- Rhodium catalysed synthesis of seleno-ketals: Via carbene transfer reactions of diazoesters
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Herein, we report on rhodium catalysed carbene transfer reactions of diazoesters with diselenides that result in the formal insertion reaction of the carbene fragment into the Se-Se bond to give seleno-ketals in up to 96% yield (35 examples) via an ionic mechanism.
- Jana, Sripati,Aseeva, Polina,Koenigs, Rene M.
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- Photosensitized oxygenation of diaryl tellurides to telluroxides and their oxidizing properties
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Photosensitized oxidation of tellurides carrying bulky aromatic substituents afforded the corresponding telluroxides which were found to react with simple alcohols to give the corresponding carbonyl compounds in excellent yields along with the starting tellurides.
- Oba, Makoto,Endo, Masaki,Nishiyama, Kozaburo,Ouchi, Akihiko,Ando, Wataru
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- HALIDE-DIRECTED NITRILE HYDROLYSYS
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Sodium bromide is an effective catalyst for promoting the hydrolysis of aroyl cyanides such that loss of the cyano group is greatly minimized.
- Photis, James M.
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- Air oxidation of p-substituted benzoin to the corresponding benzil catalyzed by Fe(II)-cysteine peptide complexes
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The Fe(II)-cysteine-containing peptide complexes were found exhibit catalytic activity for air oxidation of benzoin to benzil and methyl DL-mandelate to methyl benzoylformate. In the presence of [Fe(Z-cys-Gly-Val-OMe)4]2-, the rates of catalytic air- oxidation of p-substituted benzoin indicate a trend, Br> H> CH3 > MeO, and the isotope effect kH/kD was 3.4. The indicates that the methine hydrogen of benzoin is released as a proton in the rate determining step. Furthermore, solvent effect was found, in a non-polar solvent, e.g. 1,2-dimethoxyethane (DME), a chelating bidentate cys-peptide complex, [Fe(Z-cys-Pro-Leu-cys-Gly-Val-OMe)2]2-′ shows higher catalytic activity than that of a non-chelating cys-peptide complex, [Fe(Z-cys-Gly-Val-OMe)4]2-. This is explained by the contribution of intramolecular NH---S hydrogen bonds since such hydrogen bonds stabilize the Fe(III) state which is the active species during the oxidation.
- Sun, Wei-Yin,Ueyama, Norikazu,Nakamura, Akira
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- Oxidations of Dihydroxyalkanoates to Vicinal Tricarbonyl Compounds with a 4-BzoTEMPO-Sodium Bromite System or by Indirect Electrolysis Using 4-BzoTEMPO and Bromide Ion
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An efficient access to vicinal dioxoalkanoates, one of structural elements of potent competitive inhibitors of hydrolytic enzyme, from 2,3-dihydroxyalkanoates has been developed, which features an one-step procedure with a mild oxidizing system using recyclable 2, 2, 6, 6-tetramethylpiperidine-1-oxyl in combination with NaBrO2*3H2O or electrogenerated active bromine species as a real oxidant.
- Inokuchi, Tsutomu,Liu, Ping,Torii, Sigeru
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- A novel method for synthesis of α-keto esters with phenyliodine(III) diacetate
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A rapid and efficient synthesis of α-keto esters from β-ketonitriles using phenyliodine(III) diacetate is reported. This protocol gave α-keto esters in good yields. This is the first time to report the application of hypervalent iodine(III) reagents in the synthesis of α-keto esters. A plausible reaction mechanism is proposed.
- Xie, Yuanyuan,Liu, Jiwei,Huang, Yingyi,Yao, Lixia
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- Novel Synthesis of α-Keto Esters and Amides by an sp3 C-H Oxidation of Nitromethyl Aryl Ketones Promoted by Ion-Supported (Diacetoxyiodo)benzene
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A simple and efficient method is described for the preparation of α-keto esters or amides from nitromethyl aryl ketones. In the presence of nucleophiles (alcohols or amines), the ion-supported (di-acetoxyiodo)benzene-promoted sp3 C-H oxidation of nitromethyl aryl ketones proceeded efficiently under mild conditions to give the corresponding α-keto esters and amides in moderate to good yields. This is the first reported use of (diacetoxyiodo)benzene in the synthesis of α-keto esters and amides. The reaction is ecofriendly and has the -advantages of mild conditions, short reaction times, and a recyclable reagent.
- Jiang, Xiaoying,Gan, Bing,Liu, Jiwei,Xie, Yuanyuan
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- An efficient method for synthesis of α-keto acid esters from terminal alkynes
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α-Keto acid esters can be easily prepared in high yields in two steps from terminal alkynes via bromination and oxidation. This strategy provides a versatile access to the synthesis of biologically important natural products with an α-keto acid moiety.
- Li, Lian-Sheng,Wu, Yu-Lin
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- A Tricomponent Reaction Promoted by a Titanium Trichloride/Pyridine System Diastereoselective Synthesis of β-Amino-α-hydroxyesters
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Methyl phenylglyoxylate, aniline and aromatic aldehydes, on treatment with TiCl3/pyridine in anhydrous THF at room temperature, undergo rapid condensation to produce syn-β-amino-α-hydroxyesters.The mechanism of the reaction is rationalized.
- Clerici, Angelo,Clerici, Laura,Porta, Ombretta
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- One-pot efficient synthesis of aryl α-keto esters from aryl-ketones
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A novel one-pot synthesis of aryl α-keto esters was developed through oxidation of aryl-ketones using selenium dioxide, esterification accompanied by ketalization, and hydrolysis. Both aromatics and heteroaromatics gave good yields by this one-pot method.
- Zhuang, Jing,Wang, Changqing,Xie, Fang,Zhang, Wanbin
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- Reactivity of methyl mandelate-Ti(IV)-enediolate: Oxidative homocoupling versus aldol and direct Mannich-type syn-diastereoselective condensation
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Methyl mandelate undergoes quantitative oxidative homocoupling on treatment with TiCl4/amine at room temperature. In the presence of ArCHO, quantitative syn-diastereo-selective aldol condensation takes over the dimerization, whereas exclusive M
- Clerici, Angelo,Pastori, Nadia,Porta, Ombretta
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- Direct Access to 2-Thioxooxazolidin-4-ones and Oxazolidine-2,4-diones from α-Keto Thioesters through Thiolate Transfer
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We report a direct synthesis of 2-thioxooxazolidin-4-ones and oxazolidine-2,4-diones from α-keto thioesters with sodium thiocyanate or potassium cyanate, respectively. The reactions proceed through nucleophilic substitution of a thioester with thiocyanate/cyanate anion, thiolate anion addition to carbonyl carbon, and subsequent intramolecular C?O heterocyclization. (Figure presented.).
- Maity, Rajib,Naskar, Sandip,Mal, Kanchan,Biswas, Sandipa,Das, Indrajit
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- Synthesis of methyl phenyl glyoxylate via clean oxidation of methyl mandelate over a nanocatalyst based on heteropolyacid supported on clay
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Oxidation is an important class of reaction from both industrial and academic points of view. In recent years, a large number of oxidizing agents have been used for a variety of industrial reactions, but many of them are polluting, giving poor yields. Mandelates have played an important role in organic synthesis and are used in artificial flavoring and perfumes. Methyl phenyl glyoxylate, which contains two carbonyl groups, is an important intermediate used in fine chemical industry. Oxidation of methyl mandelate was carried out to prepare methyl phenyl glyoxylate, with 85% selectivity, by using hydrogen peroxide in the presence of a novel catalyst, namely, 20% w/w Cs 2.5H0.5PW12O40/K-10 catalyst, which is partly substituted dodecatungstophosphoric acid supported on clay. The catalyst is a nano material and reusable. The workup is easy.
- Yadav, Ganapati D.,Bhagat, Ramesh D.
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- Amine degradation by 4,5-epoxy-2-decenal in model systems
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The reactions of 4,5-epoxy-2-decenal with octylamine, benzylamine, and 2-phenylglycine methyl ester were studied to investigate if amines may suffer a Strecker type degradation by epoxyalkenals analogously to amino acids. In addition to other reactions, the studied amines were converted into their corresponding Strecker aldehydes (octanal, benzaldehyde, and methyl 2-oxo-2-phenylacetate, respectively) to an extent that depended on the pH, the temperature, the amount of epoxyalkenal, and the amine involved. Each amine exhibited an optimum pH for the reaction, but the corresponding Strecker aldehydes were produced to a significant extent within a broad pH range. In addition, the temperature mostly influenced the reaction rate, which was increased between 6.5 and 9.5 times when the reaction was carried out at 60°C than when it took place at 37°C. Furthermore, Strecker aldehyde formation was linearly correlated with the amount of the epoxyalkenal present in the reaction mixture. Nevertheless, the reaction yield mostly depended on the amine involved. Thus, octylamine only produced trace amounts of octanal, benzylamine was converted into benzaldehyde with a yield of 4.3%, and 2-phenylglycine methyl ester was converted into methyl 2-oxo-2-phenylacetate with a reaction yield of 49%. All of these results suggest that suitable amines can be degraded by epoxyalkenals to their corresponding Strecker aldehydes to a significant extent.
- Zamora, Rosario,Gallardo, Emerenciana,Hidalgo, Francisco J.
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- Enantiospecific total synthesis of (+)-tanikolide via a key [2,3]-meisenheimer rearrangement with an allylic amine N-oxide-directed epoxidation and a one-pot trichloroisocyanuric acid N-debenzylation and N-chlorination
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The enantiospecific total synthesis of the δ-lactonic marine natural product (+)-tanikolide (1), isolated from Lyngbya majuscula, was achieved using a [2,3]-Meisenheimer rearrangement as the key reaction. During this rearrangement, we discovered that the allylic amine N-oxide could direct the m-CPBA double-bond epoxidation to the syn position. The resulting syn product 8 underwent epoxide ring opening under the m-CBA conditions to give the five- and six-membered cyclic ether amine N-oxides, which we further treated with Zn and conc. HCl to obtain the reduced bisbenzyl tertiary amines 23 and 22, respectively. When 23 and 22 were treated with trichloroisocyanuric acid (TCCA) in dichloromethane, oxidation at the benzyl position occurred, forming iminium ions. These intermediates were trapped by intramolecular reaction with the hydroxyls, and the resulting intermediates were then oxidized or shifted to afford 25 and 24, respectively. The entire one-pot process involves N-debenzylation, N-chlorination, and hemiacetal oxidation. The amine N-oxide-directed epoxidation complements Davies' ammonium-directed epoxidation. Thus, TCCA N-debenzylation is described for the first time and might be a useful N-debenzylation technique.
- Xie, Yangla,Sun, Moran,Zhou, Hang,Cao, Qiwei,Gao, Kaige,Niu, Changling,Yang, Hua
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- Mechanistic Investigation of the Oxidation of the Carbanion of Methyl 2-Methoxy-2-phenylacetate by an Isoalloxazine
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Evidence from product studies and radical trapping experiments indicates that the mechanism of the oxidation of the carbanion of methyl 2-methoxy-2-phenylacetate by a model flavin compound in basic methanol is free radical in nature.
- Novak, Michael,Bruice, Thomas C.
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- Oxygenation of Phenylacetylene catalysed bu Co(salen)
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Co(salen) catalysed oxygenation of 4-substituted phenylacetylenes in alcohols results in highly selective incorporation of oxygen into the triple bond to give the corresponding acetophenones, and mandelic and phenylglyoxylic esters.
- Nishinaga, Akira,Maruyama, Kazushige,Yoda, Kohei,Okamoto, Hiromitsu
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- Benzylic and allylic oxidations with bis(trifluoroacetoxyiodo)benzene and tert -butyl hydroperoxide
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Oxidation of benzylic and allylic substrates with a bis(trifluoroacetoxyiodo)benzene/tert-butyl hydroperoxide system to the corresponding ,-unsaturated enones was investigated. The scope and reaction mechanism are discussed. Georg Thieme Verlag Stuttgart New York.
- Catir, Mustafa,Kilic, Hamdullah
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- Vanadium-catalysed Novel Oxidation of Arylacetic Esters for the Synthesis of Arylglyoxylic Esters
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Direct synthesis of arylglyoxylic esters in excellent yields from inexpensive arylacetic esters is realised for the first time by the oxidation of activated methylene using vanadium pillared clay as the catalyst and tert-butylhydroperoxide as an oxidant.
- Choudary, B. M.,Reddy, G. Vidya Sagar,Rao, K. Koteswara
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- Oxidative Decarboxylation of Propiolic Acids
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The combination of iodine and iodine pentoxide in methanol was used to convert phenylpropiolic acid and 2-hexynoic acid to the corresponding ketal esters of one less carbon.In both cases, iodoacetylenic compounds were shown to be intermediates.In the case of the phenylpropiolic acid, a diiodoalkene was isolated and shown to be a second intermediate.
- Cohen, Mark J.,McNelis, Edward
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- Rhodium-Catalyzed Hydrocarboxylation: Mechanistic Analysis Reveals Unusual Transition State for Carbon-Carbon Bond Formation
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The mechanism of rhodium-COD-catalyzed hydrocarboxylation of styrene derivatives and α,β-unsaturated carbonyl compounds with CO2 has been investigated using density functional theory (PBE-D2/IEFPCM). The calculations support a catalytic cycle as originally proposed by Mikami and co-workers including β-hydride elimination, insertion of the unsaturated substrate into a rhodium-hydride bond, and subsequent carboxylation with CO2. The CO2 insertion step is found to be rate limiting. The calculations reveal two interesting aspects. First, during C-CO2 bond formation, the CO2 molecule interacts with neither the rhodium complex nor the organozinc additive. This appears to be in contrast to other CO2 insertion reactions, where CO2-metal interactions have been predicted. Second, the substrates show an unusual coordination mode during CO2 insertion, with the nucleophilic carbon positioned up to 3.6 ? away from rhodium. In order to understand the experimentally observed substrate preferences, we have analyzed a set of five alkenes: an α,β-unsaturated ester, an α,β-unsaturated amide, styrene, and two styrene derivatives. The computational results and additional experiments reported here indicate that the lack of activity with amides is caused by an overly high barrier for CO2 insertion and is not due to catalyst inactivation. Our experimental studies also reveal two putative side reactions, involving oxidative cleavage or dimerization of the alkene substrate. In the presence of CO2, these alternative reaction pathways are suppressed. The overall insights may be relevant for the design of future hydrocarboxylation catalysts.
- Pavlovic, Ljiljana,Vaitla, Janakiram,Bayer, Annette,Hopmann, Kathrin H.
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- Novel effect of zinc nitrate/vanadyl oxalate for selective catalytic oxidation of α-hydroxy esters to α-keto esters with molecular oxygen: An in situ ATR-IR study
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Selective oxidation of α-hydroxy esters is one of the most important methods to prepare high value-added α-keto esters. An efficient catalytic system consisting of Zn(NO3)2/VOC2O4 is reported for catalytic oxidation of α-hydroxy esters with molecular oxygen. Up to 99% conversion of methyl DL-mandelate or methyl lactate could be facilely obtained with high selectivity for its corresponding α-keto ester under mild reaction conditions. Zn(NO3)2 exhibited higher catalytic activity in combination with VOC2O4 compared with Fe(NO3)3 and different nitric oxidative gases were detected by situ attenuated total reflection infrared (ATR-IR) spectroscopy. UV-vis and ATR-IR results indicated that coordination complex formed in Zn(NO3)2 in CH3CN solution was quite different from Fe(NO3)3; it is proposed that the charge-transfer from Zn2+ to coordinated nitrate groups might account for the generation of different nitric oxidative gases. The XPS result indicate that nitric oxidative gas derived from the interaction of Zn(NO3)2 with VOC2O4 could be in favor of oxidizing VOC2O4 to generate active vanadium (V) species. It might account for different catalytic activity of Zn(NO3)2 or Fe(NO3)3 combined with VOC2O4. This work contributes to further development of efficient aerobic oxidation under mild reaction conditions.
- Ju, Yongwei,Du, Zhongtian,Xiao, Chuhong,Li, Xingfei,Li, Shuang
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- Heterogeneous Esterification from α-Hydroxy Ketone and Alcohols through a Tandem Oxidation Process over a Hydrotalcite-Supported Bimetallic Catalyst
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Heterogeneous aerobic oxidative esterification between α-hydroxy ketone and alcohols catalyzed by a hydrotalcite-supported bimetallic catalyst (CuMn/HT) using O2 as a green oxidant was achieved. Recyclable CuMn/HT exhibits high catalytic activity due to increased content of oxygen vacancies and a newly generated CuMn2O4 crystal phase. This clean esterification proceeds through a tandem oxidation process in the absence of any additives and ligands and affords α-keto esters in good to excellent yields. Moreover, the catalytic system tolerates complicated bioactive molecules as raw materials and can be performed on a multigram scale.
- Meng, Xu,Bi, Xiuru,Chen, Gexin,Chen, Baohua,Zhao, Peiqing
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- Unraveling two pathways for NHPI-mediated electrocatalytic oxidation reaction
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Two pathways for N-hydroxyphthalimide (NHPI)-mediated electrocatalytic oxidation using phenylacetate derivatives as template substrates were first reported for benzylic C[sbnd]H oxidation to oxygenated and non-oxygenated products. DFT calculation indicates that the hydrogen-atom transfer (HAT) process between phthalimido-N-oxyl (PINO) and substrate is a rate-determined step. Aromatic α-keto esters and 2-((1,3-dioxoisoindolin-2-yl)oxy)-2-aryl acetate obtained by cross-coupling between benzylic radical and PINO can be selectively synthesized through controlling the concentration of PINO radical. This method provides a deep understanding for selective weak C[sbnd]H oxidation using NHPI as redox mediator.
- Xu, Leitao,Yi, Yangjie,Hu, Sideng,Ye, Jiao,Hu, Aixi
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- Electrochemical two-electron oxygen reduction reaction (ORR) induced aerobic oxidation of α-diazoesters
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Electrochemical oxygen reduction reaction (ORR) is a powerful tool for introducing oxygen functional groups in synthetic chemistry. However, compared with the well-developed one-electron oxygen reduction process, the applications of two-electron oxygen re
- Chen, Liang,Gao, Meng,Lu, Cuifen,Ma, Chao,Ruan, Mengyao,Wen, Ziyang,Yang, Fan,Yang, Guichun
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p. 2168 - 2171
(2022/02/17)
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- Visible-light photocatalytic selective oxidation of C(sp3)-H bonds by anion-cation dual-metal-site nanoscale localized carbon nitride
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Selective oxidation of C(sp3)-H bonds to carbonyl groups by abstracting H with a photoinduced highly active oxygen radical is an effective method used to give high value products. Here, we report a heterogeneous photocatalytic alkanes C-H bonds oxidation method under the irradiation of visible light (λ= 425 nm) at ambient temperature using an anion-cation dual-metal-site modulated carbon nitride. The optimized cation (C) of Fe3+or Ni2+, with an anion (A) of phosphotungstate (PW123?) constitutes the nanoscale dual-metal-site (DMS). With a Fe-PW12dual-metal-site as a model (FePW), we demonstrate a A-C DMS nanoscale localized carbon nitride (A-C/g-C3N4) exhibiting a highly enhanced photocatalytic activity with a high product yield (86% conversion), selectivity (up to 99%), and a wide functional group tolerance (52 examples). The carbon nitride performs the roles of both the visible light response, and improves the selectivity for the oxidation of C(sp3)-H bonds to carbonyl groups, along with the function of A-C DMS in promoting product yield. Mechanistic studies indicate that this reaction follows a radical pathway catalyzed by a photogenerated electron and hole on A-C/g-C3N4that is mediated by thetBuO˙ andtBuOO˙ radicals. Notably, a 10 g scale reaction was successfully achieved for alkane photocatalytic oxidation to the corresponding product with a good yield (80% conversion), and high selectivity (95%) under natural sunlight at ambient temperature. In addition, this A-C/g-C3N4photocatalyst is highly robust and can be reused at least six times and the activity is maintained.
- Duan, Limei,Li, Peihe,Li, Wanfei,Liu, Jinghai,Liu, Ying,Liu, Zhifei,Lu, Ye,Sarina, Sarina,Wang, Jinghui,Wang, Yin,Wang, Yingying,Zhu, Huaiyong
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p. 4429 - 4438
(2021/07/12)
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- Metal- And additive-free C-H oxygenation of alkylarenes by visible-light photoredox catalysis
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A metal- and additive-free methodology for the highly selective, photocatalyzed C-H oxygenation of alkylarenes under air to the corresponding carbonyls is presented. The process is catalyzed by an imide-acridinium that forms an extremely strong photooxidant upon visible light irradiation, which is able to activate inert alkylarenes such as toluene. Hence, this is an easy to perform, sustainable and environmentally friendly oxidation that provides valuable carbonyls from abundant, readily available compounds.
- García Manche?o, Olga,Kuhlmann, Jan H.,Pérez-Aguilar, María Carmen,Piekarski, Dariusz G.,Uygur, Mustafa
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supporting information
p. 3392 - 3399
(2021/05/21)
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- Copper on charcoal: Cu0nanoparticle catalysed aerobic oxidation of α-diazo esters
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By using a charcoal supported nano Cu0catalyst (Cu/C), a highly efficient oxidation of α-diazo esters to α-ketoesters with molecular oxygen as the sole oxidant has been developed. In the presence of the Cu/C catalyst, 2-aryl-α-diazo esters with both electron-donating and electron-withdrawing groups can be oxidized to the corresponding α-ketoesters efficiently. Furthermore, this Cu/C catalyst can catalyse the reaction of aryl α-diazo ester with water to form aryl ketoester, 2-aryl-2-hydroxyl acetate ester and 2-aryl acetate ester. In this case, water is split by α-diazo ester, and the diazo group is displaced by the oxygen or hydrogen atom in water. Mechanistic investigation showed that the reaction of α-diazo ester with oxygen proceeds through a radical pathway. In the presence of 2,2,6,6-tetramethyl piperidine nitrogen oxide, the reaction of α-diazo ester with oxygen is dramatically inhibited. Furthermore, the reaction of α-diazo ester with water is investigated by an isotopic tracer method, and GCMS detection showed that a disproportionation reaction occurred between α-diazo ester and water.
- Chu, Changhu,Dong, Wenwen,Lin, Jia,Teng, Jiangge,Wang, Zhiwei,Zhao, Rong
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p. 6120 - 6126
(2021/07/21)
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- Photoinduced Diverse Reactivity of Diazo Compounds with Nitrosoarenes
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A diverse reactivity of diazo compounds with nitrosoarene in an oxygen-transfer process and a formal [2 + 2] cycloaddition is reported. Nitosoarene has been exploited as a mild oxygen source to oxidize an in situ generated carbene intermediate under visible-light irradiation. UV-light-mediated in situ generated ketenes react with nitosoarenes to deliver oxazetidine derivatives. These operationally simple processes exemplify a transition-metal-free and catalyst-free protocol to give structurally diverse α-ketoesters or oxazetidines.
- Roy, Sourav,Kumar, Gourav,Chatterjee, Indranil
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p. 6709 - 6713
(2021/09/08)
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- Silyl Cyanopalladate-Catalyzed Friedel-Crafts-Type Cyclization Affording 3-Aryloxindole Derivatives
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3-Aryloxindole derivatives were synthesized through a Friedel-Crafts-type cyclization. The reaction was catalyzed by a trimethylsilyl tricyanopalladate complex generated in situ from trimethylsilyl cyanide and Pd(OAc) 2. Wide varieties of diethyl phosphates derived from N -arylmandelamides were converted almost quantitatively into oxindoles. When N, N -dibenzylamide was used instead of an anilide substrate, a benzo-fused δ-lactam was obtained. An oxindole product was subjected to substitution reactions to afford 3,3-diaryloxindoles with two different aryl groups.
- Ece, Hamdiye,Tange, Yuji,Yurino, Taiga,Ohkuma, Takeshi
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p. 935 - 939
(2021/02/22)
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- [Fe(bpy)3]2+-based porous organic polymers with boosted photocatalytic activity for recyclable organic transformations
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Three rigid metal porous organic polymers (POPs) based on an iron(ii) complex are prepared from the condensation reactions of an octahedral [Fe(bpy)3]2+-cored hexaaldehyde and three rod-like aromatic diamines. The POPs have been studied as the first series of earth-abundant metal complex-connected photocatalysts for heterogeneous visible light-driven oxidation of benzyl halides and enantioselective α-alkylation of aldehydes. Both yields and enantioselectivities of the reactions catalyzed by one of the POPs, which possesses the largest porosity, rival or even surpass those of the reactions homogeneously catalyzed by control [Fe(bpy)3]2+complexes. Moreover, POP catalysts are highly stable and exhibit a considerable activity after recycling 10 times.
- Liu, Hong-Kun,Lei, Yi-Fei,Tian, Peng-Ju,Wang, Hui,Zhao, Xin,Li, Zhan-Ting,Zhang, Dan-Wei
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supporting information
p. 6361 - 6367
(2021/03/22)
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- Preparation method for rapidly generating alpha-ketone ester through iodine-mediated alpha-diazonium ester oxidation
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The invention relates to the field of research of ketone ester compounds, in particular to a preparation method for rapidly generating alpha-ketone ester through iodine-mediated alpha-diazo ester oxidation, the preparation method comprises the following steps: in an organic solvent, stirring alpha-diazo ester and iodine elementary substance as raw materials at room temperature for about half an hour to obtain the alpha-ketone ester compound. According to the method, transition metal does not need to be used as a catalyst, a strong oxidant does not need to be used, only under the room temperature condition, the low-toxicity and cheap iodine elementary substance is used as the oxidant, and the alpha-keto ester is generated through efficient oxidation of the alpha-diazonic acid ester. The method has the advantages that the reaction time is short (about 0.5 hour), the universality is high, the alpha-diazonic acid ester with electron donating groups or electron withdrawing groups can achieve medium to excellent yield (80%-99%), a greener alternative approach is represented, and a new general synthesis route is provided for efficient preparation of alpha-ketoester.
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Paragraph 0025; 0028-0029
(2021/07/24)
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- Preparation method of alpha-ketoester compound
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The invention discloses a preparation method of an alpha-ketone ester compound. The method specifically comprises the following operation steps: adding raw materials alpha-diazo ester and an organic photocatalyst into a reaction flask, then adding an organic solvent, and reacting for 2-12 hours in air at room temperature under the irradiation of a visible light lamp; after the reaction is monitored by thin-layer chromatography (TLC), stopping the reaction, and extracting a reaction solution by using ethyl acetate; concentrating the extracting solution under reduced pressure to obtain a crude product, and performing column chromatography separation on the crude product to obtain the alpha-diazonium ester compound. According to the preparation method, clean visible light is used as reaction energy, cheap organic dye is used as a photocatalyst, air is used as a green oxidizing agent and an oxygen source, and the preparation method has the advantages of simplicity and convenience in operation, no metal residue and mild reaction conditions.
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Paragraph 0030-0093
(2021/04/21)
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- Copper-Catalyzed Cross-Dehydrogenative Coupling of α-Hydroxy Esters with Nitromethane
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An efficient copper-catalyzed tandem oxidation/nitroaldol reaction of hydroxyl compounds with nucleophiles is developed. In this work, -nitro-hydroxy esters were prepared via cross-dehydrogenative coupling reaction using -hydroxy esters as hydroxy compounds and nitromethane as a nucleophile. The reaction is believed to undergo an oxidation of the hydroxyl group and then an addition of the generated carbonyl group. It is an example of CDC reactions related to hydroxyl compounds via carbonyl intermediates.
- Xiao, Lili,Jiang, Jin
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p. 1861 - 1864
(2021/08/06)
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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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supporting information
(2021/02/20)
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- Synthesis of 1,2-Dihydroisoquinoline-1-Carboxylates Under Cobalt Catalysis
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[Figure not available: see fulltext.] A study of cobalt-catalyzed C–H functionalization of phenylglycine derivatives with alkynes is described. During the optimization studies, a range of cobalt catalysts, oxidants, base additives, and reaction solvents were evaluated. Product yield dependence on phenylglycine ester substituent was evaluated. Conditions for 1,2-dihydroisoquinoline synthesis with acceptable yield were found.
- Zagorska, Paula Amanda,Grigorjeva, Liene,Bolsakova, Jekaterina
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- Visible-Light-Induced Catalyst-Free Carboxylation of Acylsilanes with Carbon Dioxide
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Intermolecular carbon-carbon bond formation between acylsilanes and carbon dioxide (CO2) was achieved by photoirradiation under catalyst-free conditions. In this reaction, siloxycarbenes generated by photoisomerization of the acylsilanes added to the C═O bond of CO2 to give α-ketocarboxylates, which underwent hydrolysis to afford α-ketocarboxylic derivatives in good yields. Control experiments suggest that the generated siloxycarbene is likely to be from the singlet state (S1) of the acylsilane and the addition to CO2 is not in a concerted manner.
- Fan, Zhengning,Yi, Yaping,Chen, Shenhao,Xi, Chanjuan
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supporting information
p. 2303 - 2307
(2021/04/05)
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- Stoichiometric Photochemical Carbene Transfer by Bamford–Stevens Reaction
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The photolysis of diazoalkanes is a timely strategy to conduct carbene-transfer reactions under mild and metal-free reaction conditions, and has developed as an important alternative to conventional metal-catalyzed carbene-transfer reactions. One of the major limitations lies within the rapidly occurring side reaction of the carbene intermediate with remaining diazoalkane molecules that result in the use of an excess of the reaction partner and thus impacts on the reaction efficiency. Herein, we describe a protocol that takes advantage of the in situ generation of donor–acceptor diazoalkanes by Bamford–Stevens reaction. Following this strategy, the concentration of the diazoalkane reaction partner can be minimized to reduce unwanted side reactions and to now conduct photochemical carbene transfer reactions under stoichiometric reaction conditions. We have explored this approach in the C?H and N?H functionalization and cyclopropanation reaction of N-heterocycles and could demonstrate the applicability of this method in 51 examples.
- Aseeva, Polina,Empel, Claire,Jana, Sripati,Koenigs, Rene M.,Li, Fang,Verspeek, Dennis
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supporting information
p. 2586 - 2591
(2020/03/04)
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- Selective Oxidation of Benzylic C-H Bonds Catalyzed by Cu(II)/{PMo12}
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Precise catalytic regulation of carbon radical generation by a highly active oxygen radical to abstract the H atom in a C-H bond is an effective method for the selective activation of C-H synthetic chemistry. Herein, we report a facile catalyst system with commercially available copper(II)/{PMo12} to form a tert-butanol radical intermediate for the selective oxidation of benzylic C-H bonds. The reaction shows a broad range of substrates (benzyl methylene, benzyl alcohols) with good functional group tolerance and chemical selectivity. The corresponding carbonyl compounds were synthesized with good yields under mild conditions. DFT calculations and experimental analysis further demonstrated a reasonable carbon radical mechanism for this type of organic transformation reaction.
- Li, Peihe,Wang, Yingying,Wang, Xia,Wang, Yin,Liu, Ying,Huang, Keke,Hu, Jing,Duan, Limei,Hu, Changwen,Liu, Jinghai
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p. 3101 - 3109
(2020/03/23)
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- Copper/Iodine-Cocatalyzed C-C Cleavage of 1,3-Dicarbonyl Compounds Toward 1,2-Dicarbonyl Compounds
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A new, general oxidative route to transformations of 1,3-dicarbonyl compounds to 1,2-dicarbonyl compounds by merging copper and I2 catalysis is described. This method is applicable to broad 1,3-dicarbonyl compounds, including 1,3-diketones, 1,3-keto esters and 1,3-keto amides. Mechanistical studies show that the reaction is achieved via the C–C bond cleavage and CO release cascades.
- Chen, Li-Sha,Zhang, Lu-Bing,Tian, Yue,Li, Jin-Heng,Liu, Yong-Quan
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supporting information
p. 5523 - 5526
(2020/09/02)
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- Green preparation method of aryl [alpha]-keto ester compound
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The invention discloses a green preparation method of an aryl [alpha]-keto ester compound. The method comprises the specific steps that an [alpha]-diazo compound serves as a reaction raw material, copper sulfate serves as a catalyst, water serves as a solvent, a target product aryl [alpha]-keto ester compound is prepared through a reaction at the temperature of 60 DEG C, the structural general formula of the [alpha]-diazo compound is shown in the specification, and the structural general formula of the correspondingly prepared target product aryl [alpha]-keto ester compound is shown in the specification. The method for synthesizing the target product aryl [alpha]-keto ester compound by catalyzing the [alpha]-diazo compound derivative with copper sulfate has the advantages that the reactioncondition is green and mild, the catalyst is cheap and easy to obtain, the operation is simple and convenient, the yield is relatively high, the universality of a reaction substrate is wide, and thelike.
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Paragraph 0037-0040
(2020/05/30)
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- Copper(I)-catalyzed aerobic oxidation of α-diazoesters
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A practical Cu-catalyzed oxidation of α-diazoesters to α-ketoesters using molecular oxygen as an oxidant has been developed. Both electron-poor and electron-rich aryl α-diazoesters are suitable substrates and provide the α-ketoesters in good yields. In this oxidative system, α-diazo-β-ketoesters are also compatible as substrates but unexpectedly furnish α-ketoesters via C-C bond cleavage, rather than the vicinal tricarbonyl products.
- Xu, Changming,Bai, Lei,Wang, Yongchang
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p. 12579 - 12584
(2020/11/09)
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- Butenolide derivative as well as preparation method and application thereof
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The invention discloses a butenolide compound as well as a preparation method and an application thereof. The butenolide derivative has the inhibitory activity of protein tyrosine phosphatase 1B (PTP1B), improves insulin resistance of HepG2 cells, generates a remarkable hypoglycemic effect and can be used for preparing a medicine for treating diabetes mellitus.
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Paragraph 0045-0047; 0051
(2020/07/21)
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- Redox-driven deracemization of secondary alcohols by sequential ether/O2-mediated oxidation and Ru-catalyzed asymmetric reduction
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The deracemization of benzylic alcohols has been achieved using a redox-driven one-pot two-step process. The racemic alcohols were oxidized by bis(methoxypropyl) ether and oxygen to give the ketone intermediates, followed by an asymmetric transfer hydrogenation with a chiral ruthenium catalyst. This compatible oxidation/reduction process gave the enantiomerically enriched alcohols with up to 95% ee values.
- Yang, Bing,Cui, Peng,Chen, Yongsheng,Liu, Qixing,Zhou, Haifeng
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supporting information
(2020/10/14)
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- Carbene-Catalyzed Enantioselective Aromatic N-Nucleophilic Addition of Heteroarenes to Ketones
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The aromatic nitrogen atoms of heteroarylaldehydes are activated by carbene catalysts to react with ketone electrophiles. Multi-functionalized cyclic N,O-acetal products are afforded in good to excellent yields and optical purities. Our reaction involves the formation of an unprecedented aza-fulvene-type acylazolium intermediate. A broad range of N-heteroaromatic aldehydes and electron-deficient ketone substrates works effectively in this transformation. Several of the chiral N,O-acetal products afforded through this protocol exhibit excellent antibacterial activities against Ralstonia solanacearum (Rs) and are valuable in the development of novel agrichemicals for plant protection.
- Liu, Yonggui,Luo, Guoyong,Yang, Xing,Jiang, Shichun,Xue, Wei,Chi, Yonggui Robin,Jin, Zhichao
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supporting information
p. 442 - 448
(2019/11/25)
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- Nature of the Nucleophilic Oxygenation Reagent Is Key to Acid-Free Gold-Catalyzed Conversion of Terminal and Internal Alkynes to 1,2-Dicarbonyls
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2,3-Dichloropyridine N-oxide, a novel oxygen transfer reagent, allows the conductance of the gold(I)-catalyzed oxidation of alkynes to 1,2-dicarbonyls in the absence of any acid additives and under mild conditions to furnish the target species, including those derivatized by highly acid-sensitive groups. The developed strategy is effective for a wide range of alkyne substrates such as terminal- and internal alkynes, ynamides, alkynyl ethers/thioethers, and even unsubstituted acetylene (40 examples; yields up to 99%). The oxidation was successfully integrated into the trapping of reactive dicarbonyls by one-pot heterocyclization and into the synthesis of six-membered azaheterocycles. This synthetic acid-free route was also successfully applied for the total synthesis of a natural 1,2-diketone.
- Dubovtsev, Alexey Yu.,Shcherbakov, Nikolay V.,Dar'in, Dmitry V.,Kukushkin, Vadim Yu.
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p. 745 - 757
(2020/02/04)
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- Dimethyl Sulfoxide as an Oxygen Atom Source Enabled Tandem Conversion of 2-Alkynyl Carbonyls to 1,2-Dicarbonyls
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A tandem transformation of 2-alkynyl carbonyl compounds by means of a CuBr2/I2/DMSO/water system is developed, enabling the fromation of various functionalized 1,2-dicarbonyl compounds, including 1,2-diketones, α-keto amides and α-keto ester. This Cu-promoted iodine-mediated tandem procedure employs DMSO as the oxygen atom source of the formed carbonyl group through iodonium ion formation, nucleophilic DMSO addition and C?C bond cleavage cascades. (Figure presented.).
- Hu, Ming,Li, Jin-Heng,Li, Yang,Lu, Yuan,Luo, Mu-Jia
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supporting information
(2020/05/01)
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- Catalytic Activation of Carbon-Hydrogen Bonds in Lignin Linkages over Strong-Base-Modified Covalent Triazine Frameworks for Lignin Oxidative Cleavage
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The design of highly efficient catalysts for the cleavage of various lignin linkages is the key step in the depolymerization of lignin. In this paper, strong-base-modified covalent triazine frameworks (CTFs) were reported to be effective in the cleavage o
- Gao, Jin,Liu, Meng,Shi, Song,Xu, Jie,Zhao, Li,Zhu, Guozhi
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p. 7526 - 7534
(2020/08/21)
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- Blue Light-Promoted Formal [4+1]-Annulation of Diazoacetates with o-Aminoacetophenones: Synthesis of Polysubstituted Indolines and Computational Study
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A blue light-promoted formal [4+1]-annulation of diazoacetates with o-aminoacetophenones has been reported, which provides an environmentally friendly method for the synthesis of polysubstituted indoline derivatives in moderate to good yields with excellent diastereoselectivities. Detailed mechanistic studies through density functional theory calculations reveal that the (E)-enol species is the key intermediate in this transformation, and the excellent diastereoselectivity is enabled via H-bonding in the intramolecular Aldol-type addition.
- Chen, Jinzhou,Liu, Shuhao,Lv, Xinxin,Hong, Kemiao,Lei, Jinping,Xu, Xinfang,Hu, Wenhao
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p. 13920 - 13928
(2020/11/03)
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- Au-Pd alloy cooperates with covalent triazine frameworks for the catalytic oxidative cleavage of β-O-4 linkages
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To design highly efficient catalysts for the cleavage of the C-O/C-C bond is the key task in the depolymerization of lignin. Bimetallic alloy catalysts Au-Pd-CTFs were developed to be effective in the oxidative cleavage of β-O-4 lignin model compounds with O2. Au-Pd nanoparticles with an Au/Pd molar ratio between 1?:?1 and 1?:?1.5 showed the highest cleavage efficiency. The kinetics of the reaction process revealed that a synergistic effect between Au and Pd played a crucial role in the oxidation of Cα-OH into CαO, which was the rate-determining step for the whole oxidative cleavage process. Further insight revealed that the cooperative effect between Au-Pd nanoparticles and the support covalent triazine frameworks (CTFs) facilitated the cleavage of the formed β-O-4 ketone compound to the corresponding aromatics. In addition, Au-Pd-CTF catalysts also showed efficiency in the oxidative transformation of the organosolv lignin. This catalytic system will provide guidance in the oxidative cleavage of β-O-4 linkages in lignin.
- Zhao, Li,Shi, Song,Zhu, Guozhi,Liu, Meng,Gao, Jin,Xu, Jie
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p. 6707 - 6716
(2019/12/26)
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- Asymmetric Counter-Anion-Directed Aminomethylation: Synthesis of Chiral β-Amino Acids via Trapping of an Enol Intermediate
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A novel enantioselective aminomethylation reaction of diazo compound, alcohol and α-aminomethyl ether enabled by asymmetric counteranion-directed catalysis is disclosed that offers an efficient and convenient access to furnish optically active α-hydroxyl-β-amino acids in high yield with high to excellent enantioselectivities. Control experiments and DFT calculations indicate that the transformation proceeds through trapping the in situ generated enol intermediate with methylene iminium ion, and the asymmetric induction was enabled by chiral pentacarboxycyclopentadiene anion via H-bonding and electrostatic interaction.
- Kang, Zhenghui,Wang, Yongheng,Zhang, Dan,Wu, Ruibo,Xu, Xinfang,Hu, Wenhao
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supporting information
p. 1473 - 1478
(2019/01/26)
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- Controllable chemoselectivity in the coupling of bromoalkynes with alcohols under visible-light irradiation without additives: Synthesis of propargyl alcohols and α-ketoesters
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The chemoselectivity of visible-light-induced coupling reactions of bromoalkynes with alcohols can be controlled by simple changes to the reaction atmosphere (N2 or O2). A N2 atmosphere favours propargyl alcohols via a direct C-C coupling process, whereas an O2 atmosphere results in the generation of α-ketoesters through the oxidative CC/C-O coupling pathway.
- Ni, Ke,Meng, Ling-Guo,Ruan, Hongjie,Wang, Lei
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supporting information
p. 8438 - 8441
(2019/07/22)
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- Method for preparing ketone compound through ethylbenzene compound
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The invention provides a method for preparing a ketone compound through an ethylbenzene compound, and belongs to the field of catalytic chemistry. According to the method, the ethylbenzene compound isadded into a mixed solvent of water and acetonitrile, and then mixed with an oxidizing agent, and then a catalytic oxidation reaction is conducted after copper acetate and phosphomolybdic acid are added to obtain the ketone compound. According to the method, in the preparing process, a Cu/POM green catalytic system is formed to serve as a catalyst, the preparing method is simplified, preparationof polyoxometallate catalysts is not needed, polyoxometalates and metal copper salt are used together to serve as a green catalytic system, the catalytic effect is excellent, the POMs can overcome thecatalysis bottleneck of the metal copper salt, and effective catalysis of a model reaction is achieved.
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Paragraph 0076-0078
(2019/10/22)
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- CuO-catalyzed oxidation of aryl acetates with aqueous tert-butyl hydroperoxide for the synthesis of α-ketoesters
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A practical method to access α-ketoesters from readily available aryl acetates is developed. In this approach, aqueous tert-butyl hydroperoxide and CuO are employed. No additional solvents are required and it was found that the peroxide side products in the reaction can be decomposed by pyridine.
- Jiang, Jin
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p. 235 - 240
(2019/07/16)
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- A Cu-Doped ZIF-8 metal organic framework as a heterogeneous solid catalyst for aerobic oxidation of benzylic hydrocarbons
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Mixed-metal metal organic frameworks have received considerable attention in recent years and it has been shown that the activity of the parent metal organic framework (MOF) is often enhanced upon doping with external metal ions within the framework. In this context, Cu2+ ions with different loadings were incorporated within the ZIF-8 framework to obtain a series of Cu-doped ZIF-8 materials and their activity was examined in the aerobic oxidation of hydrocarbons. The as-synthesized Cu-doped solids were characterized by powder X-ray diffraction (XRD), ultraviolet diffuse reflectance spectroscopy (UV-DRS), scanning electron microscopy (SEM), Fourier Transform infrared (FT-IR), electron paramagnetic resonance (EPR) and inductively coupled plasma (ICP) analysis. The experimental results revealed that the activity of Cu-doped ZIF-8 is much higher than that of the parent ZIF-8 in all the tested substrates at 120 °C. Furthermore, the activity of the Cu-doped ZIF-8 with the highest Cu loading was eight fold higher than that of the parent ZIF-8 in the aerobic oxidation of cyclooctane (1) at 120 °C with more than 80% selectivity to the corresponding cyclooctanol/cyclooctanone (ol/one) mixture. Cu-doped ZIF-8 was reused two times with no significant drop in its activity under identical conditions. Furthermore, comparison of the two times reused solid with that of the fresh solid by powder XRD and SEM analysis revealed identical structural integrity and morphology, respectively during the oxidation reactions.
- Nagarjun, Nagarathinam,Dhakshinamoorthy, Amarajothi
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p. 18702 - 18712
(2019/12/09)
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- Novel synthesis method for oxophenylacetate
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The invention discloses a novel synthesis method for oxophenylacetate and belongs to the technical field of synthesis. The novel synthesis method comprises the steps: firstly, reacting benzonitrile and a halogenation reagent at 20-35 DEG C to obtain dihalogenated phenylacetonitrile; then, adding a mixed solution of acid and water into dihalogenated phenylacetonitrile at 35-55 DEG C, and carrying out a reaction at 50-60 DEG C for 2-8 h, wherein the molar ratio of a product I to the water to the acid is 1:(1-10):(1-10); and finally, adding alcohol into the reaction solution in the former step at50-60 DEG C, then, carrying out stirring, controlling the temperature at 60-70 DEG C, carrying out a constant-temperature reaction for 1-4 h, and carrying out cooling and extraction to obtain a target product. The reaction raw materials adopted in the method are wide in source and low in price, the operation process is simple, and the yield of the product is high.
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- Pd(OAc)2-Catalyzed Asymmetric Hydrogenation of α-Iminoesters
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An efficient Pd(OAc)2-catalyzed asymmetric hydrogenation of α-iminoesters was realized for the first time at 1 atm hydrogen pressure and room temperature. Pd(OAc)2, a less expensive Pd salt with low toxicity, was found to be the most suitable catalyst precursor rather than Pd(TFA)2 which is usually the catalyst of choice for homogeneous asymmetric hydrogenation. The chiral α-arylglycine fragments are widely found in many chiral products and bioactive molecules.
- Chen, Jianzhong,Li, Feilong,Wang, Fang,Hu, Yawen,Zhang, Zhenfeng,Zhao, Min,Zhang, Wanbin
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p. 9060 - 9065
(2019/11/19)
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- Activating molecular oxygen with Au/CeO2 for the conversion of lignin model compounds and organosolv lignin
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Au/CeO2 was demonstrated to be a high efficiency catalyst for the conversion of 2-phenoxyacetophenol (PP-ol) employing O2 as an oxidant and methyl alcohol as the solvent without using an erosive strong base or acid. Mechanistic investigations, including emission quenching experiments, electron spin-resonance (ESR) and intermediate verification experiments, were carried out. The results verified that the superoxide anion activated by Au/CeO2 from molecular oxygen plays a vital role in the oxidation of lignin model compounds, and the cleavage of both the β-O-4 and Cα-Cβ linkages was involved. Au/CeO2 also performed well in the oxidative conversion of organosolv lignin under mild conditions (453 K), producing vanillin (10.5 wt%), methyl vanillate (6.8 wt%), methylene syringate (3.4 wt%) and a ring-opened product. Based on the detailed characterization data and mechanistic results, Au/CeO2 was confirmed to be a promising catalytic system.
- Song, Wu-Lin,Dong, Qingmeng,Hong, Liang,Tian, Zhou-Qi,Tang, Li-Na,Hao, Wenli,Zhang, Hongxi
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p. 31070 - 31077
(2019/10/28)
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- Template-Directed Synthesis of Photocatalyst-Encapsulating Metal-Organic Frameworks with Boosted Photocatalytic Activity
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In the past decade, the use of visible light to promote organic transformations has gained intense attention. In this study, we developed a template-directed synthesis method to use homogeneous Ru and Ir photocatalysts as structure-directing templates and succeeded to prepare a series of photocatalyst-encapsulating metal-organic frameworks (photocatalyst@MOFs) with zeolite-like structures. The open channels and polyhedral cages of MOFs effectively dispersed the encapsulated photocatalysts and facilitated the transport of reactants and products, leading to boosted catalytic activity and good reusability toward important organic reactions such as aerobic oxidation reaction of benzyl halides and the cyclization of tertiary anilines and maleimides under visible light. Moreover, we also demonstrate the versatility and universality of our templating strategy. It not only can form MOFs which cannot be accessed by other synthesis methods, but also can encapsulate various commercially available homogeneous photocatalysts into MOFs. This work explores an avenue to prepare heterogeneous photocatalysts to catalyze value-added reactions.
- Yang, Xiaojie,Liang, Tao,Sun, Jiaxing,Zaworotko, Michael J.,Chen, Yao,Cheng, Peng,Zhang, Zhenjie
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p. 7486 - 7493
(2019/08/26)
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- Cross-linked poly(4-vinylpyridine-N-oxide) as a polymer-supported oxygen atom transfer reagent
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Oxygen atom transfer (OAT) reagents are common in biological and industrial oxidation reactions. While many heterogeneous catalysts have been utilized in OAT reactions, heterogeneous OAT reagents have not been explored. Here, cross-linked poly(4-vinylpyridine-N-oxide), called x-PVP-N-oxide, was tested as a heterogeneous OAT reagent and its oxidation chemistry compared to its molecular counterpart, pyridine-N-oxide. The insoluble oxidant x-PVP-N-oxide demonstrated comparable reactivity to pyridine-N-oxide in direct oxidation reactions of phosphines and phosphites in acetonitrile, but x-PVP-N-oxide did not react in other solvents. The polymer backbone of x-PVP-N-oxide, however, allowed for easy filtering and recycling in sequential oxidation reactions. In addition, x-PVP-N-oxide was tested as the stoichiometric oxidant in a copper-catalyzed OAT reaction to α-diazo-benzeneacetic acid methyl ester. The heterogeneous oxidant was much less reactive than pyridine-N-oxide, indicating that interaction with the metal catalyst was challenging. These results demonstrated a proof-of-concept that recyclable, polymer-supported OAT reagents could be a viable OAT reagents in direct oxidation reactions without metal catalysts.
- Bauer, Anna M.,Ramey, Erin E.,Oberle, Kjersti G.,Fata, Gretchen A.,Hutchison, Chloe D.,Turlington, Christopher R.
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supporting information
(2019/10/02)
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- Synthetic method of methyl benzoylformate (by machine translation)
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The invention discloses a synthetic method of methyl benzoylformate, and belongs to (2) the technical field of pesticide production (1) (1). By adopting the vacuum state, the reaction temperature is reduced, the reaction time is shortened, the reaction time is shortened, the reaction time is shortened, the use of the raw material benzoyl formic acid is reduced, the raw material cost is reduced, the generated 99% triwaste is less in the production reaction 2 - 3 process, and the environment is more friendly. (by machine translation)
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Paragraph 0034-0043
(2019/12/11)
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- Cobalt-Catalyzed Transfer Hydrogenation of α-Ketoesters and N-Cyclicsulfonylimides Using H2O as Hydrogen Source
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A Co-catalyzed effective transfer hydrogenation of various α-ketoesters and N-cyclicsulfonylimides by safe and environmentally benign H2O as hydrogen source is described. The reaction used easily available and easy to handle zinc metal as a reductant. Interestingly, the catalytic system does not require ligand for reduction of N-cyclicsulfonylimides. (Figure presented.).
- Gao, Yang,Zhang, Xuexin,Laishram, Ronibala Devi,Chen, Jingchao,Li, Kangkui,Zhang, Keyang,Zeng, Guangzhi,Fan, Baomin
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supporting information
p. 3991 - 3997
(2019/08/02)
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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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- Oxidation of secondary alcohols using solid-supported hypervalent iodine catalysts
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It is shown how secondary alcohols are oxidized to provide the corresponding ketones by use of Oxone and solid-supported hypervalent iodine catalysts. Under experimentally simple conditions with acetonitrile at elevated temperatures, excellent conversions were achieved with low catalyst loadings (0.2-5 mol%) when employing the conjugates 5 and 6 derived from IBX and IBS. The catalysts are broadly applicable to a range of alcohol substrates. Of primary importance with respect to sustainability issues, the metal-free catalysts are easily removed from the reaction mixture through filtration, and they can be re-used in oxidation processes for multiple times, without loss of catalytic activity.
- Ballaschk, Frederic,Kirsch, Stefan F.
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supporting information
p. 5896 - 5903
(2019/11/11)
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- Exploiting Cofactor Versatility to Convert a FAD-Dependent Baeyer–Villiger Monooxygenase into a Ketoreductase
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Cyclohexanone monooxygenases (CHMOs) show very high catalytic specificity for natural Baeyer–Villiger (BV) reactions and promiscuous reduction reactions have not been reported to date. Wild-type CHMO from Acinetobacter sp. NCIMB 9871 was found to possess an innate, promiscuous ability to reduce an aromatic α-keto ester, but with poor yield and stereoselectivity. Structure-guided, site-directed mutagenesis drastically improved the catalytic carbonyl-reduction activity (yield up to 99 %) and stereoselectivity (ee up to 99 %), thereby converting this CHMO into a ketoreductase, which can reduce a range of differently substituted aromatic α-keto esters. The improved, promiscuous reduction activity of the mutant enzyme in comparison to the wild-type enzyme results from a decrease in the distance between the carbonyl moiety of the substrate and the hydrogen atom on N5 of the reduced flavin adenine dinucleotide (FAD) cofactor, as confirmed using docking and molecular dynamics simulations.
- Xu, Jian,Peng, Yongzhen,Wang, Zhiguo,Hu, Yujing,Fan, Jiajie,Zheng, He,Lin, Xianfu,Wu, Qi
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supporting information
p. 14499 - 14503
(2019/09/17)
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- Cobalt Nanoparticles Embedded in N-Doped Porous Carbon Derived from Bimetallic Zeolitic Imidazolate Frameworks for One-Pot Selective Oxidative Depolymerization of Lignin
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Cobalt nanoparticles embedded in N-doped porous carbon (Co@CN) were prepared by the pyrolysis of bimetallic zeolitic imidazolate frameworks (BMZIFs) based on ZIF-8 and ZIF-67. The catalyst shows excellent catalytic efficiency in one-pot selective oxidative cleavage of different linkages like β-O-4, a-O-4 and β-1 in organosolv lignin and lignin model compounds in the presence of oxygen (ambient pressure) under mild conditions (383 K). Compared with traditional supported catalyst, the catalyst gives a highly hollow structure, which favored the adsorption of substrates and oxygen. The uniform cobalt nanoparticles surrounded by N-doped graphitic structures and the strong electron transfer from graphitic nitrogen to Co NPs make it hard to be oxidized prior to use and higher catalytic reactivity. Moreover, the catalyst can be easily recovered by magnetic force after the reaction, and reused after reduction for five times without an obvious change in yields.
- Sun, Kangkang,Chen, Shujie,Zhang, Jiawei,Lu, Guo-Ping,Cai, Chun
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p. 1264 - 1271
(2019/02/01)
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- Design, synthesis and evaluation of novel diaryl-1,5-diazoles derivatives bearing morpholine as potent dual COX-2/5-LOX inhibitors and antitumor agents
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In this paper, 41 hybrid compounds containing diaryl-1,5-diazole and morpholine structures acting as dual COX-2/5-LOX inhibitors have been designed, synthesized and biologically evaluated. Most of them showed potent antiproliferative activities and COX-2/5-LOX inhibitory in vitro. Among them, compound A33 displayed the most potency against cancer cell lines (IC50 = 6.43–10.97 μM for F10, HeLa, A549 and MCF-7 cells), lower toxicity to non-cancer cells than celecoxib (A33: IC50 = 194.01 μM vs. celecoxib: IC50 = 97.87 μM for 293T cells), and excellent inhibitory activities on COX-2 (IC50 = 0.17 μM) and 5-LOX (IC50 = 0.68 μM). Meanwhile, the molecular modeling study was performed to position compound A33 into COX-2 and 5-LOX active sites to determine the probable binding models. Mechanistic studies demonstrated that compound A33 could block cell cycle in G2 phase and subsequently induced apoptosis of F10 cells. Furthermore, compound A33 could significantly inhibit tumor growth in F10-xenograft mouse model, and pharmacokinetic study of compound A33 indicated that it showed better stability in vivo. In general, compound A33 could be a promising candidate for cancer therapy.
- Li, Zhang,Wang, Zhong-Chang,Li, Xin,Abbas, Muhammad,Wu, Song-Yu,Ren, Shen-Zhen,Liu, Qi-Xing,Liu, Yi,Chen, Peng-Wen,Duan, Yong-Tao,Lv, Peng-Cheng,Zhu, Hai-Liang
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p. 168 - 184
(2019/03/17)
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- Highly adequate oxidative esterification of α-carbonyl aldehydes with alkyl halides in TBAI/TBHP mediated system
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An efficient and viable synthesis of α-ketoesters from alkyl halides and α-carbonyl aldehydes has been reported under metal-free conditions. The present method involves oxidative esterification of α-carbonyl aldehydes with alkyl halide using TBAI as a promoter and TBHP as an oxidant to form α-ketoesters in good to excellent yields with versatile structural diversity. Use of commercially accessible and inexpensive substrates, broad substrate scope and good functional group tolerance are the key features of this protocol.
- Bhargude, Pooja L.,Lade, Jatin J.,Patil, Bhausaheb N.,Vadagaonkar, Kamlesh S.,Chaskar, Atul C.
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supporting information
p. 1325 - 1333
(2019/04/30)
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- Ambient and aerobic carbon-carbon bond cleavage toward α-ketoester synthesis by transition-metal-free photocatalysis
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The α-oxoesterification of the CC double bond in readily available enaminones enabling efficient synthesis of α-ketoesters is developed. The reactions showing general tolerance to the reactions of primary and secondary alcohols proceed well under air via Rose Bengal (RB)-based photocatalysis. Particularly, this mild synthetic method has been discovered to tolerate various polyhydroxylated substrates such as phenolic alcohol, diols and triols with an excellent selectivity of mono-oxoesterification. What is more noteworthy is that α-ketoester functionalized 16-dehydropregnenolone acetate resulting from the elaboration on a natural product has been obtained practically.
- Yu, Qing,Zhang, Yating,Wan, Jie-Ping
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supporting information
p. 3436 - 3441
(2019/06/24)
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- Aerobic oxidation of alcohols with air catalyzed by decacarbonyldimanganese
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The oxidation of alcohols to carbonyl compounds using air as the terminal oxidant is highly desirable. As described in previous reports, the abstraction of α-H of the alcohol is the most important step, and it typically requires not only a metal catalyst but also complex ligands, co-catalysts and bases. Herein, we report a practical and efficient method for the oxidation of primary alcohols, secondary alcohols, 1,2-diols, 1,2-amino alcohols, and other α-functionalized alcohols using a commercially available catalyst, Mn2(CO)10, and no additives. Preliminary mechanistic studies indicated that an alkoxyl radical intermediate existed in our system, and a plausible mechanism consistent with the experimental results and literature was proposed.
- Meng, Shan-Shui,Lin, Li-Rong,Luo, Xiang,Lv, Hao-Jun,Zhao, Jun-Ling,Chan, Albert S. C.
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supporting information
p. 6187 - 6193
(2019/11/20)
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