- A facile and sustainable protocol to the preparation of aryl iodides using stable arenediazonium bis(trifluoromethylsulfonyl)imide salts via the telescopic process
-
The preparation of aryl iodides in a telescopic reaction using tert-butyl nitrite as a diazotization reagent and a mixture of bis(trifluoromethane) sulfonamide and glacial acetic acid as a mild acidic agent in ethanol followed by iododediazoniation with tetraethylammonium iodide in water was investigated. The current method has other advantages such as minimized waste by avoiding solvent for the purification of products in diazotization step, simple experimental procedure, and good yield of the sterically hindered aryl amines, metal and strong acid-free waste and environmentally benign conditions. The noteworthy features of this study are the preparation of stable arenediazonium bis(trifluoromethylsulfonyl)imide salts that can be used with no significant loss activity after 1?week and bis(trifluoromethane)sulfonamide was recovered in high yields from reactions.
- Khaligh, Nader Ghaffari
-
-
Read Online
- Palladium-catalyzed, sequential, three-component cross-coupling of aryl halides, alkynes, and arynes
-
(Chemical Equation Presented) Three's a crowd? Polycyclic aromatic hydrocarbons can be synthesized efficiently and in high yield using the first palladium-catalyzed, sequential, three-component coupling of alkynes and arynes with aryl halides (see scheme). This process appears to involve the catalytic, stepwise carbopalladation of an alkyne and an aryne to generate the three-component products.
- Liu, Zhijian,Larock, Richard C.
-
-
Read Online
- Nitrite ionic liquid as a new reagent for in situ synthesis of aryl iodides and azides
-
A new ionic liquid, 1-methyl-3-(2-[2-(1-methyl-1H-imidazol-3-ium-3-yl)ethyloxy] ethyl)-1H-imidazol-3-ium dinitrite, was synthesized. This ionic liquid was used as a convenient nitrosonium source in diazotization of aryl amines into their corresponding diazonium salts, which were converted into aryl iodides and aryl azides using potassium iodide or sodium azide, respectively. Various aryl amines possessing electron-withdrawing groups or electron-donating groups were converted into the corresponding aryl iodides and aryl azides in excellent yields. Advantages of this methodology are the use of mild reaction conditions, short reaction times, and avoiding the use of toxic solvents.
- Eshghi, Hossein,Bakavoli, Mehdi,Ghasemzadeh, Marjan
-
-
Read Online
- Aryl diazonium nanomagnetic sulfate and potassium iodide: An iodination process
-
A simple and efficient procedure for the synthesis of iodoarenes is developed which involves the sequential diazotization-iodination of aromatic amines with sodium nitrite, nanomagnetic supported sulfonic acid, and potassium iodide under solvent-free conditions at room temperature.
- Kolvari, Eskandar,Amoozadeh, Ali,Koukabi, Nadiya,Otokesh, Somayeh,Isari, Mohsen
-
-
Read Online
- PREPARATION OF AROMATIC IODIDES FROM BROMIDES VIA THE REVERSE HALOGEN EXCHANGE
-
Aromatic bromides undergo halogen exchange reaction with iodide ion in the presence of copper(I) iodide in hot hexamethylphosphoric triamide, to give the corresponding iodides in good to moderate yields.
- Suzuki, Hitomi,Kondo, Akiko,Ogawa, Takuji
-
-
Read Online
- Metal-free iodination of arylboronic acids and the synthesis of biaryl derivatives
-
A simple, general and efficient method is developed for the metal-free iodination of arylboronic acids. The protocol uses very cheap molecular iodine as the halide source and potassium carbonate as the base. The method is highly tolerant of various functional groups present in the substrates. Importantly, the iodination strategy can also be applied very effectively in the one-pot, two-step synthesis of biaryl derivatives. Georg Thieme Verlag Stuttgart New York.
- Niu, Liting,Zhang, Hao,Yang, Haijun,Fu, Hua
-
-
Read Online
- The Reactivity of α-Fluoroketones with PLP Dependent Enzymes: Transaminases as Hydrodefluorinases
-
A chemical method for the treatment of harmful halogenated compounds that has recently become of interest is the reductive dehalogenation of carbon-halogen bonds. In the case of a fluorine atom, this process is called hydrodefluorination. While many transition metal-based approaches now exist to reductively defluorinate aromatic fluoroarenes, the cleavage of C?F bonds in aliphatic compounds is not so well-developed. Here we propose a biocatalytic approach exploiting a promiscuous activity exhibited by transaminases (TAs). Hence, a series of α-fluoroketones have been defluorinated with excellent conversions using Chromobacterium violaceum and Arthrobacter sp. TAs under mild conditions and in aqueous medium, using a stoichiometric amount of an amine (e. g. 2-propylamine) as reagent and formally releasing its oxidized form (e. g. acetone), with ammonia and hydrogen fluoride as by-products. It is also demonstrated that this process can be performed in a regio- or stereoselective fashion.
- García-Ramos, Marina,Cuetos, Aníbal,Kroutil, Wolfgang,Grogan, Gideon,Lavandera, Iván
-
p. 3967 - 3972
(2021/08/09)
-
- Palladium-Catalyzed Decarbonylative Iodination of Aryl Carboxylic Acids Enabled by Ligand-Assisted Halide Exchange
-
We report an efficient and broadly applicable palladium-catalyzed iodination of inexpensive and abundant aryl and vinyl carboxylic acids via in situ activation to the acid chloride and formation of a phosphonium salt. The use of 1-iodobutane as iodide source in combination with a base and a deoxychlorinating reagent gives access to a wide range of aryl and vinyl iodides under Pd/Xantphos catalysis, including complex drug-like scaffolds. Stoichiometric experiments and kinetic analysis suggest a unique mechanism involving C?P reductive elimination to form the Xantphos phosphonium chloride, which subsequently initiates an unusual halogen exchange by outer sphere nucleophilic substitution.
- Boehm, Philip,Cacherat, Bastien,Lee, Yong Ho,Martini, Tristano,Morandi, Bill
-
supporting information
p. 17211 - 17217
(2021/07/02)
-
- Selective electrochemical oxidation of aromatic hydrocarbons and preparation of mono/multi-carbonyl compounds
-
A selective electrochemical oxidation was developed under mild condition. Various mono-carbonyl and multi-carbonyl compounds can be prepared from different aromatic hydrocarbons with moderate to excellent yield and selectivity by virtue of this electrochemical oxidation. The produced carbonyl compounds can be further transformed into α-ketoamides, homoallylic alcohols and oximes in a one-pot reaction. In particular, a series of α-ketoamides were prepared in a one-pot continuous electrolysis. Mechanistic studies showed that 2,2,2-trifluoroethan-1-ol (TFE) can interact with catalyst species and generate the corresponding hydrogen-bonding complex to enhance the electrochemical oxidation performance. [Figure not available: see fulltext.]
- Li, Zhibin,Zhang, Yan,Li, Kuiliang,Zhou, Zhenghong,Zha, Zhenggen,Wang, Zhiyong
-
p. 2134 - 2141
(2021/09/29)
-
- The dehydrogenative oxidation of aryl methanols using an oxygen bridged [Cu-O-Se] bimetallic catalyst
-
Herein, we report a new protocol for the dehydrogenative oxidation of aryl methanols using the cheap and commercially available catalyst CuSeO3·2H2O. Oxygen-bridged [Cu-O-Se] bimetallic catalysts are not only less expensive than other catalysts used for the dehydrogenative oxidation of aryl alcohols, but they are also effective under mild conditions and at low concentrations. The title reaction proceeds with a variety of aromatic and heteroaromatic methanol examples, obtaining the corresponding carbonyls in high yields. This is the first example using an oxygen-bridged copper-based bimetallic catalyst [Cu-O-Se] for dehydrogenative benzylic oxidation. Computational DFT studies reveal simultaneous H-transfer and Cu-O bond breaking, with a transition-state barrier height of 29.3 kcal mol?1
- Choudhury, Prabhupada,Behera, Pradyota Kumar,Bisoyi, Tanmayee,Sahu, Santosh Kumar,Sahu, Rashmi Ranjan,Prusty, Smruti Ranjita,Stitgen, Abigail,Scanlon, Joseph,Kar, Manoranjan,Rout, Laxmidhar
-
supporting information
p. 5775 - 5779
(2021/04/12)
-
- Facile preparation of 5-alkyl-1-aryltetrazoles with arenes, acyl chlorides, hydroxylamine, and diphenylphosphoryl azide
-
Successive treatment of arenes with acyl chlorides and AlCl3, the addition of water and removal of solvent, the reaction with NH2OH?HCl and K2CO3, and the reaction with diphenylphosphoryl azide and DBU under warming conditions gave the corresponding 5-alkyl-1-aryltetrazoles efficiently in good to moderate yields. The present method is one-pot transformation of arenes into 5-alkyl-1-aryltetrazoles using the Friedel-Crafts acylation and the Beckmann rearrangement under transition-metal-free conditions.
- Shibasaki, Kaho,Togo, Hideo
-
p. 1816 - 1830
(2020/11/19)
-
- Generation of Organozinc Reagents from Arylsulfonium Salts Using a Nickel Catalyst and Zinc Dust
-
Readily available aryldimethylsulfonium triflates react with zinc powder under nickel catalysis via the selective cleavage of the sp2-hybridized carbon-sulfur bond to produce salt-free arylzinc triflates under mild conditions. This zincation displays superb chemoselectivity and thus represents a protocol that is complementary or orthogonal to existing methods. The generated arylzinc reagents show both high reactivity and chemoselectivity in palladium-catalyzed and copper-mediated cross-coupling reactions.
- Yamada, Kodai,Yanagi, Tomoyuki,Yorimitsu, Hideki
-
p. 9712 - 9718
(2021/01/09)
-
- Highly Active and Robust Ruthenium Complexes Based on Hemilability of Hybrid Ligands for C-H Oxidation
-
Evaluation of the hemilability of hybrid ligands provides a key to understand the metal-ligand cooperation in transition metal catalysis. Here, we design and synthesize a type of RuII complexes based on the hemilability of N-heterocyclic carbenes (NHCs), pyridine, and pyrazole, to compare their activity with other reported Ru catalysts in benzylic C-H oxidation. The RuII catalysts showed ultrastrong catalytic activity in water at room temperature and achieved a turnover frequency (TOF) of 114 h-1, which is the highest TOF value ever reported for Ru-catalyzed benzylic C-H oxidation. The addition of tridentate hybrid ligands in the Ru central position has two beneficial effects: NHCs with a stronger donor ability stabilize the Ru center; however, nitrogen ligands with a relatively weaker donor ability release from the Ru center, so that they induce a reaction. UV-vis, high-resolution electrospray ionization mass spectrometry (ESI-MS), electron paramagnetic resonance (EPR) spectrometry, the trapping of radicals, and the density functional theory calculations (DFT) suggested that a cation catalyst L-RuII-tBuO2H is formed via the reaction between starting RuII catalysts and tert-butyl hydroperoxide, which further undergoes a cleavage of the O-O bond to generate a radical and a cation L-RuIII-OH active intermediate.
- Bo, Chun-Bo,Bu, Qingqing,Li, Xue,Ma, Ge,Wei, Donghui,Guo, Cheng,Dai, Bin,Liu, Ning
-
p. 4324 - 4334
(2020/03/05)
-
- Light and oxygen-enabled sodium trifluoromethanesulfinate-mediated selective oxidation of C-H bonds
-
Visible light-induced organic reactions are important chemical transformations in organic chemistry, and their efficiency highly depends on suitable photocatalysts. However, the commonly used photocatalysts are precious transition-metal complexes and elaborate organic dyes, which hamper large-scale production due to high cost. Here, for the first time, we report a novel strategy: light and oxygen-enabled sodium trifluoromethanesulfinate-mediated selective oxidation of C-H bonds, allowing high-value-added aromatic ketones and carboxylic acids to be easily prepared in high-to-excellent yields using readily available alkyl arenes, methyl arenes and aldehydes as materials. The mechanistic investigations showed that the treatment of inexpensive and readily available sodium trifluoromethanesulfinate with oxygen under irradiation of light could in situ form a pentacoordinate sulfide intermediate as an efficient photosensitizer. The method represents a highly efficient, economical and environmentally friendly strategy, and the light and oxygen-enabled sodium trifluoromethanesulfinate photocatalytic system represents a breakthrough in photochemistry. This journal is
- Fu, Hua,Liu, Can,Liu, Yong,Yang, Haijun,Zhu, Xianjin
-
supporting information
p. 4357 - 4363
(2020/07/14)
-
- ipso-Bromination/iodination of arylboronic acids: Poly(4-vinylpyridine)-Br2/I2 complexes as safe and efficient reagents
-
Poly(4-vinyl pyridine) supported bromine/iodine complexes were prepared and probed for ipso-bromination/iodination of arylboronic acids. These solid complexes with catalytic amount of additive are found to be safe and efficient reagent system for the ipso-bromination/iodination. The reaction occurs under mild conditions and tolerates various functional groups resulting in products with high selectivity and yields.
- Fu, Fang,Gurung, Laxman,Czaun, Miklos,Mathew, Thomas,Prakash, G.K. Surya
-
supporting information
(2019/08/26)
-
- Direct Transformation of Arylamines to Aryl Halides via Sodium Nitrite and N-Halosuccinimide
-
A one-pot universal approach for transforming arylamines to aryl halides via reaction with sodium nitrite (NaNO2) and N-halosuccinimide (NXS) in DMF at room temperature under metal- and acid-free condition is described. This new protocol that is complementary to the Sandmeyer reaction, is suggested to involve the in situ generation of nitryl halide induce nitrosylation of aryl amine to form the diazo intermediate which is halogenated to furnish the aryl halide.
- Mukhopadhyay, Sushobhan,Batra, Sanjay
-
supporting information
p. 14622 - 14626
(2018/09/21)
-
- Oxidation of Tertiary Aromatic Alcohols to Ketones in Water
-
A new rosin-based amphiphile enables the oxidation of tertiary aromatic alcohols in water under mild conditions. The oxidation process is mediated by β-scission of alkoxy radicals. Our catalyst system including the surfactant, catalysts, and water can be easily recycled within the same reaction vial. (Figure presented.).
- Chen, Dengfeng,Zhang, Yuchen,Pan, Xingyu,Wang, Fei,Huang, Shenlin
-
supporting information
p. 3607 - 3612
(2018/09/18)
-
- A general electrochemical strategy for the Sandmeyer reaction
-
Herein we report a general electrochemical strategy for the Sandmeyer reaction. Using electricity as the driving force, this protocol employs a simple and inexpensive halogen source, such as NBS, CBrCl3, CH2I2, CCl4, LiCl and NaBr for the halogenation of aryl diazonium salts. In addition, we found that these electrochemical reactions could be performed using anilines as the starting material in a one-pot fashion. Furthermore, the practicality of this process was demonstrated in the multigram scale synthesis of aryl halides using highly inexpensive graphite as the electrode. A series of detailed mechanism studies have been performed, including radical clock and radical scavenger study, cyclic voltammetry analysis and in situ electron paramagnetic resonance (EPR) analysis.
- Liu, Qianyi,Sun, Beiqi,Liu, Zheng,Kao, Yi,Dong, Bo-Wei,Jiang, Shang-Da,Li, Feng,Liu, Guoquan,Yang, Yang,Mo, Fanyang
-
p. 8731 - 8737
(2018/12/10)
-
- Rapid Iododeboronation with and without Gold Catalysis: Application to Radiolabelling of Arenes
-
Radiopharmaceuticals that incorporate radioactive iodine in combination with single-photon emission computed tomography imaging play a key role in nuclear medicine, with applications in drug development and disease diagnosis. Despite this importance, there are relatively few general methods for the incorporation of radioiodine into small molecules. This work reports a rapid air- and moisture-stable ipso-iododeboronation procedure that uses NIS in the non-toxic, green solvent dimethyl carbonate. The fast reaction and mild conditions of the gold-catalysed method led to the development of a highly efficient process for the radiolabelling of arenes, which constitutes the first example of an application of homogenous gold catalysis to selective radiosynthesis. This was exemplified by the efficient synthesis of radiolabelled meta-[125I]iodobenzylguanidine, a radiopharmaceutical that is used for the imaging and therapy of human norepinephrine transporter-expressing tumours.
- Webster, Stacey,O'Rourke, Kerry M.,Fletcher, Conor,Pimlott, Sally L.,Sutherland, Andrew,Lee, Ai-Lan
-
supporting information
p. 937 - 943
(2017/12/26)
-
- Late stage iodination of biologically active agents using a one-pot process from aryl amines
-
A simple and effective one-pot tandem procedure that generates aryl iodides from readily available aryl amines via stable diazonium salts has been developed. The operationally simple procedure and mild conditions allow late-stage iodination of a wide range of aryl compounds bearing various functional groups and substitution patterns. A novel synthetic strategy involving the preparation of nitroaryl compounds followed by a chemoselective tin(ii) dichloride reduction and the use of the one-pot diazotisation-iodination transformation was also developed. The general applicability of this approach was demonstrated with the preparation of a number of medicinally important compounds including CNS1261, a SPECT imaging agent of the N-methyl-d-aspartate (NMDA) receptor and IBOX, a compound used to detect amyloid plaques in the brain.
- Sloan, Nikki L.,Luthra, Sajinder K.,McRobbie, Graeme,Pimlott, Sally L.,Sutherland, Andrew
-
p. 54881 - 54891
(2017/12/12)
-
- Reactions catalyzed by a binuclear copper complex: Selective oxidation of alkenes to carbonyls with O2
-
Terminal alkenes were selectively cleaved into ketones and aldehydes catalyzed by a binuclear copper catalyst bearing a simple salicylate ligand with O2 as the oxidant. The reaction was carried out under an atmosphere of O2 (balloon) with 0.5 mol% of catalyst and could be performed on a gram scale, providing a convenient and practical method for the cleavage of terminal alkenes into carbonyl compounds.
- Liu, Yuxia,Xue, Dong,Li, Chaoqun,Xiao, Jianliang,Wang, Chao
-
p. 5510 - 5514
(2017/12/08)
-
- Synthesis of Benzoxazoles Using Electrochemically Generated Hypervalent Iodine
-
The indirect ("ex-cell") electrochemical synthesis of benzoxazoles from imines using a redox mediator based on the iodine(I)/iodine(III) redox couple is reported. Tethering the redox-active iodophenyl subunit to a tetra-alkylammonium moiety allowed for anodic oxidation to be performed without supporting electrolyte. The mediator salt can be easily recovered and reused. Our "ex-cell" approach toward the electrosynthesis of benzoxazoles is compatible with a range of redox-sensitive functional groups. An unprecedented concerted reductive elimination mechanism for benzoxazole formation is proposed on the basis of control experiments and DFT calculations.
- Koleda, Olesja,Broese, Timo,Noetzel, Jan,Roemelt, Michael,Suna, Edgars,Francke, Robert
-
p. 11669 - 11681
(2017/11/24)
-
- A unified photoredox-catalysis strategy for C(sp3)-H hydroxylation and amidation using hypervalent iodine
-
We report a unified photoredox-catalysis strategy for both hydroxylation and amidation of tertiary and benzylic C-H bonds. Use of hydroxyl perfluorobenziodoxole (PFBl-OH) oxidant is critical for efficient tertiary C-H functionalization, likely due to the enhanced electrophilicity of the benziodoxole radical. Benzylic methylene C-H bonds can be hydroxylated or amidated using unmodified hydroxyl benziodoxole oxidant Bl-OH under similar conditions. An ionic mechanism involving nucleophilic trapping of a carbocation intermediate by H2O or CH3CN cosolvent is presented.
- Li, Guo-Xing,Morales-Rivera, Cristian A.,Gao, Fang,Wang, Yaxin,He, Gang,Liu, Peng,Chen, Gong
-
p. 7180 - 7185
(2017/10/05)
-
- Simple and Efficient Generation of Aryl Radicals from Aryl Triflates: Synthesis of Aryl Boronates and Aryl Iodides at Room Temperature
-
Despite the wide use of aryl radicals in organic synthesis, current methods to prepare them from aryl halides, carboxylic acids, boronic acids, and diazonium salts suffer from limitations. Aryl triflates, easily obtained from phenols, are promising aryl radical progenitors but remain elusive in this regard. Inspired by the single electron transfer process for aryl halides to access aryl radicals, we developed a simple and efficient protocol to convert aryl triflates to aryl radicals. Our success lies in exploiting sodium iodide as the soft electron donor assisted by light. This strategy enables the scalable synthesis of two types of important organic molecules, i.e., aryl boronates and aryl iodides, in good to high yields, with broad functional group compatibility in a transition-metal-free manner at room temperature. This protocol is anticipated to find potential applications in other aryl-radical-involved reactions by using aryl triflates as aryl radical precursors.
- Liu, Wenbo,Yang, Xiaobo,Gao, Yang,Li, Chao-Jun
-
supporting information
p. 8621 - 8627
(2017/07/06)
-
- Copper-catalyzed conversion of aryl and heteroaryl bromides into the corresponding iodide
-
An efficient method for the synthesis of aryl and heteroaryl iodides is described in this study. The reactions of aryl and heteroaryl bromides with potassium iodide proceeded smoothly in the presence of a copper catalyst under mild reaction conditions to produce the corresponding iodides in satisfactory to excellent yields.
- Feng, Xiujuan,Li, Lingyu,Yu, Xiaoqiang,Yamamoto, Yoshinori,Bao, Ming
-
p. 129 - 132
(2016/07/06)
-
- Easy Access to Difluoromethylene-Containing Arene Analogues through Palladium-Catalysed C–H Olefination
-
An efficient palladium-catalysed ortho-C–H olefination of α,α-difluorophenylacetic acid derivatives using 8-aminoquinoline as a bidentate directing group has been developed. A range of olefinated arenes can thus be synthesized in a concise way. This reaction provides an easy and straightforward route to a panel of difluoromethylated arene analogues in moderate to good yields, with a satisfactory tolerance of common functional groups. Transformation of the products into a variety of other difluoromethylene-containing compounds demonstrates the utility of this method.
- Shao, Changdong,Shi, Guangfa,Zhang, Yanghui
-
supporting information
p. 5529 - 5538
(2016/11/25)
-
- Using Anilines as Masked Cross-Coupling Partners: Design of a Telescoped Three-Step Flow Diazotization, Iododediazotization, Cross-Coupling Process
-
The conversion of commercially available anilines into biaryl and biarylacetylene products was realized by using a telescoped, three-reactor flow diazotization/iododediazotization/cross-coupling process. The segmented flow stream created by off-gassing during the Sandmeyer sequence was restored to a continuous column of reaction solution by using a specially designed continuous-flow unit controlled by custom software created in-house. The resultant aryl iodide was then combined with a stream of cross-coupling solution that fed into the final reactor. The system proved versatile as modifications to the diazotization/iododediazotization sequence could be made rapidly to account for any substrate specificity (e.g., solubility problems), leading to a wide substrate scope of Suzuki–Miyaura and Sonogashira cross-coupled products.
- Teci, Matthieu,Tilley, Michael,McGuire, Michael A.,Organ, Michael G.
-
supporting information
p. 17407 - 17415
(2016/11/23)
-
- A practical and general ipso iodination of arylboronic acids using N-iodomorpholinium iodide (NIMI) as a novel iodinating agent: mild and regioselective synthesis of aryliodides
-
A mild and efficient protocol for the ipso-iodination of aryl boronic acids using N-iodomorpholinium iodide (NIMI) generated in situ from morpholine and molecular iodine as a novel iodinating agent has been developed. The addition of a catalytic amount of copper iodide found to promote rate enhancement of the iodination reaction and dramatic increase in the yield depending upon the nature of the boronic acid was observed. The mechanistic study revealed that depending upon the nature of the substrate, either the classical ipso substitution or copper catalysed iododeborylation pathway overall dominates the present iodination reaction. The features such as mild reaction conditions, operational simplicity, high to excellent yields, excellent functional group compatibility and low catalyst loading make this method potentially useful in organic synthesis.
- Tale,Toradmal,Gopula
-
p. 84910 - 84919
(2015/10/28)
-
- A Single Nickel Catalyst for the Acceptorless Dehydrogenation of Alcohols and Hydrogenation of Carbonyl Compounds
-
A single homogeneous nickel(II) complex, supported by the tris(3,5-dimethylpyrazolyl)borate ligand and 2-hydroxyquinoline ancillary ligand, is shown to catalyze both acceptorless dehydrogenation of alcohols and hydrogenation of carbonyl compounds under mild conditions. Products from the catalytic reactions were isolated with good yields. A mechanistic investigation highlights the critical role of the 2-hydroxyquinoline ligand in the catalysis and argues against a stepwise dehydrogenation pathway.
- Chakraborty, Sumit,Piszel, Paige E.,Brennessel, William W.,Jones, William D.
-
supporting information
p. 5203 - 5206
(2015/11/18)
-
- Fluorous bispidine: A bifunctional reagent for copper-catalyzed oxidation and knoevenagel condensation reactions in water
-
Fluorous bispidine-type ligands have been developed to facilitate its recovery and reusability and to demonstrate its bifunctional property as a ligand and base in copper-catalyzed aerobic oxidation, the Knoevenagel condensation and tandem oxidation/Knoevenagel condensation in water under mild conditions. Application of the fluorous ligand was also extended to the surfactant-free copper-catalyzed allylic and benzylic sp3 C-H oxidation reaction in water. The fluorous ligands could be recovered using F-SPE with recovery ranging from 91-97% and could be reused five times with little loss of activity.
- Ang, Wei Jie,Chng, Yong Sheng,Lam, Yulin
-
p. 81415 - 81428
(2015/10/06)
-
- Monoamine oxidase-ω-transaminase cascade for the deracemisation and dealkylation of amines
-
Herein we report a one-pot protocol for the deracemisation of chiral benzylic amines employing a novel monoamine oxidase-ω-transaminase cascade, allowing access to enantiopure compounds in >99 % ee. We also demonstrate that the same enzymatic cascade can be employed for the dealkylation of secondary amines with >99 % conversion. Cascade ball: A monoamine oxidase- ω-transaminase cascade has been developed for the deracemisation of chiral benzylic amines, allowing access to the enantiopure compounds in >99 % ee. The same system was also employed for the efficient dealkylation of secondary amines.
- O'Reilly, Elaine,Iglesias, Cesar,Turner, Nicholas J.
-
p. 992 - 995
(2014/05/06)
-
- Fe-catalyzed acceptorless dehydrogenation of secondary benzylic alcohols
-
Oxidation of alcohols is an essential organic reaction, affording versatile carbonyl groups. To provide a sustainable solution for environmentally harmful traditional oxidation methods, the transition-metal catalyzed acceptor-free dehydrogenation of alcohols has attracted much attention. The widely used catalysts for the dehydrogenation reaction are based on precious metals, which are not economical and environmentally benign. We developed an operationally simple, economical, and environmentally benign acceptorless Fe-catalyzed dehydrogenation of various secondary benzylic alcohols to afford the corresponding ketones and H2. A simple in situ mixture of readily available Fe(III) acetylacetonate, 1,10-phenanthroline, and K2CO3 was identified as an active catalyst for this transformation.
- Song, Hansoo,Kang, Byungjoon,Hong, Soon Hyeok
-
p. 2889 - 2895
(2015/01/08)
-
- Well-defined iron catalysts for the acceptorless reversible dehydrogenation-hydrogenation of alcohols and ketones
-
Acceptorless dehydrogenation of alcohols, an important organic transformation, was accomplished with well-defined and inexpensive iron-based catalysts supported by a cooperating PNP pincer ligand. Benzylic and aliphatic secondary alcohols were dehydrogenated to the corresponding ketones in good isolated yields upon release of dihydrogen. Primary alcohols were dehydrogenated to esters and lactones, respectively. Mixed primary/secondary diols were oxidized at the secondary alcohol moiety with good chemoselectivity. The mechanism of the reaction was investigated using both experiment and DFT calculations, and the crucial role of metal-ligand cooperativity in the reaction was elucidated. The iron complexes are also excellent catalysts for the hydrogenation of challenging ketone substrates at ambient temperature under mild H2 pressure, the reverse of secondary alcohol dehydrogenation.
- Chakraborty, Sumit,Lagaditis, Paraskevi O.,F?rster, Moritz,Bielinski, Elizabeth A.,Hazari, Nilay,Holthausen, Max C.,Jones, William D.,Schneider, Sven
-
p. 3994 - 4003
(2015/01/16)
-
- Direct conversion of alcohols to α-chloro aldehydes and α-chloro ketones
-
Direct conversion of primary and secondary alcohols into the corresponding α-chloro aldehydes and α-chloro ketones using trichloroisocyanuric acid, serving both as stoichiometric oxidant and α-halogenating reagent, is reported. For primary alcohols, TEMPO has to be added as an oxidation catalyst, and for the transformation of secondary alcohols (TEMPO-free protocol), MeOH as an additive is essential to promote chlorination of the intermediary ketones.
- Jing, Yuanyuan,Daniliuc, Constantin G.,Studer, Armido
-
supporting information
p. 4932 - 4935
(2015/04/27)
-
- Mizoroki-Heck reactions of methyl acrylate in presence of a palladated rasta resin
-
Mizoroki-Heck cross-couplings of aryl halides in the presence of a palladium catalyst supported on a rasta resin bearing diphenylphosphanyl ligands are reported. In particular, we show that tiny amounts of soluble palladium species leached from the polymeric support catalyze the reaction. A one-pot two steps preparation of alkenes from aryl bromides using a Finkelstein halogen exchange reaction is also described.
- Derible, Antoine,Becht, Jean-Michel,Le Drian, Claude
-
p. 4207 - 4209
(2013/07/26)
-
- Hydration of terminal alkynes catalyzed by water-soluble cobalt porphyrin complexes
-
Water-soluble cobalt(III) porphyrin complexes were found to promote the hydration of terminal alkynes to give methyl ketones. The alkyne hydration proceeded in good to excellent yield with 0.1 to 2 mol % cobalt catalyst 1 and was compatible with the presence of acid/base- or redox-sensitive functional groups such as alkyl silyl ethers; allyl ethers; trityl ethers; benzyl ethers; carboxylic esters; boronic esters; carboxamides; nitriles; and nitro, iodo, and acetal groups. Some of the alkyne substrates tested here are otherwise difficult to hydrate. The alkyne hydration can be performed on a gram scale, and the catalyst can be recovered by aqueous workup.
- Tachinami, Tadashi,Nishimura, Takuho,Ushimaru, Richiro,Noyori, Ryoji,Naka, Hiroshi
-
supporting information
p. 50 - 53
(2013/02/23)
-
- Praseodymium incorporated alpo-5 molecular sieves for aerobic oxidation of ethylbenzene
-
PrAlPO-5 with (Al+P)/Pr ratios of 25, 50, 75 and 100 molecular sieves were successfully synthesized by hydrothermal method. These molecular sieves were characterised using XPS, TPD-NH3, ex-situ pyridine adsorbed IR, TPR, TGA, 27Al and 31P MAS-NMR and ESR studies. The incorporation of praseodymium in the framework of AlPO-5 was confirmed by XRD, DRS UV-vis and 27Al and 31P MAS-NMR analysis. ESR spectrum showed the presence of adsorbed oxygen. The nature and strength of acid sites were identified by ex-situ pyridine adsorbed IR and TPD-NH3. The BET surface area was found to be in the range of 238-272 m2 g -1. The catalytic activity of the molecular sieves was tested for the liquid phase aerobic oxidation of ethylbenzene. Acetophenone was found to be the major product with more than 90% ethylbenzene conversion. ICP-OES analysis revealed the presence of praseodymium intact in the framework of AlPO-5 up to five cycles. Copyright
- Sundaravel,Babu,Palanisamy,Palanichamy,Shanthi,Murugesan
-
p. 2507 - 2516
(2013/08/25)
-
- A simple and effective copper catalyst for the conversion of arylboronic acids to aryl iodides at room temperature
-
Simple Cu(NO3)2·3H2O was demonstrated to be of ability to catalyze the conversion of arylboronic acids to aryl iodides at room temperature. Compared with the previous copper-catalyzed method, the present procedure avoids the use of the ligand, the oxidant as well as the heating condition.
- Ren, Yun-Lai,Tian, Xin-Zhe,Dong, Chuanhua,Zhao, Shuang,Wang, Jianji,Yan, Mengjie,Qi, Xiaoguang,Liu, Guihua
-
-
- Efficient and selective oxidation of alcohols catalyzed by oxo-rhenium complexes
-
This work reports the catalytic activity of several oxo-rhenium complexes in the oxidation of alcohols, using a sulfoxide as oxidant agent. The catalytic system bis(4-chlorophenyl) sulfoxide/ReOCl3(PPh3) 2 (10 mol%) proved to be efficient for the oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones. The primary alcohols are selectively oxidized to the corresponding aldehydes with no further oxidation to acids. The bis(4-chlorophenyl) sulfide, isolated as by-product in high yields, can be used as a substrate in other reactions or can be oxidized and reused in this procedure.
- Sousa, Sara C.A.,Bernardo, Joana R.,Florindo, Pedro R.,Fernandes, Ana C.
-
p. 134 - 138
(2013/07/26)
-
- Selective benzylic oxidation of alkyl substituted aromatics to ketones over Ag/SBA-15 catalysts
-
Benzylic and cycloalkane CH bonds have selectively been oxidized into corresponding ketones with t-BuOOH over Ag/SBA-15 catalysts, which were prepared by varying the loading of Ag (2, 4, 6 and 8% by weight) on SBA-15 support using an impregnation method. The retention of mesoporous structural ordering and crystalline behavior of Ag have been confirmed by N2 adsorption and XRD studies. 4Ag/SBA-15 catalyst is found to be the best catalyst among the Ag/SBA-15 series. The influence of various parameters such as oxidant, solvent, temperature and time of reaction etc. have been systematically studied on Ag/SBA-15 catalyst.
- Anand, Narani,Reddy, Kannapu Hari Prasad,Prasad, Ganjala Venkata Siva,Rama Rao, Kamaraju Seetha,Burri, David Raju
-
scheme or table
p. 5 - 9
(2012/06/16)
-
- Ruthenium-catalyzed transformation of aryl and alkenyl triflates to halides
-
Aryl triflates were transformed to aryl bromides/iodides simply by treating them with LiBr/NaI and [Cp*Ru(MeCN)3]OTf. The ruthenium complex also catalyzed the transformation of alkenyl sulfonates and phosphates to alkenyl halides under mild conditions. Aryl and alkenyl triflates undergo oxidative addition to a ruthenium(II) complex to form η'1- arylruthenium and 1-ruthenacyclopropene intermediates, respectively, which are transformed to the corresponding halides.
- Imazaki, Yusuke,Shirakawa, Eiji,Ueno, Ryota,Hayashi, Tamio
-
supporting information
p. 14760 - 14763
(2012/11/07)
-
- Cobalt-catalyzed preparation of arylindium reagents from aryl and heteroaryl bromides
-
A cobalt-bathophenanthroline catalyst has been developed for the direct preparation of a variety of arylindium reagents from the corresponding aryl and heteroaryl bromides in the presence of indium metal and lithium chloride. The thus-formed arylindium reagents undergo efficient palladium-catalyzed cross-coupling reactions with aryl iodides, tolerating various functional groups including hydroxy and free amino groups.
- Adak, Laksmikanta,Yoshikai, Naohiko
-
experimental part
p. 7563 - 7568
(2011/11/12)
-
- Copper-catalyzed halogenation of arylboronic acids
-
In this Letter, a copper-catalyzed halogenation of arylboronic acids was described. This reaction tolerates a variety of functional groups, providing aromatic halides with good yields. It represents a facile and mild procedure to aryl halides.
- Zhang, Guangyou,Lv, Guanglei,Li, Liping,Chen, Fan,Cheng, Jiang
-
experimental part
p. 1993 - 1995
(2011/04/25)
-
- A one-pot method for the iodination of aryl amines via stable aryl diazonium silica sulfates under solvent-free conditions
-
A convenient and rapid one-pot method for the synthesis of iodoarenes is developed which involves the sequential diazotization-iodination of aromatic amines with sodium nitrite, silica sulfuric acid and potassium iodide under solvent-free conditions at room temperature. Various aromatic amines possessing electron-withdrawing groups or electron-donating groups are converted into the corresponding aryl iodides in good yields. Georg Thieme Verlag Stuttgart.
- Zarei, Amin,Hajipour, Abdol R.,Khazdoozd, Leila
-
experimental part
p. 941 - 944
(2009/12/02)
-
- A safe and reliable procedure for the iododeamination of aromatic and heteroaromatic amines in a continuous flow reactor
-
A method for the safe and reliable iododeamination of aromatic and heteroaromatic amines under copper-free conditions is described and its scope is evaluated.
- Malet-Sanz, Laia,Madrzak, Julia,Holvey, Rhian S.,Underwood, Toby
-
experimental part
p. 7263 - 7267
(2010/03/03)
-
- Sulfonic acid based cation-exchange resin: A novel proton source for one-pot diazotization-iodination of aromatic amines in water
-
A convenient and simple one-pot method for the preparation of iodoarenes at room temperature has been developed, by sequential diazotization-iodination of aromatic amines with NaNO2/KI in the presence of a sulfonic acid based cation-exchange resin in water. This inexpensive, noncorrosive and eco-friendly synthetic route is general in nature and allows for the preparation of iodoarenes with an electron-donating or -withdrawing group in various positions from the corresponding amines in 50-98% yields. Georg Thieme Verlag Stuttgart.
- Filimonov, Victor D.,Semenischeva, Nadya I.,Krasnokutskaya, Elena A.,Tretyakov, Alexei N.,Ho, Yun Hwang,Chi, Ki-Whan
-
p. 185 - 187
(2008/12/20)
-
- Iodination of aryl amines in a water-paste form via stable aryl diazonium tosylates
-
The diazotization of aryl amines at room temperature in paste form with NaNO2, p-TsOH and a small amount of water, followed by treatment with KI provides a new, simple, and effective route for the preparation of various aryl iodides. The water-paste and strong acid-free reaction conditions are environmentally friendly and compatible with acid-sensitive functional groups.
- Gorlushko, Dmitry A.,Filimonov, Victor D.,Krasnokutskaya, Elena A.,Semenischeva, Nadya I.,Go, Bong Seong,Hwang, Ho Yun,Cha, Eun Hye,Chi, Ki-Whan
-
p. 1080 - 1082
(2008/09/18)
-
- A new, one-step, effective protocol for the iodination of aromatic and heterocyclic compounds via aprotic diazotization of amines
-
We have developed a convenient one-step preparation of aromatic and some heterocyclic iodides by the sequential diazotization-iodination of the aromatic amines with a KI/NaNO2/p-TsOH system in acetonitrile at room temperature. This method has general character and allows aryl iodides with either donor or acceptor substituents in various positions to be obtained from the corresponding amines in 50-90% yield. Georg Thieme Verlag Stuttgart.
- Krasnokutskaya, Elena A.,Semenischeva, Nadya I.,Filimonov, Victor D.,Knochel, Paul
-
-
- 2,2′-bipyridine: An efficient ligand in the cobalt-catalyzed synthesis of organozinc reagents from aryl chlorides and sulfonates
-
The synthesis of functionalized arylzinc reagents from aromatic chlorides, triflates, or mesylates, via cobalt catalysis, is reported using 2,2′-bipyridine as a ligand in a mixture of acetonitrile and pyridine. This procedure allows the synthesis of a variety of functionalized arylzinc species in good to excellent yields. Some of these arylzinc compounds have been coupled with aromatic bromides under palladium catalysis. Georg Thieme Verlag Stuttgart.
- Kazmierski, Igor,Gosmini, Corinne,Paris, Jean-Marc,Périchon, Jacques
-
p. 881 - 884
(2007/10/03)
-