环钯化合物在Heck反应中的应用研究

钯催化交叉偶联反应在化学工业、合成天然产物及生物活性物质中有着广泛的应用。催化剂体系是交叉偶联反应研究的核心。环钯化合物结构简单、性能稳定,在催化交叉偶联反应中具有高活性、高选择性,引起研究者们的极大关注,不断有新的环钯化合物被合成出来,其催化性能也得到了研究。本文综述了环钯化合物的合成方法及其在Heck反应中的应用。     

环钯化合物在Heck反应中的应用研究

钯催化交叉偶联反应在化学工业、合成天然产物及生物活性物质中有着广泛的应用.催化剂体系是交叉偶联反应研究的核心.环钯化合物结构简单、性能稳定,在催化交叉偶联反应中具有高活性、高选择性,引起研究者们的极大关注,不断有新的环钯化合物被合成出来,其催化性能也得到了研究.本文综述了环钯化合物的合成方法及其在Heck反应中的应用.     

环钯化合物在Heck反应中的应用研究

钯催化交叉偶联反应在化学工业、合成天然产物及生物活性物质中有着广泛的应用.催化剂体系是交叉偶联反应研究的核心.环钯化合物结构简单、性能稳定,在催化交叉偶联反应中具有高活性、高选择性,引起研究者们的极大关注,不断有新的环钯化合物被合成出来,其催化性能也得到了研究.本文综述了环钯化合物的合成方法及其在Heck反应中的应用.     

钯催化三亚甲基甲烷的不对称[3+4]环加成反应:高区域选择性、高非对映选择性和高对映选择性构筑苯并呋喃[3,2-b]吖庚因

环加成反应是构建多官能团化环状化合物最直接、有效的方法之一.其中,三亚甲基甲烷(Trimethylenemethane,TMM)活性中间体被视为一类高效的三碳合成子.目前TMM已被广泛用于多种环加成反应,为一些重要的环状化合物以及天然化合物提供了高效、可靠的合成方法.早在1979年,Trost和Chan等[1]首次报道了Pd-TMM的[3+2]环加成反应.此后,钯催化TMM的多种催化不对称[3+2],[3+3]和[3+6]环加成反应相继得以实现[2,3],并为手性五元环、六元环及九元环类化合物提供了高效的合成策略.然而,对于钯催化TMM的不对称[3+4]环加成化反应——合成七元环状化合物的研究,目前尚无相关报道.其可能的主要原因是七元环状化合物的合成存在不利的熵效应和环化张力.     

第Ⅷ族钳形金属催化剂的研究进展

钳形金属化合物在有机合成、有机金属催化以及材料科学等领域都有着重要的应用.主要总结了本课题组近几年来在第Ⅷ族钳形金属化合物的合成与催化应用方面取得的一些进展,包括利用廉价易得的原料、通过芳环的C—H键活化方法,合成得到多种非手性和手性的PCP钳形钯(Ⅱ)化合物、PCN钳形钯(Ⅱ)和镍(Ⅱ)化合物、双(咪唑啉)苯NCN钳形钯(Ⅱ)、铂(Ⅱ)、镍(Ⅱ)、铑(Ⅲ)和铱(Ⅲ)化合物、NCN’钳形钯(Ⅱ)化合物、CNN’钳形钯(Ⅱ)和钌(Ⅱ)化合物等,尤其是探索出的"一锅煮"的膦化/金属化反应,为多种类型PCP和PCN钳形金属化合物的合成提供了新的途径,该方法毋须分离不稳定的含膦配体,并成功地实现了相关配体中心芳环2位的C—H键活化,从而简化了合成步骤,使得操作简便易行、产物收率高.所得到的钳形金属化合物被用于催化多种碳-碳键生成反应(包括不对称的催化反应)、酮的氢转移反应、不对称膦氢化反应等.相关的文献报道也将做适当讨论.     

富氮唑环类化合物的环加成合成研究进展

富氮唑环类化合物作为一种重要的氮杂环化合物,在药物化学、生物耦合、材料化学等领域有广阔的应用前景,其环加成合成的研究也越来越受人们的关注.从催化体系类型、合成不同取代类型产物等方面对近年来富氮唑环类化合物环加成合成方法的研究进展进行综述.     

缬氨醇衍生的手性二茂铁亚胺环钯化合物的合成及晶体结构

含氮配位基团的二茂铁衍生物的环钯化合物在有机合成、催化等领或有着重要的应用，尽管目前已经合成了从多的二茂铁环钯化合物，但其中绝大部分为外消旋体。二茂铁是引入平面手性的理想骨架，通过经典的拆分方法或利用光学纯的二茂铁配体进行不对称环钯化反应可得到具有平面手性的二茂铁环钯化合物，研究发现，利用平面手性的二茂铁环钯化合物与金属汞嘲、锡等的金属转移反应可方便地制备平面构型保持的手性环汞、环锡化合物；还可将它们用于外消旋氨基酸的手性拆分及催化不对称Claisen重排反应（ee值最高可达95％）。     

聚苯乙烯固载过渡金属催化剂在硅氢加成和加氢反应中的应用

聚苯乙烯树脂具有优良的物理化学性能,其与过渡金属的络合物在硅氢加成和催化加氢反应中得到了广泛应用,表现出良好的催化活性、反应选择性和重复使用性能,具有均相催化剂和其他固载型催化剂不具备的优势。利用含配位基团的化合物对聚苯乙烯改性后,可显著提高对金属的配位能力以及催化剂的稳定性,也往往表现出更好的催化性能。鉴于近年来聚苯乙烯固载的过渡金属催化剂在硅氢加成和催化加氢反应中的研究较为引人注目,本文对该类催化剂的制备方法、催化性能及相关机理进行了总结和分析。首先介绍了经胺、膦、巯基、不饱和烃等改性的聚苯乙烯固载的过渡金属催化剂在硅氢加成反应中的应用,其次介绍了聚苯乙烯固载的铂、钯、铑、钌、纳米金、铬、双金属胶体等在催化加氢反应中的应用,重点介绍了聚苯乙烯树脂与金属钯、铑的固载型催化剂,最后对该类催化剂的发展方向进行了分析和展望。     

钯催化二溴代化合物自偶联环化合成二苯并[a,e]环辛四烯

由于独特的结构和广泛的应用,多取代环辛四烯及其苯并稠环衍生物的合成方法研究具有重要意义.本文报道了一种钯催化烯基溴化物与芳基溴化物的偶联反应.利用此钯催化的环化自偶联反应,以中等至较好的收率高选择性地从双溴代芳基或烯基化合物合成了多种二苯并[a,e]环辛四烯衍生物.     

2,3-联烯醇及其衍生物的反应

2,3-联烯醇是一类含1,2-二烯官能团和羟基的化合物, 具有很高的反应活性, 它及其衍生物是一类重要的联烯化合物. 概述了2,3-联烯醇及其衍生物的反应, 包括2,3-联烯醇在过渡金属催化下的自身异构环化反应、钯催化的偶联反应、钌催化的环羰基化反应、不同条件下不同方式的扩环反应、亲电试剂参与的反应、分子内环加成反应、自由基反应等和2,3-联烯醇衍生物在零价钯催化下基于亚甲基-π-烯丙基钯中间体生成联烯或1,3-共轭二烯的区域选择性反应, S_N2'类型的加成-消除反应, 二价钯催化下的分子内环化反应以及重排反应等.     

Synthesis and catalytic activity of pyrazolyl-functionalized N-heterocyclic carbene palladium complexes

Three pyrazolyl-functionalized N-heterocyclic carbene (NHC) palladium complexes based on 1-[2-(pyrazol-1-yl)phenyl]imidazole have been synthesized and characterized by physico-chemical and spectroscopic methods, and the structures of two of the complexes have been confirmed by single-crystal X-ray diffraction. The pyrazolyl-functionalized NHCs act as chelating N,C-bidentate ligands in these three complexes. Catalytic tests have proved that these complexes exhibit highly effective catalytic activity for the Suzuki–Miyaura and Mizoroki–Heck coupling reactions in water or aqueous/organic media under air. The substituents on the pyrazolyl ring exert different influences on the catalytic activity of the complexes in these coupling reactions.     

Palladacyclic catalysts in C-C and C-heteroatom bond-forming reactions

Palladacycles are amongst the most active catalysts in Heck-type carbon-carbon bond formation and related carbon-heteroatom bond forming reactions. For instance they have recently emerged as showing the highest activity in the Suzuki coupling of electronically challenging aryl chloride substrates. In addition to the high activity they display, their ease of synthesis, facile modification and comparative stability all act to enhance their appeal.     

环戊二烯基钌配合物催化的高选择性苯乙炔二聚反应

Transition metal vinylidene complexes (M=C=CHR) have attracted a great deal of attention in recent years as a new type of organometallic intermediates that may have unusual reactivity[1]. Their reactivity has been explored and their application to organic synthesis is developed[2]. Recent reports on the ruthenium-vinylidene complexes[3]suggest that the reaction of ruthenium-vinylidene complexes with a base generates the coordinatively unsaturated ruthenium acetylide species, which are involved in a number of catalytic and stoichiometric reactions of alkynes. For example,the coordinatively unsaturated ruthenium acetylide species C5Me5Ru(PPh3)-C≡CPh,formed from the reaction of the vinylidene complex C5Me5Ru(PPh3) (Cl)=C=CHPh with a base was reactive toward a variety of small molecules and active in catalytic dimerization of terminal alkynes[4]. The dimerization of terminal alkyne is an effective method of forming enynes, but its synthetic application in organic synthesis has been limited dueto low selectivity for dimeric products[5]. In this communication, we report that three ruthenium complexes were used as catalysts for the highly selective dimerization of phenylacetylene.     

Synthesis and Reactivity of Paramagnetic Nickel Polypyridyl Complexes Relevant to C(sp2)–C(sp3)Coupling Reactions

A number of new transition metal catalyzed methods for the formation of C(sp²)–C(sp³) bonds have recently been described. These reactions often utilize bidentate polypyridyl‐ligated Ni catalysts, and paramagnetic Ni^I halide or aryl species are proposed in the catalytic cycles. However, there is little knowledge about complexes of this type. Here, we report the synthesis of paramagnetic bidentate polypyridyl‐ligated Ni halide and aryl complexes through elementary reactions proposed in catalytic cycles for C(sp²)–C(sp³) bond formation. We investigate the ability of these complexes to undergo organometallic reactions that are relevant to C(sp²)–C(sp³) coupling through stoichiometric studies and also explore their catalytic activity.     

Three types of reactions with intramolecular five-membered ring compounds in organic synthesis

There are three types of reactions with intramolecular five-membered ring compounds in organic syntheses: The first type is reactions involving intramolecular five-membered ring compounds which are utilized for the ease of synthesis of these compounds and the stability of the products. The second is reactions performed via intramolecular five-membered ring intermediates, because such intermediates are very reactive and labile compounds. The third is the metal-catalyzed reactions with the intramolecular five-membered ring compounds because these metal compounds have catalytic activities. The third type reactions involving intramolecular five-membered ring pincer compounds are also provided.The first type reactions include carbonylations, alkenylations, alkynylations, acylations, isocyanations, Diels-Alder reactions, etc. The second type reactions include carbonylations, cross-coupling reactions, hydroacylations, ring expansion reactions, carbocyclizations, etc. The third type reactions include cross-coupling reactions, rearrangements, metatheses, reductions, Michael reactions, dehydrogenations, Diels-Alder reactions, etc.     

Heterocyclic carbenes: synthesis and coordination chemistry

The chemistry of heterocyclic carbenes has experienced a rapid development over the last years. In addition to the imidazolin-2-ylidenes, a large number of cyclic diaminocarbenes with different ring sizes have been described. Aside from diaminocarbenes, P-heterocyclic carbenes, and derivatives with only one, or even no heteroatom within the carbene ring are known. New methods for the synthesis of complexes with N-heterocyclic carbene ligands such as the oxidative addition or the metal atom template controlled cyclization of beta-functionalized isocyanides have been developed recently. This review summarizes the new developments regarding the synthesis of N-heterocyclic carbenes and their metal complexes.     

Synthesis of electronically modified Ru-based neutral 16 VE allenylidene olefin metathesis precatalysts

Electronic modifications within Ru-based olefin metathesis precatalysts have provided a number of new complexes with significant differences in reactivity profiles. So far, this aspect has not been studied for neutral 16 VE allenylidenes. The first synthesis of electronically altered complexes of this type is reported. Following the classical dehydration approach (vide infra) modified propargyl alcohols were transformed to the targeted allenylidene systems in the presence of PCy?. The catalytic performance was investigated in RCM reaction (ring closing metathesis) of benchmark substrates such as diallyltosylamide and diethyl diallylmalonate.     

Atom transfer radical cyclisation reactions mediated by copper complexes

This article describes recent advances in the use of copper complexes in mediating atom transfer radical cyclisation reactions (ATRC). Recent developments have included the design of activated complexes which mediate the cyclisation of tri-, di-, and mono-halo derived substrates at ambient temperatures. Using this methodology, cyclisation to give a variety of ring sizes (4-18 membered rings) has been demonstrated. In addition tandem and radical-polar crossover reactions have also been developed. The design of solid supported and perfluorous complexes that mediate cyclisations may make this approach to the synthesis of rings more attractive towards industrial applications.