对N-杂环卡宾催化的Staudinger反应的研究

以N-杂环卡宾催化剂1催化亚胺与烯酮之间的Staudinger反应,得到相应的β-内酰胺。室温下,在四氢呋喃溶剂中进行的反应,可得到95%的产率,反式∶顺式=5∶1的非对映选择性。实验结果表明,亚胺的保护基团吸电子能力越强,越有利于顺式产物的生成。对甲苯磺酰基(TS)保护的取代基为2,4-二甲氧苯基的亚胺参与的该反应可得到68%的产率,反式∶顺式=99∶1的非对映选择性。底物拓展过程中发现Staudinger反应适用于多种不同的亚胺与烯酮。苯基乙基烯酮和环庚基的烯酮活性都很强,可以和从强缺电子结构到弱缺电子结构的芳基亚胺,以及带给电子基团的或杂芳环的芳基亚胺顺利的反应。两个苯基的烯酮活性较低,只能与活性较高的缺电子结构的芳基亚胺反应。值得注意的是,在相同条件下,烷基亚胺参与的该反应都没能得到相应的β-内酰胺。     

N-杂环卡宾催化醛的酯化反应研究

介绍了氮杂环卡宾作为有机催化剂的发展历史和催化机理,综述了近年来氮杂环卡宾催化醛的酯化反应的研究成果。     

凹凸棒土固载N-杂环卡宾催化安息香缩合反应

本文将五种不同的NHCs催化剂前体接枝到凹凸棒土表面，制备了五种负载型NHCs催化剂。通过FT-IR、元素分析、BET和SEM对五种催化剂进行了表征，表征结果表明NHCs催化剂前体成功地固定在凹凸棒土表面。进一步的实验结果表明，这些负载型NHC可以作为安息香反应的有效催化剂。接着探究了这些负载型催化剂催化安息香反应的优化条件。结果发现，当BTBCl@ATP(催化剂B, 1 mmol%咪唑盐)作为催化剂，0.4当量NaOH作为碱，2ml CH3OH作为溶剂，在110℃油浴中，在Ar气氛中反应8小时，收率最高。在此优化条件下，负载型NHCs催化剂可以催化多种芳香醛的安息香反应，产率为61-86%。催化剂的重复使用实验表明，这些负载型催化剂可以简单地从反应体系中分离出来，重复使用四次后，这些负载型催化剂的催化活性没有明显下降。     

N-杂环卡宾镍配合物的合成及其光谱性质初步研究

N-杂环卡宾因其强给电子能力、结构易修饰及拓扑学性质,成为继有机膦配体之后另一类重要的配体。其所形成的N-杂环卡宾金属配合物在化学、药物化学、材料等领域具有十分重要的应用价值,它们可用作催化剂、制备分子开关的合成子、药物,还可以作为发光材料使用。本文合成了一种N-杂环卡宾镍配合物[Ni(NHC)](PF6)2,以核磁共振谱进行了表征,并初步研究了它的紫外可见光谱与红外光谱性质。     

纳米磁性负载氮杂环卡宾配体钯催化剂对溴苯Suzuki偶联反应的催化行为研究

Suzuki反应是合成联苯结构化合物的重要手段,广泛应用于医药、液晶、天然产物合成领域。传统含磷配体催化剂通常存在空气稳定性较差,分离困难等问题。以氯甲基苯乙烯树脂包裹超顺磁性纳米四氧化三铁粒了材料作为载体,表面修饰上大位阻氮杂环卡宾配体,然后与金属钯络合形成磁性负载催化剂。实验结果显示,处对溴代芳烃与苯硼酸的Suzuki偶联反应在用量为5ppm（mol％）时仍有很好的催化作用,循环使用次数可达21次,表明用纳米磁粒予负载卡宾配体制各的钯催化剂是一种高活性、易回收的非均相绿色催化剂。     

N-杂环卡宾银配合物的合成与表征

由N-杂环卡宾配体L(L=1,3-双(苄基)苯并咪唑盐酸盐)与Ag2O反应,得到银卡宾配合物(1),通过核磁、元素分析对化合物进行全面表征。并采用溶剂挥发法得到化合物(1)的单晶,利用X-射线单晶衍射测定和研究了化合物(1)的晶体结构,晶体结构数据:单斜晶系,空间群P2(1)/c,a=9.144(8),b=9.518(9)°,c=20.789(19)°,α=90°,β=94.307(13)°,γ=90°,Z=4,V=1804(3)3。     

不对称氮杂环卡宾催化在农药活性分子合成中的应用

手性农药的不同构型对其生物活性有很大的影响。光学纯手性农药具有药效高、用药量小、对作物和环境生态更安全、相对成本更低和市场竞争力强等优势，已成为21世纪新农药研发的热点，但大多数手性农药仍以消旋体形式市售使用。针对氮杂环卡宾催化高效、高立体选择性构建中心手性、轴手性和面手性农药活性分子的方法分别作简要分析和总结，旨在为手性农药高效合成提供指导。     

氮杂环卡宾有机催化合成农药活性手性分子

手性农药单一高效构型的研发已成为新农药研发重要方向之一。介绍了氮杂环卡宾催化合成农药活性手性分子的方法及其抗细菌、真菌及病毒活性与潜在应用价值。     

氮杂环卡宾硼烷自由基氰化反应的理论研究

采用密度泛函理论对氮杂环卡宾硼烷自由基氰化反应机理进行了计算模拟,分别从加成区域的选择、取代基效应和温度等方面进行了考查,目的 是为了研究反应机理的主要影响因素.由获得的每个基元反应的热力学数据和动力学数据对可能的反应路径进行分析,结果表明:氰化反应路径优于异氰化反应路径;氰化反应中只有2f是经PathⅢ完成的,其他有...     

氮杂环卡宾催化苯偶酰的高效合成

以苯甲醛为起始原料,利用氮杂环卡宾作为有机催化剂,氧气为氧化剂,在乙醇的碱性溶液中,通过一锅内的苯甲醛安息香缩合反应和苯偶姻的氧化反应,提供了一种制备苯偶酰的高效简捷方法。无需分离中间产物便可一步获得目标产物苯偶酰。     

氮杂环卡宾前体的合成

利用三（2-氯乙基）胺[tris（2-chloroethyl）amine]和N-乙基苯并咪唑的亲核反应,成功的合成了新颖的氮杂环卡宾前体tris-[2-（3-alkylmethylbenzimidazolium-1-yl）ethyl]amine trichloride[H3 TIEtNR]-（Cl）3（R-Et）},再进行离子交换得到{tris-[2-（3-alkylmethylbenzimidazolium-1-yl）ethyl]amine trichloride[H3 TIEtNR]-（PF6）3（REt）}。该化合物通过了核磁验证。     

一种新型3-芳基咪唑卡宾前体的合成

以3,5-二三氟甲基苯胺、乙二醛、甲醛、氯化铵和氯化苄或1-溴癸烷为原料,经缩合、亲核取代反应得到氯化1-苄基-3-(3,5-二三氟甲基)苯基咪唑盐和溴化1-癸基-3-(3,5-二三氟甲基)苯基咪唑盐,收率分别达59.0%和76.6%;通过氯化1-苄基-3-(3,5-二三氟甲基)苯基咪唑盐和溴化1-癸基-3-(3,5-二三氟甲基)苯基咪唑盐的阴离子交换反应得到4种目标产物:1-苄基-3-(3,5-二三氟甲基)苯基咪唑四氟硼酸盐、1-癸基-3-(3,5-二三氟甲基)苯基咪唑四氟硼酸盐、1-苄基-3-(3,5-二三氟甲基)苯基咪唑六氟磷酸盐和1-癸基-3-(3,5-二三氟甲基)苯基咪唑六氟磷酸盐,产物结构通过1HNMR、13CNMR得以确认。考察了溶剂对亲核取代反应的影响,得出最佳反应溶剂为甲苯。     

Construction of Contiguous Tetrasubstituted Carbon Stereocenters by Intramolecular Crossed Benzoin Reactions Catalyzed by N‐Heterocyclic Carbene (NHC) Organocatalyst

Bicyclic compounds with two contiguous tetrasubstituted carbon stereocenters at bridgehead positions were synthesized by N‐heterocyclic carbene (NHC)‐catalyzed intramolecular crossed benzoin reactions of symmetrical compounds. This desymmetrization strategy was applied to asymmetric synthesis with chiral NHC organocatalysts. Transition‐state models were proposed to explain the enantioselectivity. A tricyclic compound with three contiguous tetrasubstituted carbon stereocenters was synthesized by a stepwise strategy. The molecular structure and absolute configuration of the (+)‐enantiomer of this tricyclic compound were determined by X‐ray crystallographic analysis.     

L-脯氨酰胺在不对称Aldol反应中催化应用研究进展

Aldol反应是构建C-C键最有效的有机合成方法之一,不对称Aldol反应产物是合成多种复杂有机化合物的重要原料或关键中间体。L-脯氨酰胺是催化不对称Aldol反应的重要手性催化剂之一,具有结构多样、合成简洁、立体选择性高等优点,近年来被广泛地研究。对近年来L-脯氨酰胺类手性催化剂在不对称Aldol反应中的催化应用进行综述。     

Stetter Reaction in Room Temperature Ionic Liquids and Application to the Synthesis of Haloperidol

Imidazolium‐type room temperature ionic liquids (RTILs) have been used for the Stetter reaction, affording the desired 1,4‐dicarbonyl compounds in good yields. Thiazolium salts and Et₃N are efficient catalysts for this reaction performed in ionic liquid. The possibility to recycle and reuse the solvent has been demonstrated, although it was not possible to recycle the thiazolium catalyst. This method was used in the total synthesis of haloperidol.     

Gold(I) and Gold(III) N-Heterocyclic Carbene Complexes as Antibacterial Agents and Inhibitors of Bacterial Thioredoxin Reductase

A series of (NHC)Au(I)Cl monocarbene complexes and their gold(III) analogues (NHC)Au(III)Cl₃ were prepared and investigated as antibacterial agents and inhibitors of bacterial TrxR. The complexes showed stronger antibacterial effects against the Gram-positive MRSA and E. faecium strains than against several Gram-negative bacteria. All complexes were efficient inhibitors of bacterial thioredoxin reductase, indicating that inhibition of this enzyme might be involved in their mechanism of action. The efficacy of gold(I) and gold(III) analogues was comparable in most of the assays. The cytotoxicity of the gold NHC compounds against cancer and human cells was overall weaker than the activity against the Gram-positive bacteria, suggesting that their optimization as antibacterials warrants further investigation.     

Polarity reversal induced by electrochemically generated thiazol-2-ylidenes: The Stetter reaction

The inversion of the normal reactivity (umpolung) of aldehydes has been induced via N-heterocyclic carbenes (NHCs) thiazol-2-ylidenes 2a or 3a, generated by simple electrolyses of solutions containing thiazolium salt 2 or 3. Accordingly, 1,4-dicarbonyl compounds have been obtained, in mild conditions and in moderate to very high yields, via 1,4-addition of the Breslow intermediates to the suitable Michael acceptor. The procedure has been performed in classical organic solvents (VOCs) as well as in room temperature ionic liquids (RTILs). The different reactivity of aliphatic aldehydes vs the one of aromatic and heteroaromatic aldehydes has been emphasized.     

The Rhodium‐Catalyzed Carbene Cyclization Cycloaddition Cascade Reaction of Vinylsulfonates

Vinylsulfonates have proved to be excellent dipolarophiles for carbonyl ylides derived from diazoketones in rhodium‐catalyzed intramolecular cycloadditions. Polyfunctional substrates, such as 8 and (+)‐ 15 , were readily available from hydroxy esters, e.g. 1 and the cyclopenta‐1,3‐dione 10 , respectively, and the resulting polycyclic sultones were formed under mild reaction conditions in high yields with very good diastereoselectivities. A ruthenium‐catalyzed asymmetric transfer hydrogenation was found to desymmetrize the meso‐cyclopenta‐1,3‐dione 12 efficiently.     

Synthesis of 2‐Aryl‐Substituted Indole‐3‐acetic Acid Derivatives via Intramolecular Imino‐Stetter Reaction of Aldimines with Cyanide

A general method to generate umpolung of aldimines with cyanide was developed via the addition of cyanide to aldimines followed by a proton transfer from the carbon atom to the nitrogen atom in the resulting cyanide adducts. This novel method was successfully applied to the first imino‐Stetter reaction of aldimines obtained from 2‐aminocinnamic acid derivatives and aromatic aldehydes with cyanide, affording 2‐aryl‐substituted indole‐3‐acetic acid derivatives. Furthermore, the usefulness of this method was successfully demonstrated by the synthesis of an FPTase inhibitor, one of the biologically important 2‐arylindole‐3‐acetic acid derivatives.

     

负载NHC-Pd配合物催化Suzuki偶联反应的研究进展

钯催化的Suzuki偶联反应作为有效的构建碳-碳键的方法,在天然产物、药物全合成和有机合成工业中被广泛应用。而目前广泛应用的含钯均相催化剂尽管反应活性高,但昂贵钯金属盐或配合物不易回收,痕量残留于目标产品或者废液中,导致目标产品重金属污染和环境污染等弊端,极大地增加了该反应的成本和降低了产品的安全性,因此期望以易回收使用、低钯浸出的异相催化剂来实现对该反应的高效绿色催化。氮杂环卡宾钯配合物（NHC-Pd）在催化Suzuki偶联反应中具有反应活性高、稳定好等优点常被用作异相催化剂的催化中心。该文从异相催化剂的载体材料如高分子材料、多孔硅材料、碳基材料、金属-有机框架及磁性纳米粒子等出发,综述了近年来NHC-Pd在异相催化Suzuki偶联反应中的最新研究进展,对于今后该研究方向的开展具有指导意义。