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1.
Highly Efficient CH Hydroxylation of Carbonyl Compounds with Oxygen under Mild Conditions 下载免费PDF全文
A transition‐metal‐free Cs2CO3‐catalyzed α‐hydroxylation of carbonyl compounds with O2 as the oxygen source is described. This reaction provides an efficient approach to tertiary α‐hydroxycarbonyl compounds, which are highly valued chemicals and widely used in the chemical and pharmaceutical industry. The simple conditions and the use of molecular oxygen as both the oxidant and the oxygen source make this protocol very environmentally friendly and practical. This transformation is highly efficient and highly selective for tertiary C(sp3)? H bond cleavage. 相似文献
2.
Direct Synthesis of 1,4‐Diols from Alkenes by Iron‐Catalyzed Aerobic Hydration and CH Hydroxylation 下载免费PDF全文
Takuma Hashimoto Daisuke Hirose Dr. Tsuyoshi Taniguchi 《Angewandte Chemie (International ed. in English)》2014,53(10):2730-2734
Various 1,4‐diols are easily accessible from alkenes through iron‐catalyzed aerobic hydration. The reaction system consists of a user‐friendly iron phthalocyanine complex, sodium borohydride, and molecular oxygen. Furthermore, the effect of additional ligands on the iron complex was examined for a model reaction. The second hydroxy group is installed by direct C(sp3)? H oxygenation, which is based on a [1,5] hydrogen shift process of a transient alkoxy radical that is formed by formal hydration of the olefin. 相似文献
3.
Intramolecular Redox‐Mannich Reactions: Facile Access to the Tetrahydroprotoberberine Core 下载免费PDF全文
Longle Ma Prof. Dr. Daniel Seidel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(37):12908-12913
Cyclic amines such as pyrrolidine undergo redox‐annulations with 2‐formylaryl malonates. Concurrent oxidative amine α‐C?H bond functionalization and reductive N‐alkylation render this transformation redox‐neutral. This redox‐Mannich process provides regioisomers of classic Reinhoudt reaction products as an entry to the tetrahydroprotoberberine core, enabling the synthesis of (±)‐thalictricavine and its epimer. An unusually mild amine‐promoted dealkoxycarbonylation was discovered in the course of these studies. 相似文献
4.
Dr. Amanda Sølvhøj Andreas Ahlburg Prof. Dr. Robert Madsen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(45):16272-16279
A new coupling reaction has been developed in which β‐bromostyrenes react with ethers and tertiary amines to introduce the styryl group in the α‐position. The transformation is mediated by Me2Zn/O2 with 10 % MnCl2 and is believed to proceed by a radical addition–elimination mechanism. The ether and the amine are employed as solvent and the coupling takes place through the most stable α radical for unsymmetrical substrates. The products are obtained in moderate to good yields as the pure E isomers. The coupling can be achieved with a range of smaller cyclic and acyclic ethers/amines as well as various substituted β‐bromostyrenes. 相似文献
5.
Michael C. Haibach Prof. Dr. Daniel Seidel 《Angewandte Chemie (International ed. in English)》2014,53(20):5010-5036
Known for over a century, reactions that involve intramolecular hydride‐transfer events have experienced a recent resurgence. Undoubtedly responsible for the increased interest in this research area is the realization that hydride shifts represent an attractive avenue for C? H bond functionalization. The redox‐neutral nature of these complexity‐enhancing transformations makes them ideal for sustainable reaction development. This Review summarizes recent progress in this field while highlighting key historical contributions. 相似文献
6.
Stacey L. McDonald Charles E. Hendrick Prof. Dr. Qiu Wang 《Angewandte Chemie (International ed. in English)》2014,53(18):4667-4670
Direct amination of heteroarenes and arenes has been achieved in a one‐pot C? H zincation/copper‐catalyzed electrophilic amination procedure. This amination method provides an efficient and rapid approach to access a diverse range of heteroaromatic and aromatic amines including those previously inaccessible using C? H amination methods. The mild reaction conditions and good functional‐group compatibility demonstrate its great potential for the synthesis of important and complex amines. 相似文献
7.
Sarah E. Walker Dr. James A. Jordan‐Hore Dr. David G. Johnson Prof. Dr. Stuart A. Macgregor Dr. Ai‐Lan Lee 《Angewandte Chemie (International ed. in English)》2014,53(50):13876-13879
A direct Pd‐catalyzed C? H functionalization of benzoquinone (BQ) can be controlled to give either mono‐ or disubstituted BQ, including the installation of two different groups in a one‐pot procedure. BQ can now be directly functionalized with aryl, heteroaryl, cycloalkyl, and cycloalkene groups and, moreover, the reaction is conducted in environmentally benign water or acetone as solvents. 相似文献
8.
Manuel Nappi Dr. Giulia Bergonzini Prof. Dr. Paolo Melchiorre 《Angewandte Chemie (International ed. in English)》2014,53(19):4921-4925
We report here an operationally simple protocol for the direct aromatic perfluoroalkylation and trifluoromethylation of α‐cyano arylacetates. This metal‐free approach, which occurs at ambient temperature and under visible‐light irradiation, is driven by the photochemical activity of electron donor–acceptor (EDA) complexes, formed in situ by the interaction of transiently generated enolates and perfluoroalkyl iodides. Preliminary mechanistic studies are reported. 相似文献
9.
Direct α‐Arylation of Ethers through the Combination of Photoredox‐Mediated CH Functionalization and the Minisci Reaction 下载免费PDF全文
Dr. Jian Jin Prof. Dr. David W. C. MacMillan 《Angewandte Chemie (International ed. in English)》2015,54(5):1565-1569
The direct α‐arylation of cyclic and acyclic ethers with heteroarenes has been accomplished through the design of a photoredox‐mediated C? H functionalization pathway. Transiently generated α‐oxyalkyl radicals, produced from a variety of widely available ethers through hydrogen atom transfer (HAT), were coupled with a range of electron‐deficient heteroarenes in a Minisci‐type mechanism. This mild, visible‐light‐driven protocol allows direct access to medicinal pharmacophores of broad utility using feedstock substrates and a commercial photocatalyst. 相似文献
10.
Dr. Lin He Dr. Kishore Natte Dr. Jabor Rabeah Dr. Christoph Taeschler Dr. Helfried Neumann Prof. Dr. Angelika Brückner Prof. Dr. Matthias Beller 《Angewandte Chemie (International ed. in English)》2015,54(14):4320-4324
Fluorinated organic compounds are gaining increasing interest for life science applications. The replacement of hydrogen in arenes or heteroarenes by a perfluoroalkyl group has a profound influence on the physical and biological properties of such building blocks. Here, an operationally simple protocol for the direct C? H perfluoroalkylation of (hetero)arenes with RfI or RfBr has been developed, using a robust supported platinum catalyst. The ready availability of the starting materials, the excellent substrate tolerance, and the reusability of the catalyst make this method attractive for the synthesis of a variety of perfluoroalkyl‐substituted aromatic compounds. Preliminary mechanistic studies revealed the formation of radicals to be crucial in the reaction system. 相似文献
11.
Practical Metal‐Free C(sp3)H Functionalization: Construction of Structurally Diverse α‐Substituted N‐Benzyl and N‐Allyl Carbamates 下载免费PDF全文
Zhiyu Xie Prof. Lei Liu Wenfang Chen Hongbo Zheng Qingqing Xu Prof. Huiqing Yuan Prof. Hongxiang Lou 《Angewandte Chemie (International ed. in English)》2014,53(15):3904-3908
Described is a practical and universal C? H functionalization of readily removable N‐benzyl and N‐allyl carbamates, with a wide range of nucleophiles at ambient temperature promoted by Ph3CClO4. The metal‐free reaction has an excellent functional‐group tolerance, and displays a broad scope with respect to both N‐carbamates and nucleophile partners (a variety of organoboranes and C? H compounds). The synthetic utility in target‐ as well as diversity‐oriented syntheses is demonstrated. 相似文献
12.
A Convenient Synthesis of N‐Aryl Benzamides by Rhodium‐Catalyzed ortho‐Amidation and Decarboxylation of Benzoic Acids 下载免费PDF全文
Dr. Xian‐Ying Shi Ke‐Yan Liu Juan Fan Xue‐Fen Dong Prof. Dr. Jun‐Fa Wei Prof. Dr. Chao‐Jun Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(5):1900-1903
The rhodium‐catalyzed amidation of substituted benzoic acids with isocyanates by directed C?H functionalization followed by decarboxylation to afford the corresponding N‐aryl benzamides is demonstrated, in which the carboxylate serves as a unique, removable directing group. Notably, less common meta‐substituted N‐aryl benzamides are generated readily from more accessible para‐ or ortho‐substituted groups by employing this strategy. 相似文献
13.
Boryl (Hetero)aryne Precursors as Versatile Arylation Reagents: Synthesis through CH Activation and Orthogonal Reactivity 下载免费PDF全文
Dr. Emilien Demory Karthik Devaraj Dr. Andreas Orthaber Dr. Paul J. Gates Dr. Lukasz T. Pilarski 《Angewandte Chemie (International ed. in English)》2015,54(40):11765-11769
(Pinacolato)boryl ortho‐silyl(hetero)aryl triflates are presented as a new class of building blocks for arylation. They demonstrate unique versatility by delivering boronate or (hetero)aryne reactivity chemoselectively in a broad range of transformations. This approach enables the unprecedented postfunctionalization of fluoride‐activated (hetero)aryne precursors, for example, as substrates in transition‐metal catalysis, and offers valuable new possibilities for aryl boronate postfunctionalization without the use of specialized protecting groups. 相似文献
14.
Electrochemical Intramolecular CH Amination: Synthesis of Benzoxazoles and Benzothiazoles 下载免费PDF全文
Tatsuya Morofuji Dr. Akihiro Shimizu Prof. Dr. Jun‐ichi Yoshida 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(8):3211-3214
A new method for metal‐free intramolecular C?H amination has been developed. Electrochemical oxidation of 2‐pyrimidyloxybenzenes and 2‐pyrimidylthiobenzenes, which can be easily prepared from phenols and thiophenols, respectively, followed by the treatment of the resulting pyrimidinium ions with piperidine gives 2‐aminobenzoxazoles and 2‐aminobenzothiazoles, respectively. 相似文献
15.
16.
Dr. Xuesong Wu Yan Zhao Dr. Guangwu Zhang Prof. Dr. Haibo Ge 《Angewandte Chemie (International ed. in English)》2014,53(14):3706-3710
The intramolecular dehydrogenative amidation of aliphatic amides, directed by a bidentate ligand, was developed using a copper‐catalyzed sp3 C? H bond functionalization process. The reaction favors predominantly the C? H bonds of β‐methyl groups over the unactivated methylene C? H bonds. Moreover, a preference for activating sp3 C? H bonds of β‐methyl groups, via a five‐membered ring intermediate, over the aromatic sp2 C? H bonds was also observed in the cyclometalation step. Additionally, sp3 C? H bonds of unactivated secondary sp3 C? H bonds could be functionalized by favoring the ring carbon atoms over the linear carbon atoms. 相似文献
17.
Dr. Michael Parmentier Dr. Thomas Hartung Prof. Dr. Andreas Pfaltz Dr. Dieter Muri 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(36):11496-11504
Hydrogen isotope exchange (HIE) is one of the most attractive tools for the introduction of deuterium or tritium to an organic compound. Herein, iridium complexes with N,P‐ligands, highly active catalysts for asymmetric double bond reductions, have been tested for their HIE capabilities. Electron‐rich ligands, containing dicyclohexylphosphines or phosphinites, have been identified as excellent ligands for efficient deuterium incorporation. Substrates with strong directing groups, that is, pyridines, ketones, and amides, as well as weak ligating units, such as, nitro, sulfones, and sulfonamides, could be labeled efficiently. With the addition of tris(pentafluorophenyl) borane to the reaction mixture, also highly deactivating nitrile substituents were well tolerated in the reaction. Based on the excellent results obtained with the chiral ThrePhox ligand, a structurally simpler, achiral ligand was developed. The iridium complex containing this ligand, proved to be a powerful catalyst for HIE reactions. 相似文献
18.
Palladium(II)‐Catalyzed meta‐CH Olefination: Constructing Multisubstituted Arenes through Homo‐Diolefination and Sequential Hetero‐Diolefination 下载免费PDF全文
Dr. Milan Bera Arun Maji Dr. Santosh K. Sahoo Prof. Debabrata Maiti 《Angewandte Chemie (International ed. in English)》2015,54(29):8515-8519
Divinylbenzene derivatives represent an important class of molecular building blocks in organic chemistry and materials science. Reported herein is the palladium‐catalyzed synthesis of divinylbenzenes by meta‐C? H olefination of sulfone‐based arenes. Successful sequential olefinations in a position‐selective manner provided a novel route for the synthesis of hetero‐dialkenylated products, which are difficult to access using conventional methods. Additionally, 1,3,5‐trialkenylated compounds can be generated upon successful removal of the directing group. 相似文献
19.
Catalytic 1,4‐Rhodium(III) Migration Enables 1,3‐Enynes to Function as One‐Carbon Oxidative Annulation Partners in CH Functionalizations 下载免费PDF全文
Dr. David J. Burns Prof. Hon Wai Lam 《Angewandte Chemie (International ed. in English)》2014,53(37):9931-9935
1,3‐Enynes containing allylic hydrogens cis to the alkyne are shown to act as one‐carbon partners, rather than two‐carbon partners, in various rhodium‐catalyzed oxidative annulations. The mechanism of these unexpected transformations is proposed to occur through double C? H activation, involving a hitherto rare example of the 1,4‐migration of a RhIII species. This phenomenon is general across a variety of substrates, and provides a diverse range of heterocyclic products. 相似文献
20.
Cytochrome P450 Catalyzed Oxidative Hydroxylation of Achiral Organic Compounds with Simultaneous Creation of Two Chirality Centers in a Single CH Activation Step 下载免费PDF全文
Dr. Gheorghe‐Doru Roiban Dr. Rubén Agudo Prof. Dr. Manfred T. Reetz 《Angewandte Chemie (International ed. in English)》2014,53(33):8659-8663
Regio‐ and stereoselective oxidative hydroxylation of achiral or chiral organic compounds mediated by synthetic reagents, catalysts, or enzymes generally leads to the formation of one new chiral center that appears in the respective enantiomeric or diastereomeric alcohols. By contrast, when subjecting appropriate achiral compounds to this type of C? H activation, the simultaneous creation of two chiral centers with a defined relative and absolute configuration may result, provided that control of the regio‐, diastereo‐, and enantioselectivity is ensured. The present study demonstrates that such control is possible by using wild type or mutant forms of the monooxygenase cytochrome P450 BM3 as catalysts in the oxidative hydroxylation of methylcyclohexane and seven other monosubstituted cyclohexane derivatives. 相似文献