- The Photocatalyzed Aza-Henry Reaction of N-Aryltetrahydroisoquinolines: Comprehensive Mechanism, H?- versus H+-Abstraction, and Background Reactions
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The cross-dehydrogenative coupling (CDC) reaction of N-aryltetrahydroisoquinolines (THIQ) is one of the most exploited photocatalytic transformation and a test reaction for an exceptional variety of catalysts. However, its mechanism remained unclear conce
- Bartling, Hanna,Eisenhofer, Anna,Konig, Burkhard,Gschwind, Ruth M.
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- CuBr-catalyzed direct indolation of tetrahydroisoquinolines via cross-dehydrogenative coupling between sp3 C-H and sp2 C-H bonds
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A novel and efficient C-C bond formation method was developed via the cross-dehydrogenative coupling (CDC) reaction of indoles and tetrahydroisoquinolines catalyzed by copper bromide in the presence of an oxidizing reagent, tert-BuOOH. The CDC reaction provides a simple and efficient catalytic method to construct indolyl tetrahydroisoquinolines via a combination of sp3 C-H bond and sp2 C-H bond followed by C-C bond formation. Copyright
- Li, Zhiping,Li, Chao-Jun
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- Direct Near Infrared Light–Activatable Phthalocyanine Catalysts
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The high penetration of near-infrared (NIR) light makes it effective for use in selective reactions under light-shielded conditions, such as in sealed reactors and deep tissues. Herein, we report the development of phthalocyanine catalysts directly activa
- Katsurayama, Yoshino,Ikabata, Yasuhiro,Maeda, Hajime,Segi, Masahito,Nakai, Hiromi,Furuyama, Taniyuki
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supporting information
(2021/12/22)
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- Direct Arylation of Distal and Proximal C(sp3)-H Bonds of t-Amines with Aryl Diazonium Tetrafluoroborates via Photoredox Catalysis
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A visible light-mediated arylation protocol for t-amines has been reported through the coupling of γ- and α-amino alkyl radicals with different aryl diazonium salts using Ru(bpy)3Cl2·6H2O as a photocatalyst. Structurally different 9-aryl-9,10-dihydroacridine, 1-aryl tetrahydroisoquinoline, hexahydropyrrolo[2,1-a]isoquinoline, and hexahydro-2H-pyrido[2,1-a]isoquinoline frameworks with different substitution patterns have been synthesized in good yield using this methodology.
- Mondal, Pradip Kumar,Tiwari, Sandip Kumar,Singh, Pushpendra,Pandey, Ganesh
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p. 17184 - 17196
(2021/12/02)
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- Effect of Precatalyst Oxidation State in C-N Cross-Couplings with 2-Phosphinoimidazole-Derived Bimetallic Pd(I) and Pd(II) Complexes
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We report the catalytic activity of two phosphinoimidazole-derived bimetallic palladium complexes in Pd-catalyzed amination reactions. Our studies demonstrate that the starting oxidation state (Pd(I) or Pd(II)) of the dimeric complex has a significant effect on the efficiency of the catalytic reaction. The corresponding Pd(I) complex shows higher reactivity in Buchwald-Hartwig aminations, while the Pd(II) complex is much more reactive in carbonylative amination reactions. These new dimeric palladium complexes provide good to excellent reactivity and yields in the amination reactions tested.
- Martinez, Erin E.,Moreno, Mariur Rodriguez,Barksdale, Caleb A.,Michaelis, David J.
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p. 2763 - 2767
(2021/08/27)
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- Electrocatalytic C(sp3)-H/C(sp)-H cross-coupling in continuous flow through TEMPO/copper relay catalysis
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Electrocatalytic dehydrogenative C(sp3)-H/C(sp)-H cross-coupling of tetrahydroisoquinolines with terminal alkynes has been achieved in a continuous-flow microreactor through 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO)/copper relay catalysis. The reaction
- Guo, Bin,Xu, Hai-Chao
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supporting information
p. 2650 - 2656
(2021/11/30)
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- Photoredox/cobaloxime co-catalyzed allylation of amines and sulfonyl hydrazines with olefins to access α-allylic amines and allylic sulfones
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Herein, we reported a dual-catalytic platform for the allylation of amines and sulfonyl hydrazines with olefins to selectively access α-allylic amines and allylic sulfones in good yields by combining photoredox catalysis and cobaloxime catalysis. This strategy avoided the use of a stoichiometric amount of terminal oxidant and the use of pre-functionalized allylic precursors, representing a green and ideal atom- & step-economical process. Good substrate scope and gram-scale synthesis demonstrated the utility of this protocol. Mechanistic studies revealed that a radical process is probably involved in this reaction.
- Tong, Qing-Xiao,Xu, Hui,Zhang, Hong,Zhong, Jian-Ji
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supporting information
p. 8227 - 8231
(2021/10/12)
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- Cross-Dehydrogenative Coupling of Tetrahydroisoquinolines and 2-Fluoro-1,3-benzodithiole-1,1,3,3-tetraoxide: A New Synthetic Approach to α-Monofluoromethyl Tertiary Amines
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A cross dehydrogenative coupling reaction of tetrahydroisoquinolines with 2-fluoro-1,3-benzodithiole-1,1,3,3-tetraoxide had been developed. CuBr/TBHP was identified as the best catalyst and oxidant. A variety of coupling products were obtained with good t
- Chen, Yuan,Huang, Bao-qin,Yan, Ming,Zhang, Xue-jing
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supporting information
p. 3015 - 3022
(2021/07/22)
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- Porphyrin-Catalyzed Oxidation of N-Substituted Tetrahydroisoquinolines to Dihydroisoquinolones
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A visible-light-induced direct α-oxygenation of N-substituted 1,2,3,4-Tetrahydroisoquinoline derivatives has been successfully developed. Tetraphenylporphyrinatozinc(II) has been identified as an effective and inexpensive photocatalyst for this transformation with a wide range of substrates. This protocol provides a convenient route to the desired products in moderate to good yields at room temperature under air.
- Li, Ao,Pan, Bin,Mu, Chao,Wang, Na,Li, Yu-Long,Ouyang, Qin
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supporting information
p. 679 - 684
(2021/02/01)
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- An oxidant- And catalyst-free electrooxidative cross-coupling approach to 3-tetrahydroisoquinoline substituted coumarins
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A direct electrooxidative cross-dehydrogenative-coupling (CDC) reaction betweenN-aryl-tetrahydroisoquinolines and 4-hydroxycoumarins has been realized. This protocol provides a green, mild and fast method to construct 3-tetrahydroisoquinoline substituted coumarins in the absence of any catalysts and exogenous oxidants. A variety ofN-aryl-tetrahydroisoquinolines and 4-hydroxycoumarins are compatible with this transformation to give the corresponding products in moderate to excellent yields. Moreover, the results of control experiments, cyclic voltammetry experiments, and density functional theory (DFT) calculations indicated that the electrooxidative CDC reaction might involve both radical addition and nucleophilic addition processes.
- Kong, Yanyan,Kim, Jung Keun,Li, Yabo,Zhang, Jianye,Huang, Mengmeng,Wu, Yangjie
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supporting information
p. 1274 - 1279
(2021/02/26)
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- Covalent Organic Frameworks toward Diverse Photocatalytic Aerobic Oxidations
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Photoactive two-dimensional covalent organic frameworks (2D-COFs) have become promising heterogenous photocatalysts in visible-light-driven organic transformations. Herein, a visible-light-driven selective aerobic oxidation of various small organic molecules by using 2D-COFs as the photocatalyst was developed. In this protocol, due to the remarkable photocatalytic capability of hydrazone-based 2D-COF-1 on molecular oxygen activation, a wide range of amides, quinolones, heterocyclic compounds, and sulfoxides were obtained with high efficiency and excellent functional group tolerance under very mild reaction conditions. Furthermore, benefiting from the inherent advantage of heterogenous photocatalysis, prominent sustainability and easy photocatalyst recyclability, a drug molecule (modafinil) and an oxidized mustard gas simulant (2-chloroethyl ethyl sulfoxide) were selectively and easily obtained in scale-up reactions. Mechanistic investigations were conducted using radical quenching experiments and in situ ESR spectroscopy, all corroborating the proposed role of 2D-COF-1 in photocatalytic cycle.
- Liu, Shuyang,Tian, Miao,Bu, Xiubin,Tian, Hua,Yang, Xiaobo
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supporting information
p. 7738 - 7744
(2021/05/07)
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- Visible-light induced Cross-Dehydrogenative-Coupling (CDC) reactions of N-aryl tetrahydroisoquinolines under aerobic conditions
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A visible-light induced cross-dehydrogenative-coupling (CDC) reaction of N-aryl tetrahydroisoquinolines was developed under mild aerobic conditions. This protocol proceeded smoothly with a large range of nucleophiles (nitroalkane, dimethyl phosphite, dimethyl malonate, N-methyl indole, TMSCN) under metal-free conditions and an oxygen atmosphere, forming a new C–C bond. Visible-light played a significant acceleration effect in this reaction.
- Lin, Chao,Li, Peiwu,Wang, Lin
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supporting information
(2021/05/19)
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- A Short Approach to N -Aryl-1,2,3,4-tetrahydroisoquinolines from N -(2-Bromobenzyl)anilines via a Reductive Amination/Palladium-Catalyzed Ethoxyvinylation/Reductive N -Alkylation Sequence
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N -Aryl-1,2,3,4-tetrahydroisoquinolines are obtained via a convenient and short protocol with a broad range of substituents on both aromatic rings and high functional group tolerance. Starting from readily available ortho -brominated aromatic aldehydes and primary aromatic amines, condensation of these building blocks under reductive conditions gives N -aryl 2-bromobenzylamines. The C-3/C-4-unit of the tetrahydroisoquinoline is introduced using commercially available 2-ethoxyvinyl pinacolboronate under Suzuki conditions. Finally, the obtained crude ortho -ethoxyvinyl benzylamines are cyclized via an intramolecular reductive amination using the combination of triethylsilane/TFA to give the desired N -aryl-1,2,3,4-tetrahydroisoquinolines.
- Glas, Carina,Wirawan, Ricky,Bracher, Franz
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p. 1943 - 1954
(2021/01/18)
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- Nickel-Catalyzed Amination of Aryl Chlorides with Amides
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A nickel-catalyzed amination of aryl chlorides with diverse amides via C-N bond cleavage has been realized under mild conditions. A broad substrate scope with excellent functional group tolerance at a low catalyst loading makes the protocol powerful for synthesizing various aromatic amines. The aryl chlorides could selectively couple to the amino fragments rather than the carbonyl moieties of amides. Our protocol complements the conventional amination of aryl chlorides and expands the usage of inactive amides.
- Li, Jinpeng,Huang, Changyu,Wen, Daheng,Zheng, Qingshu,Tu, Bo,Tu, Tao
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supporting information
p. 687 - 691
(2021/01/09)
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- N-Phenyl-1,2,3,4-tetrahydroisoquinoline: An Alternative Scaffold for the Design of 17β-Hydroxysteroid Dehydrogenase 1 Inhibitors
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17β-Hydroxysteroid dehydrogenases catalyse interconversion at the C17 position between oxidized and reduced forms of steroidal nuclear receptor ligands. The type 1 enzyme, expressed in malignant cells, catalyses reduction of the less-active estrone to estradiol, and inhibitors have therapeutic potential in estrogen-dependent diseases such as breast and ovarian cancers and in endometriosis. Synthetic decoration of the nonsteroidal N-phenyl-1,2,3,4-tetrahydroisoquinoline (THIQ) template was pursued by using Pomeranz-Fritsch-Bobbitt, Pictet-Spengler and Bischler-Napieralski approaches to explore the viability of this scaffold as a steroid mimic. Derivatives were evaluated biologically in vitro as type 1 enzyme inhibitors in a bacterial cell homogenate as source of recombinant protein. Structure-activity relationships are discussed. THIQs possessing a 6-hydroxy group, lipophilic substitutions at the 1- or 4-positions in combination with N-4′-chlorophenyl substitution were most favourable for activity. Of these, one compound had an IC50 of ca. 350 nM as a racemate, testifying to the applicability of this novel approach.
- Mottinelli, Marco,Sinreih, Ma?a,Ri?ner, Tea L.,Leese, Mathew P.,Potter, Barry V. L.
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p. 259 - 291
(2020/12/07)
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- Molecular Oxygen-Mediated Radical Alkylation of C(sp3)-H Bonds with Boronic Acids
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A direct and site-specific alkylation of (sp3)C-H bond with aliphatic boronic acid was achieved. By simply heating glycinates and amines together with alkylboronic acids under an oxygen atmosphere, a variety of unnatural α-amino acids and peptides could b
- Yang, Le,Qiu, Zhihong,Wu, Jintao,Zhao, Jianyou,Shen, Tong,Huang, Xuan,Liu, Zhong-Quan
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supporting information
p. 3207 - 3210
(2021/05/04)
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- Tunable Redox Potential Photocatalyst: Aggregates of 2,3-Dicyanopyrazino Phenanthrene Derivatives for the Visible-Light-Induced α-Allylation of Amines
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This work highlights the tunable redox potential of 6,11-dibromo-2,3-dicyanopyrazinophenanthrene (DCPP3) aggregates, which can be formed through physical π-πstacking interactions with other DCPP3 monomers. Electrochemical and scanning electron microscopy showed that the reduction potential of [DCPP3]n aggregates could be increased by decreasing their size. The size of [DCPP3]n aggregates could be regulated by controlling the concentration of DCPP3 in an organic solvent. As such, a fundamental understanding of this tunable redox potential is essential for developing new materials for photocatalytic applications. The [DCPP3]n aggregates as a visible-light photocatalyst in combination with Pd catalysts in the visible-light-induced α-allylation of amines were used. This [DCPP3]n photocatalyst exhibits excellent photo- and electrochemical properties, including a remarkable visible-light absorption, long excited-state lifetime (16.6 μs), good triplet quantum yield (0.538), and high reduction potential (Ered([DCPP3]n/[DCPP3]n-) > -1.8 V vs SCE).
- Bao, Ming,He, Min,Wang, Yi,Yu, Xiaoqiang
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p. 14720 - 14731
(2021/11/16)
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- Solvent-driven C(sp3)-H thiocarbonylation of benzylamine derivatives under catalyst-free conditions
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Due to the particularity of the thiocarbonyl group (C S bond), only limited C(sp3)-H thiocarbonylation methods, especially efficient and convenient methods, have been developed for the synthesis of thioamides. Inspired by the “solvent-specifici
- Zhou, Jingwei,Wang, Songping,Lu, Yaoming,Li, Lamei,Duan, Wentao,Wang, Qi,Wang, Hong,Wei, Wentao
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supporting information
p. 767 - 773
(2021/02/09)
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- Phenazine Radical Cations as Efficient Homogeneous and Heterogeneous Catalysts for the Cross-Dehydrogenative Aza-Henry Reaction
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The redox activity of molecular phenazine catalysts has been previously exploited for aerobic oxidative amine homo- and cross-coupling reactions. In this contribution, we have extended the reaction scope of this novel type of organocatalyst and used them in the cross-dehydrogenative aza-Henry coupling of isoquinolines with nitromethane under aerobic conditions. Additionally, we have designed and prepared a novel porous organic polymer by cross-linking of tetrakis(4-bromophenyl)silane and dihydrophenazine through Pd-catalyzed Buchwald-Hartwig cross-coupling. This new type of heterogeneous catalyst, apart from being robust and easily reusable, also showed outstanding catalytic activities and improved selectivity compared to its molecular counterpart. A plausible reaction mechanism was proposed based on spectroscopic and kinetic measurements.
- Unglaube, Felix,Hünem?rder, Paul,Guo, Xuewen,Chen, Zixu,Wang, Dengxu,Mejía, Esteban
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- Photocatalyst- And transition-metal-free α-allylation of: N -aryl tetrahydroisoquinolines mediated by visible light
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A convenient and efficient α-allylation of N-aryl tetrahydroisoquinolines has been achieved. This transformation can be realized under only visible light irradiation without the aid of transition metals or photocatalysts. The mechanism involves a novel in situ-generated electron-donor-acceptor (EDA) complex between the N-aryl tetrahydroisoquinolines and an allyl or a benzyl bromide. Irradiation with purple light triggered single-electron transfer (SET) from the N-aryl tetrahydroisoquinolines to the allyl or benzyl bromide of the EDA complex, inducing the formation of the corresponding allyl or benzyl radical and the subsequent radical-radical coupling. This approach represents the first example of a photocatalyst- and transition-metal-free α-allylic and benzylic functionalization of N-aryl tetrahydroisoquinolines.
- Li, Zhuohua,Ma, Pengju,Tan, Yongzhu,Liu, Yufei,Gao, Min,Zhang, Yujun,Yang, Bo,Huang, Xuan,Gao, Yuan,Zhang, Junmin
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supporting information
p. 646 - 650
(2020/02/21)
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- Tracing and elucidating visible-light mediated oxidation and C-H functionalization of amines using mass spectrometry
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The co-existing mechanism of visible light mediated direct oxidation and C-H functionalization of amines was investigated by capturing all the intermediates using online mass spectrometry. The two-step dehydrogenation of amine involving a proton coupled electron transfer (PCET) process was revealed for the first time.
- Ai, Wanpeng,Gao, Yunpeng,Xue, Jinjuan,Liu, Xiaoyun,Liu, Huwei,Wang, Jianbo,Bai, Yu
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supporting information
p. 2163 - 2166
(2020/02/26)
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- Organic/Inorganic Heterogeneous Silica-Based Photoredox Catalyst for Aza-Henry Reactions
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The transformation of light into chemical energy is a leitmotiv in the development of sustainable and environmentally concerned chemical processes. Chemists invented original concepts to address this purpose, like photoredox catalysis, which became a wond
- Cormier, Morgan,Daou, T. Jean,Goddard, Jean-Philippe,Lebeau, Bénédicte,Neunlist, Serge,Soria-Castro, Silvia M.
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supporting information
p. 1572 - 1578
(2019/11/28)
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- CuII/TEMPO-Catalyzed Enantioselective C(sp3)–H Alkynylation of Tertiary Cyclic Amines through Shono-Type Oxidation
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A novel strategy for asymmetric Shono-type oxidative cross-coupling has been developed by merging copper catalysis and electrochemistry, affording C1-alkynylated tetrahydroisoquinolines with good to excellent enantioselectivity. The use of TEMPO as a co-catalytic redox mediator is crucial not only for oxidizing a tetrahydroisoquinoline to an iminium ion species but also for decreasing the oxidation potential of the reaction. A novel bisoxazoline ligand is also reported.
- Chen, Zhi-Hao,Gao, Pei-Sen,Mei, Tian-Sheng,Sun, Bing,Wang, Zhen-Hua,Weng, Xin-Jun,You, Shu-Li,Zheng, Chao
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supporting information
p. 15254 - 15259
(2020/06/23)
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- Practical direct synthesis of: N -aryl-substituted azacycles from N -alkyl protected arylamines using TiCl4and DBU
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A novel transformation of N-alkyl protected arylamines and cyclic ethers into N-aryl substituted azacycles is described. Alkyl groups have been used for the protection of amines in organic syntheses. In this synthesis, N-alkyl protected arylamines were reacted with cyclic ethers in the presence of TiCl4 and DBU, crucial reagents affording five- and six-membered azacycles. In particular, utilization of the novel TiCl4/DBU-mediated reaction allows various N-alkyl protected arylamines such as N-methyl-, N-ethyl-, N-isopropyl, and N-tert-butyl arylamines to be readily converted into N-aryl substituted azacycles in high yields. This practical approach using various N-alkyl arylamines leads to the efficient preparation of azacycles.
- Kang, Soosung,Kim, Hee-Kwon,La, Minh Thanh,Tran, Van Hieu
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p. 5008 - 5016
(2020/07/30)
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- Catalyst-free photodecarbonylation ofortho-amino benzaldehyde
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It is almost a consensus that decarbonylation of the aldehyde group (-CHO) needs to not only be mediated by transition metal catalysts, but also requires severe reaction conditions (high temperature and long reaction time). In this work, inspired by the “conformational-selectivity-based” design strategy, we broke this consensus and discovered a catalyst-free photodecarbonylation of the aldehyde group. It revealed that decarbonylation can be easily achieved with visible light irradiation by introducing a tertiary amine into theortho-position of the aldehyde group. A diverse array of tertiary amines is tolerated by our photodecarbonylation under mild conditions. Furthermore, the (QM) computations of the mechanism and the experiments on well-designed special substrates revealed that our photodecarbonylation depends on the conformational specificity of the aldehyde group and tertiary amine, and occurs through an unusual [1,4]-H shift and a subsequent [1,3]-H shift.
- Li, Lamei,Wang, Songping,Wei, Wentao,Yan, Ming,Zhou, Jingwei
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p. 3421 - 3426
(2020/06/25)
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- Metal-free late-stage C(sp2)-H functionalization of: N -aryl amines with various sodium salts
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Metal-free consecutive C(sp2)-X (X = Cl, Br, S, N) bond formations of N-aryl amines (cyclic, fused, carbamate, and aminium radicals) were achieved under mild conditions using [bis(trifluoroacetoxy)iodo]benzene (PIFA) and simple nonharmful sodium salts. This direct and selective C(sp2)-H functionalization showed excellent functional group compatibility, cost effectiveness, and late-stage applicability for the synthesis of biologically active natural products. Two mechanisms were proposed to explain the ortho- or para-preference, as well as the accelerating effect of CH3NO2
- Mudithanapelli, Chandrashekar,Kim, Mi-Hyun
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p. 450 - 464
(2020/02/03)
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- Photocatalytic deaminative benzylation and alkylation of tetrahydroisoquinolines with N-alkylpyrydinium salts
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A ruthenium-catalyzed photoredox coupling of substituted N-aryltetrahydroisoquinolines (THIQs) and different bench-stable pyridinium salts was successfully developed to give fast access to 1-benzyl-THIQs. Furthermore, secondary alkyl and allyl groups were also successfully introduced via the same method. Additionally, the typically applied N-phenyl group in the THIQ substrate could be replaced by the cleavable p-methoxyphenyl (PMP) group and successful N-deprotection was demonstrated.
- No?l, Timothy,Sambiagio, Carlo,Sch?nbauer, David,Schnürch, Michael
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supporting information
p. 809 - 817
(2020/05/18)
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- Visible Light-Driven α-Alkylation of N-Aryl tetrahydroisoquinolines Initiated by Electron Donor-Acceptor Complexes
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The visible light-driven α-alkylation of N-aryl tetrahydroisoquinolines was initiated through electron donor-acceptor complex photochemistry. The reaction can proceed smoothly without the addition of any photocatalysts, transition-metal catalysts, or additional oxidants. The proposed mechanism was supported by various mechanistic studies, and the reactive open-shell alkyl radicals were generally produced from an alkylamine and underwent radical coupling for alkylating a wide range of N-aryl tetrahydroisoquinolines.
- Dai, Peng,Deng, Hongping,Li, Yufei,Wang, Xinmin,Xia, Qing,Zhang, Wei-Hua
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supporting information
p. 7290 - 7294
(2020/10/12)
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- Electron Donor-Acceptor Complex-Initiated Photochemical Cyanation for the Preparation of α-Amino Nitriles
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An electron donor-acceptor complex-initiated α-cyanation of tertiary amines has been described. The reaction protocol provides a novel method to synthesize various α-amino nitriles under mild conditions. The reaction can proceed smoothly without the presence of photocatalysts and transition metal catalysts, and either oxidants are unnecessary or O2 is the only oxidant. The practicality of this method is showcased not only by the late-stage functionalization of natural alkaloid derivatives and pharmaceutical intermediate, but also by the applicability of a stop-flow microtubing reactor.
- Xia, Qing,Li, Yufei,Cheng, Lan,Liang, Xin,Cao, Chenlin,Dai, Peng,Deng, Hongping,Zhang, Weihua,Wang, Qingmin
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supporting information
p. 9638 - 9643
(2020/12/21)
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- Electrochemical Cross-Dehydrogenative Coupling of N-Aryl-tetrahydroisoquinolines with Phosphites and Indole
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A metal- and reagent-free, electrochemical cross-dehydrogenative coupling reaction of N-aryl-tetrahydroisoquinolines with phosphites and indole is developed. This method provides an environmentally benign and simple approach for the construction of C–P an
- Xie, Wenxia,Liu, Nian,Gong, Bowen,Ning, Shulin,Che, Xin,Cui, Lili,Xiang, Jinbao
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p. 2498 - 2501
(2019/04/01)
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- Nickel(II) Tetraphenylporphyrin as an Efficient Photocatalyst Featuring Visible Light Promoted Dual Redox Activities
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Nickel(II) tetraphenylporphyrin (NiTPP) is presented as a robust, cost-effective and efficient visible light induced photoredox catalyst. The ground state electrochemical data (CV) and electronic absorption (UV-Vis) spectra reveal the excited state redox potentials for [NiTPP]*/[NiTPP].? and NiTPP].+/[NiTPP]* couples as +1.17 V and ?1.57 V vs SCE respectively. The potential values represent NiTPP as a more potent photocatalyst compare to the well-explored [Ru(bpy)3]2+. The non-precious photocatalyst exhibits excited state redox reactions in dual fashions, i. e., it is capable of undergoing both oxidative as well as reductive quenching pathways. Such versatility of a photocatalyst based on first-row transition metals is very scarce. This unique phenomenon allows one to perform diverse types of redox reactions by employing a single catalyst. Two different sets of chemical reactions have been performed to represent the synthetic utility. The catalyst showed superior efficiency in both carbon-carbon and carbon-heteroatom bond-forming reactions. Thus, we believe that NiTPP is a valuable addition to the photocatalyst library and this study will lead to more practical synthetic applications of earth-abundant-metal-based photoredox catalysts. (Figure presented.).
- Mandal, Tanumoy,Das, Sanju,De Sarkar, Suman
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supporting information
p. 3200 - 3209
(2019/05/16)
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- Isoindolinone Synthesis: Selective Dioxane-Mediated Aerobic Oxidation of Isoindolines
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N-Alkyl and N-aryl-isoindolinones were prepared by a dioxane-mediated oxidation of isoindoline precursors. The transformation exhibits unique chemoselectivity for isoindonlines. A chiral tertiary (3°)-benzylic position was not racemized during oxidation, and methyl indoprofen was prepared by late stage oxidation. Mechanistic studies suggest a selective H atom transfer, which avoids many known oxidation (by-)products of isoindolinones.
- Thapa, Pawan,Corral, Esai,Sardar, Sinjinee,Pierce, Brad S.,Foss, Frank W.
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p. 1025 - 1034
(2019/01/24)
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- Importance of Singlet Oxygen in Photocatalytic Reactions of 2-Aryl-1,2,3,4-tetrahydroisoquinolines Using Chalcogenorosamine Photocatalysts
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Aerobic oxidation of 2-aryl-1,2,3,4-tetrahydroisoquinolines was achieved photocatalytically using chalcogenorosamine photocatalysts and LED irradiation. The photocatalytic aza-Henry reaction between these substrates and nitromethane was more efficient wit
- Clark, Jennifer L.,Hill, Jackie E.,Rettig, Irving D.,Beres, Joshua J.,Ziniuk, Roman,Ohulchanskyy, Tymish Y.,McCormick, Theresa M.,Detty, Michael R.
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supporting information
p. 2431 - 2442
(2019/07/02)
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- Thiyl radical promoted iron-catalyzed-selective oxidation of benzylic sp3 C-H bonds with molecular oxygen
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A ligand-free iron-catalyzed method for the oxygenation of benzylic sp3 C-H bonds by molecular oxygen (1 atm) using a thiyl radical as a cocatalyst has been developed. This transformation provides a facile access to amides, esters and ketones from readily accessible corresponding amines, ethers and alkanes. It features high regioselectivity, mild oxidative conditions and excellent functional group compatibility, providing good opportunities to the site-selective functionalization of complex molecules. Preliminary mechanistic studies suggest that this reaction may not undergo a benzylic cation intermediate pathway and the carbonyl oxygen atom in the products may be derived from molecular oxygen.
- Geng, Shasha,Xiong, Baojian,Zhang, Yun,Zhang, Juan,He, Yun,Feng, Zhang
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supporting information
p. 12699 - 12702
(2019/10/28)
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- Aerobic α-Oxidation of N-Substituted Tetrahydroisoquinolines to Dihydroisoquinolones via Organo-photocatalysis
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An efficient visible-light-induced α-oxidation of N-substituted tetrahydroisoquinolines to dihydroisoquinolones has been developed using eosin Y as an organo-photocatalyst and oxygen as a green oxidant. The reactions were carried out under mild reaction conditions; the desired dihydroisoquinolones were obtained in up to 96% yield at room temperature under oxygen atmosphere. This transformation provides a convenient route to dihydroisoquinolones with a wide range of substrates. (Figure presented.).
- Aganda, Kim Christopher C.,Hong, Boseok,Lee, Anna
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supporting information
p. 1124 - 1129
(2019/01/25)
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- Exogenous-oxidant-free electrochemical oxidative C-H phosphonylation with hydrogen evolution
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We herein report a versatile and environmentally friendly electrochemical oxidative C-H phosphonylation protocol. This protocol features a broad substrate scope; not only C(sp2)-H phosphonylation, but also C(sp3)-H phosphonylation is tolerated well under exogenous-oxidant-free and metal catalyst-free electrochemical oxidation conditions.
- Yuan, Yong,Qiao, Jin,Cao, Yangmin,Tang, Jingmei,Wang, Mengqin,Ke, Guojuan,Lu, Yichen,Liu, Xue,Lei, Aiwen
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supporting information
p. 4230 - 4233
(2019/04/30)
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- Visible-Light-Mediated C(sp3)–H Thiocarbonylation for Thiolactam Preparation with Potassium Sulfide
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We report herein a protocol for thiolactam preparation with potassium sulfide via visible-light-mediated C(sp3)–H thiocarbonylation, in which polysulfide dianions and radical anions generated from potassium sulfide were the key active species. A variety of thiolactams were straightforward established under mild conditions. Moreover, it was successfully applied to structural modification of tetrahydroberberine.
- Tan, Wei,Wang, Cuihong,Jiang, Xuefeng
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supporting information
p. 1234 - 1238
(2019/11/21)
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- Phosphoryl chloride-mediated solvent-free synthesis of N-aryl-substituted azacycles from arylamines and cyclic ethers
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A solvent- and metal-free protocol for preparation of N-aryl substituted azacycles from arylamines and cyclic ethers is described. In this method, the combination of POCl3 and DBU is crucial for conversion of arylamines and cyclic ethers to five- and six-membered azacycles. Without solvent, a variety of N-aryl-substituted, five-membered azacycles (pyrrolidines, 2-methylpyrrolidines, and piperidine) and six-membered azacycles (isoindolines and tetrahydroisoquinolines) are synthesized in high yields. This green method provides a sustainable and efficient approach for the preparation of azacycles from various cyclic ethers.
- Tran, Van Hieu,La, Minh Thanh,Kim, Hee-Kwon
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supporting information
p. 1860 - 1863
(2019/06/19)
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- Metal-Free Synthesis of N-Aryl-Substituted Azacycles from Cyclic Ethers Using POCl3
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A facile method for the synthesis of N-aryl-substituted azacycles from arylamines and cyclic ethers has been developed. In this study, arylamines were treated with cyclic ethers in the presence of POCl3 and DBU to provide five- A nd six-membered azacycles. Using this method, various azacycloalkanes, isoindolines, and tetrahydroisoquinolines were prepared in high yields. This synthetic method offers an efficient approach to the production of azacycles from cyclic ethers.
- La, Minh Thanh,Kang, Soosung,Kim, Hee-Kwon
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p. 6689 - 6696
(2019/06/14)
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- Robust Buchwald-Hartwig amination enabled by ball-milling
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An operationally simple mechanochemical method for the Pd catalysed Buchwald-Hartwig amination of arylhalides with secondary amines has been developed using a Pd PEPPSI catalyst system. The system is demonstrated on 30 substrates and applied in the context of a target synthesis. Furthermore, the performance of the reaction under aerobic conditions has been probed under traditional solution and mechanochemical conditions, the observations are discussed herein.
- Cao, Qun,Nicholson, William I.,Jones, Andrew C.,Browne, Duncan L.
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supporting information
p. 1722 - 1726
(2019/02/20)
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- Visible-light induced enhancement in the multi-catalytic activity of sulfated carbon dots for aerobic carbon-carbon bond formation
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The development of carbonaceous materials as metal-free catalysts integrating different types of catalysis in a single system represents a significant advance in cascade/tandem organic synthesis. Zero-dimensional carbon dots with tuneable optical properties and easily modifiable surface functionalities can be harnessed as a carbocatalyst for merging photooxidation and acid-catalyzed reactions in one pot. Herein, we explore carbon dots decorated with hydrogen sulfate groups as a photocatalyst for the dehydrogenative cross-coupling of xanthenes with ketones, arenes and 1,3-dicarbonyl compounds that showed high efficiency and selectivity under visible-light irradiation. The sulphated carbon dots demonstrate dual catalytic properties, wherein they induced the rapid photooxidation of xanthenes in the presence of molecular oxygen to form a hydroperoxy intermediate followed by coupling of nucleophiles catalysed by the acidic surface functional groups. The methodology represents an operationally simple pathway for the generation of C-C coupling products in a short reaction time with wide substrate scopes under mild conditions. The catalyst is easily separable and can be reused over multiple cycles with good efficiency.
- Sarma, Daisy,Majumdar, Biju,Sarma, Tridib K.
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supporting information
p. 6717 - 6726
(2019/12/26)
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- Radical alkylation of C(sp3)-H bonds with diacyl peroxides under catalyst-free conditions
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Herein, we describe a protocol for alkylation reactions of C(sp3)-H bonds with diacyl peroxides by means of a process involving cross-coupling between an alkyl radical and an α-Aminoalkyl radical. The mild, catalyst-And additive-free conditions make this protocol superior to previously reported C(sp3)-H alkylation strategies. The protocol was applied to 1,2,3,4-Tetrahydroisoquinolines and a tetrahydro-β-carboline derivative and could be carried out on a gram scale, indicating its utility for the alkylation of late-stage synthetic intermediates.
- Tian, Hao,Xu, Wentao,Liu, Yuxiu,Wang, Qingmin
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supporting information
p. 14813 - 14816
(2019/12/24)
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- Uncatalyzed Oxidative C?H Amination of 9,10-Dihydro-9-Heteroanthracenes: A Mechanistic Study
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A new method for the one-step C?H amination of xanthene and thioxanthene with sulfonamides is reported, without the need for any metal catalyst. A benzoquinone was employed as a hydride (or two-electron and one-proton) acceptor. Moreover, a previously unknown and uncatalyzed reaction between iminoiodanes and xanthene, thioxanthene and dihydroacridines (9,10-dihydro-9-heteroanthracenes or dihydroheteroanthracenes) is disclosed. The reactions proceed through hydride transfer from the heteroarene substrate to the iminoiodane or benzoquinone, followed by conjugate addition of the sulfonamide to the oxidized heteroaromatic compounds. These findings may have important mechanistic implications for metal-catalyzed C?H amination processes involving nitrene transfer from iminoiodanes to dihydroheteroanthracenes. Due to the weak C?H bond, xanthene is an often-employed substrate in mechanistic studies of C?H amination reactions, which are generally proposed to proceed via metal-catalyzed nitrene insertion, especially for reactions involving nitrene or imido complexes that are less reactive (i.e., less strongly oxidizing). However, these substrates clearly undergo non-catalyzed (proton-coupled) redox coupling with amines, thus providing alternative pathways to the widely assumed metal-catalyzed pathways.
- van Leest, Nicolaas P.,Grooten, Lars,van der Vlugt, Jarl Ivar,de Bruin, Bas
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supporting information
p. 5987 - 5993
(2019/04/03)
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- PIFA-Promoted, Solvent-Controlled Selective Functionalization of C(sp2)-H or C(sp3)-H: Nitration via C-N Bond Cleavage of CH3NO2, Cyanation, or Oxygenation in Water
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A novel nitration (via C(sp3)-N breaking/C(sp2)-N formation with CH3NO2) mediated by [bis(trifluoroacetoxy)iodo]benzene (PIFA) is described. The NO2 transfer from CH3NO2 to the aromatic group of the substrate is possible with careful selection of the solvent, NaX, and oxidant. In addition, the solvent-controlled C(sp2)-H functionalization can shift to an α-C(sp3)-H functionalization (cyanation or oxygenation) of the α-C(sp3)-H of cyclic amines.
- Mudithanapelli, Chandrashekar,Dhorma, Lama Prema,Kim, Mi-Hyun
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supporting information
(2019/05/07)
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- A metal-free direct C (sp3)-H cyanation reaction with cyanobenziodoxolones
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A metal-free protocol of direct C(sp3)-H cyanation with cyanobenziodoxolones functioning as both cyanating reagents and oxidants was developed. Unactivated substrates, such as alkanes, ethers and tertiary amines, were thereby transformed to the corresponding nitriles in moderate to high yields. Mechanistic studies indicated that the cyanation proceeded with two potential pathways, which is highly dependent on the substrates: (1) a free radical case for alkanes and ethers and (2) an oxidative case for tertiary amines.
- Sun, Ming-Xue,Wang, Yao-Feng,Xu, Bao-Hua,Ma, Xin-Qi,Zhang, Suo-Jiang
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supporting information
p. 1971 - 1975
(2018/03/23)
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- Tropylium-Promoted Oxidative Functionalization of Tetrahydroisoquinolines
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Structural modification of the tetrahydroisoquinoline (THIQ) framework is of significant interest to organic chemists due to its central role in heterocyclic and medicinal chemistry. Here we demonstrate an efficient metal-free method for the oxidative fun
- Oss, Giulia,De Vos, Sander D.,Luc, Kevin N. H.,Harper, Jason B.,Nguyen, Thanh V.
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p. 1000 - 1010
(2018/01/28)
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- Synthesis of α-aminonitriles using aliphatic nitriles, α-amino acids, and hexacyanoferrate as universally applicable non-toxic cyanide sources
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In cyanation reactions, the cyanide source is often directly added to the reaction mixture, which restricts the choice of conditions. The spatial separation of cyanide release and consumption offers higher flexibility instead. Such a setting was used for the cyanation of iminium ions with a variety of different easy-to-handle HCN sources such as hexacyanoferrate, acetonitrile or α-amino acids. The latter substrates were first converted to their corresponding nitriles through oxidative decarboxylation. While glycine directly furnishes HCN in the oxidation step, the aliphatic nitriles derived from α-substituted amino acids can be further converted into the corresponding cyanohydrins in an oxidative C-H functionalization. Mn(OAc)2 was found to catalyze the efficient release of HCN from these cyanohydrins or from acetone cyanohydrin under acidic conditions and, in combination with the two previous transformations, permits the use of protein biomass as a non-toxic source of HCN.
- Nauth, Alexander M.,Konrad, Tim,Papadopulu, Zaneta,Vierengel, Nina,Lipp, Benjamin,Opatz, Till
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supporting information
p. 4217 - 4223
(2018/09/29)
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- TiO2Nanoparticles Functionalized with Non-innocent Ligands Allow Oxidative Photocyanation of Amines with Visible/Near-Infrared Photons
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Photosynthesis is an efficient mechanism for converting solar light energy into chemical energy. We report on a strategy for the aerobic photocyanation of tertiary amines with visible and near-infrared (NIR) light. Panchromatic sensitization was achieved
- Nauth,Schechtel, Eugen,D?ren, René,Tremel, Wolfgang,Opatz, Till
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supporting information
p. 14169 - 14177
(2018/10/26)
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- Cobalt-Catalyzed Oxidative C(sp3)-H Phosphonylation for α-Aminophosphonates via C(sp3)-H/P(O)-H Coupling
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The first oxidative C(sp3)-H phosphonylation of tertiary aliphatic amines has been developed. The use of cobalt acetate as a catalyst, N-hydroxyphthalimide as a cocatalyst, and air as an oxidant enabled the conversion of tertiary aromatic and aliphatic amines into α-aminophosphonates in moderate to excellent yields under mild conditions via a cross dehydrogenative coupling reaction.
- Lin, Binzhou,Shi, Shanshan,Lin, Rongcan,Cui, Yiqun,Fang, Meijuan,Tang, Guo,Zhao, Yufen
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p. 6754 - 6761
(2018/05/31)
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- Intermolecular acetoxyaminoalkylation of α-diazo amides with (diacetoxyiodo)benzene and amines
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Multicomponent reactions of diazo compounds have attracted much attention in recent years. Such transformations are generally conducted by applying transition metal catalysis and involve the corresponding metal carbenes as key intermediates. In this letter, a metal-free three-component intermolecular acetoxyaminoalkylation of α-diazo amides with tertiary aryl amines and (diacetoxyiodo)benzene is presented.
- D?ben, Nadine,Yan, Hong,Kischkewitz, Marvin,Mao, Jincheng,Studer, Armido
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supporting information
p. 7933 - 7936
(2019/01/04)
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- Metal-Free Synthesis of α-Aminophosphonates from Tertiary Amines and P(O)H Compounds via a Cross-Dehydrogenative Coupling Reaction
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The various α-aminophosphonates have been prepared from tertiary aromatic and aliphatic amines with P(O)H compounds via a tert -butyl hydroperoxide mediated cross-dehydrogenative coupling reaction, eliminating the need for transition-metal catalysts. The
- Lin, Binzhou,Lu, Guozhang,Lin, Rongcan,Cui, Yiqun,Liu, Yan,Tang, Guo,Zhao, Yufen
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supporting information
p. 2697 - 2700
(2018/12/13)
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- Iminium Ion and N-Hydroxyimide as the Surrogate Components in DEAD-Promoted Oxidative Ugi Variant
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A practical metal-free oxidative Ugi-type three-component assembly has been achieved efficiently, employing a tertiary-amine-derived iminium ion as an imine surrogate, N-hydroxyimide as an acid surrogate, and DEAD as an oxidant. This dual-surrogate Ugi variant proceeded with a broad substrate scope and desired functional group tolerance, leading to a wide range of N-alkyl-N-acyl aminophthalimide and N-alkyl-N-acylaminosuccinimide derivatives in good isolated yields.
- Wang, Jiankun,Sun, Yilin,Jiang, Mu-Han,Hu, Tian-Yu,Zhao, Yong-Jie,Li, Xin,Wang, Guangji,Hao, Kun,Zhen, Le
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p. 13121 - 13131
(2018/11/20)
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