共查询到20条相似文献,搜索用时 46 毫秒
1.
2.
3.
4.
芳基烯烃是一类具有重要应用价值的化合物,其合成方法已被广泛研究。目前,过渡金属催化非官能化芳烃与烯烃的直接氧化偶联反应是构造芳基烯烃最高效、最简捷的方法,同Heck偶联反应相比,其底物无需预先官能化,这不仅大大缩短了反应步骤,并且能从源头上杜绝废盐的产生,特别是当以氧气或空气作氧化剂时,副产物仅为水,不会对环境造成任何危害。该方法同传统制备芳基烯烃的诸多方法相比具有原子利用率高、原子经济性好和环境友好等绿色化学的典型特性。本文根据催化剂的种类、底物类型及导向基类型对近年来过渡金属催化非官能化芳烃与烯烃的直接偶联反应进行了分类详述,并对若干重要体系的反应机理进行了详细讨论。 相似文献
5.
本文综述了饱和烃C-H键活化的新进展以及利用可溶过渡金属多氢化物对饱和烃C-H键进行活化、选择性催化官能化。 相似文献
6.
7.
8.
报道了一种无金属催化条件下合成吡啶-2-甲酰胺的方法.在质子酸的促进作用下,简单的吡啶和异氰通过2位碳-氢键的胺甲酰化反应生成吡啶-2-甲酰胺类化合物.产物的形成主要经历二水合草酸存在下异腈对吡啶环的亲电加成、水解和过氧化二叔丁酯氧化下的吡啶环芳构化转化.优化部分的对比实验证实质子酸和氧化剂的存在对于该反应都是必须条件.大体而言,所有反应都是将各反应物和试剂一次性加入,在空气氛围下100℃加热进行良好.环上不同位置含有甲基、叔丁基、环状二烷基、甲氧基、卤素等基团的吡啶底物均展示了良好兼容性.另一方面,烷基和芳基官能化的异腈也都能用于该反应,得到相应的N-烷基和N-芳基吡啶甲酰胺产物.初步结果显示异腈的稳定性对于反应结果有明显影响,相对稳定的2,6-二甲基苯基异腈参与反应生成的产物产率高于其它异腈参与的反应.和已知合成类似产物时采用银、钯盐等催化活化吡啶的2-位碳-氢键的方法相比,本文报道的合成方法优势在于完全无需金属催化剂、专一的碳-2位区域选择性反应、广泛的底物适用性以及高原子经济性.因此,这样的合成方法可望成为对已有合成方法的补充用于合成结构多样和有用的吡啶-2-甲酰胺化合物. 相似文献
9.
烯烃的多组分双官能化是一类高效快速构建结构多样性分子的重要有机反应,具有原子经济性高、底物范围广及条件温和等诸多优点,近年来成为有机合成领域的主要研究热点.许多金属或非金属催化条件下的烯烃多组分双官能化反应已经被大量报道,借助手性配体,有的反应还成功地实现了不对称双官能化.然而,与贵重金属催化剂(钌、铑、铱、钯、银)相... 相似文献
10.
11.
Zi-Yang Zhang Dr. Xuepeng Zhang Dr. Jia Yuan Chang-Duo Yue Dr. Sixuan Meng Dr. Jian Chen Prof. Guang-Ao Yu Prof. Chi-Ming Che 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(22):5037-5050
A facile approach to the synthesis of diaryl- and dialkyl-substituted monophosphino-o-carboranes by rhodium(I)-catalyzed phosphine-directed B3,6−H activation has been developed for the first time. Upon switching rhodium(I) to palladium(II), C-arylated and B6-halogenated products were obtained by using tBuOLi and Li2CO3 as base, respectively. These discoveries provide some simple and efficient approaches to the modification of monophosphino-o-carboranes. 相似文献
12.
在手性分子中,轴手性化合物占据着非常重要的地位.从原子和步骤经济性方面考虑,利用不对称碳-氢官能团化反应构建轴手性化合物是最简洁高效的方法.随着过渡金属催化的不对称碳-氢键官能团化领域的逐步发展,利用该策略来构建轴手性联芳基化合物的研究成果也不断涌现.本文综述了通过过渡金属钯、铑和铱催化的不对称碳-氢键官能团化反应合成轴手性联芳基化合物的最新进展.此外,还介绍了利用这些方法合成多种轴手性配体及其催化的不对称反应,以及这些方法在天然产物合成中的应用. 相似文献
13.
Since the pioneering work on Cr(Ⅲ)-catalyzed enantioselective[4+2]/allylboration reported by Hall and co-workers,a variety of catalytic methodologies for the as... 相似文献
14.
Catalytic asymmetric transformations involving carbon-carbon bond cleavages open intriguing strategies for the synthesis of chiral complex molecules.The transie... 相似文献
15.
Paul Müller Daniel Fernandez Patrice Nury Jean-Claude Rossier 《Helvetica chimica acta》1999,82(6):935-945
Olefins undergo cyclopropanation with diphenylsulfonium (ethoxycarbonyl)methylide (=diphenylsulfonium 2-ethoxy-2-oxoethylide; 3a ) in the presence of chiral CuI or RhII catalysts. trans/cis Ratios and ee's of the cyclopropanes 6 obtained with this ylide in the presence of a chiral CuI catalyst 7 are identical with those obtained with ethyl diazoacetate ( 4 ). In the case of catalysis with RhII, the trans/cis ratios of the cyclopropanes as well as the enantioselectivity change slightly upon going from the ylide 3a to diazoacetate 4 . 相似文献
16.
过渡金属催化的酰胺C-N键活化已成为有机化学和金属有机化学热门的研究领域之一。酰胺中羰基C-N键的切断可分为5种不同模式:1)氧化加成反应;2)形成季铵盐后的酰基转移反应;3)质子解反应;4)氢化反应;5)脱羧反应。而酰胺非羰基C-N键的切断可分为4种不同模式:1)氧化加成反应;2)亲核取代反应;3)形成亚胺或亚胺盐;4)β-氨基消除反应。本文综述了近年来过渡金属催化的酰胺中羰基C-N键和非羰基C-N键的不同切断模式。 相似文献
17.
Prof. Barry M. Trost Dr. Zhijun Zuo Dr. Johnathan E. Schultz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(67):15354-15377
The efficient and selective synthesis of functionalized seven-membered rings remains an important pursuit within synthetic organic chemistry, as this motif appears in numerous drug-like molecules and natural products. Use of cycloaddition reactions remains an attractive approach for their construction within the perspective of atom and step economy. Additionally, the ability to combine multiple components in a single reaction has the potential to allow for efficient combinatorial strategies of diversity-oriented synthesis. The inherent entropic penalty associated with achieving these transformations has impressively been overcome with development of catalysis, whereby the reaction components can be pre-organized through activation by transition-metal-catalysis. The fine-tuning of metal/ligand combinations as well as reaction conditions allows for achieving chemo-, regio-, diastereo- and enantioselectivity in these transformations. Herein, we discuss recent advances in transition-metal-catalyzed construction of seven-membered rings via combination of 2–4 components mediated by a variety of metals. An emphasis is placed on the mechanistic aspects of these transformations to both illustrate the state of the science and to highlight the unique application of novel processes of transition-metals in these transformations. 相似文献
18.
Dr. Sandip Kumar Das Dr. Satyajit Roy Prof. Dr. Buddhadeb Chattopadhyay 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(2):e202210912
Over the past few years, the development of efficient methods to construct high-valued N-heterocyclic molecules have received massive attention owing to their extensive application in the areas of medicinal chemistry, drug discovery, natural product synthesis and so on. To access those high-valued N-heterocycles, many methods have been developed. In this context, transition-metal-catalyzed denitrogenative annulation of 1,2,3-triazoles and 1,2,3,4-tetrazoles has appeared as a powerful synthetic tool because it offers a step- and atom-economical route for the preparation of the nitrogen-rich molecules. Compared with the denitrogenative annulation of various 1,2,3-triazole frameworks, annulation of 1,2,3,4-tetrazole remains more challenging due to the inertness of the tetrazole moiety. This Review summarizes the significant achievements made in the field of denitrogenative annulation of various 1,2,3-triazoles and 1,2,3,4-tetrazoles including some pioneering examples in this area of research. We anticipate that this denitrogenative annulation reaction will find broad applications in the pharmaceutical industry, drug discovery and other fields of medicinal chemistry. 相似文献
19.
Prof. Dr. Xiantao Ma Xiaoyu Yan Jing Yu 《European journal of organic chemistry》2023,26(29):e202300468
The direct use of alcohols as the much greener and more sustainable alkylated reagents in substitution reactions is one of the emerging areas in green chemisty. However, owing to the poor leaving character of OH group, the direct substitution of alcohols is not an easy thing. Transition metal (TM) catalysis such as Pd-catalyzed allylic/benzyl substitution and Ir-catalyzed borrowing hydrogen provides efficient protocols for the direct substitution of alcohols, however, an organic solvent and servely anhydrous conditions are generally required. In recent decade, TM-catalyzed direct substitution of alcohols in aqueous media was developed as a much greener alternative. In this review, the recent develpoments of this area are summarized. The activation mechanism of alcohols in aqueous reactions are emphatically discussed. 相似文献
20.
Leijun Hao John F. Harrod Anne-Marie Lebuis Ying Mu Ronghua Shu Edmond Samuel Hee-Gweon Woo 《Angewandte Chemie (International ed. in English)》1998,37(22):3126-3129
The color change from yellow to violet allows the formation of the intermediate [Cp2Ti(SiHMePh)(pyridine)] to be monitored in the reaction of PhMeSiH2 with a pyridine in the presence of the precatalyst [Cp2TiMe2] [Eq. (a)]; the hydride [Cp2TiH] is postulated to be the key intermediate in the catalytic cycle. The regioselective hydrosilylation of pyridine and also substituted pyridines can be catalyzed by the titanocene [Cp2TiMe2]. R=Me, CO2Et. 相似文献