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1.
A Visible‐Light‐Mediated Radical Smiles Rearrangement and its Application to the Synthesis of a Difluoro‐Substituted Spirocyclic ORL‐1 Antagonist 下载免费PDF全文
Dr. James J. Douglas Haley Albright Martin J. Sevrin Dr. Kevin P. Cole Prof. Corey R. J. Stephenson 《Angewandte Chemie (International ed. in English)》2015,54(49):14898-14902
A visible‐light‐mediated radical Smiles rearrangement has been developed to address the challenging synthesis of the gem‐difluoro group present in an opioid receptor‐like 1 (ORL‐1) antagonist that is currently in development for the treatment of depression and/or obesity. This method enables the direct and efficient introduction of the difluoroethanol motif into a range of aryl and heteroaryl systems, representing a new disconnection for the synthesis of this versatile moiety. When applied to the target compound, the photochemical step could be conducted on 15 g scale using industrially relevant [Ru(bpy)3Cl2] catalyst loadings of 0.01 mol %. This transformation is part of an overall five‐step route to the antagonist that compares favorably to the current synthetic sequence and demonstrates, in this specific case, a clear strategic benefit of photocatalysis. 相似文献
2.
Visible‐Light Photoredox Catalysis: Direct Synthesis of Sulfonated Oxindoles from N‐Arylacrylamides and Arylsulfinic Acids by Means of a Cascade C−S/C−C Formation Process 下载免费PDF全文
A novel photocatalytic synthesis of sulfonated oxindoles from N‐arylacrylamides and arylsulfinic acids was developed by means of a cascade C?S/C?C bond‐formation process. This method provides mild, efficient, and atom‐economical access to various sulfonated oxindoles in water. 相似文献
3.
Xiao‐Li Lai Xiao‐Min Shu Jinshuai Song Hai‐Chao Xu 《Angewandte Chemie (International ed. in English)》2020,59(26):10626-10632
Decarboxylative C?H functionalization reactions are highly attractive methods for forging carbon–carbon bonds considering their inherent step‐ and atom‐economical features and the pervasiveness of carboxylic acids and C?H bonds. An ideal approach to achieve these dehydrogenative transformations is through hydrogen evolution without using any chemical oxidants. However, effective couplings by decarboxylative carbon–carbon bond formation with proton reduction remain an unsolved challenge. Herein, we report an electrophotocatalytic approach that merges organic electrochemistry with photocatalysis to achieve the efficient direct decarboxylative C?H alkylation and carbamoylation of heteroaromatic compounds through hydrogen evolution. This electrophotocatalytic method, which combines the high efficiency and selectivity of photocatalysis in promoting decarboxylation with the superiority of electrochemistry in effecting proton reduction, enables the efficient coupling of a wide range of heteroaromatic bases with a variety of carboxylic acids and oxamic acids. Advantageously, this method is scalable to decagram amounts, and applicable to the late‐stage functionalization of drug molecules. 相似文献
4.
Smiles重排反应是有机合成中被广泛使用的人名反应之一, 是芳基化合物构建策略的一种独特方法. Smiles重排经历了近一个世纪的发展, 从传统的离子型Smiles反应、Truce-Smiles反应等, 发展到后期的自由基型Smiles重排, 这些进展极大地丰富了该反应在合成化学、材料化学等领域的应用. 近年来, 光催化氧化还原反应获得了广泛关注, 这一新颖催化模式高效利用光能, 能在温和的条件下产生自由基中间体, 实现了很多选择性反应. 过去的五年中, 化学家逐渐将这一催化模式应用到了Smiles重排反应中, 发展了一系列新颖、实用的合成方法. 本文对这些进展进行综述, 主要依据促进重排反应的自由基种类和成键类型进行分类. 相似文献
5.
《Angewandte Chemie (International ed. in English)》2017,56(35):10521-10524
Cleavage of unstrained C−C bonds under mild, redox‐neutral conditions represents a challenging endeavor which is accomplished here in the context of a flexible, visible‐light‐mediated, γ‐functionalization of amines. In situ generated C‐centered radicals are harvested in the presence of Michael acceptors, thiols and alkyl halides to efficiently form new C(sp3)−C(sp3), C(sp3)−H and C(sp3)−Br bonds, respectively. 相似文献
6.
Visible‐Light Photoredox‐Catalyzed C−H Difluoroalkylation of Hydrazones through an Aminyl Radical/Polar Mechanism 下载免费PDF全文
Pan Xu Guoqiang Wang Yuchen Zhu Weipeng Li Prof. Dr. Yixiang Cheng Prof. Dr. Shuhua Li Prof. Dr. Chengjian Zhu 《Angewandte Chemie (International ed. in English)》2016,55(8):2939-2943
An unprecedented visible‐light‐induced direct C?H bond difluoroalkylation of aldehyde‐derived hydrazones was developed. This reaction represents a new way to synthesize substituted hydrazones. The salient features of this reaction include difluorinated hydrazone synthesis rather than classical amine synthesis, extremely mild reaction conditions, high efficiency, wide substrate scope, ease in further transformations of the products, and one‐pot syntheses. Mechanistic analyses and theoretical calculations indicate that this reaction is enabled by a novel aminyl radical/polar crossover mechanism, with the aminyl radical being oxidized into the corresponding aminyl cation through a single electron transfer (SET) process. 相似文献
7.
Michal Majek Fabiana Filace Prof. Dr. Axel Jacobi von Wangelin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(12):4518-4522
The defunctionalization of anilines is an important strategy in aromatic‐substitution chemistry. Herein, we report on visible light mediated hydro‐ and deuterodediazonations in solutions of DMF. The mild reaction conditions (DMF, RT, no additives) tolerate various functional groups and allow the site‐specific introduction of D atoms to the arene. Mechanistic investigations indicate the participation of photoredox and radical chain pathways and competing abstraction of methyl and formyl hydrogen atoms from DMF. 相似文献
8.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(18):5183-5187
A novel and catalyst‐free multicomponent reaction with cyclic tertiary amines, electron‐deficient aryl halides or heteroaromatic halides, and Na2S enabled by facile C−N bond cleavage of the cyclic tertiary amines was developed. This direct and operationally simple method can be applied with a wide range of functional groups and provides an efficient and rapid approach to potentially drug‐like products containing amine, azaarene, thioether, or phenol ether functionalities in good to excellent yields. The utility of this method was demonstrated by the rapid synthesis of the analgesic ruzadolane. 相似文献
9.
Highly Chemoselective Iridium Photoredox and Nickel Catalysis for the Cross‐Coupling of Primary Aryl Amines with Aryl Halides 下载免费PDF全文
Dr. Martins S. Oderinde Natalie H. Jones Antoine Juneau Prof. Mathieu Frenette Dr. Brian Aquila Sharon Tentarelli Dr. Daniel W. Robbins Dr. Jeffrey W. Johannes 《Angewandte Chemie (International ed. in English)》2016,55(42):13219-13223
A visible‐light‐promoted iridium photoredox and nickel dual‐catalyzed cross‐coupling procedure for the formation C?N bonds has been developed. With this method, various aryl amines were chemoselectively cross‐coupled with electronically and sterically diverse aryl iodides and bromides to forge the corresponding C?N bonds, which are of high interest to the pharmaceutical industries. Aryl iodides were found to be a more efficient electrophilic coupling partner. The coupling reactions were carried out at room temperature without the rigorous exclusion of molecular oxygen, thus making this newly developed Ir‐photoredox/Ni dual‐catalyzed procedure very mild and operationally simple. 相似文献
10.
Cross‐Coupling of Organolithium with Ethers or Aryl Ammonium Salts by C−O or C−N Bond Cleavage 下载免费PDF全文
Ze‐Kun Yang Dong‐Yu Wang Hiroki Minami Hiroyuki Ogawa Takashi Ozaki Dr. Tatsuo Saito Dr. Kazunori Miyamoto Dr. Chao Wang Prof. Dr. Masanobu Uchiyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(44):15693-15699
Various aryl‐, alkenyl‐, and/or alkyllithium species reacted smoothly with aryl and/or benzyl ethers with cleavage of the inert C?O bond to afford cross‐coupled products, catalyzed by commercially available [Ni(cod)2] (cod=1,5‐cyclooctadiene) catalysts with N‐heterocyclic carbene (NHC) ligands. Furthermore, the coupling reaction between the aryllithium compounds and aryl ammonium salts proceeded under mild conditions with C?N bond cleavage in the presence of a [Pd(PPh3)2Cl2] catalyst. These methods enable selective sequential functionalizations of arenes having both C?N and C?O bonds in one pot. 相似文献
11.
Metal‐Free Dehydrogenation of N‐Heterocycles by Ternary h‐BCN Nanosheets with Visible Light 下载免费PDF全文
Dr. Meifang Zheng Jiale Shi Tao Yuan Prof. Xinchen Wang 《Angewandte Chemie (International ed. in English)》2018,57(19):5487-5491
An efficient metal‐free catalytic system has been developed based on hexagonal boron carbon nitride (h‐BCN) nanosheets for the dehydrogenation of N‐heterocycles with visible light; hydrogen gas is released in the process, and thus no proton acceptor is needed. This acceptorless dehydrogenation of hydroquinolines, hydroisoquinolines, and indolines to the corresponding aromatic N‐heterocycles occurred in excellent yield under visible‐light irradiation at ambient temperature. With h‐BCN as the photocatalyst and water as the solvent, this environmentally benign protocol shows broad substitution tolerance and high efficiency. 相似文献
12.
Melanie A. Short J. Miles Blackburn Prof. Dr. Jennifer L. Roizen 《Angewandte Chemie (International ed. in English)》2018,57(1):296-299
Masked alcohols are particularly appealing as directing groups because of the ubiquity of hydroxy groups in organic small molecules. Herein, we disclose a general strategy for aliphatic γ‐C(sp3)?H functionalization guided by a masked alcohol. Specifically, we determine that sulfamate ester derived nitrogen‐centered radicals mediate 1,6‐hydrogen‐atom transfer (HAT) processes to guide γ‐C(sp3)?H chlorination. This reaction proceeds through a light‐initiated radical chain‐propagation process and is capable of installing chlorine atoms at primary, secondary, and tertiary centers. 相似文献
13.
Metal‐mediated cleavage of aromatic C?C bonds has a range of potential synthetic applications: from direct coal liquefaction to synthesis of natural products. However, in contrast to the activation of aromatic C?H bonds, which has already been widely studied and exploited in diverse set of functionalization reactions, cleavage of aromatic C?C bonds remains Terra incognita. This Minireview summarizes the recent progress in this field and outlines key challenges to be overcome to develop synthetic methods based on this fundamental organometallic transformation. 相似文献
14.
Rhodium PCcarbeneP complexes 1‐L {L=PPh3, PPh2(C6F5)} react with isothiocyanate, carbodiimide and disulphide to enable C?S, C?N and S?S bond cleavage. The cleaved molecules are sequestered by the metal center and the pincer alkylidene linkage, forming η2‐coordinated sulfide or imide centered pincer complexes. When a C?S or S?S bond is cleaved, the resulting complexes can bridge two rhodium centers through sulphur forming dimeric complexes and eliminating a monodentate phosphine ligand. 相似文献
15.
A Visible Light Photocatalytic Cross‐Dehydrogenative Coupling/Dehydrogenation/6π‐Cyclization/Oxidation Cascade: Synthesis of 12‐Nitroindoloisoquinolines from 2‐Aryltetrahydroisoquinolines 下载免费PDF全文
Fabian Rusch Lisa‐Natascha Unkel Dirk Alpers Dr. Frank Hoffmann Prof. Dr. Malte Brasholz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(23):8336-8340
A visible light‐induced photocatalytic dehydrogenation/6π‐cyclization/oxidation cascade converts 1‐(nitromethyl)‐2‐aryl‐1,2,3,4‐tetrahydroisoquinolines into novel 12‐nitro‐substituted tetracyclic indolo[2,1‐a]isoquinoline derivatives. Various photocatalysts promote the reaction in the presence of air and a base, the most efficient being 1‐aminoanthraquinone in combination with K3PO4. Further, the 12‐nitroindoloisoquinoline products can be accessed directly from C1‐unfunctionalized 2‐aryl‐1,2,3,4‐tetrahydroisoquinolines by extending the one‐pot protocol with a foregoing photocatalytic cross‐dehydrogenative coupling reaction, resulting in a quadruple cascade transformation. 相似文献
16.
Pin Xu Peng‐Yu Chen Hai‐Chao Xu 《Angewandte Chemie (International ed. in English)》2020,59(34):14275-14280
Heteroarenes are structural motifs found in many bioactive compounds and functional materials. Dehydrogenative cross‐coupling of heteroarenes with aliphatic C?H bonds provides straightforward access to functionalized heteroarenes from readily available materials. Established methods employ stoichiometric chemical oxidants under conditions of heating or light irradiation. By merging electrochemistry and photochemistry, we have achieved efficient photoelectrochemical dehydrogenative cross‐coupling of heteroarenes and C(sp3)?H donors through H2 evolution, without the addition of metal catalysts or chemical oxidants. Mechanistically, the C(sp3)?H donor is converted to a nucleophilic carbon radical through H‐atom transfer with chlorine atom, which is produced by light irradiation of anodically generated Cl2 from Cl?. The carbon radical then undergoes radical substitution to the heteroarene to afford alkylated heteroarene products. 相似文献
17.
Frontispiece: A Visible Light Photocatalytic Cross‐Dehydrogenative Coupling/Dehydrogenation/6π‐Cyclization/Oxidation Cascade: Synthesis of 12‐Nitroindoloisoquinolines from 2‐Aryltetrahydroisoquinolines 下载免费PDF全文
Fabian Rusch Lisa‐Natascha Unkel Dirk Alpers Dr. Frank Hoffmann Prof. Dr. Malte Brasholz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(23)
18.
19.
Mild and Low‐Pressure fac‐Ir(ppy)3‐Mediated Radical Aminocarbonylation of Unactivated Alkyl Iodides through Visible‐Light Photoredox Catalysis 下载免费PDF全文
Dr. Shiao Y. Chow Marc Y. Stevens Linda Åkerbladh Sara Bergman Prof. Dr. Luke R. Odell 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(27):9155-9161
A novel, mild and facile preparation of alkyl amides from unactivated alkyl iodides employing a fac‐Ir(ppy)3‐catalyzed radical aminocarbonylation protocol has been developed. Using a two‐chambered system, alkyl iodides, fac‐Ir(ppy)3, amines, reductants, and CO gas (released ex situ from Mo(CO)6), were combined and subjected to an initial radical reductive dehalogenation generating alkyl radicals, and a subsequent aminocarbonylation with amines affording a wide range of alkyl amides in moderate to excellent yields. 相似文献