- Kinetic and product studies on the side-chain fragmentation of 1-arylalkanol radical cations in aqueous solution: Oxygen versus carbon acidity
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A kinetic and product study of the side-chain fragmentation reactions of a series of 1-arylalkanol radical cations (4-MeOC6H4CH(OH)R?+) and some of their methyl ethers was carried out; the radical cations were generated by pulse radiolysis and γ radiolysis in aqueous solution. The radical cations undergo side-chain fragmentation involving the Cα-H and/or Cα-Cβ bonds, and their reactivity was studied both in acidic (pH ≤ 4) and basic (pH 10 - 11) solution. At pH 4, the radical cations decay with first-order kinetics, and the exclusive reaction is Cα-H deprotonation for 1?+, 2?+, and 3?+ (R = H, Me, and Et, respectively) but Cα-Cβ bond cleavage for 5?+, 6?+, and 7?+ (R = tBu, CH(OH)Me, and CH(OMe)Me, respectively). Both types of cleavage are observed for 4?+ (R = iPr). The radical cations of the methyl ethers 8?+, 9?+, and 10?+ (R = H, Et, and iPr, respectively) undergo exclusive deprotonation, whereas C-C fragmentation predominates for 11?+ (R = tBu). Large Cα deuterium kinetic isotope effects (4.5 and 5.0, respectively) were found for 1?+ and its methyl ether 8?+. Replacement of an α-OH group by OMe has a very small effect on the decay rate when the radical cation undergoes deprotonation, but a very large, negative effect in the case of C-C bond cleavage. It is suggested that hydrogen bonding of the α-OH group with the solvent stabilizes the transition state of the C-C bond fragmentation reaction but not that of the deprotonation process; however, other factors could also contribute to this phenomenon. The decay of the radical cations is strongly accelerated by HO-, and all the α-OH substituted radical cations react with HO- at a rate (≈1010M-1S-1) very close to the limit of diffusion control and independent of the nature of the bond that is finally broken in the process (C-H or C-C). The methyl ether 8?+, which exclusively undergoes C-H bond cleavage, reacts significantly slower (by a factor of ca. 50) than the corresponding alcohol 1?+. These data indicate that 1-arylalkanol radical cations, which display the expected carbon acidity in water, become oxygen acids in the presence of a strong base such as HO- and undergo deprotonation of the O-H group; diffusion-controlled formation of the encounter complex between HO- and the radical cation is the rate-deter- mining step of the reaction. It is sug- gested that, within the complex, the proton is transferred to the base to give a benzyloxyl radical, either via a radical zwitterion (which undergoes intramolecular electron transfer) or directly (electron transfer coupled with deprotonation). The latter possibility seems more in line with the general base catalysis (β ≈ 0.4) observed in the reaction of 5?+, which certainly involves O-H deprotonation. The benzyloxyl radical can then undergo a β C-C bond cleavage to form 4-methoxybenzalde-hyde and R? or a formal 1,2-H shift to form an a-hydroxybenzyl-type radical. The factors of importance in this carbon/ oxygen acidity dichotomy are discussed.
- Baciocchi, Enrico,Bietti, Massimo,Steenken, Steen
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- Microwave- and ultrasound-assisted semisynthesis of natural methoxylated propiophenones from isomeric mixture of phenylpropenes in minutes
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A rapid and practical semisynthesis of natural methoxylated propiophenones (3a-3f) is realized by reacting stereo- and regio-isomeric mixture of phenylpropenes (1a-1f) with a catalytic amount of palladium chloride - sodium formate in formic acid, methanol, and water (2:1:2) into single product phenylpropanes (2a-2f) followed by its oxidation with 2,3-dichloro-5,6- dicyanobenzoquinone (DDQ) in wet dioxane, containing a few drops of formic acid. Conventional, ultrasound, and microwave heating were compared through these studies.
- Joshi, Bhupendra P.,Sharma, Anuj,Sinha, Arun K.
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- Triton X-100 functionalized Cu(II) dihydrazone based complex immobilized on Fe3O4@dopa: A highly efficient catalyst for oxidation of alcohols, alkanes, and sulfides and epoxidation of alkenes
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Here, we have presented a protocol for green synthesis, characterization, and catalytic application of TX100/Fe3O4@dopa@CuL (FDCTX) magnetically separable nanoparticles. Fe3O4@dopa@CuL (FDC) was synthesized using a four-step procedure: (i) synthesis of a dihydrazone derivative, (ii) reaction of the dihydrazone derivative with copper perchlorate salt to generate a copper complex of the dihydrazone derivative, (iii) immobilization of the complex onto Fe3O4@dopa to generate FDC, and (iv) coating of FDC with surfactant Triton X-100. The as-synthesized homogeneous complex was well characterized using UV–Vis., Fourier-transform infrared (FT-IR), electrospray ionization–mass spectrometry, and single-crystalX-ray techniques. Single-crystalX-ray analysis revealed the tetranuclear framework of the complex. The heterogeneous nanoparticles (FDCTX) were characterized using FT-IR, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersiveX-ray spectroscopy, magnetic hysteresis, and dynamic light scattering techniques. Finally, both the homogeneous and heterogeneous catalysts were utilized for efficient oxidation of alcohols, alkanes, and sulfides and epoxidation of alkenes. A most probable mechanism for the oxidation reaction is proposed at the end of the article.
- Chakraborty, Tonmoy,Mondal, Rimpa,Ghanta, Rinku,Chakraborty, Aratrika,Chattopadhyay, Tanmay
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- One electron oxidation of α-alkylbenzyl alcohols induced by potassium 12-tungstocobalt(III)ate - Comparison with the oxidation promoted by microsomal cytochrome P450
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The chemical and microsomal oxidations of a number of 4-methoxy substituted α-alkylbenzyl alcohols 4-MeOPh-CH(R)OH (Eox = 1.6-1.7 V vs SCE) were investigated. Using potassium 12-tungstocobalt(III)ate, a bona fide one electron oxidant, competition between Cα-H and Cα-Cβ bond cleavage in the intermediate radical cation was observed when the side-chain alkyl group R was Et (2) and iPr (3). With R = Me (1), only C-H bond cleavage took place, whereas with R = tBu (4) C-C bond cleavage was the exclusive fragmentation process. In contrast, the microsomal oxidation of the two substrates 3 and 4 led in both cases to the exclusive formation of the corresponding ketone. Thus, an electron transfer mechanism appears unlikely for the microsomal oxidation of α-alkylbenzyl alcohols, even though the oxidation potential of these species is lower than or comparable to that of the active oxidant in the enzyme. A hydrogen atom transfer mechanism is more in line with these results.
- Baciocchi, Enrico,Belvedere, Sandro,Bietti, Massimo,Lanzalunga, Osvaldo
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- Microwave-assisted acylation of aromatic compounds using carboxylic acids and zeolite catalysts
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Acylation of aromatic compounds with carboxylic acids smoothly proceeded at 190-230 °C in the presence of zeolite catalysts under microwave irradiation to give aromatic ketones efficiently. H-Y (SiO2/Al2O 3 = 30-80) and H-beta (25) zeolites were active for the acylation reaction, giving the aromatic ketones in good yields. Carboxylic acids such as hexanoic and butyric acid smoothly underwent the acylation, while propionic acid showed somewhat lower reactivity. Anisole gave the para-acylation products nearly selectively. Anisole, 2,3-dihydrobenzofuran, and thiophene were reactive aromatic compounds. 2,3-Dihydrobenzofuran also reacted at the para position to the oxygen atom predominantly to give the corresponding ketones as the major products. The microwave reactions were generally faster than the conventional oil bath reactions and gave higher yields of the acylation products. Activation energies for the reaction of anisole with butyric acid by microwave and by oil bath heating were also estimated on the basis of the Arrhenius plots.
- Yamashita, Hiroshi,Mitsukura, Yumi,Kobashi, Hiroko
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- Acidity versus metal-induced Lewis acidity in zeolites for Friedel–Crafts acylation
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Acid catalysts including Ni, Ag and Fe-loaded zeolites of different structures were prepared either via cationic exchange or impregnation techniques from pristine H-zeolites (BEA, and MFI). Their catalytic activity was evaluated in the liquid-phase Friedel–Crafts acylation of anisole with propanoic acid. It turned out that, whatever the doping procedure was, the zeolite loaded with transition metals led to considerable decrease in propanoic acid conversion, regardless of the nature or the metal content. However, the extent of this detrimental effect followed the order: Ag+?>?Ni2+?>?Fe3+. Pristine acidic zeolites were not only found to be the most active, but also to be the most selective toward ortho- and para-acylation products. H-ZSM-5 zeolites yielded the highest intrinsic activity, with TOF values of 0.09?h?1. The catalyst activity proved to be essentially attributed to the density and accessibility of Br?nsted acid sites, playing a key role in the activation of the reactants. Br?nsted sites are proposed to be the most likely catalytic species for performing this Friedel–Crafts acylation.
- Bernardon, Claire,Ben Osman, Manel,Laugel, Guillaume,Louis, Beno?t,Pale, Patrick
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- Direct Hydrodecarboxylation of Aliphatic Carboxylic Acids: Metal- and Light-Free
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A mild and inexpensive method for direct hydrodecarboxylation of aliphatic carboxylic acids has been developed. The reaction does not require metals, light, or catalysts, rendering the protocol operationally simple, easy to scale, and more sustainable. Crucially, no additional H atom source is required in most cases, while a broad substrate scope and functional group tolerance are observed.
- Burns, David J.,Lee, Ai-Lan,McLean, Euan B.,Mooney, David T.
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supporting information
p. 686 - 691
(2022/01/28)
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- A Mild Heteroatom (O -, N -, and S -) Methylation Protocol Using Trimethyl Phosphate (TMP)-Ca(OH) 2Combination
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A mild heteroatom methylation protocol using trimethyl phosphate (TMP)-Ca(OH)2combination has been developed, which proceeds in DMF, or water, or under neat conditions, at 80 °C or at room temperature. A series of O-, N-, and S-nucleophiles, including phenols, sulfonamides, N-heterocycles, such as 9H-carbazole, indole derivatives, and 1,8-naphthalimide, and aryl/alkyl thiols, are suitable substrates for this protocol. The high efficiency, operational simplicity, scalability, cost-efficiency, and environmentally friendly nature of this protocol make it an attractive alternative to the conventional base-promoted heteroatom methylation procedures.
- Tang, Yu,Yu, Biao
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- Development of Trifluoromethanesulfonic Acid-Immobilized Nitrogen-Doped Carbon-Incarcerated Niobia Nanoparticle Catalysts for Friedel-Crafts Acylation
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Heterogeneous trifluoromethanesulfonic acid-immobilized nitrogen-doped carbon-incarcerated niobia nanoparticle catalysts (NCI-Nb-TfOH) that show excellent catalytic performance with low niobium loading (1 mol %) in Friedel-Crafts acylation have been developed. These catalysts exhibit higher activity and higher tolerance to catalytic poisons compared with the previously reported TfOH-treated NCI-Ti catalysts, leading to a broader substrate scope. The catalysts were characterized via spectroscopic and microscopic studies.
- Yang, Xi,Yasukawa, Tomohiro,Yamashita, Yasuhiro,Kobayashi, Shū
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p. 15800 - 15806
(2021/10/25)
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- Well-Dispersed Trifluoromethanesulfonic Acid-Treated Metal Oxide Nanoparticles Immobilized on Nitrogen-Doped Carbon as Catalysts for Friedel–Crafts Acylation
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Although strong acid-treated metal oxides are useful heterogeneous superacid catalysts for various organic transformations, they usually have a limited density of acidic sites due to their low surface areas. Herein, heterogeneous trifluoromethanesulfonic acid immobilized nitrogen-doped carbon-incarcerated titanium nanoparticle (NP) catalysts have been developed that are composed of well-dispersed, small Ti NPs (ca 7 nm) that are otherwise difficult to achieve using acid-treated metal oxides. The catalysts showed high activity for Friedel–Crafts acylation with low titanium loading (2 mol%, 1 mg of metal for 1 mmol of substrate). A range of microscopic, spectroscopic and physicochemical studies revealed that the nitrogen-doped carbon immobilized the trifluoromethanesulfonic acid and that the addition of metals further changed the nature of the acidic species and enhanced catalytic activity.
- Yang, Xi,Yasukawa, Tomohiro,Maki, Tei,Yamashita, Yasuhiro,Kobayashi, Shū
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supporting information
p. 232 - 236
(2020/12/30)
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- V2O5@TiO2 Catalyzed Green and Selective Oxidation of Alcohols, Alkylbenzenes and Styrenes to Carbonyls
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The versatile application of different functional groups such as alcohols (1° and 2°), alkyl arenes, and (aryl)olefins to construct carbon-oxygen bond via oxidation is an area of intense research. Here, we report a reusable heterogeneous V2O5@TiO2 catalyzed selective oxidation of various functionalities utilizing different mild and eco-compatible oxidants under greener reaction conditions. The method was successfully applied for the alcohol oxidation, oxidative scission of styrenes, and benzylic C?H oxidation to their corresponding aldehydes and ketones. The utilization of mild and eco-friendly oxidizing reagents such as K2S2O8, H2O2 (30 % aq.), TBHP (70 % aq.), broad substrate scope, gram-scale synthesis, and catalyst recyclability are notable features of the developed protocol.
- Upadhyay, Rahul,Kumar, Shashi,Maurya, Sushil K.
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p. 3594 - 3600
(2021/07/02)
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- Visible-light-promoted α-methoxymethylation and aminomethylation of ketones with methanol as the C1 source
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Visible-light-promoted α-methoxymethylation and aminomethylation of ketones using methanol as a sustainable C1 source have been developed. With rose bengal as the photosensitizer and air as the green oxidant, the methoxymethylation reactions proceeded smoothly under visible light irradiation at ambient temperature. Additionally, a one-pot one-step α-aminomethylation of ketones was achieved by adding N-nucleophiles. Preliminary mechanism studies suggest that the reaction mainly proceedsviaa radical pathway.
- Yang, Jingya,Liu, Cai,Zhou, Hongyan,Fan, Rundong,Ma, Ben,Li, Zheng
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supporting information
p. 5572 - 5576
(2021/07/02)
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- Method for preparing ketone compound from olefin
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The invention belongs to the technical field of organic chemical synthesis, and discloses a method for preparing a ketone compound from olefin by using an iron catalyst. According to the invention, the ligand and the iron salt form an iron catalyst in the on-site reaction, the raw materials in the formula are easy to obtain, and the synthesis is simple. By using the catalyst, olefin can be efficiently converted into ketone compounds, and compared with a palladium catalyst, the price is very low, and the catalyst is suitable for industrial application.
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Paragraph 0044-0047
(2021/08/19)
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- Catalytic Aerobic Oxidation of Alkenes with Ferric Boroperoxo Porphyrin Complex; Reduction of Oxygen by Iron Porphyrin
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We herein describe the development of a mild and selective catalytic aerobic oxidation process of olefins. This catalytic aerobic oxidation reaction was designed based on experimental and spectroscopic evidence assessing the reduction of atmospheric oxygen using a ferric porphyrin complex and pinacolborane to form a ferric boroperoxo porphyrin complex as an oxidizing species. The ferric boroperoxo porphyrin complex can be utilized as an in-situ generated intermediate in the catalytic aerobic oxidation of alkenes under ambient conditions to form oxidation products that differ from those obtained using previously reported ferric porphyrin catalysis. Moreover, the mild reaction conditions allow chemoselective oxidation to be achieved.
- Kimura, Kento,Kurahashi, Takuya,Matsubara, Seijiro,Murano, Shunpei
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supporting information
p. 2493 - 2497
(2021/12/29)
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- Photoredox/nickel-catalyzed hydroacylation of ethylene with aromatic acids
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We report a general, practical and scalable hydroacylation reaction of ethylene with aromatic carboxylic acids with the synergistic combination of nickel and photoredox catalysis. Under ambient temperature and pressure, feedstock chemicals such as ethylene can be converted into high-value-added aromatic ketones in moderate to good yields (up to 92%) with reaction time of 2-6 hours.
- Chen, Shuai,He, Hengchi,Li, Weipeng,Xie, Jin,Zhang, Lili,Zhu, Chengjian
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supporting information
p. 9064 - 9067
(2021/09/15)
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- Copper-Catalyzed Methoxylation of Aryl Bromides with 9-BBN-OMe
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A Cu-catalyzed cross-coupling reaction between aryl bromides and 9-BBN-OMe to provide aryl methyl ethers under mild conditions is reported. The oxalamide ligand BHMPO plays a key role in the transformation. Various functional groups on bromobenzenes are well tolerated, providing the desired anisole products in moderate to high yields.
- Li, Chen,Song, Zhi-Qiang,Wang, Dong-Hui,Wang, Jing-Ru
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supporting information
p. 8450 - 8454
(2021/11/17)
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- Non-plasmonic Ni nanoparticles catalyzed visible light selective hydrogenolysis of aryl ethers in lignin under mild conditions
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Light-driven catalysis on catalytically versatile group VIII metals, which has been widely used in thermal catalysis, holds great potential in solar-to-chemical conversion. We report a novel photocatalysis process for the selective hydrogenolysis of aryl ethers in lignin on a heterogeneous catalyst of non-precious Ni nanoparticles supported on ZrO2. Three aryl ether bonds in lignin were successfully cleaved under mild conditions with excellent conversion and good to excellent selectivity under visible light irradiation. We also used solar irradiation to demonstrate a significant reduction in the total energy consumption. The light irradiation excited interband transitions in Ni nanoparticles and the resultant energetic electrons enhanced the activity of reductive cleavage of the aryl ethers. Its application potential was illustrated by the depolymerization of dealkaline lignin to give a total monomer yield of 9.84 wt% with vanillin, guaiacol, and apocynin as the three major products.
- Baeyens, Jan,Li, Peifeng,Ouyang, Yixuan,Sarina, Sarina,Su, Haijia,Xiao, Gang,Zhao, Yilin,Zhu, Huai-Yong
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supporting information
p. 7780 - 7789
(2021/10/12)
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- Iron-Catalyzed C-C Single-Bond Cleavage of Alcohols
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An iron-catalyzed deconstruction/hydrogenation reaction of alcohols through C-C bond cleavage is developed through photocatalysis, to produce ketones or aldehydes as the products. Tertiary, secondary, and primary alcohols bearing a wide range of substituents are suitable substrates. Complex natural alcohols can also perform the transformation selectively. A investigation of the mechanism reveals a procedure that involves chlorine radical improved O-H homolysis, with the assistance of 2,4,6-collidine.
- Liu, Wei,Wu, Qiang,Wang, Miao,Huang, Yahao,Hu, Peng
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supporting information
p. 8413 - 8418
(2021/11/01)
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- Iridium Complexes as Efficient Catalysts for Construction of α-Substituted Ketones via Hydrogen Borrowing of Alcohols in Water
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Ketones are of great importance in synthesis, biology, and pharmaceuticals. This paper reports an iridium complexes-catalyzed cross-coupling of alcohols via hydrogen borrowing, affording a series of α-alkylated ketones in high yield (86 %–95 %) and chemoselectivities (>99 : 1). This methodology has the advantages of low catalyst loading (0.1 mol%) and environmentally benign water as the solvent. Studies have shown the amount of base has a great impact on chemoselectivities. Meanwhile, deuteration experiments show water plays an important role in accelerating the reduction of the unsaturated ketones intermediates. Remarkably, a gram-scale experiment demonstrates this methodology of iridium-catalyzed cross-coupling of alcohols has potential application in the practical synthesis of α-alkylated ketones.
- Luo, Nianhua,Zhong, Yuhong,Wen, Huiling,Shui, Hongling,Luo, Renshi
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p. 1355 - 1364
(2021/03/03)
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- Rhenium(I)-Catalyzed C-Methylation of Ketones, Indoles, and Arylacetonitriles Using Methanol
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A ReCl(CO)5/MeC(CH2PPh2)3 (L2) system was developed for the C-methylation reactions utilizing methanol and base, following the borrowing hydrogen strategy. Diverse ketones, indoles, and arylacetonitriles underwent mono-and dimethylation selectively up to 99% yield. Remarkably, tandem multiple methylations were also achieved by employing this catalytic system.
- Shee, Sujan,Kundu, Sabuj
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p. 6943 - 6951
(2021/05/29)
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- Facile preparation of 5-alkyl-1-aryltetrazoles with arenes, acyl chlorides, hydroxylamine, and diphenylphosphoryl azide
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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
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p. 1816 - 1830
(2020/11/19)
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- AN IMPROVED AND COMMERCIALLY VIABLE PROCESS FOR PREPARATION OF ARYL KETONES
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The present disclosure provides a process for preparing an aryl ketone of Formula I, comprising reacting a substituted benzene of Formula II with a carboxylic acid of formula IIIa and/or a carboxylic anhydride of formula IIIb in presence of an alkyl sulfonic acid acting as catalyst cum solvent/contacting medium. I, II, IIIa, IIIb, wherein, R1, R2, R3 and R4 are as defined in the description.
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Paragraph 0071-0075; 0078-0082; 0087
(2020/09/12)
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- Br?nsted acid/visible-light-promoted Markovnikov hydroamination of vinylarenes with arylamines
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A Br?nsted acid/visible-light-promoted Markovnikov hydroamination of vinylarenes with arylamines in the presence of TPT and CF3CO2H has been developed. This transformation provides a green approach to alpha-amino-substituted arylalkanes under metal-free conditions.
- Gui, Jiao,Xie, Haisheng,Chen, Fengjuan,Liu, Zhipeng,Zhang, Xiaoqi,Jiang, Fubin,Zeng, Wei
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supporting information
p. 956 - 963
(2020/02/15)
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- A sodium trifluoromethanesulfinate-mediated photocatalytic strategy for aerobic oxidation of alcohols
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A sodium trifluoromethanesulfinate-mediated photocatalytic strategy for the aerobic oxidation of alcohols has been developed for the first time, and the photoredox aerobic oxidation of secondary and primary alcohols provided the corresponding ketones and carboxylic acids, respectively, in high to excellent yields.
- Zhu, Xianjin,Liu, Can,Liu, Yong,Yang, Haijun,Fu, Hua
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p. 12443 - 12446
(2020/10/30)
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- Combination of organocatalytic oxidation of alcohols and organolithium chemistry (RLi) in aqueous media, at room temperature and under aerobic conditions
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A tandem protocol to access tertiary alcohols has been developed which combines the organocatalytic oxidation of secondary alcohols to ketones followed by their chemoselective addition by several RLi reagents. Reactions take place at room temperature, under air and in aqueous solutions, a trio of conditions that are typically forbidden in polar organometallic chemistry.
- Elorriaga, David,García-álvarez, Joaquín,González-Sabín, Javier,Hevia, Eva,Morís, Francisco,Presa Soto, Alejandro,Ríos-Lombardía, Nicolás,Rodríguez-álvarez, María Jesús
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supporting information
p. 8932 - 8935
(2020/08/17)
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- Rhodium-terpyridine catalyzed redox-neutral depolymerization of lignin in water
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Simple rhodium terpyridine complexes were found to be suitable catalysts for the redox neutral cleavage of lignin in water. Apart from cleaving lignin model compounds into ketones and phenols, the catalytic system could also be applied to depolymerize dioxasolv lignin and lignocellulose, affording aromatic ketones as the major monomer products. The (hemi)cellulose components in the lignocellulose sample remain almost intact during lignin depolymerization, providing an example of a "lignin-first" process under mild conditions. Mechanistic studies suggest that the reaction proceeds via a rhodium catalyzed hydrogen autotransfer process.
- Liu, Yuxuan,Li, Changzhi,Miao, Wang,Tang, Weijun,Xue, Dong,Xiao, Jianliang,Zhang, Tao,Wang, Chao
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supporting information
p. 33 - 38
(2020/01/13)
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- Utility of Organoboron Reagents in Arylation of Cyclopropanols via Chelated Pd(II) Catalysis: Chemoselective Access to β-Aryl Ketones
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Organoborane reagents were investigated as coupling partners to cyclopropanol-derived β-ketone enolates in the presence of a chelated Pd(II) catalyst. Efficient coupling of a range of electronically and sterically diverse cyclopropanols and aryl/alkenyl boronic derivatives (39 examples, 65-94% yield) could be achieved with the generation of synthetically important β-aryl ketone intermediates in a chemoselective fashion. This reactivity paradigm, which broadens the scope of aryl donor partners to homoenolates, allows open-flask conditions, water as a cosolvent, and preparation of halogen-bearing β-aryl ketones that are distinct from previous methods. This chelated Pd(II) catalysis appears to be different from the Pd(0) pathway, as evident from deuterium scrambling studies that could reveal differentiating protonolysis of an α-keto carbopalladium complex in the terminal step.
- Ilangovan, Andivelu,Ramar, Thangeswaran,Subbaiah, Murugaiah A. M.
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- Visible-light-promoted site-specific and diverse functionalization of a c(sp3)-c(sp3) bond adjacent to an arene
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We report here a strategy for inert C-C bond functionalization. Site-specific cleavage and functionalization of a saturated C(sp3)-C(sp3) bond via a visible-light-induced radical process have been achieved. The general features of this reaction are as follows. (1) Both linear and cyclic C(sp3)-C(sp3) bonds with a vicinal arene can be specifically functionalized. (2) One carbon is converted into a ketone, and another can be tunably converted into nitrile, peroxide, or halide. (3) The typical conditions include 1.0 mol % of Ru(bpy)3Cl2, 1.0 or 5.0 equiv of Zhdankin reagent, white CFL (24 W), open flask, and room temperature. These reactions offer powerful tools to modify carbon skeletons that are intractable by conventional methods. Good selectivity and functional group tolerance, together with mild and open air conditions, make these transformations valuable and attractive.
- Fang, Fang,Liu, Zhong-Quan,Sun, Minzhi,Wang, Nengyong,Wang, Yaxin,You, Huichao,Zhao, Jianyou
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p. 6603 - 6612
(2020/07/27)
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- Dual aminoquinolate diarylboron and nickel catalysed metallaphotoredox platform for carbon-oxygen bond construction
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Herein, aminoquinolate diarylboron complexes are utilized as photocatalysts in dual Ni/photoredox catalyzed carbon-oxygen construction reactions. Via this unified metallaphotoredox platform, diverse (hetero)aryl halides can be conveniently coupled with acids, alcohols and water. This method features operational simplicity, broad substrate scope and good compatibility with functional groups. This journal is
- Day, Craig,Jia, Xin,Wei, Lanfeng,Xu, Liang,Zu, Weisai
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supporting information
p. 8273 - 8276
(2020/08/17)
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- Method for preparing alpha-alkyl substituted ketone compound
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The invention relates to a method for preparing an alpha-alkyl substituted ketone compound, which comprises the following steps: preparing a primary alcohol compound and a secondary alcohol compound as raw materials, adding alkali; with a cyclic iridium complex as a catalyst and water as a reaction medium, heating and stirring the mixture and reacting for 10 to 24 hours under the protection of inert gas, and cooling a reaction product to room temperature after the reaction is finished; carrying out reduced pressure distillation and concentration to obtain a crude product, and carrying out column chromatography purification to obtain a series of alpha alkyl substituted ketone compounds. The method is simple to operate, available in raw materials, low in price, high in reaction efficiency and selectivity, good in adaptability to various functional groups and wide in substrate universality; since water is used as a reaction medium to meet the green and environment-friendly requirements, the method is environmentally friendly and is carried out at gram level, so that the potential of industrially synthesizing the alpha alkyl substituted ketone compound is achieved; therefore, The method has expanded application in the fields of medicines, organic synthesis and the like.
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Paragraph 0157-0164
(2020/12/29)
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- Novel benzene-based carbamates for ache/bche inhibition: Synthesis and ligand/structure-oriented sar study
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A series of new benzene-based derivatives was designed, synthesized and comprehensively characterized. All of the tested compounds were evaluated for their in vitro ability to potentially inhibit the acetyl-and butyrylcholinesterase enzymes. The selectivity index of individual molecules to cholinesterases was also determined. Generally, the inhibitory potency was stronger against butyryl-compared to acetylcholinesterase; however, some of the compounds showed a promising inhibition of both enzymes. In fact, two compounds (23, benzyl ethyl(1-oxo-1-phenylpropan-2-yl)carbamate and 28, benzyl (1-(3-chlorophenyl)-1-oxopropan-2-yl) (methyl)carbamate) had a very high selectivity index, while the second one (28) reached the lowest inhibitory concentration IC50 value, which corresponds quite well with galanthamine. Moreover, comparative receptor-independent and receptor-dependent structure–activity studies were conducted to explain the observed variations in inhibiting the potential of the investigated carbamate series. The principal objective of the ligand-based study was to comparatively analyze the molecular surface to gain insight into the electronic and/or steric factors that govern the ability to inhibit enzyme activities. The spatial distribution of potentially important steric and electrostatic factors was determined using the probability-guided pharmacophore mapping procedure, which is based on the iterative variable elimination method. Additionally, planar and spatial maps of the host–target interactions were created for all of the active compounds and compared with the drug molecules using the docking methodology.
- Bak, Andrzej,Kozik, Violetta,Kozakiewicz, Dariusz,Gajcy, Kamila,Strub, Daniel Jan,Swietlicka, Aleksandra,Stepankova, Sarka,Imramovsky, Ales,Polanski, Jaroslaw,Smolinski, Adam,Jampilek, Josef
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- Electrochemical [4+2] Annulation-Rearrangement-Aromatization of Styrenes: Synthesis of Naphthalene Derivatives
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We report the first electrochemical strategy to synthesize functionalized naphthalene derivatives through [4+2] annulation—rearrangement–aromatization from styrenes under mild conditions. The electrolysis does not require metals, oxidants and high valence substrates, indicating the atom and step-economy ideals. The dehydrodimer produced through [4+2] cycloaddition of 4-methoxy α-methyl styrene is isolated and proved to be the key intermediate for the following oxydehydrogenation to form carbon cation, which undergoes rearrangement–aromatization to afford the final products. This reaction represents a powerful access to construct multi-substituted naphthalene blocks in a single step.
- Ma, Yueyue,Lv, Jufeng,Liu, Chengyu,Yao, Xiantong,Yan, Guoming,Yu, Wei,Ye, Jinxing
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supporting information
p. 6756 - 6760
(2019/04/17)
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- One-Pot Transformation of Ketoximes into Optically Active Alcohols and Amines by Sequential Action of Laccases and Ketoreductases or ω-Transaminases
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An enzymatic one-pot process for asymmetric transformation of prochiral ketoximes into alcohols or amines was developed by sequential coupling of a laccase-catalyzed deoximation either with a ketone reduction (ketoreductase, KRED) or bioamination (ω-transaminase, ω-TA) in aqueous medium. An accurate selection of biocatalysts provided the corresponding products in excellent enantiomeric excesses and overall conversions ranging from 83 to >99 % for alcohols and 70 to >99 % for amines. Likewise, the employment of exclusively 1 % (w/w) of Cremophor, a polyethoxylated castor oil, as co-solvent enabled to reach concentrations up to 100 mM in the chiral alcohols cascade.
- Correia Cordeiro, Raquel S.,Ríos-Lombardía, Nicolás,Morís, Francisco,Kourist, Robert,González-Sabín, Javier
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p. 1272 - 1277
(2019/01/24)
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- Ruthenium-Catalyzed Redox Isomerizations inside Living Cells
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Tailored ruthenium(IV) complexes can catalyze the isomerization of allylic alcohols into saturated carbonyl derivatives under physiologically relevant conditions, and even inside living mammalian cells. The reaction, which involves ruthenium-hydride intermediates, is bioorthogonal and biocompatible, and can be used for the "in cellulo" generation of fluorescent and bioactive probes. Overall, our research reveals a novel metal-based tool for cellular intervention, and comes to further demonstrate the compatibility of organometallic mechanisms with the complex environment of cells.
- Vidal, Cristian,Tomás-Gamasa, María,Gutiérrez-González, Alejandro,Mascarenas, José L.
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p. 5125 - 5129
(2019/03/29)
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- Additive-Free Isomerization of Allylic Alcohols to Ketones with a Cobalt PNP Pincer Catalyst
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Catalytic isomerization of allylic alcohols in ethanol as a green solvent was achieved by using air and moisture stable cobalt (II) complexes in the absence of any additives. Under mild conditions, the cobalt PNP pincer complex substituted with phenyl groups on the phosphorus atoms appeared to be the most active. High rates were obtained at 120 °C, even though the addition of one equivalent of base increases the speed of the reaction drastically. Although some evidence was obtained supporting a dehydrogenation–hydrogenation mechanism, it was proven that this is not the major mechanism. Instead, the cobalt hydride complex formed by dehydrogenation of ethanol is capable of double-bond isomerization through alkene insertion–elimination.
- Spiegelberg, Brian,Dell'Acqua, Andrea,Xia, Tian,Spannenberg, Anke,Tin, Sergey,Hinze, Sandra,de Vries, Johannes G.
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supporting information
p. 7820 - 7825
(2019/05/22)
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- Manganese PNP-pincer catalyzed isomerization of allylic/homo-allylic alcohols to ketones-activity, selectivity, efficiency
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We report the first manganese catalyzed isomerization of allylic alcohols to produce the corresponding carbonyl compounds. The ligand plays a decisive role in the efficiency of this reaction. Very high conversions could be obtained using a solvent-free reaction system. A detailed DFT study reveals a self-dehydrogenation/hydrogenation reaction mechanism which was verified by the isolation of the α,β-unsaturated ketone as intermediate and a deuterium labeling experiment. It also provided a rationale for the observed selectivity and the higher efficiency of phenyl over isopropyl substitution.
- Xia, Tian,Spiegelberg, Brian,Wei, Zhihong,Jiao, Haijun,Tin, Sergey,Hinze, Sandra,De Vries, Johannes G.
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p. 6327 - 6334
(2019/11/20)
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- Visible light induced redox neutral fragmentation of 1,2-diol derivatives
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A homogeneous, redox-neutral photo fragmentation of diol derivatives was developed. Under photo/hydrogen atom transfer (HAT) dual catalysis, diol derivatives such as lignin model compounds and diol monoesters undergo selective β C(sp3)-O bond cleavage to afford ketones, phenols and acids effectively.
- Chen, Kang,Schwarz, Johanna,Karl, Tobias A.,Chatterjee, Anamitra,K?nig, Burkhard
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p. 13144 - 13147
(2019/11/11)
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- Mild Redox-Neutral Depolymerization of Lignin with a Binuclear Rh Complex in Water
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A mild redox-neutral lignin depolymerization system featuring a water-soluble binuclear Rh complex has been developed. The catalytic system could be successfully applied to the depolymerization of a lignin-like polymer, alkaline lignin, as well as raw lignocellulose samples to produce aromatic ketones, providing a homogeneous catalytic system for "lignin-first" biorefinery in water. Mechanistic studies on the model substrate suggest that the reaction proceeds via a metal-catalyzed dehydrogenation step to afford a carbonyl intermediate, followed by C-O bond cleavage to afford ketone and phenol products. Deuterium labeling study shows that the hydrogen used for cleavage of the C-O bond originates from the alcohol moiety in the substrate.
- Liu, Yuxuan,Li, Changzhi,Miao, Wang,Tang, Weijun,Xue, Dong,Li, Chaoqun,Zhang, Bo,Xiao, Jianliang,Wang, Aiqin,Zhang, Tao,Wang, Chao
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p. 4441 - 4447
(2019/05/14)
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- Production technique to prepare anethole by catalyzing dewatering of 3-(4-methoxyphenyl)-1-propanol
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The invention discloses a production technique to prepare anethole by catalyzing dewatering of 3-(4-methoxyphenyl)-1-propanol. The production technique comprises: using acid alumina and/or aluminum hydroxide weak-acidity solid material to catalyze dewatering of 3-(4-methoxyphenyl)-1-propanol at 100-150 DEG C to generate anethole. The production technique has the advantages that the reaction process is free of waste gas, the reaction rate is high, the yield is high, few polymer impurities occur to anethole, the economic value is high, the reaction requires no post-treatment or solvent, the requirement on equipment is low, and the production technique is easy to industrially popularize.
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Paragraph 0100-0167; 0172; 0173; 0176; 0177
(2018/09/13)
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- Isomerization of Allylic Alcohols to Ketones Catalyzed by Well-Defined Iron PNP Pincer Catalysts
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[Fe(PNP)(CO)HCl] (PNP=di-(2-diisopropylphosphanyl-ethyl)amine), activated in situ with KOtBu, is a highly active catalyst for the isomerization of allylic alcohols to ketones without an external hydrogen supply. High reaction rates were obtained at 80 °C, but the catalyst is also sufficiently active at room temperature with most substrates. The reaction follows a self-hydrogen-borrowing mechanism, as verified by DFT calculations. An alternative isomerization through alkene insertion and β-hydride elimination could be excluded on the basis of a much higher barrier. In alcoholic solvents, the ketone product is further reduced to the saturated alcohol.
- Xia, Tian,Wei, Zhihong,Spiegelberg, Brian,Jiao, Haijun,Hinze, Sandra,de Vries, Johannes G.
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supporting information
p. 4043 - 4049
(2018/01/27)
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- Programming cascade reactions interfacing biocatalysis with transition-metal catalysis in: Deep Eutectic Solvents as biorenewable reaction media
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The first application of Deep Eutectic Solvents (DESs) in the asymmetric bioreduction of ketones has been accomplished for purified ketoreductases (KREDs). The performance of the biocatalysts was enhanced by increasing the percentage of neoteric solvent in DES-buffer mixtures. At a buffer content of 50% (w/w) and even 20% (w/w), the combination of either choline chloride (ChCl)/glycerol (Gly) (1:2) or ChCl/sorbitol (1:1) proved to be most effective for achieving up to >99% conversion and up to >99% enantiomeric excess of the corresponding secondary alcohols. Moreover, this reaction medium was used to perform the first example of a chemoenzymatic cascade process in DES-buffer mixtures, namely the ruthenium-catalysed isomerisation of racemic allylic alcohols coupled with a further enantioselective bioreduction, in both sequential and concurrent modes.
- Cicco, Luciana,Ríos-Lombardía, Nicolás,Rodríguez-álvarez, María J.,Morís, Francisco,Perna, Filippo M.,Capriati, Vito,García-álvarez, Joaquín,González-Sabín, Javier
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supporting information
p. 3468 - 3475
(2018/08/07)
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- Palladium-catalyzed room temperature acylative cross-coupling of activated amides with trialkylboranes
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A highly efficient acylative cross-coupling of trialkylboranes with activated amides has been effected at room temperature to give the corresponding alkyl ketones in good to excellent yields by using 1,3-bis(2,6-diisopropyl)phenylimidazolylidene and 3-chloropyridine co-supported palladium chloride, the PEPPSI catalyst, in the presence of K2CO3 in methyl tert-butyl ether. The scope and limitations of the protocol were investigated, showing good tolerance of acyl, cyano, and ester functional groups in the amide counterpart while halo group competed via the classical Suzuki coupling. The trialkylboranes generated in situ by hydroboration of olefins with BH3 or 9-BBN performed similarly to those separately prepared, making this protocol more practical.
- Shi, Weijia,Zou, Gang
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- MeZnOMe-mediated reaction of aldehydes with Grignard reagents: A glance into nucleophilic addition/Oppenauer oxidation pathway
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A novel organozincate of RMgX ?MeZnOMe ?LiCl type, formed in situ via transmetalation of Grignard reagent RMgBr ?LiCl with MeZnOMe, is shown to be an excellent organometallic species in the nucleophilic addition/Oppenauer oxidation of aldehydes to generate aromatic ketones in high yield. This transformation allows quick access to structurally diverse aryl, heteroaryl, benzyl and alkyl ketones with broad substrate scope and excellent functional group tolerance.
- Fu, Ying,Ma, Xian-Zhen,Shi, Chun-Zhao,Shen, Tong,Du, Zhengyin
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- Catalytic Cyclopropanol Ring Opening for Divergent Syntheses of γ-Butyrolactones and δ-Ketoesters Containing All-Carbon Quaternary Centers
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Catalytic ring opening cross coupling reactions of strained cyclopropanols have been useful for the syntheses of various β-substituted carbonyl products. Among these ring opening cross coupling reactions, the formation of α,β-unsaturated enone byproducts often competes with the desired cross coupling processes and has been a challenging synthetic problem to be addressed. Herein, we describe our efforts in developing divergent syntheses of a wide range of γ-butyrolactones and δ-ketoesters containing all-carbon quaternary centers via copper-catalyzed cyclopropanol ring opening cross couplings with 2-bromo-2,2-dialkyl esters. Our mechanistic studies reveal that unlike the previously reported cases, the formation of α,β-unsaturated enone intermediates is actually essential for the γ-butyrolactone synthesis and also contributes to the formation of the δ-ketoester product. The γ-butyrolactone synthesis is proposed to go through an intermolecular radical conjugate addition to the in situ generated α,β-unsaturated enone followed by an intramolecular radical cyclization to the ester carbonyl double bond. The reactions are effective to build all-carbon quaternary centers and have broad substrate scope.
- Ye, Zhishi,Cai, Xinpei,Li, Jiawei,Dai, Mingji
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p. 5907 - 5914
(2018/05/24)
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- Selective reductive cleavage of C–O bond in lignin model compounds over nitrogen-doped carbon-supported iron catalysts
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Lignin has recently attracted much attention as a promising resource to produce fuels and aromatic chemicals. The selective cleavage of C–O bond while preserving the aromatic nature has become one of the major challenges in the catalytic valorization of lignin to aromatic chemicals. In this work, we report that the selective reductive cleavage of C–O bond in lignin model compounds can be successfully achieved through heterogeneous iron catalysis. The hydrogenolysis of α-O-4 model linkage shows that the iron catalyst prepared by the simultaneous pyrolysis of iron acetate and 1,10-phenanthroline on activated carbon at 800 °C is the most active iron catalyst, affording phenol and toluene with yields of 95% and 90%, respectively. This aromatics selectivity is found to be much higher than that obtained over noble metal catalysts. The presence of N?Fe species as the active center of heterogeneous iron catalyst was confirmed by various technologies especially XPS and H2-TPR. For the β-O-4 model linkage, the vicinal –OH group was essential for the iron-catalyzed hydrogenolysis of ether linkage. The oxidation of the α-carbon in the β-O-4 model compounds can significantly decrease the bond dissociation energy of ether linkage, giving depolymerization products in moderate to excellent yields.
- Li, Jiang,Sun, Hui,Liu, Jia-xing,Zhang, Jun-jie,Li, Zhen-xing,Fu, Yao
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- Pd-catalyzed Oxidative Cross-coupling of Alkyl Chromium(0) Fischer Carbene Complexes with Organoboronic Acids
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Alkyl chromium(0) carbene complexes have been explored as the cross-coupling partners in the palladium-catalyzed reaction with aryl or alkenyl boronic acids. This coupling reaction displays the versatile reactivities of alkyl chromium(0) carbenes under palladium catalysis. Mechanistically, this transformation is proposed to involve deprotonation of the alkyl chromium carbene substrate to generate a vinyl chromium anion intermediate that undergoes transmetalation to organopalladium species and reductive elimination.
- Wang, Kang,Yang, Jinghui,Yao, Xingqi,Wang, Jianbo
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supporting information
p. 3165 - 3168
(2018/10/15)
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- Solvent free, light induced 1,2-bromine shift reaction of α-bromo ketones
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Photolysis of α-bromopropiophenones in acetonitrile results in formation of β-bromopropiophenones with good product selectivity, which can be coined as 1,2-Br shift reaction. The product selectivity increases when the reaction is done in neat or solid state, where only the 1,2-Br shift product is formed in some cases. The reaction is suggested to proceed by C–Br bond homolysis to give a radical pair, followed by disproportionation and conjugate addition of HBr to the α,β-unsaturated ketone intermediate. When the unsaturated intermediate is stabilized by an extra conjugation, the reaction stops at the stage, in which the unsaturated ketone becomes a major product. The synthetic method described in this research fits in a category of eco-friendly organic synthesis nicely since the reaction does not use volatile organic solvents and any other additives such as acid, base or metal catalysts, etc. Besides, the method fits into perfect atom economy, which does not give any side products. The synthetic method should find much advantage over other alternative methods to obtain β-bromo carbonyl compounds.
- An, Sejin,Moon, Da Yoon,Park, Bong Ser
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p. 6922 - 6928
(2018/10/24)
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- KOtBu-Mediated Domino Isomerization and Functionalization of Aromatic Allylic Alcohols
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Transition-metal- as well as ligand-free base-mediated domino isomerization and alkylation of allylic alcohols is presented. This protocol features the conversion of simple allylic alcohols into the corresponding ketones through isomerization in the presence of a simple base. Significantly, these in situ generated ketones subsequently undergo alkylation with styrenes as electrophiles, in a domino one-pot fashion, as an atom- and step-economical chemical process.
- Suchand, Basuli,Satyanarayana, Gedu
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p. 3886 - 3895
(2017/07/22)
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- Mononuclear Ruthenium and Osmium Complexes with a Bicyclic Guanidinate Ligand: Synthesis and Catalytic Behavior in Olefin Isomerization Processes
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The preparation of the first mononuclear RuII, RuIV, and OsII complexes containing the anion of the bicyclic guanidine 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (Hhpp) as a chelating ligand, namely [RuX{κ2-(N,N′)-hpp}(η6-arene)] [arene = p-cymene, X = Cl (2a), Br (2b), I (2c); arene = C6Me6, X = Cl (7)], [RuCl{κ2-(N,N′)-hpp}(η3:η3-C10H16)] (9; C10H16 = 2,7-dimethylocta-2,6-diene-1,8-diyl), and [OsCl{κ2-(N,N′)-hpp}(η6-p-cymene)] (11), is described. Compounds 2a–c, 7, 9, and 11 have been fully characterized by elemental analysis, HRMS, IR and NMR spectroscopy. In addition, the structure of 2a has been unequivocally confirmed by single-crystal X-ray diffraction methods. The catalytic behavior of these metal guanidinate complexes in the base-free redox isomerization of allylic alcohols is explored, with the ruthenium(IV) derivative 9 showing the best performance (TOF up to 5940 h–1). All of the synthesized complexes have also proven to be active in the isomerization of the allylbenzene estragole into the industrially relevant 1-propenylbenzene anethole, with a trans selectivity of up to 95 %.
- Gámez-Rivera, Sebastián A.,Francos, Javier,Borge, Javier,Cadierno, Victorio
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p. 4138 - 4146
(2017/09/28)
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- Alcohol Oxidations Using Reduced Polyoxovanadates
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A full account of our recently communicated room temperature alcohol oxidation using reduced polyoxovanadates (r-POVs) is presented. Extensive optimizations revealed optimal conditions employing 0.02 equiv. of r-POV catalyst Cs5(V14As8O42Cl), 5 equiv. tert-butyl hydrogen peroxide (tBuOOH) as the terminal co-oxidant, in an acetone solvent for the quantitative oxidation of aryl-substituted secondary alcohols to their ketone products. The substrate scope tolerates most aryl substituted secondary alcohols in good to quantitative yields while alkyl secondary and primary activated alcohols were sluggish in comparison under similar conditions. Catalyst recyclability was successful on a 1.0?mmol scale of starting alcohol 1-phenylethanol. The oxidation was also successfully promoted by the VIV/VV mixed valent polyoxovanadate (POV) Cs11Na3Cl5(V15O36Cl). Finally, a third POV, Cs2.64(V5O9)(AsO4)2, was investigated for catalytic activity using our established reaction protocol, but proved ineffective as compared to the other two r-POV catalysts. This study expands the field of POM-mediated alcohol oxidations to include underexplored r-POV catalysts. While our catalysts do not supplant the best catalysts known for the transformation, their study may inform the development of other novel oxidative transformations mediated by r-POVs.
- Campbell, McKenzie L.,Sulejmanovic, Dino,Schiller, Jacqueline B.,Turner, Emily M.,Hwu, Shiou-Jyh,Whitehead, Daniel C.
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- Promoting Lignin Depolymerization and Restraining the Condensation via an Oxidation-Hydrogenation Strategy
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For lignin valorization, simultaneously achieving the efficient cleavage of ether bonds and restraining the condensation of the formed fragments represents a challenge thus far. Herein, we report a two-step oxidation-hydrogenation strategy to achieve this goal. In the oxidation step, the O2/NaNO2/DDQ/NHPI system selectively oxidizes CαH-OH to Cα=O within the β-O-4 structure. In the subsequent hydrogenation step, the α-O-4 and the preoxidized β-O-4 structures are further hydrogenated over a NiMo sulfide catalyst, leading to the cleavage of Cβ-OPh and Cα-OPh bonds. Besides the transformation of lignin model compounds, the yield of phenolic monomers from birch wood is up to 32% by using this two-step strategy. The preoxidation of CαH-OH to Cα=O not only weakens the Cβ-OPh ether bond but also avoids the condensation reactions caused by the presence of Cα+ from dehydroxylation of CαH-OH. Furthermore, the NiMo sulfide prefers to catalyze the hydrogenative cleavage of the Cβ-OPh bond connecting with a Cα=O rather than catalyze the hydrogenation of Cα=O back to the original CαH-OH, which further ensures and utilizes the advantages of preoxidation.
- Zhang, Chaofeng,Li, Hongji,Lu, Jianmin,Zhang, Xiaochen,Macarthur, Katherine E.,Heggen, Marc,Wang, Feng
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p. 3419 - 3429
(2017/06/09)
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- Method for degrading lignin
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The invention discloses a method for degrading lignin. Water is used as a solvent. The method includes carrying out reaction on the lignin under the effects of double-rhodium catalysts or terpyridine rhodium trichloride catalysts and alkali under the protection of inert gas at the temperatures of 100-120 DEG C for 10-16 hours to degrade the lignin. Compared with existing methods, the method has the advantages that extra hydrogen sources can be omitted, the water is used as the solvent, reaction conditions are mild, the method is easy to implement, high in reaction yield and low in industrial production cost and is green and environmentally friendly, and environmental pollution can be abated.
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Paragraph 0042; 0043; 0044
(2017/10/28)
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- Benzylic C(sp3)-H Functionalization for C-N and C-O Bond Formation via Visible Light Photoredox Catalysis
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A visible light mediated highly selective benzylic C-H bond functionalization for intermolecular C-N and C-O bond formation is reported. This cross-dehydrogenative coupling reaction demonstrates a straightforward protocol for incorporating the heteroaromatics to the benzylic position. Benzylic oxidation of various alkyl aryls to corresponding carbonyl compounds has also been reported.
- Pandey, Ganesh,Laha, Ramkrishna,Singh, Deepak
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p. 7161 - 7171
(2016/08/30)
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- Novel CRAC channel conditioning agent, and preparation method and applications thereof
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The invention provides a novel CRAC (calcium release-activated calcium) channel conditioning agent, and a preparation method and applications thereof, and more specifically, the invention provides a compound represented by formula I, and the groups are defined in the patent specification. The invention also provides the preparation method of the compound represented by formula I, and applications of the compound as a CRAC channel conditioning agent.
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