共查询到20条相似文献,搜索用时 31 毫秒
1.
Katharina J. Hock Anja Knorrscheidt Ren Hommelsheim Junming Ho Martin J. Weissenborn Rene M. Koenigs 《Angewandte Chemie (International ed. in English)》2019,58(11):3630-3634
The functionalization of C?H bonds with non‐precious metal catalysts is an important research area for the development of efficient and sustainable processes. Herein, we describe the development of iron porphyrin catalyzed reactions of diazoacetonitrile with N‐heterocycles yielding important precursors of tryptamines, along with experimental mechanistic studies and proof‐of‐concept studies of an enzymatic process with YfeX enzyme. By using readily available FeTPPCl, we achieved the highly efficient C?H functionalization of indole and indazole heterocycles. These transformations feature mild reaction conditions, excellent yields with broad functional group tolerance, can be conducted on gram scale, and thus provide a unique streamlined access to tryptamines. 相似文献
2.
Ordered Porous Nitrogen‐Doped Carbon Matrix with Atomically Dispersed Cobalt Sites as an Efficient Catalyst for Dehydrogenation and Transfer Hydrogenation of N‐Heterocycles 下载免费PDF全文
Dr. Yunhu Han Dr. Ziyun Wang Ruirui Xu Dr. Wei Zhang Dr. Wenxing Chen Dr. Lirong Zheng Jian Zhang Dr. Jun Luo Konglin Wu Dr. Youqi Zhu Dr. Chen Chen Dr. Qing Peng Dr. Qiang Liu Prof. Dr. P. Hu Prof. Dr. Dingsheng Wang Prof. Dr. Yadong Li 《Angewandte Chemie (International ed. in English)》2018,57(35):11262-11266
Single‐atom catalysts (SACs) have been explored widely as potential substitutes for homogeneous catalysts. Isolated cobalt single‐atom sites were stabilized on an ordered porous nitrogen‐doped carbon matrix (ISAS‐Co/OPNC). ISAS‐Co/OPNC is a highly efficient catalyst for acceptorless dehydrogenation of N‐heterocycles to release H2. ISAS‐Co/OPNC also exhibits excellent catalytic activity for the reverse transfer hydrogenation (or hydrogenation) of N‐heterocycles to store H2, using formic acid or external hydrogen as a hydrogen source. The catalytic performance of ISAS‐Co/OPNC in both reactions surpasses previously reported homogeneous and heterogeneous precious‐metal catalysts. The reaction mechanisms are systematically investigated using first‐principles calculations and it is suggested that the Eley–Rideal mechanism is dominant. 相似文献
3.
Copper/Silver‐Mediated Direct ortho‐Ethynylation of Unactivated (Hetero)aryl CH Bonds with Terminal Alkyne 下载免费PDF全文
Yue‐Jin Liu Yan‐Hua Liu Xue‐Song Yin Wen‐Jia Gu Prof. Dr. Bing‐Feng Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):205-209
A copper/silver‐mediated oxidative ortho‐ethynylation of unactivated aryl C?H bonds with terminal alkyne has been developed. The reaction uses the removable PIP directing group and features broad substrate scope, high functional‐group tolerance, and compatibility with a wide range of heterocycles, providing an efficient synthesis of aryl alkynes. This procedure highlights the potential of copper catalysts to promote unique, synthetically enabling C?H functionalization reactions that lie outside of the current scope of precious metal catalysis. 相似文献
4.
Iron‐Catalyzed Cross‐Couplings in the Synthesis of Pharmaceuticals: In Pursuit of Sustainability 下载免费PDF全文
《Angewandte Chemie (International ed. in English)》2018,57(35):11116-11128
The scarcity of precious metals has led to the development of sustainable strategies for metal‐catalyzed cross‐coupling reactions. The establishment of new catalytic methods using iron is attractive owing to the low cost, abundance, ready availability, and very low toxicity of iron. In the last few years, sustainable methods for iron‐catalyzed cross‐couplings have entered the critical area of pharmaceutical research. Most notably, iron is one of the very few metals that have been successfully field‐tested as highly effective base‐metal catalysts in practical, kilogram‐scale industrial cross‐couplings. In this Minireview, we critically discuss the strategic benefits of using iron catalysts as green and sustainable alternatives to precious metals in cross‐coupling applications for the synthesis of pharmaceuticals. The Minireview provides an essential introduction to the fundamental aspects of practical iron catalysis, highlights areas for improvement, and identifies new fields to be explored. 相似文献
5.
Navjeet Kaur 《合成通讯》2019,49(5):617-661
A wide variety of biological activities are possessed by nitrogen, oxygen, and sulfur containing heterocycles and many methods are explored for the preparation of these heterocyclic compounds. Metal catalysts are used in organic reactions with high activity. The synthesis of heterocycles with the help of metal catalysts became very important in organic synthesis. New protocols have been investigated for the synthesis of heterocycles in the last decades. In present review article I have concentrated on the synthesis of seven and higher-membered heterocylces in the presence of ruthenium catalyst. 相似文献
6.
Navjeet Kaur 《Phosphorus, sulfur, and silicon and the related elements》2019,194(3):186-209
Nitrogen, oxygen, and sulfur containing heterocycles have a wide range of biological activities. Metal and nonmetal catalysts are used in organic reactions with high activity. New strategies have been developed for the preparation of heterocycles in the last decades. The metal and nonmetal catalyzed synthesis of heterocycles is becoming an important and highly rewarding protocol in organic synthesis. In this review article, the synthesis of seven and higher-membered S-heterocycles is presented with the application of metal and nonmetal catalysts for the period from 1968 to 2018. 相似文献
7.
Dr. Lu Yang Xiayu Liang Yuyang Ding Prof. Xinran Li Xuefeng Li Prof. Qingle Zeng 《Chemical record (New York, N.Y.)》2023,23(11):e202300173
Enantiomerically enriched five- and six-membered benzo oxygen heterocycles are privileged architectures in functional organic molecules. Over the last several years, many effective methods have been established to access these compounds. However, comprehensive documents cover updated methodologies still in highly demand. In this review, recent transition metal catalyzed transformations lead to chiral five- and six-membered benzo oxygen heterocycles are presented. The mechanism and chirality transfer or control processes are also discussed in details. 相似文献
8.
Huan Wang Yanfei Zhao Fengtao Zhang Yunyan Wu Ruipeng Li Junfeng Xiang Zhenpeng Wang Buxing Han Zhimin Liu 《Angewandte Chemie (International ed. in English)》2020,59(29):11850-11855
O‐heterocycles have wide applications, and their efficient and green synthesis is very interesting. Herein, we report hydrogen‐bonding catalyzed ring‐closing metathesis of aliphatic ethers to O‐heterocycles over ionic liquid (IL) catalyst under metal‐ and solvent‐free conditions. The IL 1‐butylsulfonate‐3‐methylimidazolium trifluoromethanesulfonate ([SO3H‐BMIm][OTf]) is discovered to show outstanding performance, better than the reported catalysts. An interface effect plays an important role in mediating the reaction rate due to the immiscibility between the products and the IL catalyst, and the products can be spontaneously separated. NMR analysis and DFT calculation suggest that a pair of cation and anion of [SO3H‐BMIm][OTf] could form three strong H‐bonds with an ether molecule, which catalyze the ether transformation via a cyclic oxonium intermediate. A series of O‐heterocycles including tetrahydrofurans, tetrahydropyrans, morpholines and dioxane can be obtained from their corresponding ethers in excellent yields (e.g., >99 %). This work opens an efficient and metal‐free way to produce O‐heterocycles from aliphatic ethers. 相似文献
9.
Prakash T. Parvatkar Dr. Perunninakulath S. Parameswaran Prof. Dr. Santosh G. Tilve 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(18):5460-5489
Heterocyclic scaffolds represent the key structural subunits of many biologically active compounds. Over the last few years iodine‐mediated reactions have been extensively studied due to their low cost and eco‐friendliness. This Review covers advances in the field of iodine‐mediated synthesis of heterocyclic compounds since 2006, especially with an emphasis on mechanisms of ring formation. In this article, syntheses of different heterocycles are classified based on the manipulation of functional groups. 相似文献
10.
Base‐Promoted/Gold‐Catalyzed Intramolecular Highly Selective and Controllable Detosylative Cyclization 下载免费PDF全文
Chenghao Zhu Dr. Lin Qiu Guangyang Xu Dr. Jian Li Prof. Dr. Jiangtao Sun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(37):12871-12875
A highly selective, controllable and synthetically useful base‐promoted intramolecular detosylative cyclization of bis‐N‐tosylhydrazones has been achieved, affording N‐containing heterocycles and cyclic olefins under transition‐metal‐free or gold‐catalyzed procedures, respectively. Moreover, an effective and practical metal‐free or gold‐catalyzed approach to synthesize polycyclic aromatic compounds is also reported. 相似文献
11.
Experimental and Computational Study of the Catalytic Asymmetric 4π‐Electrocyclization of N‐Heterocycles 下载免费PDF全文
Dr. Sadiya Raja Dr. Masaki Nakajima Prof. Dr. Magnus Rueping 《Angewandte Chemie (International ed. in English)》2015,54(9):2762-2765
The first asymmetric metal‐catalyzed Nazarov cyclization of N‐heterocycles has been developed. The use of a chiral catalyst allows the enantioselective electrocyclization of N‐heterocycles under mild conditions and the corresponding products are obtained in good yields with excellent enantio‐ and diastereoselectivity. The reaction mechanism and the absolute configuration of the obtained products are explained by means of computational studies. 相似文献
12.
Kankanala Ramakrishna Jyoti Prasad Biswas Sadhan Jana Tapas Kumar Achar Sandip Porey Debabrata Maiti 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(39):13946-13950
Distal C?H bond functionalization of heterocycles remained extremely challenging with covalently attached directing groups (DG). Lack of proper site for DG attachment and inherent catalyst poisoning by heterocycles demand alternate routes for site selective functionalization of their distal C?H bonds. Utilizing non‐productive coordinating property to hold the heterocycle into the cavity of a template system in a host–guest manner, we report distal C?H alkylation (C‐5 of quinoline and thiazole, C‐7 of benzothiazole and benzoxazole) of heterocycles. Upon complexation with heterocyclic substrate, nitrile DG in template directs the metal catalyst towards close vicinity of the specific distal C?H bond of the heterocycles. Our hypothesized pathway has been supported by various X‐ray crystallographically characterized intermediates. 相似文献
13.
Masahiro Kojima Prof. Dr. Motomu Kanai 《Angewandte Chemie (International ed. in English)》2016,55(40):12224-12227
Catalytic acceptorless dehydrogenation is an environmentally benign way to desaturate organic compounds. This process is traditionally accomplished with transition‐metal‐based catalysts. Herein, a borane‐catalyzed, metal‐free acceptorless dehydrogenation of saturated N‐heterocycles is disclosed. Tris(pentafluorophenyl)borane was identified as a versatile catalyst, which afforded several synthetically important N‐heteroarenes in up to quantitative yield. Specifically, the present metal‐free catalytic system exhibited a uniquely high tolerance toward sulfur functionalities, and demonstrated superior reactivity in the synthesis of benzothiazoles compared to conventional metal‐catalyzed systems. This protocol can thus be regarded as the first example of metal‐free acceptorless dehydrogenation in synthetic organic chemistry. 相似文献
14.
Edon Vitaku David T. Smith Prof. Dr. Jon T. Njardarson 《Angewandte Chemie (International ed. in English)》2016,55(6):2243-2247
Nitrogen heterocycles are found in a majority of approved small‐molecule pharmaceuticals, and the number of approved fluorinated drugs is increasing each decade. Therefore, new approaches for accessing fluorinated nitrogen heterocycles are of great significance. A novel, scalable, and metal‐free method for accessing a wide range of fluorinated indoles is described. This oxidative‐dearomatization‐enabled approach assembles 2‐trifluoromethyl NH‐indole products from simple commercially available anilines with hexafluoroacetylacetone in the presence of an organic oxidant. The nature of the aniline N‐capping group is critical for the success of this new reaction. Furthermore, the indole products contain a 3‐trifluoroacetyl group, which can be exploited to access a plethora of useful functional groups. 相似文献
15.
Navjeet Kaur 《合成通讯》2019,49(13):1633-1658
A wide variety of biological activities are possessed by N-, O-, and S-containing heterocycles and recently many reports appeared for the synthesis of these heterocycles. The synthesis of heterocycles with the help of metal and nonmetal became highly rewarding and important method in organic synthesis. This review article concentrated on the synthesis of multiple-nitrogen containing five-membered heterocylces in the presence of metal and nonmetal. It describes the formation of five-, six-, and seven-membered heterocyclic rings. 相似文献
16.
Fan Xu Hao Long Jinshuai Song Hai‐Chao Xu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(27):9115-9119
Benzimidazolone and benzoxazolone moieties are important scaffolds in a variety of pharmaceutical molecules. These bicyclic heterocycles are usually prepared from a benzene derivative through the construction of an additional five‐membered heterocyclic ring. We report herein a method that enables the efficient synthesis of highly substituted benzimidazolone and benzoxazolone derivatives by building both the benzene and the heterocyclic rings through a dehydrogenative cyclization cascade. Readily available arylamine‐tethered 1,5‐enynes undergo a biscyclization/dehydrogenation cascade to afford functionalized benzanellated heterocycles in a single step with complete control of regioselectivity. These electricity‐powered oxidative transformations proceed with H2 evolution, thus obviating the need for transition‐metal‐based catalysts and oxidizing reagents. 相似文献
17.
Navjeet Kaur 《合成通讯》2019,49(10):1205-1230
A wide variety of biological activities are possessed by N, O, and S containing heterocycles and recently many reports appeared for the synthesis of these heterocycles. The synthesis of heterocycles with the help of metal became highly rewarding and important method in organic synthesis. This review article concentrated on the synthesis of nitrogen containing five-membered heterocylces in the presence of palladium dibenzylideneacetone as a catalyst. 相似文献
18.
催化裂化是石油化工的核心单元之一.从催化裂化尾气中分离出来的碳四馏分富含许多的不饱和烯烃,如1-丁烯、顺、反式-2-丁烯以及少量的1,3-丁二烯,这些不饱和烯烃可以通过后续聚合反应,生成合成橡胶和工程塑料的重要原料,具有重要的应用价值.上述工艺过程对原料中1,3-丁二烯的含量(<100~200 ppm)有严苛的要求.采用选择性加氢技术对碳四馏分中的1,3-丁二烯进行选择性加氢,将其转化为更高附加值的单烯烃是一个理想的解决方案.然而,1,3-丁二烯加氢反应得到的单烯烃可能发生深度加氢得到副产物丁烷.因此,开发高效选择性加氢催化剂对碳四资源的利用具有重要的现实意义.另一方面,1,3-丁二烯加氢反应可以作为模型反应,用来考察选择性加氢催化剂的性能.基于此,该反应无论在工业界还是学术界均受到广泛关注.尽管如此,有关1,3-丁二烯加氢催化剂研究进展方面的综述极少.仅有关于1,3-丁二烯加氢作为模型反应的综述报道.本文对过去半个世纪以来1,3-丁二烯加氢反应中不同催化剂的发展历程进行系统综述,特别是包括Pd,Pt和Au等的单一贵金属催化剂.重点介绍以下内容:(1)固体催化剂构效关系,包括活性金属尺寸效应、晶面和形貌效应以及载体效应(晶相、孔道和酸碱性);(2)高性能催化剂的设计新策略,如单原子催化剂、核壳结构催化剂、金属-离子液复合催化体系以及载体的形貌调控;(3)催化剂的反应机理和失活机理.提出了1,3-丁二烯选择性加氢高性能催化剂开发面临的挑战,并对潜在的发展方向进行了展望.本文认为随着纳米技术和金属纳米材料合成方法的快速发展,对贵金属活性组分进行原子层面上的调控(包括形貌、尺寸以及单原子配位环境等)已成为可能.这将有助于研制出一类新型高性能选择性加氢催化材料,从而实现高转化率条件下高附加值单烯烃的定向转化.此外,载体的酸碱性和孔道结构的调控有助于进一步调节催化剂的抗积炭性能,也是未来发展的一个重要方向. 相似文献
19.
A growing number of products, including many heterocycles, can be prepared by the one‐pot MultiComponent Reactions (MCRs) just by mixing three or more educts, and in many cases practically quantitative yields of pure products can be obtained. The 3CR by α‐aminoalkylations of nucleophiles began in the middle of the last century, and the syntheses of heterocycles by MCRs of three and four components were introduced by Hantzsch in the 1880s. The MCRs of the isocyanides with four and more educts began in 1959, and their compound libraries were mentioned since 1961. However, only since 1995 the often automated one‐pot chemistry of the MCR of the isocyanides is used extensively. If a chemical compound can be prepared by a sequence of two component reactions or a suitable MCR, the latter is always a superior procedure. The U‐4CR can be combined with other chemical reactions and MCRs as one‐pot reactions of n > 4 components, and such unions even have a much greater variety of structurally and stereochemically different products. The educts and products of Ugi‐type MCRs are more variable than those of all previous chemical reactions and other MCRs. Due to the progress in screening and automation processes in the last few years, many new compounds have been formed and investigated more rapidly than ever before. The search for new desirable products can be accomplished more than 10,000 times faster than by the older conventional methods. The now popular chemistry of the MCRs of the isocyanides fills the since long empty part of organic chemistry. 相似文献
20.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(36):10994-10997
Herein a non‐precious transition‐metal catalyst system for the selective synthesis of dialkoxymethane ethers from carbon dioxide and molecular hydrogen is presented. The development of a tailored catalyst system based on cobalt salts in combination with selected Triphos ligands and acidic co‐catalysts enabled a synthetic pathway, avoiding the oxidation of methanol to attain the formaldehyde level of the central CH2 unit. This unprecedented productivity based on the molecular cobalt catalyst is the first example of a non‐precious transition‐metal system for this transformation utilizing renewable carbon dioxide sources. 相似文献