- H2O2-mediated room temperature synthesis of 2-arylacetophenones from arylhydrazines and vinyl azides in water
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An environmentally benign, cost-efficient and practical methodology for the room temperature synthesis of 2-arylacetophenones in water has been discovered. The facile and efficient transformation involves the oxidative radical addition of arylhydrazines with α-aryl vinyl azides in the presence of H2O2 (as a radical initiator) and PEG-800 (as a phase-transfer catalyst). From the viewpoint of green chemistry and organic synthesis, the present protocol is of great significance because of using cheap, non-toxic and readily available starting materials and reagents as well as amenability to gram-scale synthesis, which provides an attractive strategy to access 2-arylacetophenones.
- Luo, Mengqiang,Zhang, Yaohong,Fang, Ping,Li, Yan,Qi, Chenze,Li, Yong,Shen, Runpu,Cheng, Kai,Wang, Hai
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supporting information
p. 630 - 635
(2022/02/01)
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- Combined Theoretical and Experimental Studies Unravel Multiple Pathways to Convergent Asymmetric Hydrogenation of Enamides
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We present a highly efficient convergent asymmetric hydrogenation of E/Z mixtures of enamides catalyzed by N,P-iridium complexes supported by mechanistic studies. It was found that reduction of the olefinic isomers (E and Z geometries) produces chiral amides with the same absolute configuration (enantioconvergent hydrogenation). This allowed the hydrogenation of a wide range of E/Z mixtures of trisubstituted enamides with excellent enantioselectivity (up to 99% ee). A detailed mechanistic study using deuterium labeling and kinetic experiments revealed two different pathways for the observed enantioconvergence. For α-aryl enamides, fast isomerization of the double bond takes place, and the overall process results in kinetic resolution of the two isomers. For α-alkyl enamides, no double bond isomerization is detected, and competition experiments suggested that substrate chelation is responsible for the enantioconvergent stereochemical outcome. DFT calculations were performed to predict the correct absolute configuration of the products and strengthen the proposed mechanism of the iridium-catalyzed isomerization pathway.
- Yang, Jianping,Massaro, Luca,Krajangsri, Suppachai,Singh, Thishana,Su, Hao,Silvi, Emanuele,Ponra, Sudipta,Eriksson, Lars,Ahlquist, M?rten S. G.,Andersson, Pher G.
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supporting information
p. 21594 - 21603
(2021/12/27)
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- Nickel-Mediated Photoreductive Cross Coupling of Carboxylic Acid Derivatives for Ketone Synthesis**
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A simple visible light photochemical, nickel-catalyzed synthesis of ketones from carboxylic acid-derived precursors is presented. Hantzsch ester (HE) functions as a cheap, green and strong photoreductant to facilitate radical generation and also engages in the Ni-catalytic cycle to restore the reactive species. With this dual role, HE allows for the coupling of a large variety of radicals (1°,2°, benzylic, α-oxy & α-amino) with aroyl and alkanoyl moieties, a new feature in reactions of this type. With both precursors deriving from abundant carboxylic acids, this protocol is a welcome addition to the organic chemistry toolbox. The reaction proceeds under mild conditions without the need for toxic metal reagents or bases and shows a wide scope, including pharmaceuticals and complex molecular architectures.
- Brauer, Jan,Quraishi, Elisabeth,Kammer, Lisa Marie,Opatz, Till
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supporting information
p. 18168 - 18174
(2021/11/30)
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- Benzylic aroylation of toluenes with unactivated tertiary benzamides promoted by directed ortho-lithiation
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The deprotonative functionalization of toluenes, for their weak acidity, generally needs strong bases, thus leading to the requirement of harsh conditions and the generation of by-products. Direct nucleophilic acyl substitution reaction of amides with organometallic reagents could provide an ideal solution for ketone synthesis. However, the inert amides and highly reactive organometallic reagents bring great challenges for an efficient and selective synthetic approach. Herein, we reported an lithium diisopropylamide (LDA)-promoted benzylic aroylation of toluenes with unactivated tertiary benzamides, providing a direct and efficient synthesis of various aryl benzyl ketones. This process features a kinetic deprotonative functionalization of toluenes with a readily available base LDA. Mechanism studies revealed that the directed ortho-lithiation of the tertiary benzamide with LDA promoted the benzylic kinetic deprotonation of toluene and triggered the nucleophilic acyl substitution reaction with the amide. [Figure not available: see fulltext.].
- Bao, Can-Can,Luo, Yan-Long,Du, Hui-Zhen,Guan, Bing-Tao
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p. 1349 - 1354
(2021/07/12)
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- Ring size and nothing else matters: unusual regioselectivity of alkyne hydration by NHC gold(i) complexes
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We have investigated the role of ring sizes and substituents in NHC ligands in some (NHC)Au(i) complexes in the hydration of internal alkynes. Despite the fact that using (NHC)Au(i) complexes in the hydration of diarylacetylenes leads to Markovnikov-type products, the precise tuning of ligands allows changing the regioselectivity in arylalkylacetylene hydration to the anti-Markovnikov-type.
- Ageshina, Alexandra A.,Asachenko, Andrey F.,Chesnokov, Gleb A.,Minaeva, Lidiya I.,Nechaev, Mikhail S.,Philippova, Anna N.,Rzhevskiy, Sergey A.,Topchiy, Maxim A.
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supporting information
p. 5686 - 5689
(2021/06/16)
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- Regioselection in the synthesis of 4-benzyltetral-1-ones and the new 4-arylbenzosuber-1-ones
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The intramolecular Friedel-Crafts acylation of 4,5-diarylpentanoic acids has the possibility to cyclise to either a 6-membered ring to give 4-benzyltetral-1-one or a 7-membered ring to give 4-arylbenzosuber-1-one. Of these, only the former compound class has previously been reported. The impact of the substituents positioning on the outcome of the cyclisation has been investigated. The complete formation of either the tetralone or the benzosuberone regioisomer was possible under the same reaction conditions, dependent upon the ring activation and/or deactivation of the chosen substituents. Selected bromo or methoxy substituents could be used as auxiliaries, included in precursors to afford the desired regioisomer and then subsequently removed.
- Truong, Daniel,Howard, Brittany L.,Thompson, Philip E.
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- 1,2-Aryl Migration Induced by Amide C?N Bond-Formation: Reaction of Alkyl Aryl Ketones with Primary Amines Towards α,α-Diaryl β,γ-Unsaturated γ-Lactams
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Rearrangement reactions incorporated into cascade reactions play an important role in rapidly increasing molecular complexity from readily available starting materials. Reported here is a Cu-catalyzed cascade reaction of α-(hetero)aryl-substituted alkyl (hetero)aryl ketones with primary amines that incorporates an unusual 1,2-aryl migration induced by amide C?N bond formation to produce a class of structurally novel α,α-diaryl β,γ-unsaturated γ-lactams in generally good-to-excellent yields. This cascade reaction has a broad substrate scope with respect to primary amines, allows a wide spectrum of (hetero)aryl groups to smoothly undergo 1,2-migration, and tolerates electronically diverse α-substituents on the (hetero)aryl ring of the ketones. Mechanistically, this 1,2-aryl migration may stem from the intramolecular amide C?N bond formation which induces nucleophilic migration of the aryl group from the acyl carbon center to the electrophilic carbon center that is conjugated with the resulting iminium moiety.
- Hu, Rong,Tao, Yigao,Zhang, Xiaofeng,Su, Weiping
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supporting information
p. 8425 - 8430
(2021/03/16)
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- Iron-Catalyzed Enantioselective Radical Carboazidation and Diazidation of α,β-Unsaturated Carbonyl Compounds
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Azidation of alkenes is an efficient protocol to synthesize organic azides which are important structural motifs in organic synthesis. Enantioselective radical azidation, as a useful strategy to install a C-N3 bond, remains challenging due to the inherently instability and unique structure of radicals. Here, we disclose an efficient enantioselective radical carboazidation and diazidation of α,β-unsaturated ketones and amides catalyzed by chiral N,N′-dioxide/Fe(OTf)2 complexes. An array of substituted alkenes was transformed to the corresponding α-azido carbonyl derivatives in good to excellent enantioselectivities, benefiting the preparation of chiral α-amino ketones, vicinal amino alcohols, and vicinal diamines. Control experiments and mechanistic studies proved the radical pathway in the reaction process. The DFT calculations showed that the azido transferred to the radical intermediate via an intramolecular five-membered transition state with the internal nitrogen of the Fe-N3 species.
- Dong, Shunxi,Feng, Xiaoming,He, Jun,Liu, Wen,Liu, Xiaohua,Pu, Maoping,Wu, Yun-Dong,Zhang, Tinghui
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supporting information
p. 11856 - 11863
(2021/08/16)
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- Aerobic oxygenation of α-methylene ketones under visible-light catalysed by a CeNi3complex with a macrocyclic tris(salen)-ligand
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A hetero-tetranuclear CeNi3 complex with a macrocyclic ligand catalysed the aerobic oxygenation of a methylene group adjacent to a carbonyl group under visible-light radiation to produce the corresponding α-diketones. The visible-light induced homolysis of the Ce-O bond of a bis(enolate) intermediate is proposed prior to aerobic oxygenation.
- Fujiwara, Sakiko,Kon, Yoshihiro,Mashima, Kazushi,Nagae, Haruki,Okuda, Jun,Sakamoto, Kazutaka,Sato, Kazuhiko,Schindler, Tobias
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supporting information
p. 11169 - 11172
(2021/11/04)
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- Enolizable Ketones as Activators of Palladium(II) Precatalysts in Amine Arylation Reactions
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Enolizable ketones have been identified as effective activators for palladium(II) precatalysts in the coupling of aryl bromides and aniline. N-arylation reactions catalyzed by [(DTBNpP)PdCl2]2 (DTBNpP = (bis(tert-butyl)neopentylphosphine) and PEPPSI-IPr precatalysts are activated by the addition of acetone, mesityl oxide, and 3-pentanone. 3-Pentanone was the most effective activator. Mechanistic studies show that acetone, 3-pentanone, and mesityl oxide reduce [(DTBNpP)PdCl2]2 in the presence of NaO-t-Bu to Pd0(DTBNpP)2
- Hu, Huaiyuan,Gilliam, Ashley M.,Qu, Fengrui,Shaughnessy, Kevin H.
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p. 4127 - 4135
(2020/05/05)
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- Synthesis of unsymmetrical ketones by applying visible-light benzophenone/nickel dual catalysis for direct benzylic acylation
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Herein, we report a dual catalytic system for the direct benzylic C-H acylation reaction furnishing a variety of unsymmetrical ketones. A benzophenone-derived photosensitizer combined with a nickel catalyst has been established as the catalytic system. Both acid chlorides and anhydrides are able to acylate the benzylic position of toluene and other methylbenzenes. The method offers a valuable alternative to late transition metal catalyzed C-H acylation reactions.
- Krach, Patricia E.,Dewanji, Abhishek,Yuan, Tingting,Rueping, Magnus
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supporting information
p. 6082 - 6085
(2020/06/18)
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- Combined Photoredox and Carbene Catalysis for the Synthesis of Ketones from Carboxylic Acids
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As a key element in the construction of complex organic scaffolds, the formation of C?C bonds remains a challenge in the field of synthetic organic chemistry. Recent advancements in single-electron chemistry have enabled new methods for the formation of various C?C bonds. Disclosed herein is the development of a novel single-electron reduction of acyl azoliums for the formation of ketones from carboxylic acids. Facile construction of the acyl azolium in situ followed by a radical–radical coupling was made possible merging N-heterocyclic carbene (NHC) and photoredox catalysis. The utility of this protocol in synthesis was showcased in the late-stage functionalization of a variety of pharmaceutical compounds. Preliminary investigations using chiral NHCs demonstrate that enantioselectivity can be achieved, showcasing the advantages of this protocol over alternative methodologies.
- Betori, Rick C.,Davies, Anna V.,Fitzpatrick, Keegan P.,Scheidt, Karl A.
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supporting information
p. 9143 - 9148
(2020/03/30)
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- Blue Light Promoted Difluoroalkylation of Aryl Ketones: Synthesis of Quaternary Alkyl Difluorides and Tetrasubstituted Monofluoroalkenes
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A facile and cost-effective method for the preparation of fluoroalkylated compounds has been described by the direct photoexcitation of halofluoroalkanes with blue light absorptivity, enabling the difluoroalkylation of aryl ketones. The methodology has provided an efficient, mild, and catalyst-free synthetic method for quaternary difluoroalkylated arenes and tetrasubstituted monofluoroalkenes.
- Li, Kangkui,Chen, Jingchao,Yang, Chunhui,Zhang, Keyang,Pan, Chunxiang,Fan, Baomin,Fan, Baomin
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supporting information
p. 4261 - 4265
(2020/06/04)
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- Discovery of an Orally Bioavailable Pan αv Integrin Inhibitor for Idiopathic Pulmonary Fibrosis
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The heterodimeric transmembrane αv integrin receptors have recently emerged as potential targets for the treatment of idiopathic pulmonary fibrosis. Herein, we describe how subtle modifications of the central aromatic ring of a series of phenylbutyrate-based antagonists of the vitronectin receptors αvβ3 and αvβ5 significantly change the biological activities against αvβ6 and αvβ8. This resulted in the discovery of a pan αv antagonist (compound 39, 4-40 nM for the integrin receptors named above) possessing excellent oral pharmacokinetic properties in rats (with a clearance of 7.6 mL/(min kg) and a bioavailability of 97%).
- Anderson, Niall A.,Campos, Sebastien,Butler, Sharon,Copley, Royston C. B.,Duncan, Ian,Harrison, Stephen,Le, Joelle,Maghames, Rosemary,Pastor-Garcia, Aleix,Pritchard, John M.,Rowedder, James E.,Smith, Claire E.,Thomas, Jack,Vitulli, Giovanni,Macdonald, Simon J. F.
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supporting information
p. 8796 - 8808
(2019/10/16)
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- Palladate Precatalysts for the Formation of C-N and C-C Bonds
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A series of imidazolium-based palladate precatalysts has been synthesized and the catalytic activity of these air- and moisture-stable complexes evaluated as a function of the nature of the imidazolium counterion. These precatalysts can be converted under
- Zinser, Caroline M.,Warren, Katie G.,Nahra, Fady,Al-Majid, Abdullah,Barakat, Assem,Islam, Mohammad Shahidul,Nolan, Steven P.,Cazin, Catherine S. J.
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p. 2812 - 2817
(2019/08/12)
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- Salicylic Acid-Catalyzed Arylation of Enol Acetates with Anilines
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α-Aryl ketones are both structure moieties commonly found in bioactive compounds and versatile synthetic intermediates for the preparation of drug-like molecules. An operationally simple and scalable protocol has been developed to prepare α-aryl ketones from readily available aromatic amines and enol acetates (or silyl enol ethers). This metal-free methodology features the use of salicylic acid as a convenient catalyst to promote the formation of aryl radicals from in-situ generated aryl diazonium salts, without demanding thermal or photochemical activation. The mild reaction conditions used are compatible with anilines substituted with diverse functionalities. Structural elaboration of some prepared α-aryl ketones was accomplished to illustrate their usefulness as building blocks. (Figure presented.).
- Felipe-Blanco, Diego,Gonzalez-Gomez, Jose C.
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supporting information
p. 2773 - 2778
(2018/07/29)
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- Nickel-Catalyzed Transformation of Aryl 2-Pyridyl Ethers via Cleavage of the Carbon-Oxygen Bond: Synthesis of Mono-α-arylated Ketones
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The nickel/IPr-catalyzed reaction of aryl 2-pyridyl ethers with propiophenone and acetophenone derivatives via C-OPy bond cleavage is performed in the presence of t -BuOLi to give mono-α-arylated ketones in moderate yields. The method is suitable for electron-rich and electron-poor ethers as well as heteroaryl ethers and tolerates a range of active functional groups.
- Li, Jing,Wang, Zhong-Xia
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p. 3217 - 3223
(2018/06/08)
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- Two-Step One-Pot Synthesis of Unsymmetrical (Hetero)Aryl 1,2-Diketones by Addition-Oxygenation of Potassium Aryltrifluoroborates to (Hetero)Arylacetonitriles
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An efficient one-pot two-step procedure for the synthesis of unsymmetrical (hetero)aryl 1,2-diketones has been developed. The reaction proceeds through a palladium-catalyzed nucleophilic addition of potassium aryltrifluoroborates to aliphatic nitriles followed by a copper-catalyzed aerobic benzylic C–H oxygenation using molecular oxygen as a green oxidant. This represents the first example of the direct synthesis of unsymmetrical diaryl 1,2-diketones from arylacetonitriles. This method utilizes inexpensive, stable, nontoxic, and readily available starting materials, is highly effective in the presence of both electron-rich and electron-poor nitriles and aryltrifluoroborates, and tolerates a wide variety of functional groups. The synthetic utility of this transformation was shown by increasing the scale of the reaction and by carrying out the one-pot protocol for the preparation of quinoxaline and benzimidazole derivatives. A plausible reaction mechanism has also been proposed.
- Kumar, Yogesh,Jaiswal, Yogesh,Kumar, Amit
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p. 494 - 505
(2018/02/09)
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- Novel bisamide palladium(II) pincer complexes: effective catalysts in α-arylation of ketones
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Three benzenedicarboxamide ligands (L) were designed and synthesized, and each was used to prepare a palladium(II) complex Pd(L)Br and Pd(L)(OAc). These NCN pincer complexes were used to catalyze the α-arylations of a variety of ketones with aryl chlorides or bromides in various solvents, and moderate-to-excellent yields were obtained (up to 95%). Further research showed that unactivated and sterically hindered aryl halides and ketones are also suitable substrates for the synthesis of α-arylation. Graphical Abstract: [Figure not available: see fulltext.].
- Kai, Wang,Liu, Dabin,Qian, Hua,Ye, Zhiwen
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p. 443 - 450
(2017/07/12)
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- Metal-free benzannulation to synthesis of 2,3-disubstituted naphthalenes: Reaction of 2-(Phenylethynyl)benzaldehyde and alkynes by Br?nsted acid
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Metal-free benzannulation reaction of 2-(phenylethynyl)- benzaldehyde and alkynes proceeded in the presence of Br?nsted acid under microwave irradiation to give the 2,3- disubstituted naphthalenes.
- Umeda, Rui,Ikeda, Naoki,Ikeshita, Masahiro,Sumino, Keita,Nishimura, Sota,Nishiyama, Yutaka
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p. 213 - 215
(2017/08/09)
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- Metal-free synthesis of ketones by visible-light induced aerobic oxidative radical addition of aryl hydrazines to alkenes
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A green and cost-effective method has been developed for the conversion of alkenes to ketones under metal-free conditions. The reaction involves the oxidative addition of alkenes with aryl radicals, which are generated by visible-light induced aerobic oxidation of arylhydrazines. The key features of this reaction include broad substrate scope, readily available reagents and amenability to gram-scale synthesis.
- Ding, Ya,Zhang, Wenkai,Li, Hao,Meng, Yunge,Zhang, Te,Chen, Qiu-Yun,Zhu, Chunyin
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supporting information
p. 2941 - 2944
(2017/07/24)
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- Selective Metal-Free Deoxygenation of Unsymmetrical 1,2-Dicarbonyl Compounds by Chlorotrimethylsilane and Sodium Iodide
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For the first time, the combination of chlorotrimethylsilane with NaI is used as a selective reducting system toward 1,2-diketones. This combination is successfully evaluated with several unsymmetrically benzil derivatives, which are reduced in good yield
- Yuan, Ling-Zhi,Renko, Dolor,Khelifi, Ilhem,Provot, Olivier,Brion, Jean-Daniel,Hamze, Abdallah,Alami, Mouad
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supporting information
p. 3238 - 3241
(2016/07/14)
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- The Stabilized Cation Pool Method: Metal- and Oxidant-Free Benzylic C-H/Aromatic C-H Cross-Coupling
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Electrochemical oxidation of toluene derivatives in the presence of a sulfilimine gave benzylaminosulfonium ions as stabilized benzyl cation pools, which reacted with subsequently added aromatic nucleophiles to give the corresponding cross-coupling produc
- Hayashi, Ryutaro,Shimizu, Akihiro,Yoshida, Jun-Ichi
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supporting information
p. 8400 - 8403
(2016/07/27)
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- Nickel catalyzed α-arylation of ketones with aryltrimethylammonium triflates
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Nickel-catalyzed α-arylation of ketones involving aromatic C-N cleavage has been accomplished. Intermolecular coupling of aromatic ketones with a variety of aryltrimethylammonium triflates was achieved in the presence of Ni(COD)2, IPr·HCl, and LiOBut, giving α-arylated ketones in reasonable to excellent yields.
- Li, Jing,Wang, Zhong-Xia
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p. 7579 - 7584
(2016/08/16)
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- One-Pot, Modular Approach to Functionalized Ketones via Nucleophilic Addition of Alkyllithium Reagents to Benzamides and Pd-Catalyzed α-Arylation
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An efficient, in situ sequential 1,2-addition of alkyllithium reagents to benzamides followed by α-arylation of the resulting alkyl ketones is reported. The use of Pd[P(t-Bu)3]2, as catalyst for the α-arylation reaction, allows access to a wide variety of functionalized benzyl ketones in a modular way. The decomposition of the tetrahedral intermediate originated from the 1,2-addition liberates in situ a lithium amide, therefore avoiding the need of an external base for the α-arylation. The method affords good overall yields with a variety of alkyl lithium reagents, benzamides, and aryl bromides, bearing a range of functional groups with complete selectivity toward the monoarylated products.
- Wolters, Alexander T.,Hornillos, Valentin,Heijnen, Dorus,Giannerini, Massimo,Feringa, Ben L.
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p. 2622 - 2625
(2016/04/26)
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- Exploiting Aryl Mesylates and Tosylates in Catalytic Mono-α-arylation of Aryl- and Heteroarylketones
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The first general palladium catalyst for the catalytic mono-α-arylation of aryl- and heteroarylketones with aryl mesylates and tosylates is described. The newly developed indolyl-derived phosphine ligand L7 has been identified to promote this reaction eff
- Fu, Wai Chung,So, Chau Ming,Yuen, On Ying,Lee, Irene Toi Chuk,Kwong, Fuk Yee
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supporting information
p. 1872 - 1875
(2016/05/19)
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- NOVEL PRECATALYST SCAFFOLDS FOR CROSS-COUPLING REACTIONS, AND METHODS OF MAKING AND USING SAME
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The present invention provides novel transition-metal precatalysts that are useful in preparing active coupling catalysts. In certain embodiments, the precatalysts of the invention are air-stable and moisture-stable. The present invention further provides methods of making and using the precatalysts of the invention.
- -
-
Page/Page column 62; 63
(2016/05/02)
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- COMPLEXES
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The present invention provides apalladium(II)complex of formula (1) or a palladium(II) complex of formula (2). R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R18, R19, R20, R21, R22, R23 and R24, m, E and X are described in the specification. The invention also provides a process for the preparation of the complexes, and their use in carbon-carbon and carbon-heteroatom coupling reactions.
- -
-
Page/Page column 44
(2016/01/01)
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- Copper-catalyzed base-accelerated direct oxidation of C-H bond to synthesize benzils, isatins, and quinoxalines with molecular oxygen as terminal oxidant
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We describe herein an efficient and general copper (II)-catalyzed base-accelerated oxidation of the C-H bond to synthesize benzils and isatins. With similar oxidation system an efficient one-pot procedure for the synthesis of quinoxaline derivatives was realized. The two protocols feature using molecular oxygen as terminal oxidant, low catalyst loading, wide substrate scope, and high functional-group tolerance.
- Yu, Jing-Wen,Mao, Shuai,Wang, Yong-Qiang
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supporting information
p. 1575 - 1580
(2015/03/14)
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- Preparation of an Arenylmethylzinc Reagent with Functional Groups by Chemoselective Cross-Coupling Reaction of Bis(iodoazincio)methane with Iodoarenes
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Palladium-catalyzed cross-coupling reaction of bis(iodozincio)methane with iodoarenes carrying various functionalities such as ester, boryl, cyano, and halo groups proceeded chemoselectively to give the corresponding arenylmethylzinc species efficiently. The moderate reactivity of the gem-dizinc reagent imparted functional group tolerance to the process. The transformations from iodoheteroarenes were also performed; in the case of iodopyridine derivatives, the nickel-catalyzed reaction gave the corresponding organozinc species efficiently. The obtained arenylmethylzinc species underwent the copper-mediated coupling reaction with a range of organic halides.
- Shimada, Yukako,Haraguchi, Ryosuke,Matsubara, Seijiro
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p. 2395 - 2398
(2015/10/19)
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- Alternative approach toward the generation of benzylic zinc reagent: Direct oxidative addition of active zinc into the carbon-oxygen bond of benzyl mesylates
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The use of highly active zinc, prepared by the Rieke method, for the direct preparation of benzylic zinc mesylate was investigated. The oxidative addition of highly active zinc to benzyl mesylate was easily completed under mild conditions. The resulting benzylic zinc mesylates were employed in subsequent cross-coupling reactions with a broad range of electrophiles, and the formation of the corresponding products was successful.
- Jung, Hye-Soo,Kim, Seung-Hoi
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p. 666 - 670
(2015/03/14)
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- Design of a versatile and improved precatalyst scaffold for palladium-catalyzed cross-coupling: (η3-1-tBu-indenyl)2(μ-Cl)2Pd2
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We describe the development of (η3-1-tBu-indenyl)2(μ-Cl)2Pd2, a versatile precatalyst scaffold for Pd-catalyzed cross-coupling. Our new system is more active than commercially available (η3-cinnamyl)2(μ-Cl)2Pd2 and is compatible with a range of NHC and phosphine ligands. Precatalysts of the type (η3-1-tBu-indenyl)Pd(Cl)(L) can either be isolated through the reaction of (η3-1-tBu-indenyl)2(μ-Cl)2Pd2 with the appropriate ligand or generated in situ, which offers advantages for ligand screening. We show that the (η3-1-tBu-indenyl)2(μ-Cl)2Pd2 scaffold generates highly active systems for a number of challenging cross-coupling reactions. The reason for the improved catalytic activity of systems generated from the (η3-1-tBu-indenyl)2(μ-Cl)2Pd2 scaffold compared to (η3-cinnamyl)2(μ-Cl)2Pd2 is that inactive PdI dimers are not formed during catalysis.
- Melvin, Patrick R.,Nova, Ainara,Balcells, David,Dai, Wei,Hazari, Nilay,Hruszkewycz, Damian P.,Shah, Hemali P.,Tudge, Matthew T.
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p. 3680 - 3688
(2015/06/16)
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- Generating Active L-Pd(0) via Neutral or Cationic π-Allylpalladium Complexes Featuring Biaryl/Bipyrazolylphosphines: Synthetic, Mechanistic, and Structure-Activity Studies in Challenging Cross-Coupling Reactions
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Two new classes of highly active yet air- and moisture-stable π-R-allylpalladium complexes containing bulky biaryl- and bipyrazolylphosphines with extremely broad ligand scope have been developed. Neutral π-allylpalladium complexes incorporated a range of biaryl/bipyrazolylphosphine ligands, while extremely bulky ligands were accommodated by a cationic scaffold. These complexes are easily activated under mild conditions and are efficient for a wide array of challenging C-C and C-X (X = heteroatom) cross-coupling reactions. Their high activity is correlated to their facile activation to a 12-electron-based L-Pd(0) catalyst under commonly employed conditions for cross-coupling reactions, noninhibitory byproduct release upon activation, and suppression of the off-cycle pathway to form dinuclear (μ-allyl)(μ-Cl)Pd2(L)2 species, supported by structural (single crystal X-ray) and kinetic studies. A broad scope of C-C and C-X coupling reactions with low catalyst loadings and short reaction times highlight the versatility and practicality of these catalysts in organic synthesis.
- Deangelis,Gildner, Peter G.,Chow, Ruishan,Colacot, Thomas J.
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p. 6794 - 6813
(2015/10/06)
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- Catalytic, regioselective, and green methods for rearrangement of 1,2-diaryl epoxides to carbonyl compounds employing metallic triflates, Br?nsted-acidic ionic liquids (ILs), and IL/microwave; experimental and computational substituent effect study on aryl versus hydrogen migration
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The Lewis-acid catalyzed rearrangement of parent trans-stilbene oxide 1 was studied with M(OTf)3/DCM and M(OTf)3/[BMIM][BF4] (M = Bi, Al, Ga, Sc, and Yb; [BMIM] = butylmethylimidazolium) and Zn(NTf2)2, and with Bi(OTf)3/[BMIM][X] (X = NTf2, OTf, PF6, and BF4), employing 5 mol% of catalyst. Selective formation of 2,2-dipheylacetaldehyde 2 (phenyl migration product) was observed in all cases, with Bi(OTf)3 proving most efficient. The rearrangement of 1 was also effected in [BMIM][X] (X = NTf2, OTf, PF6, and BF4) without an added catalyst under microwave MW irradiation, and X = PF6 gave the highest yield and selectivity. Efficient and selective rearrangement of 1-2 was also observed with 0.1-0.3equiv. of [BMIM(SO3H)][OTf] in DCM and in [BMIM][X]. A substituent effect study was performed with a series of singly substituted 1,2-diphenyl oxiranes (with X = OMe, Me, F, CN, and NO2) with 5mol% Bi(OTf)3 in DCM and in [BMIM][NTf2]. Notable formation of ketones was observed with the NO2 and CN derivatives. Competing formation of ketones was also observed in [BMIM][PF6] under MW and under Br?nsted acid catalysis with [BMIM(SO3H)][OTf] in DCM and in [BMIM][NTf2]. The aryl versus H migration was studied computationally by DFT and MP2 methods and by including solvation effects (IEFPCM).
- Jamalian, Arezu,Rathman, Benjamin,Borosky, Gabriela L.,Laali, Kenneth K.
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- Catalytic, regioselective, and green methods for rearrangement of 1,2-diaryl epoxides to carbonyl compounds employing metallic triflates, Br?nsted-acidic ionic liquids (ILs), and IL/microwave; Experimental and computational substituent effect study on aryl versus hydrogen migration
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The Lewis-acid catalyzed rearrangement of parent trans-stilbene oxide 1 was studied with M(OTf)3/DCM and M(OTf)3/[BMIM][BF 4] (M = Bi, Al, Ga, Sc, and Yb; [BMIM] = butylmethylimidazolium) and Zn(NTf2)2, and with Bi(OTf)3/[BMIM][X] (X = NTf2, OTf, PF6, and BF4), employing 5 mol% of catalyst. Selective formation of 2,2-dipheylacetaldehyde 2 (phenyl migration product) was observed in all cases, with Bi(OTf)3 proving most efficient. The rearrangement of 1 was also effected in [BMIM][X] (X = NTf 2, OTf, PF6, and BF4) without an added catalyst under microwave MW irradiation, and X = PF6 gave the highest yield and selectivity. Efficient and selective rearrangement of 1-2 was also observed with 0.1-0.3 equiv. of [BMIM(SO3H)][OTf] in DCM and in [BMIM][X]. A substituent effect study was performed with a series of singly substituted 1,2-diphenyl oxiranes (with X = OMe, Me, F, CN, and NO2) with 5 mol% Bi(OTf)3 in DCM and in [BMIM][NTf2]. Notable formation of ketones was observed with the NO2 and CN derivatives. Competing formation of ketones was also observed in [BMIM][PF6] under MW and under Br?nsted acid catalysis with [BMIM(SO3H)][OTf] in DCM and in [BMIM][NTf2]. The aryl versus H migration was studied computationally by DFT and MP2 methods and by including solvation effects (IEFPCM).
- Jamalian, Arezu,Rathman, Benjamin,Borosky, Gabriela L.,Laali, Kenneth K.
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- An expedient route to heterocycles through α-arylation of ketones and arylamides by microwave induced thermal SRN1 reactions
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Microwave irradiation promotes a quick aromatic nucleophilic substitution by a thermally induced electron transfer process to form new C-C bonds by the coupling of aryl radicals and enolate nucleophiles. Diverse 2-aryl-1- phenylethanones can be prepared by the direct α-arylation of acetophenone with different haloarenes. The ketone enolate anion is generated by deprotonation with tBuOK in DMSO and the reaction is carried out in a closed microwave vessel at 70-100°C for 10 min. This simple procedure also allows the synthesis of deoxybenzoin and indole heterocycle derivatives by inter- or intra-molecular ring closure reactions, with moderate to excellent substitution yields. This journal is the Partner Organisations 2014.
- Soria-Castro, Silvia M.,Caminos, Daniel A.,Penenory, Alicia B.
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p. 17490 - 17497
(2014/05/06)
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- Borontribromide-mediated C-C bond formation in cyclic ketones: A transition metal free approach
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Borontribromide (BBr3) is a well-known demethylating agent. The current investigation was focused on a new application of borontribromide as a C-C bond forming agent in cyclic ketones. In this study, borontribromide mediated C-C bond formation reactions of tetralones, chromenone, thiochromenone and indanones were explored. A methoxy group containing ketones showed selective C-C bond formation reaction instead of demethylation of the methoxy group. MM2 steric energy calculations for the final products showed that the reaction favored the formation of exo- or endo-cyclic double bond containing products, depending upon their low MM2 steric energy in a specific frame structure, as observed in X-ray crystallography. A comprehensive crystallographic and pi-stacking analysis of product 10a demonstrated the formation of 10a as an enantiomeric mixture, and its centre of inversion was stabilized by a set of three unique pi-pi interactions.
- Ahmad, Imran,Pathak, Vinay,Vasudev, Prema G.,Maurya, Hardesh K.,Gupta, Atul
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p. 24619 - 24634
(2014/07/07)
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- DIALKYL(2-ALKOXY-6-AMINOPHENYL)PHOSPHINE, THE PREPARATION METHOD AND USE THEREOF
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The present invention relates to the compound of dialkyl(2-alkoxy-6-aminophenyl)phosphine and the preparation method thereof and the application in the palladium catalyzed coupling reactions of aryl chloride and ketone. The dialkyl(2-alkoxy-6-aminophenyl)phosphine of the present invention could coordinate with the palladium catalyst to highly selectively activate the inert carbon-chlorine bond, and to catalyze direct arylation reaction in the α-position of ketones to produce corresponding coupling compounds. The preparation method of the present invention is a simple one-step method which produces the air-stable dialkyl(2-alkoxy-6-aminophenyl)phosphine. Compared with the synthetic routes of ligands to be used in the activation of carbon-chlorine bonds in the prior arts, the preparation method of the present invention has the advantages of short route and easy operation.
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Paragraph 0055; 0056
(2014/10/29)
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- Catalytic oxidative 1,2-shift in 1,1′-disubstituted olefins using arene(iodo)sulfonic acid as the precatalyst and oxone as the oxidant
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An efficient, catalytic hypervalent iodine-mediated oxidative 1,2-shift of 1,1′-disubstituted olefins is described. This methodology provides concise access to homobenzylic ketones with electron-donating substituents. In the case of cyclic systems, this transformation results in ring-expanded β-benzocycloalkanones, which are useful for further elaboration.
- Purohit, Vikram C.,Allwein, Shawn P.,Bakale, Roger P.
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supporting information
p. 1650 - 1653
(2013/06/27)
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- Pd-catalyzed carbonylative α-arylation of aryl bromides: Scope and mechanistic studies
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Reaction conditions for the three-component synthesis of aryl 1,3-diketones are reported applying the palladium-catalyzed carbonylative α-arylation of ketones with aryl bromides. The optimal conditions were found by using a catalytic system derived from [Pd(dba)2] (dba=dibenzylideneacetone) as the palladium source and 1,3-bis(diphenylphosphino)propane (DPPP) as the bidentate ligand. These transformations were run in the two-chamber reactor, COware, applying only 1.5 equivalents of carbon monoxide generated from the CO-releasing compound, 9-methylfluorene-9-carbonyl chloride (COgen). The methodology proved adaptable to a wide variety of aryl and heteroaryl bromides leading to a diverse range of aryl 1,3-diketones. A mechanistic investigation of this transformation relying on 31P and 13C NMR spectroscopy was undertaken to determine the possible catalytic pathway. Our results revealed that the combination of [Pd(dba)2] and DPPP was only reactive towards 4-bromoanisole in the presence of the sodium enolate of propiophenone suggesting that a [Pd(dppp)(enolate)] anion was initially generated before the oxidative-addition step. Subsequent CO insertion into an [Pd(Ar)(dppp)(enolate)] species provided the 1,3-diketone. These results indicate that a catalytic cycle, different from the classical carbonylation mechanism proposed by Heck, is operating. To investigate the effect of the dba ligand, the Pd0 precursor, [Pd(η3-1-PhC 3H4)(η5-C5H5)], was examined. In the presence of DPPP, and in contrast to [Pd(dba)2], its oxidative addition with 4-bromoanisole occurred smoothly providing the [PdBr(Ar)(dppp)] complex. After treatment with CO, the acyl complex [Pd(CO)Br(Ar)(dppp)] was generated, however, its treatment with the sodium enolate led exclusively to the acylated enol in high yield. Nevertheless, the carbonylative α-arylation of 4-bromoanisole with either catalytic or stoichiometric [Pd(η3-1-PhC3H4) (η5-C5H5)] over a short reaction time, led to the 1,3-diketone product. Because none of the acylated enol was detected, this implied that a similar mechanistic pathway is operating as that observed for the same transformation with [Pd(dba)2] as the Pd source. CO-operation is the key! The first palladium-catalyzed carbonylative α-arylation of aryl bromides is described. A wide array of different aryl 1,3-diketones can be isolated in good-to-excellent yields using only stoichiometric amounts of CO (see scheme). A mechanistic study is presented that suggests the need for enolate coordination prior to oxidative addition when [Pd(dba)2] is employed as the precatalyst. Copyright
- Nielsen, Dennis U.,Lescot, Camille,Gogsig, Thomas M.,Lindhardt, Anders T.,Skrydstrup, Troels
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supporting information
p. 17926 - 17938
(2014/01/17)
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- Visible light-mediated oxidative quenching reaction to electron-rich epoxides: Highly regioselective synthesis of α-bromo (di)ketones and mechanism study
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A novel and simple procedure was developed for the regioselective synthesis of α-bromo (di)ketones from electron-rich epoxides via visible light photoredox catalysis. Through optimization of solvent and light source, the reaction can be rapidly achieved under mild conditions. Moreover, the possible reaction mechanism was proposed and further supported by control experiments.
- Guo, Lin,Yang, Chao,Zheng, Lewei,Xia, Wujiong
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p. 5787 - 5792
(2013/09/12)
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- Oxidative C-C bond cleavage of aldehydes via visible-light photoredox catalysis
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The visible-light mediated oxidative C-C bond cleavage of aldehydes has been achieved in good yields at ambient temperature and open to air using Ru(bpy)3Cl2 (bpy = 2,2′-bipyridine) as the photoredox catalyst. Moreover, we further demonstrated the application in a tandem Michael/oxidative C-C bond cleavage reaction.
- Sun, Hongnan,Yang, Chao,Gao, Fei,Li, Zhe,Xia, Wujiong
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supporting information
p. 624 - 627
(2013/04/23)
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- Nickel-catalyzed intermolecular insertion of aryl iodides to nitriles: A novel method to synthesize arylketones
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A novel procedure for the NiCl2(DME)/dppp/Zn system catalyzed intermolecular insertion of aryl iodides to nitriles was developed, which afforded variously substituted arylketone derivatives in moderate to good yields with tolerance of a wide variety of functional groups.
- Hsieh, Jen-Chieh,Chen, Yen-Chung,Cheng, An-Yi,Tseng, Hsiao-Chun
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supporting information; experimental part
p. 1282 - 1285
(2012/04/23)
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- Synthesis, spectral studies and biological evaluation of a novel series of 2-substituted-5,6-diarylsubstituted imidazo(2,1-b)-1,3, 4-thiadiazole derivatives as possible anti-tubercular agents
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A novel series of 18 analogs of 2-substituted-5,6- diarylsubstituted imidazo(2,1-b)-1,3,4-thiadiazole 6a-r have been synthesized by the reaction of 2-amino-5-substituted- 1,3,4-thiadiazoles 5a-d and an appropriately substituted a-bromo-1,2-(p-substituted)diaryl-1-ethanones 4a-e. Structures of these compounds were established by physiochemical, elemental analysis and spectral data. All the title compounds were tested for their in-vitro anti-tubercular activity against Mycobacterium tuberculosis H37Rv using Alamar Blue susceptibility test and the activity expressed as the minimum inhibitory concentration (MIC) in lg/ml. Among synthesized compounds, compound 6h (MIC = 1.25 μg/ml) exhibited excellent anti-tubercular activity with respect to other synthesized compounds and reference drugs. Compounds 6c, 6f, and6g have also displayed an encouraging anti-tubercular activity profile. Further, some title compounds were also assessed for their cytotoxic activity (IC 50) against in a mammalian Vero cell line using MTT assay. The results reveal that these compounds exhibit anti-tubercular activity at non-cytotoxic concentrations. Springer Science+Business Media, LLC 2011.
- Palkar, Mahesh B.,Noolvi, Malleshappa N.,Maddi, Veeresh S.,Ghatole, Mangala,Nargund, Laxmivenkat G.
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experimental part
p. 1313 - 1321
(2012/08/07)
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- N-heterocyclic carbene adducts of cyclopalladated ferrocenylpyridazine: Synthesis, structural characterization, and application in α-arylation of ketones with aryl chlorides
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A new ferrocene-based ligand 3-chloro-6-pyridazinylferrocene 1 and its N-heterocyclic carbene adducts 2-3 were synthesized and characterized by 1H NMR and IR spectroscopy, ESI-MS, and elemental analysis. Additionally, detailed structures of complexes 2-3 have been determined by single-crystal X-ray analysis. Complex 3 exhibited high catalytic activity for α-arylation of ketones with aryl chlorides. Typically, using 1mol% catalyst in the presence of 1.5 equivalents of tBuOK as base in dioxane at 100°C provided coupled products in good yields.
- Xu, Chen,Li, Hong-Mei,Wang, Zhi-Qiang,Fu, Wei-Jun,Zhang, Yu-Qing,Ji, Bao-Ming
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experimental part
p. 366 - 370
(2012/07/16)
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- Palladium-catalyzed mono-α-arylation of carbonyl-containing compounds with aryl halides using dalphos ligands
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We report the extension and optimization of the [Pd(cinnamyl)Cl] 2/DalPhos catalyst system, previously found effective for the mono-α-arylation of acetone, to the mono-α-arylation of a variety of carbonyl-containing compounds with aryl halides and heteroaryl halides. Aryl methyl ketones, heteroaryl methyl ketones, propiophenones, malonates, and methoxyacetone can be α-arylated under relatively mild conditions and in good yields. We also report the limitations of the ligand/catalyst system towards other classes of carbonyl-containing compounds. We report the application of the [Pd(cinnamyl)Cl]2/DalPhos catalyst system, previously found effective for the mono-α-arylation of acetone, to the mono-α-arylation of a variety of carbonyl-containing compounds with aryl halides and heteroaryl halides.
- Crawford, Sarah M.,Alsabeh, Pamela G.,Stradiotto, Mark
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p. 6042 - 6050,9
(2020/09/02)
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- N-heterocyclic carbene-palladium(II)-1-methylimidazole complex catalyzed α-arylation of ketones with aryl chlorides
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An easily available NHC-Pd(II)-Im (NHC=N-heterocyclic carbene, Im=1-methylimidazole) complex was found to be an efficient catalyst for the α-arylation reaction between ketones and aryl chlorides. Under the optimal conditions, all reactions proceeded smoot
- Xiao, Zheng-Kang,Shao, Li-Xiong
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experimental part
p. 711 - 716
(2012/04/04)
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- Arylation of α-pivaloxyl ketones with arylboronic reagents via Ni-catalyzed sp3 C-O activation
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A Suzuki-Miyaura coupling of α-pivaloxyl ketones via Ni-catalyzed sp3 C-O activation to produce α-aryl ketones is developed. This study offers a convenient method to construct α-arylation products from readily available α-hydroxyl carbonyl compounds.
- Huang, Kun,Li, Gang,Huang, Wei-Ping,Yu, Da-Gang,Shi, Zhang-Jie
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supporting information; experimental part
p. 7224 - 7226
(2011/08/09)
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- Palladium-catalyzed α-ketone arylation under mild conditions
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The α-arylation of ketones with aryl halides catalyzed by the easily prepared and air-stable palladium complex (SIPr)Pd(Py)Cl2 (3) is described. Complex 3 displays high activity for a variety of aryl halides (activated, unactivated, and sterically hindered aryl halides) under mild conditions. Moreover, both aryl and alkyl ketones can be arylated. The α-arylation of some alkyl ketones can even be run at room temperature. The mono- or diarylated products of the unhindered dialkyl ketone 3-pentanone could be controlled by temperature and the ratio of ketones to aryl halides. Palladium-catalyzed α-ketone arylation of aryl and alkyl ketones with aryl halides is described. A total of 31 examples is presented with yields ranging from 45 to 95%.The mono- or diarylated product of the unhindered dialkyl ketone 3-pentanone could be controlled. Copyright
- Cao, Changsheng,Wang, Lingling,Cai, Zhengyuan,Zhang, Lingqiao,Guo, Jin,Pang, Guangsheng,Shi, Yanhui
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supporting information; experimental part
p. 1570 - 1574
(2011/04/17)
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- Synthesis and structural study of benzamarones by X-ray and NMR spectroscopy
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In this work only one diastereomer of benzamarone (1,2,3,4,5- pentaphenylpentan-1,5-dione) 1 was isolated from tandem condensation/addition reaction between deoxybenzoin and benzaldehyde in alkaline medium and by Michael addition of deoxybenzoin to (E)-2-
- Mufato, Jorge D.,Vega, Daniel R.,Aguirre, José M.,De La Faba, Diego J.,Lanta?o, Beatriz
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body text
p. 119 - 125
(2011/04/14)
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