- Selectivity Modulation of the Ley–Griffith TPAP Oxidation with N-Oxide Salts
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A wide variety of novel non-hygroscopic N-oxide tetraphenylborate salts were synthesized and evaluated as co-oxidants in the Ley–Griffith (TPAP) oxidation of benzylic and allylic alcohols under non-anhydrous conditions. The novel DABCOO·TPB (2:1) salt was herein unearthed as a viable competitor to the first-generation NMO·TPB (2:1) salt, but more importantly gave increased performance under oxidative competition. X-ray crystal structure analysis and NMR spectroscopy revealed that depending on the crystallization conditions 1:1, 2:1 or 3:2 N-oxide–tetraphenylborate salts could be formed.
- Moore, Peter W.,Jiao, Yanxiao,Mirzayans, Paul M.,Sheng, Lexter Ng Qi,Hooker, Jordan P.,Williams, Craig M.
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- Efficient cyanation of aryl bromides with K4[Fe(CN)6] catalyzed by a palladium-indolylphosphine complex
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This study describes a general palladium-catalyzed cyanation of aryl bromides using K4[Fe(CN)6] as the cyanide surrogate. The reactions can be successfully conducted under mild reaction conditions (at 50 °C) in mixed solvents (water/MeCN = 1:1) without any surfactant additives, and afford the desired aryl nitriles in good-to-excellent yields. Particularly noteworthy is that this system allows the mildest reaction temperature reported so far for palladium-catalyzed cyanation of aryl bromides with K 4[Fe(CN)6] source in general. Common functional groups, including keto, aldehyde, free amine, and heterocyclic substrates are compatible under this system. Interestingly, the phosphine ligands bearing -PCy 2 moiety, which usually show excellent activity in aryl halide couplings, are found less effective than the corresponding ligands with -PPh2 group.
- Yeung, Pui Yee,Tsang, Chun Pui,Kwong, Fuk Yee
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- Copper-catalyzed cyanation of arylboronic acids using DDQ as cyanide source
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In this paper, a copper-catalyzed cyanation of arylboronic acids is achieved with DDQ, providing nitriles with good yields. This new approach represents a safe method for the synthesis of aryl nitriles. Georg Thieme Verlag Stuttgart ? New York.
- Zhang, Guangyou,Chen, Shuyou,Fei, Haiyang,Cheng, Jiang,Chen, Fan
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- Mild palladium-catalyzed cyanation of (hetero)aryl halides and triflates in aqueous media
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A mild, efficient, and low-temperature palladium-catalyzed cyanation of (hetero)aryl halides and triflates is reported. Previous palladium-catalyzed cyanations of (hetero)aryl halides have required higher temperatures to achieve good catalytic activity. This current reaction allows the cyanation of a general scope of (hetero)aryl halides and triflates at 2-5 mol % catalyst loadings with temperatures ranging from rt to 40 °C. This mild method was applied to the synthesis of lersivirine, a reverse transcriptase inhibitor.
- Cohen, Daniel T.,Buchwald, Stephen L.
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- An effective synthesis of N,N-dimethylamides from carboxylic acids and a new route from N,N-dimethylamides to 1,2-diaryl-1,2-diketones
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Carboxylic acids were heated at 150 °C in DMF in the presence of 1.25 equiv of thionyl chloride to give corresponding N,N-dimethylamides in good yields. Tandem chlorination and amidation reactions occurred in the one-pot procedure. Dicarboxylic acids needed prolonged reaction time to produce bisamides in good yields. Some benzamides were efficiently converted into corresponding 1,2-diaryl-1,2-diketones (benzils) under acyloin condensation conditions in the presence of 4,4′-di-tert-butylbiphenyl (DBB) in THF. Ultrasonic irradiation effectively accelerates the reaction, but it is not critical. However, the presence of DBB is fatal to the reaction. Although a few synthetic methods for benzils from benzoic acids have been reported so far, this method is one of the most convenient and highly reproducible procedures.
- Kumagai, Takashi,Anki, Tomohiro,Ebi, Takahiro,Konishi, Akihito,Matsumoto, Kouzou,Kurata, Hiroyuki,Kubo, Takashi,Katsumoto, Kenta,Kitamura, Chitoshi,Kawase, Takeshi
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- Electrochemical Activation of Galactose Oxidase: Mechanistic Studies and Synthetic Applications
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The enzyme galactose oxidase (GOase) is a copper radical oxidase that catalyzes the aerobic oxidation of primary alcohols to the aldehydes and has been utilized to that end in large-scale pharmaceutical processes. To maintain its catalytic activity and ensure high substrate conversion, GOase needs to be continuously (re)activated by 1e- oxidation of the constantly formed out-of-cycle species (GOasesemi) to the catalytically active state (GOaseox). In this work, we report an electrochemical activation method for GOase that replaces the previously used expensive horseradish peroxidase activator in a GOase-catalyzed oxidation reaction. First, the formation of GOaseox of a specifically engineered variant via nonenzymatic oxidation of GOasesemi was studied by UV-vis spectroscopy. Second, electrochemical oxidation of GOase by mediators was studied using cyclic voltammetry. The electron-transfer rates between GOase and various mediators at different pH values were determined, showing a dependence on both the redox potential of the mediator and the pH. This observation suggests that the oxidation of GOase by mediators at pH 7-9 likely occurs via a concerted proton-coupled electron-transfer (PCET) mechanism under anaerobic conditions. Finally, this electrochemical GOase activation method was successfully applied to the development of a bioelectrocatalytic GOase-mediated aerobic oxidation of benzyl alcohol derivatives, cinnamyl alcohol, and aliphatic polyols, including the desymmetrizing oxidation of 2-ethynylglycerol, a key step in the biocatalytic cascade used to prepare the promising HIV therapeutic islatravir.
- Fryszkowska, Anna,Klapars, Artis,Marshall, Nicholas,Ruccolo, Serge,Strotman, Neil A.,Zhang, Shaoguang
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- New selective metal-free oxidations of primary alcohols by HNO3 or HNO3 and O2, catalyzed by Br2
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Primary benzylic alcohols are selectively oxidized to the corresponding aromatic aldehydes by molecular oxygen at atmospheric pressure, under Br 2-HNO3 catalysis in a biphasic medium (1,2-dichloroethane- water, 5:1) at 60 °C. Under paragonable experimental conditions the aliphatic alcohols are oxidized to esters.
- Minisci, Francesco,Porta, Ombretta,Recupero, Francesco,Punta, Carlo,Gambarotti, Cristian,Pierini, Monica,Galimberti, Laura
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- 4CzIPN catalyzed photochemical oxidation of benzylic alcohols
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A green photoredox oxidation of benzylic primary and secondary alcohols to aldehydes and ketones with air as an oxidant was reported. The oxidation shows broad substrate scope and excellent selectivity over benzylic alcohols to the aliphatic alcohols. Further mechanistic studies revealed a quinuclidine mediated HAT process, and blue LEDs promoted 4CzlPN (1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene) photoredox cycle were involved in our oxidation.
- Zhang, Heng,Guo, Tianyun,Wu, Mingzhong,Huo, Xing,Tang, Shouchu,Wang, Xiaolei,Liu, Jian
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- Tungstate-loaded triazine-based magnetic poly(Bis-imidazolium ionic liquid): An effective bi-functional catalyst for tandem selective oxidation/Knoevenagel condensation in water
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A novel bi-functional polymeric catalyst was synthesized by immobilization of tungstate anions onto the nitrogen rich poly(ionic liquid)/magnetic nanocomposite. The resulting catalyst has two types of catalytic sites: (i) immobilized WO4 anions with bis-imidazolium ionic liquid cation for selective oxidation of alcohols and (ii) basic amine groups for Knoevenagel condensation between produced aldehyde and malononitrile. Due to the polymeric nature of the catalyst, large amounts of tungstate and basic nitrogen groups were presented on the solid surface which led to a decrease in the applied catalyst mass for catalytic reaction. High catalytic activity and excellent selectivity of catalyst in water medium make this protocol a green way for production of fine chemicals.
- Zohreh, Nasrin,Tavakolizadeh, Maryam,Hosseini, Seyed Hassan,Pourjavadi, Ali,Bennett, Craig
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- Efficient and Highly Selective Solvent-Free Oxidation of Primary Alcohols to Aldehydes Using Bucky Nanodiamond
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Selective oxidation of alcohols to aldehydes is widely applicable to the synthesis of various green chemicals. The poor chemoselectivity for complicated primary aldehydes over state-of-the-art metal-free or metal-based catalysts represents a major obstacle for industrial application. Bucky nanodiamond is a potential green catalyst that exhibits excellent chemoselectivity and cycling stability for the selective oxidation of primary alcohols in diverse structures (22 examples, including aromatic, substituted aromatic, unsaturated, heterocyclic, and linear chain alcohols) to their corresponding aldehydes. The results are comparable to reported transition-metal catalysts including conventional Pt/C and Ru/C catalysts for certain substrates under solvent-free conditions. The possible activation process of the oxidant and substrates by the surface oxygen groups and defect species are revealed with model catalysts, ex situ electrochemical measurements, and ex situ attenuated total reflectance. The zigzag edges of sp2 carbon planes are shown to play a key role in these reactions.
- Lin, Yangming,Wu, Kuang-Hsu Tim,Yu, Linhui,Heumann, Saskia,Su, Dang Sheng
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- Tetra-n-butylammonium bromide: A simple but efficient organocatalyst for alcohol oxidation under mild conditions
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A simple but efficient organocatalytic system with 5 mol% tetra-n-butylammonium bromide (TBAB) as the catalyst has been identified for alcohol oxidation for the first time. This organocatalytic system is compatible with a broad range of benzylic/allylic alcohols with various catalytically reactive groups. Besides, it shows excellent selectivity for secondary benzylic alcohols over aliphatic alcohols, and good selectivity over the primary benzylic alcohol site in 4-(1-hydroxyethyl)benzyl alcohol. Thus, the features of simplicity, high efficiency, selectivity and mildness of reaction conditions associated with this TBAB organocatalytic system suggest its potential for widespread use in synthetic chemistry.
- Ma, Xinyi,Li, Zhongfeng,Liu, Feijie,Cao, Shengli,Rao, Honghua
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- One-pot oxidant-free dehydrogenation-Knoevenagel tandem reaction catalyzed by a recyclable magnetic base-metal bifunctional catalyst
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A new base-metal bifunctional catalyst NH-Pd(0)@MNP was prepared via a facile procedure and fully characterized. The as-prepared catalyst was used as an efficient relay catalyst for the one-pot oxidant-free dehydrogenation-Knoevenagel condensation tandem reaction from benzyl alcohol in H2O under mild conditions and generated benzalmalononitriles with yield up to 96%. Meanwhile, the catalyst could be easily recovered from the reaction system by an external magnetic field, and is reusable with little loss of activity up to 6 runs (5%).
- Yuan, Xiaofeng,Wan, Zijuan,Ning, Jinfeng,Zhang, Qiang,Luo, Jun
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- Contrasting reactivity of 2-mesityl-1,8-naphthyridine (Mes-NP) with singly-bonded [RhIIRhII] and [RuIRu I] compounds
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Reaction of cis-[Rh2(CH3COO) 2 (CH 3CN) 6](BF4)2 with two equivalents of 2-mesityl-1,8- naphthyridine (Mes-NP) affords trans-[Rh2(CH3COO) 2(Mes-NP) 2](BF4) 2 (1). X-ray structure reveals weak RhC(ipso) interaction, and a short RhRh distance. The same ligand, in contrast, oxidatively cleaves the RuRu bond in cis-[Ru2 (CO) 4 (CH3CN) 6](BF4)2 and results in trans-[Ru(Mes-NP) 2 (CH3CN) 2](BF4)2 (2). Both compounds adopt trans geometry to relieve the steric strain. Compound 2 exhibits moderate activity for the alcohol oxidation and aldehyde olefination reactions. CSIRO 2011.
- Saha, Biswajit,Rahaman, S. M. Wahidur,Sinha, Arup,Bera, Jitendra K.
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- Candida parapsilosis ATCC 7330 mediated oxidation of aromatic (activated) primary alcohols to aldehydes
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A green, simple and high yielding [up to 86% yield] procedure is developed for the oxidation of aromatic (activated) primary alcohols to aldehydes using whole cells of Candida parapsilosis ATCC 7330. The biotransformation is carried out under mild conditions at 25 °C, in hexane: water (48 : 2) (v/v).
- Sivakumari, Thakkellapati,Chadha, Anju
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- Synthesis of new Zn (II) complexes for photo decomposition of organic dye pollutants, industrial wastewater and photo-oxidation of methyl arenes under visible-light
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Synthesis of new Schiff's base Zn-complexes for photo-oxidation of methyl arenes and xylenes are reported under visible light irradiation conditions. All the synthesized new ligands and Zn-complexes are thoroughly characterized with various spectral analyses and confirmed as 1:1 ratio of Zn and ligand with distorted octahedral structure. The bandgap energies of the ligands are higher than its Zn-complexes. These synthesized new Zn(II) complexes are used for the photo-fragmentation of organic dye pollutants, photodegradation of food industrial wastewater and oxidation of methyl arenes which are converted into its respective aldehydes with moderate yields under visible light irradiation. The photooxidation reaction dependency on the intensity of the visible light was also studied. With the increase in the dosage of photocatalyst, the methyl groups are oxidized to get aldehydes and mono acid products, which are also identified from LC-MS data. Finally, [Zn(PPMHT)Cl] is with better efficiency than [Zn(PTHMT)Cl] and [Zn(MIMHPT)Cl] for oxidation of methyl arenes is reported under visible-light-driven conditions.
- Ahemed, Jakeer,Bhongiri, Yadagiri,Chetti, Prabhakar,Gade, Ramesh,Kore, Ranjith,Pasha, Jakeer,Pola, Someshwar,Rao D, Venkateshwar
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- Artificial Metallooxidases from Cyclodextrin Diacids
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Unprecedented simple artificial metalloenzymes were made from cyclodextrin diacids. Six α- and β-cyclodextrin diacids were prepared and their metal-binding and acid properties were investigated. The diacids formed fairly stable complexes with copper, zinc, and iron, with dissociation constants of 0.4–8×10?4 m. The iron complexes were found to catalyse a Fenton-like oxidation reaction of benzylic alcohols, which displayed Michaelis–Menten catalysis and rate accelerations up to 2700.
- Wang, Bo,Bols, Mikael
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- Highly Productive Oxidative Biocatalysis in Continuous Flow by Enhancing the Aqueous Equilibrium Solubility of Oxygen
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We report a simple, mild, and synthetically clean approach to accelerate the rate of enzymatic oxidation reactions by a factor of up to 100 when compared to conventional batch gas/liquid systems. Biocatalytic decomposition of H2O2 is used to produce a soluble source of O2 directly in reaction media, thereby enabling the concentration of aqueous O2 to be increased beyond equilibrium solubility under safe and practical conditions. To best exploit this method, a novel flow reactor was developed to maximize productivity (g product L?1 h?1). This scalable benchtop method provides a distinct advantage over conventional bio-oxidation in that no pressurized gas or specialist equipment is employed. The method is general across different oxidase enzymes and compatible with a variety of functional groups. These results culminate in record space-time yields for bio-oxidation.
- Chapman, Michael R.,Cosgrove, Sebastian C.,Turner, Nicholas J.,Kapur, Nikil,Blacker, A. John
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- Merging visible light photocatalysis of dye-sensitized TiO2 with TEMPO: The selective aerobic oxidation of alcohols
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The selective oxidation of alcohols to aldehydes or ketones is very difficult to accomplish when the oxidant is molecular oxygen (O2) and the reaction is carried out under ambient conditions. To meet these challenges, visible light photocatalysis was exploited to enable the use of O2 for the selective oxidation of alcohols at room temperature. In this scheme, eosin Y, an organic dye, was connected with TiO2 to capture visible light, leading to consequential photocatalytic processes. More importantly, these photocatalytic processes can be neatly merged with the redox catalytic cycles of TEMPO, which in turn induce the oxidation of alcohols under visible light irradiation. This work suggests that the merger of visible light photocatalysis and TEMPO catalysis has great potential for execution of challenging oxidative transformations.
- Zhang, Yichi,Wang, Zhan,Lang, Xianjun
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- Selective oxidation of alcohols using ferrocene-labeled Merrifield resin-supported ionic liquid phase catalysts
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Abstract: A novel ferrocene-labeled Merrifield resin-supported ionic liquid phase catalysts has been synthesized and successfully utilized for the selective oxidation of primary alcohols into corresponding aldehydes. The catalysts were recovered by simple filtration which greatly simplified the purification step and allowed successive reuse for multiple times without significant loss in activity. Graphical Abstract: [Figure not available: see fulltext.]
- Kurane, Rajanikant,Bansode, Prakash,Khanapure, Sharanabasappa,Salunkhe, Rajashri,Rashinkar, Gajanan
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- Copper(I)-mediated cyanation of boronic acids
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A simple cyanation reaction of boronic acids with cuprous cyanide is achieved, providing nitriles in moderate to good yields. In the presence of copper(I) iodide, trimethylsilyl cyanide is also a good cyanating reagent. The reaction can be conducted on a 10-mmol scale. Thus, this new approach represents an exceedingly practical method for the synthesis of nitriles.
- Zhang, Guoying,Zhang, Lingli,Hu, Maolin,Cheng, Jiang
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- Mechanisms of the Aerobic Oxidation of Alcohols to Aldehydes and Ketones, Catalysed under Mild Conditions by Persistent and Non-Persistent Nitroxyl Radicals and Transition Metal Salts - Polar, Enthalpic, and Captodative Effects
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The oxidation of alcohols to aldehydes and ketones by air or oxygen under mild conditions (room temperature and atmospheric pressure), catalysed by persistent and non-persistent nitroxyl radicals in combination with transition metal salts, appears to be the most convenient of the numerous processes developed for these purposes. The thermochemistry, the kinetics, and the Hammett correlations have allowed us to establish, on a quantitative basis, the fundamental difference between the oxidation catalysed by persistent and non-persistent nitroxyl catalysts. In the latter case, an interesting significant captodative effect is displayed for the first time for the oxidation of substituted benzyl alcohols; the importance of enthalpic and polar effects is emphasised.
- Minisci, Francesco,Recupero, Francesco,Cecchetto, Andrea,Gambarotti, Cristian,Punta, Carlo,Faletti, Roberta,Paganelli, Roberto,Pedulli, Gian Franco
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- TEMPO-catalyzed oxidation of benzylic alcohols to aldehydes with the H 2O2/HBr/ionic liquid [bmim]PF6 system
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A selective oxidation of benzylic alcohols to the corresponding aldehydes in room temperature ionic liquid was achieved by using TEMPO/HBr/H 2O2 system, and both ether-insoluble acetamido-TEMPO and ionic liquid [bmim]PF6 can be successfully recovered and reused for the oxidation of the same (different) substrate.
- Jiang, Nan,Ragauskas, Arthur J.
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- Convenient oxidation of benzylic and allylic halides to aldehydes and ketones
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Benzylic and allylic halides were conveniently oxidized to aldehydes and ketones by pyridine N-oxide in the presence of silver oxide under mild conditions.
- Chen, David X.,Ho, Chi M.,Rudy Wu,Wu, Peter R.,Wong, Freeman M.,Wu, Weiming
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- Integration of aerobic oxidation and intramolecular asymmetric aza-Friedel-Crafts reactions with a chiral bifunctional heterogeneous catalyst
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A new class of chiral bifunctional heterogeneous materials composed of Au/Pd nanoparticles and chiral phosphoric acids as active orthogonal catalysts was prepared by utilizing a facile pseudo-suspension co-polymerization method. It was found that this heterogeneous catalyst was capable of facilitating the sequential aerobic oxidation-asymmetric intramolecular aza-Friedel-Crafts reaction between benzyl alcohols and N-aminoethylpyrroles. Moreover, the designed chiral heterogeneous catalyst could be recovered and reused several times without significant loss of activity or enantioselectivity.
- Cheng, Hong-Gang,Miguélez, Javier,Miyamura, Hiroyuki,Yoo, Woo-Jin,Kobayashi, Shū
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- The Room-Temperature Palladium-Catalyzed Cyanation of Aryl Bromides and Iodides with Tri-t-butylphosphine as Ligand
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The palladium-catalyzed cyanation of aryl bromides and iodides to the corresponding nitriles occurs at room temperature when tri-t-butylphosphine is used as ligand, Zn(CN)2 as the cyanide source and Zn dust as a co-catalyst in DMF as solvent. A variety of aromatic halides, including electron-withdrawing and electron-donating, can be efficiently cyanated under these conditions. The reactions are completed in less than 1 hour and products are produced in good to excellent yield.
- Ramnauth, Jailall,Bhardwaj, Namrta,Renton, Paul,Rakhit, Suman,Maddaford, Shawn P.
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- Polymer bromide-DMSO: Novel reagent system for the oxidation of alcohols to carbonyl compounds
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A novel method for the oxidation of alcohols to aldehydes is described using polymer bromide-DMSO at room temperature. The condition described enables clean and fast conversion to desired carbonyl compounds and a broad range of substrates are tolerated. The resin recovery and recyclability make the protocol more ecofriendly.
- Prasanna,Mohanaraju
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- Oxidant free dehydrogenation of alcohols using chitosan/polyacrylamide entrapped Ag nanoparticles
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Silver nanoparticles encaged in a nanoporous chitosan/polyacrylamide interpenetrating polymer network (Ag@IPN) were synthesized and characterized by various techniques such as Fourier Transform Infra Red (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDX), Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA) and ICP-AES. This material exhibits good catalytic activity for the oxidant free dehydrogenation of alcohols to the corresponding carbonyl compounds. The reusability of Ag@IPN for this reaction was compared with a chitosan-silver complex under the same reaction conditions. It was found that encaging silver nanoparticles in interpenetrating polymer networks (IPN) has improved their stability by avoiding leaching and aggregation.
- Kurhe, Deepak K.,Fernandes, Thomson A.,Deore, Tushar S.,Jayaram, Radha V.
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- Photocatalysis with Quantum Dots and Visible Light: Selective and Efficient Oxidation of Alcohols to Carbonyl Compounds through a Radical Relay Process in Water
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Selective oxidation of alcohols to aldehydes/ketones has been achieved with the help of 3-mercaptopropionic acid (MPA)-capped CdSe quantum dot (MPA-CdSe QD) and visible light. Visible-light-prompted electron-transfer reaction initiates the oxidation. The thiyl radical generated from the thiolate anion adsorbed on a CdSe QD plays a key role by abstracting the hydrogen atom from the C?H bond of the alcohol (R1CH(OH)R2). The reaction shows high efficiency, good functional group tolerance, and high site-selectivity in polyhydroxy compounds. The generality and selectivity reported here offer a new opportunity for further applications of QDs in organic transformations.
- Zhao, Lei-Min,Meng, Qing-Yuan,Fan, Xiang-Bing,Ye, Chen,Li, Xu-Bing,Chen, Bin,Ramamurthy, Vaidhyanathan,Tung, Chen-Ho,Wu, Li-Zhu
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- C- vsN-Oxidations of Benzyltriazanes: Selective Access to Triazones, Azimines, and Triazenes
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The oxidation of several benzyltriazanes has been studied. Routes to the selective formation of triazenes, azimines, and triazones via C- or N-oxidation (and rearrangement) were devised. The rich reactivity of triazanes shows that trinitrogen chains are interesting functions, whose reactivity has been overlooked despite their interest as 3-N building blocks.
- Glowacki, Aurore,Jeux, Victorien,Gasnier, Gwéna?l,Joucla, Lionel,Jacob, Guy,Lac?te, Emmanuel
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- A DFT and experimental study of the spectroscopic and hydrolytic degradation behaviour of some benzylideneanilines
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The spectroscopic and hydrolytic degradation behaviour of some N-benzylideneanilines are investigated experimentally and theoretically via high quality density function theoretical (DFT) modelling techniques. Their absorption and vibrational spectra, accurately predicted by DFT calculations, are highly dependent on the nature of the substituents on the aromatic rings, hence, though some of their spectroscopic features are similar, energetic differences exist due to differences in their electronic structures. Whereas the o-hydroxy aniline derived adducts undergo hydrolysis via two pathways, the most energetically economical of which is initiated by a fast enthalpy driven hydration, over a conservative free energy (ΔG?) barrier of 53 kJ mol?1, prior to the rate limiting entropy controlled lysis step which occurs via a conservative barrier of ca.132 kJ mol?1, all other compounds hydrolyse via a slower two-step pathway, limited by the hydration step. Barriers heights for both pathways are controlled primarily by the structure and hence, stability of the transition states, all of which are cyclic for both pathways.
- Nelson, Peter N.,Robertson, Tahjna I.
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- Radical induced disproportionation of alcohols assisted by iodide under acidic conditions
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The disproportionation of alcohols without an additional reductant and oxidant to simultaneously form alkanes and aldehydes/ketones represents an atom-economical transformation. However, only limited methodologies have been reported, and they suffer from a narrow substrate scope or harsh reaction conditions. Herein, we report that alcohol disproportionation can proceed with high efficiency catalyzed by iodide under acidic conditions. This method exhibits high functional group tolerance including aryl alcohol derivatives with both electron-withdrawing and electron-donating groups, furan ring alcohol derivatives, allyl alcohol derivatives, and dihydric alcohols. Under the optimized reaction conditions, a 49% yield of 5-methyl furfural and a 49% yield of 2,5-diformylfuran were obtained simultaneously from 5-hydroxymethylfurfural. An initial mechanistic study suggested that the hydrogen transfer during this redox disproportionation occurred through the inter-transformation of HI and I2. Radical intermediates were involved during this reaction.
- Huang, Yang,Jiang, Haiwei,Li, Teng,Peng, Yang,Rong, Nianxin,Shi, Hexian,Yang, Weiran
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supporting information
p. 8108 - 8115
(2021/10/29)
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- Development and Molecular Understanding of a Pd-Catalyzed Cyanation of Aryl Boronic Acids Enabled by High-Throughput Experimentation and Data Analysis
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A synthetic method for the palladium-catalyzed cyanation of aryl boronic acids using bench stable and non-toxic N-cyanosuccinimide has been developed. High-throughput experimentation facilitated the screen of 90 different ligands and the resultant statistical data analysis identified that ligand σ-donation, π-acidity and sterics are key drivers that govern yield. Categorization into three ligand groups – monophosphines, bisphosphines and miscellaneous – was performed before the analysis. For the monophosphines, the yield of the reaction increases for strong σ-donating, weak π-accepting ligands, with flexible pendant substituents. For the bisphosphines, the yield predominantly correlates with ligand lability. The applicability of the designed reaction to a wider substrate scope was investigated, showing good functional group tolerance in particular with boronic acids bearing electron-withdrawing substituents. This work outlines the development of a novel reaction, coupled with a fast and efficient workflow to gain understanding of the optimal ligand properties for the design of improved palladium cross-coupling catalysts.
- De Jesus Silva, Jordan,Bartalucci, Niccolò,Jelier, Benson,Grosslight, Samantha,Gensch, Tobias,Schünemann, Claas,Müller, Bernd,Kamer, Paul C. J.,Copéret, Christophe,Sigman, Matthew S.,Togni, Antonio
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- Water-Dispersible Pd–N-Heterocyclic Carbene Complex Immobilized on Magnetic Nanoparticles as a New Heterogeneous Catalyst for Fluoride-Free Hiyama, Suzuki–Miyaura and Cyanation Reactions in Aqueous Media
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Abstract: Pd–N-heterocyclic carbine complex immobilized on magnetic nanoparticles is synthesized and characterized by different techniques such as FT-IR, XPS, TEM, EDX, FESEM, VSM, TGA, and ICP. The synthesized catalyst was used as a new water dispersible heterogeneous catalyst in the fluoride-free Hiyama, Suzuki–Miyaura and cyanation reactions in pure water. By this method, different types of biaryls and aryl nitriles were synthesized in good to high yields by the reaction of a variety of aryl iodides, bromides and chlorides with triethoxyphenylsilane, phenylboronic acid and K4[Fe(CN)6]·3H2O, respectively. The presence of sulfonates as hydrophilic groups on the surface of the catalyst confers a highly water dispersible, active and yet magnetically recoverable Pd catalyst. The possibility to perform the reaction in water as a green medium, ease of the catalyst recovery and reuse by magnetic separation, and the absence of any additives or co-solvents make this method as an eco-friendly and economical protocol for the synthesis of biaryl derivatives and aryl nitriles. Graphic Abstract: A new water dispersible heterogeneous Pd–N-heterocyclic carbene for the efficient fluoride-free Hiyama, Suzuki–Miyaura and cyanation reactions in pure water is developed.[Figure not available: see fulltext.].
- Chahkamali, Farhad Omarzehi,Sansano, José Miguel,Sobhani, Sara
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- Recyclable and Reusable Pd(OAc)2/XPhos–SO3Na/PEG-400/H2O System for Cyanation of Aryl Chlorides with Potassium Ferrocyanide
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Pd(OAc)2/XPhos–SO3Na in a mixture of poly(ethylene glycol) (PEG-400) and water is shown to be a highly efficient catalyst for the cyanation of aryl chlorides with potassium ferrocyanide. The reaction proceeded smoothly at 100 or 120?oC with K2CO3 or KOAc as base, delivering a variety of aromatic nitriles in good to excellent yields. The isolation of the crude products is facilely performed by extraction with cyclohexane and more importantly, both expensive Pd(OAc)2 and XPhos–SO3Na in PEG-400/H2O system could be easily recycled and reused at least six times without any apparent loss of catalytic efficiency. Graphical Abstract: Palladium-catalyzed cyanation of aryl chlorides with potassium ferrocyanide leading to aryl nitriles by using Pd(OAc)2/XPhos–SO3Na/PEG-400/H2O as a highly efficient and recyclable catalytic system is described.[Figure not available: see fulltext.]
- Cai, Mingzhong,Huang, Bin,Liu, Rong,Xu, Caifeng
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- Selective Electrochemical Oxygenation of Alkylarenes to Carbonyls
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An efficient electrochemical method for benzylic C(sp3)-H bond oxidation has been developed. A variety of methylarenes, methylheteroarenes, and benzylic (hetero)methylenes could be converted into the desired aryl aldehydes and aryl ketones in moderate to excellent yields in an undivided cell, using O2 as the oxygen source and lutidinium perchlorate as an electrolyte. On the basis of cyclic voltammetry studies, 18O labeling experiments, and radical trapping experiments, a possible single-electron transfer mechanism has been proposed for the electrooxidation reaction.
- Li, Xue,Bai, Fang,Liu, Chaogan,Ma, Xiaowei,Gu, Chengzhi,Dai, Bin
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supporting information
p. 7445 - 7449
(2021/10/02)
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- Core-shell Co-MOF-74@Mn-MOF-74 catalysts with Controllable shell thickness and their enhanced catalytic activity for toluene oxidation
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A series of core-shell Co-MOF-74@Mn-MOF-74 samples with different shell thicknesses were prepared by the seed growth method, which were characterized by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), inductively coupled plasma mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy, nitrogen adsorption-desorption and scanning electron microscopy (SEM). The shell thickness of these MOF samples were successfully controlled by adjusting the mass ratio between MnCl2·4H2O and Co-MOF-74. On this basis, these MOFs were applied to the catalytic oxidation of toluene. The results showed that with the growth of Mn-MOF-74 in the outer layer of Co-MOF-74, the oxidative selectivity of the substrate to benzaldehyde was greatly improved for the synergy between the core layer and shell layer. The conversion of toluene was 22.4%, and the selectivity of benzaldehyde was 98.1%. In addition, the catalyst can transform various substituted toluene into the corresponding aldehydes in highly selectivity and still keep good stability after four catalytic cycles. The selectivity of the corresponding aldehyde is generally above 80%.
- Gu, Xiangyu,Huang, Cheng,Xu, Zengchuang,Wu, Hao,Dong, Ruilan,Liu, Rui,Chen, Jing,Zhu, Hongjun
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- Oxidation/ MCR domino protocol for direct transformation of methyl benzene, alcohol, and nitro compounds to the corresponding tetrazole using a three-functional redox catalytic system bearing TEMPO/Co(III)-porphyrin/ Ni(II) complex
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A redox catalytic system for oxidation-reduction reactions and the domino preparation of tetrazole compounds from nitro and alcohol precursors was designed, prepared and characterized by UV–vis, GPC, TGA, XRD, EDX, XPS, VSM, FE-SEM, TEM, DLS, BET, NMR, and ICP analyses. The catalyst was prepared via several successive steps by demetalation of chlorophyll b, copolymerization with acrylated TEMPO monomers, complexation with Ni and Co metals (In two different steps), then immobilized on magnetic nanoparticles. The presence of three functional groups including TEMPO, coordinated cobalt, and coordinated nickel in the catalyst, allowed the oxidation of various types of alcohols, alkyl benzenes as well as the reduction of nitro compounds by a single catalyst. All reactions yielded up to 97 % selectivity for oxidation and reduction reactions. Next, the ability of the catalyst to successfully convert alcohol, methyl benzenes and nitro to their corresponding tetrazoles was studied.
- Mahmoudi, Boshra,Rostami, Amin,Kazemnejadi, Milad,Hamah-Ameen, Baram Ahmed
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- One-Pot Direct Oxidation of Primary Amines to Carboxylic Acids through Tandem ortho-Naphthoquinone-Catalyzed and TBHP-Promoted Oxidation Sequence
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Biomimetic oxidation of primary amines to carboxylic acids has been developed where the copper-containing amine oxidase (CuAO)-like o-NQ-catalyzed aerobic oxidation was combined with the aldehyde dehydrogenase (ALDH)-like TBHP-mediated imine oxidation protocol. Notably, the current tandem oxidation strategy provides a new mechanistic insight into the imine intermediate and the seemingly simple TBHP-mediated oxidation pathways of imines. The developed metal-free amine oxidation protocol allows the use of molecular oxygen and TBHP, safe forms of oxidant that may appeal to the industrial application.
- Kim, Hun Young,Oh, Kyungsoo,Si, Tengda
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supporting information
p. 18150 - 18155
(2021/12/09)
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- Nitrosoarene-Catalyzed HFIP-Assisted Transformation of Arylmethyl Halides to Aromatic Carbonyls under Aerobic Conditions
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A rare metal-free nucleophilic nitrosoarene catalysis accompanied by highly hydrogen-bond-donor (HBD) solvent, 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), organocatalytically converts arylmethyl halides to aromatic carbonyls. This protocol offers an effective means to access a diverse array of aromatic carbonyls with good chemoselectivity under mild reaction conditions. The activation of arylmethyl halides by HFIP to generate stable carbocation and autoxidation of in situ generated hydroxylamine to nitrosoarene in the presence of atmospheric O2 are the keys to success.
- Pradhan, Suman,Sharma, Vishali,Chatterjee, Indranil
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supporting information
p. 6148 - 6152
(2021/08/03)
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- SBA-15 Supported 1-Methyl-2-azaadamanane N-Oxyl (1-Me-AZADO) as Recyclable Catalyst for Oxidation of Alcohol
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Herein, we designed and synthesized an SBA-15 supported 1-methyl-2-azaadamanane N-oxyl (1-Me-AZADO) and investigated its catalytic performance for selective oxidation of alcohols under Anelli's conditions. The first example of immobilization of 1-Me-AZADO was very important to advance the oxgenation effectively because this supported N-oxyl has excellent catalytic activity for oxidation of alcohols to carbonyl compounds, and more importantly, it can be conveniently recovered and reused at least 6 times without significant effect on its catalytic efficiency.
- Tian, Yangwu,Guo, Xiaqun,Li, Meichao,Li, Chunmei,Hu, Xinquan,Jin, Liqun,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu
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supporting information
p. 3928 - 3932
(2021/05/26)
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- Magneto-structural properties and reliability of (Mn/Ni/Zn) substituted cobalt-copper ferrite heterogeneous catalyst for selective and efficient oxidation of aryl alcohols
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Herein, M2+ substituted CoCuFe2O4 (M2+ = Mn, Zn, Ni) ferrites have been synthesized using the sol-gel auto combustion method. The structural, morphological and magnetic studies confirm the phase formation of pure magnetic cubic spinel MCoCuFe2O4 (M2+ = Mn, Zn, Ni) ferrites. The substitution with Mn, Ni and Zn does not show large variation in binding energies obtained from XPS of Cu (2p) that specifies identical copper concentration (Cu0.5) and substitution of only cobalt (Co2+) in Mn-F, Ni-F and Zn-F catalysts. Interestingly, MCoCuFe2O4 magnetic catalysts were explored for selective oxidation of a series of substituted benzyl alcohols. Catalyst Mn-F showed 93% conversion of benzyl alcohol while, Ni-F showed 95% conversion of 4-nitrobenzyl alcohol. Whereas, the catalyst Zn-F was showed 96% conversion for 4-methoxybenzyl alcohol. Additionally the results also indicate an efficient separation and recovery of the magnetic catalysts after four successive reuses without any considerable loss in its catalytic activity.
- Dhabbe, Rohant,Gaikwad, Pratapsingh,Kakade, Bhalchandra,Kamble, Prakash,Kurane, Rajnikant,Parase, Haridas,Sabale, Sandip
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- Chemoselective and ligand-free aerobic oxidation of benzylic alcohols to carbonyl compounds using alumina-supported mesoporous nickel nanoparticle as an efficient recyclable heterogeneous catalyst
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An economically efficient and operationally simple ligand-free protocol for the chemoselective oxidation of benzylic alcohols to carbonyl compounds has been developed using alumina-supported nickel nanoparticles as a stable recyclable heterogeneous catalyst along with potassium tert-butoxide in the presence of aerial oxygen as an eco-friendly oxidant. The aliphatic alcohols remained unaffected under the present condition. Excellent chemoselectivity has also been demonstrated through intermolecular and intramolecular competition experiments. This protocol accommodates a diverse range of substituents with the tolerance of various sensitive moieties during the reaction. The catalyst could be recovered by filtration and reused consecutively without any significant loss in the catalytic activity. Moreover, the heterogeneity of the catalyst has also been established by the “hot filtration method (Sheldon's test)”.
- Das, Asit Kumar,Nandy, Sneha,Bhar, Sanjay
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- Selective aerobic oxidation of benzylic and allylic alcohols catalyzed by Cu(OAc)2/TEMPO/Et2NH
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Selective oxidation of benzylic and allylic alcohols to their corresponding aldehyde/ketone derivative without affecting saturated alcohols is still a challenging endeavor in organic synthesis. Various metal complexes, especially the copper complexes in the presence of TEMPO are being used very often for such transformations under aerobic conditions, but they are not selective to allylic and benzylic alcohols. The use of copper salt for oxidation of alcohols in the absence of a ligand are very scarcely studied except for the one catalyzed by CuCl/TEMPO where chloride inhibition and lack of selective oxidation have been noted upon use of CuCl2. Herein we report a Cu(OAc)2 catalyzed and TEMPO mediated selective aerobic oxidation of benzylic and allylic alcohols to aldehyde/ketone in the presence of Et2NH. The method avoids pre-synthesis of the catalyst as in the case of Cu(II)/(I) complexes/TEMPO catalyzed oxidation reactions, requires low catalyst loading, employs cheaper copper salt, and gives excellent selectivity for oxidation of benzylic and allylic alcohols.
- Bez, Ghanashyam,Gogoi, Achinta,Pasupuleti, Bala Gangadhar
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p. 589 - 597
(2021/09/28)
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- Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones
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We have developed a cerium-photocatalyzed aerobic oxidation of primary and secondary benzylic alcohols to aldehydes and ketones using inexpensive CeCl3 7H2O as photocatalyst and air oxygen as the terminal oxidant.
- K?nig, Burkhard,Kumar, Sumit,Stahl, Jessica,Yatham, Veera Reddy,Yedase, Girish Suresh
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supporting information
p. 1727 - 1732
(2021/08/05)
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- Combining photo-redox and enzyme catalysis for the synthesis of 4H-pyrimido[2,1-b] benzothiazole derivatives in one pot
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A novel strategy combining visible-light and enzyme catalysis in one pot for the synthesis of 4H-pyrimido[2,1-b] benzothiazole derivatives from alcohols is described for the first time. Fourteen 4H-pyrimido[2,1-b] benzothiazole derivatives were prepared with yields of up to 98% under mild reaction conditions by a simple operation. The photoorgano catalyst rose Bengal (rB) was employed to oxyfunctionalise alcohols to aldehydes. Compared with aldehydes, alcohols with more stable properties and lower cost, thus we used photocatalysis to oxidize alcohols into aldehydes. Next, the enzyme was used to further catalyze the reaction of Biginelli to produce the target product of 4H-pyrimidine [2,1-b] benzothiazole. Experimental results show that this method provides a more efficient and eco-friendly strategy for the synthesis of 4H-pyrimido[2,1-b] benzothiazole derivatives.
- Yu, Yuan,Lu, Wei-Fan,Yang, Zeng-Jie,Wang, Na,Yu, Xiao-Qi
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supporting information
(2020/12/25)
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- Palladium-Catalyzed Reductive Carbonylation of (Hetero) Aryl Halides and Triflates Using Cobalt Carbonyl as CO Source
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An efficient protocol for the reductive carbonylation of (hetero) aryl halides and triflates under CO gas-free conditions using Pd/Co2(CO)8 and triethylsilane has been developed. The mild reaction conditions, enhanced chemoselectivity and, easy access to heterocyclic and vinyl carboxaldehydes highlights its importance in organic synthesis.
- Dogga, Bhushanarao,Joseph, Jayan T.,Kumar, C. S. Ananda
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supporting information
p. 309 - 313
(2020/12/23)
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- A Magnetically Recyclable Palladium-Catalyzed Formylation of Aryl Iodides with Formic Acid as CO Source: A Practical Access to Aromatic Aldehydes
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A magnetically recyclable palladium-catalyzed formylation of aryl iodides under CO gas-free conditions has been developed by using a bidentate phosphine ligand-modified magnetic nanoparticles-anchored- palladium(II) complex [2P-Fe 3O 4@SiO 2-Pd(OAc) 2] as catalyst, yielding a wide variety of aromatic aldehydes in moderate to excellent yields. Here, formic acid was employed as both the CO source and the hydrogen donor with iodine and PPh 3as the activators. This immobilized palladium catalyst can be obtained via a simple preparative procedure and can be facilely recovered simply by using an external magnetic field, and reused at least 9 times without any apparent loss of catalytic activity.
- You, Shengyong,Zhang, Rongli,Cai, Mingzhong
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p. 1962 - 1970
(2021/01/25)
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- Method for preparing aldehyde compounds by oxidative cleavage of carbon-carbon bonds of terminal alkene compounds
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The invention discloses a method for preparing aldehyde compounds by oxidizing and breaking carbon-carbon bonds of terminal alkene compounds. The method comprises the following steps: adding an alkene-terminated compound, an additive and a nitrogen-doped mesoporous carbon-loaded monatomic catalyst into a fatty primary alcohol solvent, putting into a pressure container, sealing, introducing oxygen source gas with a certain pressure, controlling the pressure of the oxygen source gas to be 0.1-1MPa and the reaction temperature to be 80-150 DEG C, and obtaining a reaction product, namely the aldehyde compound. The nitrogen-doped mesoporous carbon-loaded monatomic catalyst adopted by the invention is high in activity, the highest separation yield of the aldehyde compound as a reaction product reaches 99%, the method is wide in application range, the reaction conditions are easy to control, the catalyst can be recycled, the post-treatment is simple, and the method is suitable for industrial production.
- -
-
Paragraph 0059-0060; 0089-0090
(2021/06/06)
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- DIBALH: From known fundamental to an unusual reaction; Chemoselective partial reduction of tertiary amides in the presence of esters
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This study presents a quick and reliable approach to the chemoselective partial reduction of tertiary amides to aldehydes in the presence of readily reducible ester groups using commercial DIBALH reagent. Moreover, the developed method was also extended to multi-functional molecules bearing ester moieties, which were successfully chemoselectively reduced to the corresponding aldehydes. This journal is
- An, Duk Keun,Heo, Yu Jin,Jaladi, Ashok Kumar,Kim, Hyun Tae
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p. 33809 - 33813
(2021/12/09)
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- Cobalt-catalysed selective synthesis of aldehydes and alcohols from esters
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Efficient and selective reduction of esters to aldehydes and alcohols is reported in which a simple cobalt pincer catalyst catalyses both transformations using diethylsilane as a reductant. Remarkably, the reaction selectivity is controlled by the stoichiometry of diethylsilane. This journal is
- Pattanaik, Sandip,Gunanathan, Chidambaram
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supporting information
p. 7345 - 7348
(2020/07/14)
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- Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas
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The reductive carbonylation of aryl iodides to aryl aldehydes possesses broad application prospects. We present an efficient and facile Rh-based catalytic system composed of the commercially available Rh salt RhCl3·3H2O, PPh3 as phosphine ligand, and Et3N as the base, for the synthesis of arylaldehydes via the reductive carbonylation of aryl iodides with CO and H2 under relatively mild conditions with a broad substrate range affording the products in good to excellent yields. Systematic investigations were carried out to study the experimental parameters. We explored the optimal ratio of Rh salt and PPh3 ligand, substrate scope, carbonyl source and hydrogen source, and the reaction mechanism. Particularly, a scaled-up experiment indicated that the catalytic method could find valuable applications in industrial productions. The low gas pressure, cheap ligand and low metal dosage could significantly improve the practicability in both chemical researches and industrial applications.
- Chen, Suqing,Liu, Zhenghui,Mu, Tiancheng,Wang, Peng,Yan, Zhenzhong,Yu, Dongkun,Zhao, Xinhui
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p. 645 - 656
(2020/05/14)
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- A Strategy for Accessing Aldehydes via Palladium-Catalyzed C?O/C?N Bond Cleavage in the Presence of Hydrosilanes
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We report the catalytic reduction of both active esters and amides by selective C(acyl)?X (X=O, N) cleavage to access aldehyde functionality via a palladium-catalyzed strategy. Reactions are promoted by hydrosilanes as reducing reagents with good to excellent yields and with excellent chemoselectivity for C(acyl)?N and C(acyl)?O bond cleavage. Carboxylic acid C(acyl)?O bonds are activated by 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) to form triazine ester intermediates, which further react with hydrosilanes to yield aldehydes in one-pot two-step procedures. We demonstrate that C(acyl)?O cleavage/formylation offers higher yields and broader substrate scopes compared with C(acyl)?N cleavage under the same reaction conditions.
- He, Zhanyu,Liu, Tingting,Ru, Junxiang,Wang, Yulin,Wang, Zijia,Zeng, Zhuo
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p. 5794 - 5800
(2020/12/01)
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- Visible-light assisted of nano Ni/g-C3N4 with efficient photocatalytic activity and stability for selective aerobic C?H activation and epoxidation
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A selective, economical, and ecological protocol has been described for the oxidation of methyl arenes and their analogs to the corresponding carbonyl compounds and epoxidation reactions of alkenes with molecular oxygen (O2) or air as a green oxygen source, under mild reaction conditions. The nano Ni/g-C3N4 exhibited high photocatalytic activity, stability, and selectivity in the C?H activation of methyl arenes, methylene arenes, and epoxidation of various alkenes under visible- light irradiation without the use of an oxidizing agent and under base free conditions.
- Akrami, Zahra,Hosseini-Sarvari, Mona
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supporting information
(2020/10/13)
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- Photochemical oxidation of benzylic primary and secondary alcohols utilizing air as the oxidant
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A mild and green photochemical protocol for the oxidation of alcohols to aldehydes and ketones was developed. Utilizing thioxanthenone as the photocatalyst, molecular oxygen from air as the oxidant and cheap household lamps or sunlight as the light source, a variety of primary and secondary alcohols were converted into the corresponding aldehydes or ketones in low to excellent yields. The reaction mechanism was extensively studied.
- Nikitas, Nikolaos F.,Tzaras, Dimitrios Ioannis,Triandafillidi, Ierasia,Kokotos, Christoforos G.
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supporting information
p. 471 - 477
(2020/02/13)
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- Organophotoredox-Mediated Amide Synthesis by Coupling Alcohol and Amine through Aerobic Oxidation of Alcohol
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The combination of an organic photocatalyst [4CzIPN (1,2,3,5-tetrakis(carbazol-9-yl)-4,6 dicyanobenzene) or 5MeOCzBN (2,3,4,5,6-pentakis(3,6-dimethoxy-9 H-carbazol-9-yl)benzonitrile)], quinuclidine, and tetra-n-butylammonium phosphate (hydrogen-bonding catalyst) was employed for amide bond formations. The hydrogen-bonded OH group activated the adjacent C?H bond of alcohols towards hydrogen atom transfer (HAT) by a radical species. The quinuclidinium radical cation, generated through single-electron oxidation of quinuclidine by the photocatalyst, employed to abstract a hydrogen atom from the α-C?H bond of alcohols selectively due to a polarity effect-produced α-hydroxyalkyl radical, which subsequently converted to the corresponding aldehyde under aerobic conditions. Then the coupling of the aldehyde and an amine formed a hemiaminal intermediate that upon photocatalytic oxidation produced the amide.
- Samanta, Samya,Shah, Sk. Sheriff,Shee, Maniklal,Singh, Amit Kumar,Singh, N. D. Pradeep,Venkatesh, Yarra
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supporting information
(2020/03/05)
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- Palladium-catalyzed external-CO-free reductive carbonylation of aryl sulfonates
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Pd-catalyzed reductive carbonylation of aryl sulfonates using N-formylsaccharin as a carbon monoxide (CO) surrogate was developed. This external-CO-free carbonylation provides a safe and practical access to aldehydes from phenol derivatives. The reaction has a broad substrate scope, rendering it an attractive method for synthesizing aldehydes.
- Konishi, Hideyuki,Kumon, Minoru,Yamaguchi, Miyuki,Manabe, Kei
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- Iron-Promoted Decarboxylation of Arylacetic Acids for the Synthesis of Aromatic Nitriles with Sodium Nitrite as the Nitrogen Source
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A new and effective method was developed for the synthesis of aromatic nitriles from arylacetic acids by using NaNO 2as the nitrogen source and Fe(OTf) 3as the promoter at 50 °C. A series of arylacetic acids underwent this transformation to give the targeted products in yields of 51-90%. Because of the mild conditions, the reaction is compatible with a broad range of functional groups, including ester, carboxy, hydroxy, acetamido, halo, nitro, cyano, methoxy, and even highly reactive formyl groups.
- Shen, Zhenpeng,Liu, Wenbo,Tian, Xinzhe,Zhao, Zhe,Ren, Yun-Lai
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supporting information
p. 1805 - 1808
(2020/11/02)
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- Palladium-Catalyzed Cyanation under Mild Conditions: A Case Study to Discover Appropriate Substrates among Halides and Pseudohalides
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A case study has been effectively carried out to identify a suitable substrate among halides and pseudohalides for the palladium-catalyzed cyanation reactions under mild conditions. Among the various substrates considered for evaluation, aryl pentafluorobenzenesulfonates and nonaflates were identified to be the best substrates when compared to corresponding halides and pseudohalides. The substoichiometric use of nontoxic, environmentally benign potassium hexacyanoferrate as a cyanide source and exceptionally milder conditions further highlights the significance of the protocol developed. A wide range of electronically biased and sterically challenging substrates provided the corresponding the nitriles in good to excellent yields.
- Rajendra, Merla Arjuna,Sunil,Sajith, Ayyiliath Meleveetil,Joy, Muthipeedika Nibin,Bakulev, Vasiliy A.,Haridas, Karickal Raman
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supporting information
p. 1629 - 1633
(2020/09/15)
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- Heterogeneous carbon nitride photocatalyst for C-C bond oxidative cleavage of vicinal diols in aerobic micellar medium
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A green and efficient visible-light promoted aerobic oxidative C-C bond cleavage of vicinal diols in micellar medium has been developed. This protocol used graphitic carbon nitride with nitrogen vacancies (CN620) as a metal-free recyclable photocatalyst and CTAB as surfactant in water. Control experiments and the ESR results indicated that superoxide radicals and valence band holes played an important role in the reaction. Further isotope experiments suggested both a β-scission/HAT pathway and an oxidation/hydrolysis/dehydration pathway for the reaction, which is different from previous reports. The semiconductor/micellar catalyst system can be recycled at least 10 times without a significant reduction in activity. Furthermore, this reaction could be carried out under solar light irradiation and was applicable to large-scale reactions with similar results.
- Chen, Jiayang,Chen, Shengjun,Dong, Xinyu,Hong, Mei,Ni, Bangqing,Niu, Tengfei,Zhang, Tianhao
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supporting information
p. 5042 - 5049
(2020/08/25)
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- Continuous flow synthesis of aryl aldehydes by Pd-catalyzed formylation of phenol-derived aryl fluorosulfonates using syngas
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This communication describes the palladium-catalyzed reductive carbonylation of aryl fluorosulfonates (ArOSO2F) using syngas as an inexpensive and sustainable source of carbon monoxide and hydrogen. The conversion of phenols to aryl fluorosulfonates can be conveniently achieved by employing the inexpensive commodity chemical sulfuryl fluoride (SO2F2) and base. The developed continuous flow formylation protocol requires relatively low loadings for palladium acetate (1.25 mol%) and ligand (2.5 mol%). Good to excellent yields of aryl aldehydes were obtained within 45 min for substrates containing electron withdrawing substituents, and 2 h for substrates containing electron donating substituents. The optimal reaction conditions were identified as 120 °C temperature and 20 bar pressure in dimethyl sulfoxide (DMSO) as solvent. DMSO was crucial in suppressing Pd black formation and enhancing reaction rate and selectivity. This journal is
- Hanselmann, Paul,Hone, Christopher A.,Hu, Guixian,K?ckinger, Manuel,Kappe, C. Oliver
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p. 22449 - 22453
(2020/07/03)
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- Organophotoredox assisted cyanation of bromoarenes: via silyl-radical-mediated bromine abstraction
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The insertion of a nitrile (-CN) group into arenes through the direct functionalization of the C(sp2)-Br bond is a challenging reaction. Herein, we report an organophotoredox method for the cyanation of aryl bromides using the organic photoredox catalyst 4CzIPN and tosyl cyanide (TsCN) as the nitrile source. A photogenerated silyl radical, via a single electron transfer (SET) mechanism, was employed to abstract bromine from aryl bromide to provide an aryl radical, which was concomitantly intercepted by TsCN to afford the aromatic nitrile. A range of substrates containing electron-donating and -withdrawing groups was demonstrated to undergo cyanation at room temperature in good yields.
- Shah, Sk. Sheriff,Shee, Maniklal,Singh, N. D. Pradeep
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supporting information
p. 4240 - 4243
(2020/04/22)
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- Palladium-Catalyzed Cyanation of Aryl Halides Using Formamide and Cyanuric Chloride as a New “CN” Source
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A new source of “CN” employing formamide and cyanuric chloride is introduced for the cyanation reactions. The treatment of formamide and 2,4,6-trichloro-1,3,5-triazine (TCT; cyanuric chloride) afforded an efficient cyanating agent which it can be used as a nontoxic, readily available, and non-expensive reagent in the cyanation transformations. In this study, palladium-catalyzed cyanation of aryl halides was successfully accomplished using this new “CN” source in high yields.
- Niknam, Esmaeil,Panahi, Farhad,Khalafi-Nezhad, Ali
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p. 2699 - 2707
(2020/04/08)
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- Donor-Flexible Bis(pyridylidene amide) Ligands for Highly Efficient Ruthenium-Catalyzed Olefin Oxidation
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An exceptionally efficient ruthenium-based catalyst for olefin oxidation has been designed by exploiting N,N′-bis(pyridylidene)oxalamide (bisPYA) as a donor-flexible ligand. The dynamic donor ability of the bisPYA ligand, imparted by variable zwitterionic and neutral resonance structure contributions, paired with the redox activity of ruthenium provided catalytic activity for Lemieux–Johnson-type oxidative cleavage of olefins to efficiently prepare ketones and aldehydes. The ruthenium bisPYA complex significantly outperforms state-of-the-art systems and displays extraordinary catalytic activity in this oxidation, reaching turnover frequencies of 650 000 h?1 and turnover numbers of several millions.
- Albrecht, Martin,Salzmann, Kevin,Segarra, Candela
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supporting information
p. 8932 - 8936
(2020/04/22)
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- Method for converting aromatic aldehyde into aromatic nitrile by using sulfur powder promoted inorganic ammonium as nitrogen source (by machine translation)
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The invention discloses a method for converting aromatic aldehyde into aromatic nitrile. The method is conversion of high yield of aromatic aldehyde one-pot reaction of sulfur powder promoted inorganic ammonium as a nitrogen source into aromatic nitrile. The method has the advantages of no need of metal participation, no need of strong oxide, compatibility of reaction to air, easiness in amplification to a gram scale and the like, and overcomes the problems of harsh reaction conditions, complex operation, low functional group compatibility and the like in the prior art. (by machine translation)
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Paragraph 0066; 0067
(2020/09/12)
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- Visible-light mediated facile dithiane deprotection under metal free conditions
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Visible light mediated facile and selective dithiane deprotection under metal free conditions is developed. Eosin Y (1 mol%) proved to be an effective catalyst for the dithiane deprotection under the ambient photoredox conditions. The standard household compact fluorescent light source (CFL bulb) proved to be effective under open-air conditions in aqueous acetonitrile at room temperature. The protocol that exhibits a broad substrate scope and functional group tolerance has been shown to expand to a range of transformations for the electron-rich and -deficient thioacetals and thioketals. The synthetic utility of this protocol has also been demonstrated by gram-scale application.
- Dharpure, Pankaj D.,Bhowmick, Anindita,Warghude, Prakash K.,Bhat, Ramakrishna G.
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- Identification and Structure–Activity Relationship (SAR) of potent and selective oxadiazole-based agonists of sphingosine-1-phosphate receptor (S1P1)
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Agonism of S1P1 receptor has been proven to be responsible for peripheral blood lymphopenia and elicts the identification of various S1P1 modulators. In this paper we described a series of oxadiazole-based S1P1 direct-acting agonists disubstituted on terminal benzene ring, with high potency for S1P1 receptor and favorable selectivity against S1P3 receptor. In addition, two representative agents named 16-3b and 16-3g demonstrated impressive efficacy in lymphocyte reduction along with reduced effect on heart rate when orally administered. Furthermore, these compounds have been shown to possess desired pharmacokinetic (PK) and physicochemical profiles. The binding mode between 16-3b and the activated S1P1 model was also studied.
- Liu, Tianqi,Jin, Jing,Chen, Yonghui,Xi, Qiumu,Hu, Jinping,Jia, Wenqiang,Chen, Xiaoguang,Li, Yan,Wang, Xiaojian,Yin, Dali
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- Immobilized palladium nanoparticles on a cyclodextrin-polyurethane nanosponge (Pd-CD-PU-NS): An efficient catalyst for cyanation reaction in aqueous media
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Immobilized palladium nanoparticles on a cyclodextrin-polyurethane nanosponge (Pd-CD-PU-NS) were found to be an efficient heterogeneous catalyst in the cyanation reaction of aryl halides in aqueous media. This catalyst system is containing palladium nanoparticles with a size of ～7 nm. Moreover, the CD-PU-NS support formed microsphere-shaped structures with a size of ～100–200 nm. The TEM images show that Pd nanoparticles were formed in near spherical shape morphology and were immobilized in the structure of the CD-PU-NS support. Under our optimized reaction conditions, aryl cyanides were obtained in high yields in the presence of the Pd-CD-PU-NS catalyst. Our results demonstrated that the Pd-CD-PU-NS catalyst is highly effective in the cyanation reaction in aqueous media. Furthermore, the catalyst could be simply extracted from the reaction mixture, providing an efficient methodology for the synthesis of aryl cyanides. The Pd-CD-PU-NS catalyst could be recycled four times with almost consistent catalytic efficiency.
- Khajeh Dangolani, Soheila,Sharifat, Sara,Panahi, Farhad,Khalafi-Nezhad, Ali
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supporting information
p. 256 - 265
(2019/06/07)
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- Rhenium-Catalyzed Reduction of Carboxylic Acids with Hydrosilanes
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Re2(CO)10 efficiently catalyzes the direct reduction of various carboxylic acids under mild conditions (rt, irradiation 350 or 395 nm). While aliphatic carboxylic acids were readily converted to the corresponding disilylacetals with low catalyst loading (0.5 mol %) in the presence of Et3SiH (2.2 equiv), aromatic analogues required more drastic conditions (Re2(CO)10 5 mol %, Ph2MeSiH 4.0 equiv) to afford the corresponding aldehydes after acid treatment.
- Wei, Duo,Buhaibeh, Ruqaya,Canac, Yves,Sortais, Jean-Baptiste
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supporting information
p. 7713 - 7716
(2019/10/10)
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- Synthesis method of P-formyl benzoic acid (by machine translation)
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The transparent colorless crystals obtained by heating the reaction, kettle in an :(1) acidic 20mL condition by heating the reaction, kettle in a liquid 130 - 135 °C, phase ammoxidation DMF, one-step, (2) method on methylbenzonitrile are obtained through, further oxidative synthesis of p-methylbenzonitrile in the, (3) reaction kettle through the reaction solution under, acidic conditions 110 - 115 °C, DMF, 900mL/min, 100mL/min, 2 - 3h. (by machine translation)
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Paragraph 0009-0011
(2019/12/25)
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- A method for the preparation of aldehydes
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The invention discloses a method for the preparation of ketone, relates to the field of organic synthesis. This invention adopts the organic solvent as a medium, cyclopropene [...] derivative as an active agent, activated DMSO oxidation [...] oxidation. The method of the invention is simple, easy to operate, rapid reaction rate, mild reaction, the reaction rate can be adjusted, more economic, to achieve industrial laid the foundation.
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Paragraph 0106; 0107
(2019/05/28)
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- A Simple, Mild and General Oxidation of Alcohols to Aldehydes or Ketones by SO2F2/K2CO3 Using DMSO as Solvent and Oxidant
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A practical, general and mild oxidation of primary and secondary alcohols to carbonyl compounds proceeds in yields of up to 99% using SO2F2 as electrophile in DMSO as both the oxidant and the solvent at ambient temperature. No moisture- and oxygen-free conditions are required. Stoichiometric amount of inexpensive K2CO3, which generates easy to separate by-products, is used as the base. Thus, 5-gram scale runs proceeded in nearly quantitative yields by a simple filtration as the work-up. The use of a polar solvent such as DMSO, which usually promotes competing Pummerer rearrangement, is also noteworthy. This protocol is compatible with a variety of common N-, O-, and S-functional groups on (hetero)arene, alkene and alkyne substrates (68 examples). The protocol was applied (99% yield) to a formal synthesis of the important cholesterol-lowering drug Rosuvastatin. (Figure presented.).
- Zha, Gao-Feng,Fang, Wan-Yin,Leng, Jing,Qin, Hua-Li
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supporting information
p. 2262 - 2267
(2019/04/17)
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- Metal-free mechanochemical oxidations in Ertalyte jars
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The authors acknowledge Form-Tech Scientific for the loan of the FTS-1000 Shaker Mill apparatus (Form-Tech Scientific, Canada, https://formtechscientific.com/). Authors are grateful to MIUR (Italy, PRIN project: multifunctional polymer composites based on grown materials). A. P. is grateful to MIUR for “Finanziamento delle Attività Base di Ricerca (FABR 2017)“.
- Porcheddu, Andrea,Delogu, Francesco,De Luca, Lidia,Fattuoni, Claudia,Colacino, Evelina
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supporting information
p. 1786 - 1794
(2019/08/07)
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- A molybdenum based metallomicellar catalyst for controlled and chemoselective oxidation of activated alcohols in aqueous medium
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A surfactant based oxodiperoxo molybdenum complex, which could activate molecular oxygen, has been employed as a catalyst for controlled oxidation of benzylic alcohols to corresponding carbonyls. The oxidation reactions were carried out under aqueous environment, however, in the absence of any extraneous base or co-catalyst. Sensitive/oxidizable functional groups like cyano, sulfide, hydroxyl, aryl-hydroxyl, alkene (internal/terminal), alkyne (internal/terminal), and acetal were tolerated during the transformations. Such selectivity is attributed to the mild nature of the catalyst. The methodology could also be scaled-up for multi-gram synthesis and the protocol is likely to find practical use since it requires an inexpensive recyclable-catalyst and easily available oxidant (under green conditions). A plausible mechanism is proposed with the help of preliminary computational study.
- Thiruvengetam, Prabaharan,Chakravarthy, Rajan Deepan,Chand, Dillip Kumar
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p. 123 - 133
(2019/07/19)
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