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1.
Palladium‐Catalyzed Synthesis of Phenanthridine/Benzoxazine‐Fused Quinazolinones by Intramolecular CH Bond Activation 下载免费PDF全文
Puneet K. Gupta Nisha Yadav Subodh Jaiswal Mohd. Asad Dr. Ruchir Kant Dr. Kanchan Hajela 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(38):13210-13215
A highly efficient synthesis of phenanthridine/benzoxazine‐fused quinazolinones by ligand‐free palladium‐catalyzed intramolecular C?H bond activation under mild conditions has been developed. The C?C coupling provides the corresponding N‐fused polycyclic heterocycles in good to excellent yields and with wide functional group tolerance. 相似文献
2.
Suzuka Kinoshita Ryota Yamano Yu Shibata Yusuke Tanaka Kyoichi Hanada Takashi Matsumoto Kazunori Miyamoto Atsuya Muranaka Masanobu Uchiyama Ken Tanaka 《Angewandte Chemie (International ed. in English)》2020,59(27):11020-11027
An S‐shaped double helicene‐like molecule (>99 % ee), possessing stable helical chirality, has been synthesized by the rhodium(I)/difluorphos complex‐catalyzed highly diastereo‐ and enantioselective intramolecular double [2+2+2] cycloaddition of a 2‐naphthol‐ and benzene‐linked hexayne. The collision between two terminal naphthalene rings destabilizes the helical chirality of the S‐shaped double helicene‐like molecule, but the introduction of two additional fused benzene rings significantly increases the configurational stability. Thus, no epimerization and racemization were observed even at 100 °C. The enantiopure S‐shaped double helicene‐like molecule forms a trimer through the multiple C?H???π and C?H???O interactions in the solid‐state. The trimers stack to form columnar packing structures, in which neighboring stacks have opposite dipole directions. The accumulation of helical structures in the same direction in the S‐shaped double helicene‐like molecule enhanced the chiroptical properties. 相似文献
3.
Zhishuo Wang Jiangliang Yin Fulin Zhou Yunqi Liu Jingsong You 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(1):260-264
Reported herein is a rhodium(III)‐catalyzed three‐component annulation reaction of simple pyridines, alkynes, and 1,2‐dichloroethane (DCE), affording a streamlined pathway to diverse ring‐fused pyridiniums. DCE not only serves as a vinyl equivalent but also as an in situ activating agent for pyridine C2?H activation. A cationic five‐membered rhodacycle complex has been isolated and proposed as a possible intermediate. This strategy can be extended to other N‐containing heteroarenes for the synthesis of multiring‐fused pyridiniums. These multicomponent reactions exhibit excellent regioselectivity for 1,3‐diynes, paving a path to the cascade cyclization of 3‐fluoropyridine or N‐methylpyridin‐3‐amine with 1,3‐diynes for the construction of brand‐new tricyclic‐fused pyrano‐ or hydropyridoquinolizinium salts. These ionic fluorophores have been investigated as potential biomarkers. 相似文献
4.
Oxidative C−H/C−H Cross‐Coupling Reactions between N‐Acylanilines and Benzamides Enabled by a Cp*‐Free RhCl3/TFA Catalytic System 下载免费PDF全文
Yang Shi Luoqiang Zhang Prof. Dr. Jingbo Lan Min Zhang Fulin Zhou Wenlong Wei Prof. Dr. Jingsong You 《Angewandte Chemie (International ed. in English)》2018,57(29):9108-9112
By making use of a dual‐chelation‐assisted strategy, a completely regiocontrolled oxidative C?H/C?H cross‐coupling reaction between an N‐acylaniline and a benzamide has been accomplished for the first time. This process constitutes a step‐economic and highly efficient pathway to 2‐amino‐2′‐carboxybiaryl scaffolds from readily available substrates. A Cp*‐free RhCl3/TFA catalytic system was developed to replace the [Cp*RhCl2]2/AgSbF6 system generally used in oxidative C?H/C?H cross‐coupling reactions between two (hetero)arenes (Cp*=pentamethylcyclopentadienyl, TFA=trifluoroacetic acid). The RhCl3/TFA system avoids the use of the expensive Cp* ligand and AgSbF6. As an illustrative example, the procedure developed herein greatly streamlines the total synthesis of the naturally occurring benzo[c]phenanthridine alkaloid oxynitidine, which was accomplished in excellent overall yield. 相似文献
5.
Iridium‐Catalyzed Annulation Reactions of Thiophenes with Carboxylic Acids: Direct Evidence for a Heck‐type Pathway 下载免费PDF全文
Guangying Tan Qiulin You Prof. Dr. Jingbo Lan Prof. Dr. Jingsong You 《Angewandte Chemie (International ed. in English)》2018,57(21):6309-6313
The functionalization of thiophenes is a fundamental and important reaction. Herein, we disclose iridium‐catalyzed one‐pot annulation reactions of (benzo)thiophenes with (hetero)aromatic or α,β‐unsaturated carboxylic acids, which afford thiophene‐fused coumarin‐type frameworks. Dearomatization reactions of 2‐substituted thiophenes with α,β‐unsaturated carboxylic acids deliver various thiophene‐containing spirocyclic products. The occurrence of two interconnected reactions provides direct evidence for a Heck‐type pathway. The mechanistic scenario described herein is distinctly different from the SEAr and concerted metalation–protodemetalation (CMD) pathways encountered in the well‐described oxidative C?H/C?H cross‐coupling reactions of thiophenes with other heteroarenes. 相似文献
6.
Miyoko Kamigauchi Yukiko Maekawa Chisato Tode Yasuko In Toshimasa Ishida 《Helvetica chimica acta》2010,93(1):25-32
The X‐ray crystal analyses of the two 11‐deoxy‐didehydrohexahydrobenzo[c]phenanthridine‐type alkaloid derivatives 3 and 4 , derived from (±)‐corynoline ( 1 ) and (+)‐chelidonine ( 2 ), established their structures as (±)‐(5bRS,12bRS)‐5b,12b,13,14‐tetrahydro‐5b,13‐dimethyl[1,3]benzodioxolo[5,6‐c]‐1,3‐dioxolo[4,5‐i]phenanthridine ( 3 ) and (+)‐rel‐(12bR)‐7,12b,13,14‐tetrahydro‐13‐methyl[1,3]benzodioxolo[5,6‐c]‐1,3‐dioxolo[4,5‐i]phenanthridine ( 4 ). The conformations of 3 and 4 in CDCl3 were determined on the basis of 1H‐ and 13C‐NMR spectroscopy. 相似文献
7.
Base‐Controlled Selectivity in the Synthesis of Linear and Angular Fused Quinazolinones by a Palladium‐Catalyzed Carbonylation/Nucleophilic Aromatic Substitution Sequence 下载免费PDF全文
Jianbin Chen Dr. Kishore Natte Dr. Anke Spannenberg Dr. Helfried Neumann Prof. Dr. Peter Langer Prof. Dr. Matthias Beller Prof. Dr. Xiao‐Feng Wu 《Angewandte Chemie (International ed. in English)》2014,53(29):7579-7583
A new approach for the facile synthesis of fused quinazolinone scaffolds through a palladium‐catalyzed carbonylative coupling followed by an intramolecular nucleophilic aromatic substitution is described. The base serves as the key modulator: Whereas DBU gives rise to the linear isomers, Et3N promotes the preferential formation of angular products. Interestingly, a light‐induced 4+4 reaction of the product was also observed. 相似文献
8.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(12):3280-3284
Internally 1,3‐phenylene‐ and 2,5‐thienylene‐bridged [46]decaphyrins 2 and 3 have been synthesized. While 2 shows modest aromatic character derived from the global 46π‐conjugated circuit, 3 displays larger aromatic character owing to the contribution of an (annuleno)annulene‐type network consisting of two twisted Möbius aromatic thia[28]hexaphyrin segments in addition to the global 46π‐network. Upon protonation, these [46]decaphyrins underwent large structural changes to acquire strong aromaticity. Protonated 3 has been revealed to take on a planar structure composed of fused two triangular thia[28]hexaphyrin segments. 相似文献
9.
One‐pot Annulation for Biaryl‐fused Monocarba‐closo‐dodecaborate through Aromatic B−H Bond Disconnection 下载免费PDF全文
Gaku Akimoto Mai Otsuka Dr. Kazunori Miyamoto Dr. Atsuya Muranaka Dr. Daisuke Hashizume Dr. Ryo Takita Prof. Dr. Masanobu Uchiyama 《化学:亚洲杂志》2018,13(8):913-917
We have developed a one‐pot annulation reaction of monocarba‐closo‐dodecaborate with cyclic diaryliodonium salts to afford biaryl‐fused derivatives. Aryl functionalities are introduced at both the 1‐carbon and unreactive ortho‐boron vertices of the “σ‐aromatic” carborane cage without the need for pre‐functionalization. DFT calculations revealed that the palladium‐catalyzed C?B bond‐formation step in this process proceeds through a concerted metalation–deprotonation (CMD)‐type pathway for the B?H bond disconnection on the aromatic cage, though such bonds are generally regarded as hydridic. 相似文献
10.
Wei‐Jun Kong Zhigao Shen Lars H. Finger Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2020,59(14):5551-5556
Nitrogen‐doped polycyclic aromatic hydrocarbons (aza‐PAHs) have found broad applications in material sciences. Herein, a modular electrochemical synthesis of aza‐PAHs was developed via a rhodium‐catalyzed cascade C?H activation and alkyne annulation. A multifunctional O‐methylamidoxime enabled the high chemo‐ and regioselectivity. The isolation of two key rhodacyclic intermediates made it possible to delineate the exact order of three C?H activation steps. In addition, the metalla‐electrocatalyzed multiple C?H transformation is characterized by unique functional group tolerance, including highly reactive iodo and azido groups. 相似文献
11.
《Angewandte Chemie (International ed. in English)》2017,56(46):14727-14731
The first electrochemical dehydrogenative C−C cross‐coupling of thiophenes with phenols has been realized. This sustainable and very simple to perform anodic coupling reaction enables access to two classes of compounds of significant interest. The scope for electrochemical C−H‐activating cross‐coupling reactions was expanded to sulfur heterocycles. Previously, only various benzoid aromatic systems could be converted, while the application of heterocycles was not successful in the electrochemical C−H‐activating cross‐coupling reaction. Here, reagent‐ and metal‐free reaction conditions offer a sustainable electrochemical pathway that provides an attractive synthetic method to a broad variety of bi‐ and terarylic products based on thiophenes and phenols. This method is easy to conduct in an undivided cell, is scalable, and is inherently safe. The resulting products offer applications in electronic materials or as [OSO]2− pincer‐type ligands. 相似文献
12.
Yoshiyasu Ichikawa Yohei Matsukawa Mari Tamura Fumiyo Ohara Minoru Isobe Hiyoshizo Kotsuki 《化学:亚洲杂志》2006,1(5):717-723
A new method for the synthesis of urea‐linked disaccharides in aqueous media has been developed. The key feature of our approach is two strained Steyermark‐type gluco‐ and galactopyranosyl oxazolidinones. Each oxazolidinone is attached to a pyranose ring in a di‐equatorial trans‐annulation framework. Reaction of these oxazolidinones with 4‐aminohexopyranose in water proceeded smoothly to afford the urea‐tethered cellobiose and lactose analogues. The galactose‐type oxazolidinone proved to be more reactive than the glucose‐type, which is explained by the presence of an axial hydroxy group at C4 in the former. 相似文献
13.
Metal‐ and Oxidant‐Free Alkenyl C−H/Aromatic C−H Cross‐Coupling Using Electrochemically Generated Iodosulfonium Ions 下载免费PDF全文
Dr. Ryutaro Hayashi Dr. Akihiro Shimizu Jonathan A. Davies Yu Ishizaki Prof. Dr. Chris Willis Prof. Dr. Jun‐ichi Yoshida 《Angewandte Chemie (International ed. in English)》2018,57(39):12891-12895
A three‐step transformation consisting of 1) addition of electrochemically generated iodosulfonium ions to vinylarenes to give (1‐aryl‐2‐iodoethoxy)sulfonium ions, 2) nucleophilic substitution by subsequently added aromatic compounds to give 1,1‐diaryl‐2‐iodoethane, and 3) elimination of HI with a base to give 1,1‐diarylethenes was developed. The transformation serves as a powerful metal‐ and chemical‐oxidant‐free method for alkenyl C?H/aromatic C?H cross‐coupling. 相似文献
14.
Rhodium‐Catalyzed Direct Amination of Arenes with Nitrosobenzenes: A New Route to Diarylamines 下载免费PDF全文
Dr. Juanjuan Du Dr. Yaxi Yang Huijin Feng Dr. Yuanchao Li Dr. Bing Zhou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(19):5727-5731
A RhIII‐catalyzed addition of aryl C?H bonds to nitrosobenzenes, followed by cleavage of the resulting hydroxylamines in situ, has been reported. Different directing groups, such as N‐based heterocycles and ketoximes, can be used in this C?H amination process, providing valuable diarylamines in excellent yields. Most importantly, this process provides a new method for attaching arylamine groups to aromatic rings. 相似文献
15.
Evan R. Darzi Joyann S. Barber Neil K. Garg 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(28):9519-9524
We report a modular synthetic strategy for accessing heteroatom‐containing polycyclic aromatic hydrocarbons (PAHs). Our approach relies on the controlled generation of transient heterocyclic alkynes and arynes. The strained intermediates undergo in situ trapping with readily accessible oxadiazinones. Four sequential pericyclic reactions occur, namely two Diels–Alder/retro‐Diels–Alder sequences, which can be performed in a stepwise or one‐pot fashion to assemble four new carbon–carbon (C?C) bonds. These studies underscore how the use of heterocyclic strained intermediates can be harnessed for the preparation of new organic materials. 相似文献
16.
Mizuho Uryu Taito Hiraga Yoshito Koga Yutaro Saito Kei Murakami Kenichiro Itami 《Angewandte Chemie (International ed. in English)》2020,59(16):6551-6554
Polycyclic aromatic hydrocarbons (PAHs) represent an emerging class of π‐conjugated molecules in the area of optoelectronic devices and materials. Unprecedented synthetic routes to various PAHs from simple phenol derivatives by a palladium‐catalyzed annulative dimerization of phenylene triflate through twofold inter‐ and intramolecular C?H activation have been established. The initially formed partially fused PAHs can be smoothly transformed into a variety of fully fused PAHs by the Scholl reaction. Furthermore, the reactions of phenanthrene‐substituted aryl triflates proceeded regioselectively. The findings inspired the development of a rapid and efficient synthesis of polybenzoacene derivatives. This study not only allows transformation of phenyl triflates, but also discloses a new retrosynthetic strategy towards PAHs, especially polybenzoacenes. 相似文献
17.
Silver‐Catalyzed Cross‐Coupling of Isocyanides and Active Methylene Compounds by a Radical Process 下载免费PDF全文
Jianquan Liu Zhenhua Liu Dr. Peiqiu Liao Dr. Lin Zhang Prof. Tao Tu Prof. Xihe Bi 《Angewandte Chemie (International ed. in English)》2015,54(36):10618-10622
Isocyanides are versatile building blocks, and have been extensively exploited in C? H functionalization reactions. However, transition‐metal‐catalyzed direct C? H functionalization reactions with isocyanides suffer from over‐insertion of isocyanides. Reported herein is a radical coupling/isomerization strategy for the cross‐coupling of isocyanides with active methylene compounds through silver‐catalysis. The method solves the over‐insertion issue and affords a variety of otherwise difficult to synthesize β‐aminoenones and tricarbonylmethanes under base‐ and ligand‐free conditions. This report presents a new fundamental C? C bond‐forming reaction of two basic chemicals. 相似文献
18.
Chiral Counteranion Strategy for Asymmetric Oxidative C(sp3)H/C(sp3)H Coupling: Enantioselective α‐Allylation of Aldehydes with Terminal Alkenes 下载免费PDF全文
Pu‐Sheng Wang Hua‐Chen Lin Yu‐Jia Zhai Zhi‐Yong Han Prof. Dr. Liu‐Zhu Gong 《Angewandte Chemie (International ed. in English)》2014,53(45):12218-12221
The first enantioselective α‐allylation of aldehydes with terminal alkenes has been realized by combining asymmetric counteranion catalysis and palladium‐catalyzed allylic C? H activation. This method can tolerate a wide scope of α‐branched aromatic aldehydes and terminal alkenes, thus affording allylation products in high yields and with good to excellent levels of enantioselectivity. Importantly, the findings suggest a new strategy for the future creation of enantioselective C? H/C? H coupling reactions. 相似文献
19.
The carbon‐carbon (C—C) σ‐bonds construct the fundamental frameworks of organic molecules. The direct functionalization of C—C bonds represents one of the most efficient and step‐economical transformations in synthetic chemistry. The past few decades have witnessed the fast development of transition‐metal mediated C—C bond activation. In contrast, the radical‐promoted C—C bond cleavage has received relatively less attention. As the occurrence of ring strain significantly facilitates the fission of cyclic C—C bonds via radical approaches, the strain relief‐driven C—C bond activation mostly relies on the three‐ and four‐membered rings. The C—C activation of non‐strained molecules such as medium‐ or large‐sized rings and linear alkanes remains challenging. In this review, we will focus on the recent advances in radical‐mediated C—C bond activation of non‐strained molecules. Herein, the alkoxy‐ and iminyl‐radical triggered scission of non‐strained C—C bonds and C—C cleavage via the strategy of remote functional group migration is summarized. 相似文献
20.
Visible‐Light‐Induced Trifluoromethylation of Isonitrile‐Substituted Methylenecyclopropanes: Facile Access to 6‐(Trifluoromethyl)‐7,8‐Dihydrobenzo[k]phenanthridine Derivatives 下载免费PDF全文
Yu‐Chao Yuan Hou‐Lu Liu Xu‐Bo Hu Prof. Dr. Yin Wei Prof. Dr. Min Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(37):13059-13063
A new visible‐light‐induced trifluoromethylation of isonitrile‐substituted methylenecyclopropanes is developed. A range of substituted 6‐(trifluoromethyl)‐7,8‐dihydrobenzo[k]phenanthridine derivatives are readily furnished by this newly developed tandem reaction with moderate to good yields. This reaction allows the direct formation of two six‐membered rings and three new C?C bonds, including the C?CF3 bond, under visible light irradiation. 相似文献