行解聚,不仅简便、高效地合成了二茂铁烯丙基钯卡宾络合物Ⅱ,而且避免了使用不稳定的卡宾。通过IR、1HNMR、13CNMR、MS、HRMS和X射线单晶衍射对其结构进行鉴定。络合物Ⅱ对空气和湿气稳定,且对芳基氯代物参与的Suzuki-Miyaura偶联反应和Buchwald-Hartwig胺化反应展现较高的催化活性。在反应温度70℃、0.4%(以氯代芳烃物质的量为基准计算得到,下同)络合物Ⅱ催化芳基氯代物与芳基硼酸的偶联反应时,产物收率为92%～100%;在反应温度100℃、0.5%络合物Ⅱ催化氯苯与多样化胺的偶联反应时,获得38%～99%的收率。     

含吡啶基的HBC衍生物的合成

以四芳基取代环戊二烯酮2与二烷基取代的二苯乙炔3通过Diels-Alder环加成反应得到六芳基取代苯4。化合物4在路易斯酸催化下通过Scholl环氧化脱氢反应,生成化合物5,5再与4-硼酸吡啶发生Suzuki偶联反应生成目标化合物1。     

β-偕二氟氨基酸衍生物及其Suzuki交叉偶联反应

本文探索了一条基于钯催化的、通过β-偕二氟氨基酸衍生物与杂环硼酸的Suzuki交叉偶联反应,制备氨基酸衍生物的合成路线。合成路线的起始原料是二苄胺和溴乙酸乙酯,经过胺醛缩合反应、亲核加成反应、羟基Appel溴化反应、heck重排、Suzuki还原交叉偶联等5个反应步骤,成功合成了2-(苄基(3-(4-(呋喃-3-基)苯基)烯丙基)氨基)-3-苯基己酸乙酯等氨基酸衍生物。该合成路线的起始原料价廉易得,合成步骤简便,具有清洁易操作、条件温和等优点,可为非天然氨基酸的合成提供参考。     

二茂铁烯丙基卡宾钯络合物的合成及催化性能

采用一锅法将咪唑盐对二茂铁烯丙基钯二聚体I在室温下进行解聚，避免了使用不稳定的卡宾，简便、高效地合成了二茂铁烯丙基卡宾钯络合物II。通过IR，1H NMR，13C NMR，MS，HRMS和X射线单晶衍射对其结构进行鉴定。络合物II对空气和湿气稳定，且对芳基氯代物参与的Suzuki-Miyaura 偶联反应和Buchwald-Hartwig胺化反应展现较高的催化活性。在反应温度70 oC，0.4 mol％络合物II催化芳基氯代物与芳基硼酸的偶联反应时，取得95-100%收率；在反应温度100 oC，0.5 mol％钯络合物II催化氯苯与多样化胺的偶联反应时，也获得中等至好的的收率。     

1-芳基-3-芳甲酰基中氮茚的合成

合成了九个1-芳基中氮茚衍生物。首先由取代苯乙酮,碘,乙酸和吡啶四组分一锅煮反应合成中间体1-碘代中氮茚,然后在钯催化剂作用下,使用制得的的1-碘代中氮茚和芳基硼酸的Suzuki偶联反应合成得到目标化合物,所合成化合物结构通过红外,核磁及质谱进行了表征。     

Expanded Heterogeneous Suzuki–Miyaura Coupling Reactions of Aryl and Heteroaryl Chlorides under Mild Conditions

A mesoporous LTA zeolite (MP‐LTA)‐supported palladium catalyst was developed for the highly efficient Suzuki–Miyaura reaction of aryl and heteroaryl chlorides. The couplings of various aryl chlorides with arylboronic acids in aqueous ethanol were efficiently achieved in the presence of 1.0 mol% of the catalyst. Furthermore, the scope of this catalyst was extended to the coupling of heteroaryl chlorides. Regardless of the substituents, all of the coupling reactions were very clean and highly efficient under mild heating. It shows that our catalyst is one of the most powerful heterogeneous catalysts for the coupling of a wide range of aryl and heteroaryl chlorides. The catalyst could be repetitively used at least 10 times without a significant loss of its catalytic activity. Compared to mesoporous SBA‐15 and MCM‐41 materials, the MP‐LTA support proved to be very stable and robust to prevent degradation upon reuse.     

Aerobic Ligand‐Free Suzuki Coupling Reaction of Aryl Chlorides Catalyzed by In Situ Generated Palladium Nanoparticles at Room Temperature

An aerobic, ligand‐free Suzuki coupling reaction catalyzed by in situ generated palladium nanoparticles in polyethylene glycol with an average molecular weight of 400 Da (PEG‐400) at room temperature has been developed. This catalytic system is a very simple and highly active protocol for the Suzuki coupling of aryl chlorides with arylboronic acids, which proceed smoothly in excellent yields in short times using low catalyst loadings. Control experiments demonstrated that the Suzuki reaction catalyzed by the in situ generated palladium nanoparticles can be carried out much quicker than that using the preprepared particles under the same conditions. The formation of palladium nanoparticles in PEG‐400 was promoted by arylboronic acids.     

Highly Active,Well‐Defined (Cyclopentadiene)(N‐heterocyclic carbene)palladium Chloride Complexes for Room‐Temperature Suzuki–Miyaura and Buchwald–Hartwig Cross‐Coupling Reactions of Aryl Chlorides and Deboronation Homocoupling of Arylboronic Acids

A new class of well‐defined N‐heterocyclic carbene (NHC)‐(cyclopentadiene)palladium chloride complexes such as CpPd(NHC)Cl wasw synthesized from the readily available starting NHC‐palladium(II) chloride dimers. These air‐stable, coordinatively saturated NHC‐Pd complexes bearing the cyclopentadiene (Cp) unit exhibit high catalytic activity in the room temperature Suzuki–Miyaura and Buchwald–Hartwig cross‐coupling reactions involving unactive aryl chlorides as the substrates. In addition, they are found to be extremely efficient catalysts in the deboronation homocoupling of arylboronic acids at room temperature.     

Suzuki偶联反应中钯配合物催化剂的研究进展

Suzuki偶联反应是在零价钯配合物催化剂的催化下,芳基硼酸与卤代芳烃进行的交叉偶联反应,可以高效、高选择性地构建C-C键.钯配合物催化剂对Suzuki偶联反应的活性和选择性起着决定性的影响,是研究Suzuki偶联反应的关键.对含有膦配体、N-卡宾配体、亚胺配体、胺配体和其它配体的钯配合物催化剂催化效果进行了综述.     

Regioselective Palladium(0)‐Catalyzed Cross‐Coupling Reactions and Metal‐Halide Exchange Reactions of Tetrabromothiophene: Optimization,Scope and Limitations

The Suzuki reaction of tetrabromothiophene with arylboronic acids provides a regioselective approach to various 5‐aryl‐2,3,4‐tribromothiophenes, symmetrical 2,5‐diaryl‐3,4‐dibromothiophenes, and tetraarylthiophenes. Unsymmetrical 2,5‐diaryl‐3,4‐dibromothiophenes are prepared by Suzuki reaction of 5‐aryl‐2,3,4‐tribromothiophenes. Tetraarylthiophenes containing two different types of aryl groups are obtained by Suzuki reactions of 2,5‐diaryl‐3,4‐dibromothiophenes. During the optimization of the conditions of each individual reaction, the solvent, the catalyst and the temperature play an important role. In several cases, classical conditions [use of tetrakis(triphenylphosphane)palladium(0), Pd(PPh₃)₄, as the catalyst] gave excellent yields. The yields of those transformations which failed or proceeded sluggishly could be significantly improved by application of a new biarylmonophosphine ligand developed by Buchwald and co‐workers. Regioselective metal‐halide exchange reactions of tetrabromothiophene provide a convenient approach to various 2,5‐disubstituted 3,4‐dibromothiophenes. 5‐Alkyl‐2‐trimethylsilyl‐3,4‐dibromothiophenes could be prepared in one pot by sequential addition of trimethylchlorosilane and alkyl bromides. The reaction of tetrabromothiophene with methyl chloroformate and subsequent Suzuki reactions afforded 3,4‐diaryl‐2,5‐bis(methoxycarbonyl)thiophenes.     

Access to 2‐Aminopyridines – Compounds of Great Biological and Chemical Significance

2‐Aminopyridines are key structural cores of bioactive natural products, medicinally important compounds, and organic materials and thus, extremely valuable synthetic targets. The few reported 6‐substituted 2‐aminopyridines and the lack of flexible, efficient and general applicable methods for their synthesis demonstrates the urgent need of new methods for their preparation. Reactions between 2,6‐dibromopyridine and primary or secondary, cyclic or acyclic, and aliphatic or aromatic amines were shown to selectively yield the respective 6‐bromopyridine‐2‐amines in very high yields which were successfully used as substrates for subsequent C C cross‐coupling reactions. The recently introduced dichloro‐bis[1‐(dicyclohexylphosphanyl)piperidine]palladium ( 1 ) was used as catalyst for the cross‐coupling of 6‐bromopyridine‐2‐amines with arylboronic acids, diaryl‐ and dialkylzinc reagents or olefins and hence, is also an excellent C C cross‐coupling catalyst for this type of substrate. Moreover, all the reaction protocols presented were in each of the catalyses uniformly applied. The scope of both the amination and the cross‐coupling reactions are well defined and allow one to simply adapt the reaction protocols directly to other amines and/or coupling partners and, thus, provide for the first time a very flexible and generally applicable reaction protocol to get access to 2‐aminopyridines.     

Synthesis of Benzimidazole‐Substituted Arylboronic Acids via Aerobic Oxidation of 1,2‐Arylenediamines and Formyl‐Substituted Aryl MIDA Boronates using Potassium Iodide as a Catalyst

A highly efficient protocol for the synthesis of benzimidazole‐substituted arylboronic acids was developed via aerobic oxidative cyclization of 1,2‐aryldiamines and formyl‐substituted aryl MIDA (N‐methyliminodiacetic acid) boronates using potassium iodide as a nucleophilic catalyst. Furthermore, a one‐pot protocol for the synthesis of benzimidazole‐substituted arylboronic acids from 1,2‐phenylenediamines and formyl‐substituted arylboronic acids was developed without the isolation of any intermediates. The resulting boronic acids were further subjected to Suzuki–Miyaura coupling reactions without isolation, leading to diaryl‐substituted benzimidazoles with only one separation step.

     

Polymer‐Supported Electron‐Rich Oxime Palladacycle as an Efficient Heterogeneous Catalyst for the Suzuki Coupling Reaction

Various electron‐rich oxime palladacycle resins designed as heterogeneous catalysts were employed for the Suzuki coupling reaction of aryl halides with arylboronic acids. The electron‐richness of the oxime ligand was controlled by the substituted alkoxy groups. Evaluation based on the electronic effect of the catalysts revealed that the alkoxy‐substituted oxime palladacycle resins showed better catalytic activity than palladated Kaiser oxime resin in the Suzuki coupling reactions and that the catalytic activity of oxime palladacycle resins increased as the electron‐richness of oxime ligand increased. The most electron‐rich oxime palladacycle resin exhibited an excellent catalytic performance for the synthesis of both biaryl and heterobiaryl compounds, despite its heterogeneous system. As a practical application of the catalyst, a valsartan precursor was synthesized in high yield under mild conditions. The electron‐rich oxime resin could also be reused for up to 5 cycles while maintaining good catalytic activity in the Suzuki coupling reaction.

     

Palladium Nanoparticles Immobilized on Nano‐Silica Triazine Dendritic Polymer (Pdnp‐nSTDP): An Efficient and Reusable Catalyst for Suzuki–Miyaura Cross‐Coupling and Heck Reactions

A new catalyst based on palladium nanoparticles immobilized on nano‐silica triazine dendritic polymer (Pd_np‐nSTDP) was synthesized and characterized by FT‐IR spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy, energy dispersive X‐ray, transmission electron microscopy and elemental analysis. The size of the palladium nanoparticles was determined to be 3.1±0.5 nm. This catalytic system showed high activity in the Suzuki–Miyaura cross‐coupling of aryl iodides, bromides and chlorides with arylboronic acids and also in the Heck reaction of these aryl halides with styrenes. These reactions were best performed in a dimethylformamide (DMF)/water mixture (1:3) in the presence of only 0.006 mol% and 0.01 mol% of the catalyst, respectively, under conventional conditions and microwave irradiation to afford the desired coupling products in high yields. The Pd_np‐nSTDP was also used as an efficient catalyst for the preparation of a series of star‐ and banana‐shaped compounds with a benzene, pyridine, pyrimidine or 1,3,5‐triazine unit as the central core. Moreover, the catalyst could be recovered easily and reused several times without any considerable loss of its catalytic activity.