- Formal asymmetric hydration of non-activated alkenes in aqueous medium through a "chemoenzymatic catalytic system"
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A direct one-pot conversion of (substituted) styrene(s) into the corresponding (substituted) (R)-phenylethan-1-ol(s) in a highly enantioselective manner has been achieved by using a "chemoenzymatic catalytic system", comprising a palladium-catalyzed Wacker-Tsuji oxidation and subsequent enantioselective enzymatic reduction of the in situ formed (substituted) acetophenone(s) (see scheme). Copyright
- Schnapperelle, Ingo,Hummel, Werner,Groeger, Harald
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- Friedel-Crafts acylation of aromatic hydrocarbons using zeolites
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A convenient heterogeneous catalytic methodology for Friedel-Crafts acylation of benzene and toluene using various aliphatic carboxylic anhydrides over zeolites at 250°C is described. An interesting para selectivity is observed in the case of acylation of toluene over HZSM-5.
- Sreekumar,Padmakumar, Raghavakaimal
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- Structural effects on the β-scission reaction of alkoxyl radicals. Direct measurement of the absolute rate constants for ring opening of benzocycloalken-1-oxyl radicals
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(Chemical Equation Presented) The absolute rate constants for β-scission of a series of benzocycloalken-1-oxyl radicals and of the 2-(4-methylphenyl)-2-butoxyl radical have been measured directly by laser flash photolysis. The benzocycloalken-1-oxyl radicals undergo ring opening with rates which parallel the ring strain of the corresponding cycloalkanes. In the 1-X-indan-1-oxyl radical series, ring opening is observed when X = H, Me, whereas exclusive C-X bond cleavage occurs when X = Et. The factors governing the fragmentation regioselectivity are discussed.
- Bietti, Massimo,Lanzalunga, Osvaldo,Salamone, Michela
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- One-pot one-step deracemization of amines using ω-transaminases
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In this study, we developed a one-pot one-step deracemization method for the production of various enantiomerically pure amines using two opposite enantioselective ω-TAs. Using this method, various aromatic amines were successfully converted to their (R)-forms (>99%) with good conversion.
- Shin, Giyoung,Mathew, Sam,Shon, Minsu,Kim, Byung-Gee,Yun, Hyungdon
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- Copper(I) Catalyzed Differential Peroxidation of Terminal and Internal Alkenes Using TBHP
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Terminal and internal alkenes react contrarily with tert-butyl hydroperoxide (TBHP) giving various products. A Cu(I) catalyzed decarbonylative C–C bond formation followed by a carbonylation–peroxidation of vinyl arenes has been achieved using tert-butyl hydroperoxide (TBHP) as the oxidant in acetonitrile. Whereas, α-methyl styrenes yielded aryl methyl ketones and the α-substituted unsymmetrical internal alkenes afforded selective α-peroxidation under the identical reaction conditions. Concurrent peroxidation–carbonylation–cycloalkylation/cycloetherifiction of internal cyclic alkene such as indene is achieved by switching the solvent system from acetonitrile to cycloalkanes/cyclic ether. All these reactions proceed via radical paths generating interesting peroxo-compounds.
- Mir, Bilal Ahmad,Rajamanickam, Suresh,Begum, Pakiza,Patel, Bhisma K.
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- Manganese/Copper Co-catalyzed Electrochemical Wacker-Tsuji-Type Oxidation of Aryl-Substituted Alkenes
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A manganese/copper co-catalyzed electrochemical Wacker-Tsuji-type oxidation of aryl-substituted alkenes has been developed. The process involves the use of 5 mol % MnBr2 and 7.5 mol % CuCl2, in 4:1 acetonitrile/water in an undivided cell at 60 °C, with 2.8 V constant applied potential. α-Aryl ketones are formed in moderate to excellent yields, with the advantages of avoidance of palladium as a catalyst and any external chemical oxidant in an easily operated, cost-effective procedure.
- Lai, Junshan,Pericàs, Miquel A.
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- Continuous liquid phase acylation of toluene over HBEA zeolite: Solvent effects and origin of the deactivation
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The continuous liquid phase Friedel-Crafts acylation of toluene (T) by acetic anhydride (AA) over HBEA zeolite was carried out in a fixed bed reactor, with acetic acid (AC) as a solvent. 4-Methylacetophenone (4-MAP) was selectively formed in the initial reaction stage. However, a rapid catalyst deactivation occurred with a sharp decrease of the conversion of acetic anhydride, and this was mainly caused by 4-MAP and heavy compounds ('coke') existing in the zeolite pore, which poisoned the active sites of the catalyst. The use of excess toluene and moderate acetic acid enhanced catalyst activity and stability to some extent as it limited both the retention of 4-MAP and the formation of 'coke'. Moreover, a considerable reduction of Broensted acid sites after deactivation revealed that the toluene acylation is primarily a Broensted acid catalyzed reaction.
- Chen, Zhihua,Chen, Wenqi,Tong, Tianxia,Zeng, Aiwu
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- Novel palladium nanoparticles supported on mesoporous natural phosphate: Catalytic ability for the preparation of aromatic hydrocarbons from natural terpenes
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Various ratios of palladium nanoparticles supported on mesoporous natural phosphate (Pd@NP) were prepared using the wetness impregnation method. The prepared catalysts were characterized by IR, XRD, CV, SEM, EDX, XRF, TEM and BET analysis. The reduction and preparation of the palladium nanoparticles afford a crystallite size of 10.88 nm. The performance of the synthesized catalyst was investigated in the solvent-free dehydroaromatization of α-, β- and γ-himachalene mixture from Cedrus atlantica oil as a model substrate. In order to achieve an efficient and selective catalysis, the catalytic dehydroaromatization of various terpenes such as limonene, limonaketone, carvone, carveol and perillyl alcohol was studied. The Pd@NP catalyst performed a high catalytic activity, selectivity and recyclability in the terpenes dehydroaromatization reaction.
- Mekkaoui, Ayoub Abdelkader,Aberkouks, Abderrazak,Fkhar, Lahcen,Ait Ali, Mustapha,El Firdoussi, Larbi,El Houssame, Soufiane
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- PENTACOORDINATE ORGANOSILICATE AS AN ALKYLATING REAGENT: PALLADIUM CATALYZED METHYLATION OF ARYL HALIDES
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Under the influence of palladium catalyst, tris(diethylamino)sulfonium difluorotrimethylsilicate is found to deliver the methyl group to aryl halides highly chemoselectively, and the corresponding methylated aromatic compounds are produced in moderate to high yields.
- Hatanaka, Yasou,Hiyama, Tamejiro
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- Nitrogen-doped carbon nanotubes encapsulate cobalt nanoparticles as efficient catalysts for aerobic and solvent-free selective oxidation of hydrocarbons
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The selective oxidation of hydrocarbons to the corresponding ketones with solvent-free and molecular oxygen as an oxidant is of great importance in academic and industrial fields in view of economy and environment. In this respect, we present the facile synthesis and characterization of excellent catalysts comprising cobalt nanoparticles encapsulated into graphitic nitrogen-doped carbon nanotubes (Co@GCNs) via one-pot pyrolysis of a chelate compound containing citric acid, melamine, and CoCl2·6H2O. The selective oxidation of ethylbenzene under molecular oxygen and solvent-free conditions is employed as a probe reaction to investigate the catalytic performance; the optimized catalyst shows the best conversion (68%) and selectivity for acetophenone (93%). Combination of the catalytic results of the control group and the different characterization methods demonstrates that high catalytic activity is due to the synergistic effect between metallic cobalt and nitrogen-doped carbon nanotubes. Moreover, the catalyst has high catalytic activity for the aerobic and solvent-free oxidation of other arylalkane substrates. The proposed mechanistic study illustrates that the reaction is a free radical reaction progressing through superoxide radical anions (?O2-).
- Lin, Xiu,Nie, Zhenzhen,Zhang, Liyun,Mei, Shuchuan,Chen, Yuan,Zhang, Bingsen,Zhu, Runliang,Liu, Zhigang
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- The Acetylations of Toluene and Benzene with Acetyl Chloride and Bromide and Acetic Anhydride Catalyzed by Calcined Iron Sulfate Activated by Exposure to a Mixture of Benzyl Chloride and the Aromatics.
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The acetylation of toluene and benzene with acetyl halides and acetic anhydride were studied over catalysts prepared by heat-treating FeSO4 in air, followed by activation on exposure to benzyl chloride in toluene or benzene at 40-80 deg C for 1 h, together with FeCl3 and AlCl3.The sulfates treated at 700 and 800 deg C showed high activity.The former, activated at 60 deg C, gave 68percent methylacetophenones, and the latter, more than 90percent, with an isomer distribution of 2percent ortho-, 1percent meta-, and 97percent para-form in the reaction of toluene with acetyl halides at room temperature, while the maximum yield was 24percent with FeCl3 and 29percent with AlCl3.A high yield of acetophenone, 77percent, was obtained over the FeSO4 (700 deg C) catalyst in the reaction of benzene with acetyl bromide at 60 deg C for 1 h.The present catalysts were also highly active for the acetylation of toluene with acetic anhydride; e.g., 55percent methylacetophenones were obtained over the FeSO4 (800 deg C) catalyst at 100 deg C for 5 h.FeCl3 and AlCl3 gave quite low yield compared with the present catalysts.
- Arata, Kazushi,Hino, Makoto
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- Friedel-Crafts acylation of toluene using superacid catalysts in a solvent-free medium
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Sulfated tin oxide and sulfated zirconia containing different amounts of sulfate and Al2O3-sulfated zirconia catalysts were prepared. The materials were characterized by DTA/TGA/DTG, XRD, FT-IR, and BET surface-area techniques. Surface acidity was determined using TGA of pyridine-pretreated samples, and acid strength was determined by potentiometric titration of the solid catalysts with n-butylamine in non-aqueous media. The catalytic activity of prepared samples was tested by Friedel-Crafts acylation of toluene with acetic acid anhydride. Incorporation of sulfate into SnO 2 impedes sintering and is associated with a decrease of surface area. Sulfated tin oxide has greater acidity and higher acid strength than Al3+-impregnated sulfated zirconia, giving, therefore, a higher yield of acylation products. Sulfated tin oxide was found to pass through maxima of higher acidity and higher efficiency for the acylation reaction when sulfate loading is 10 wt%. A good relationship between structural characteristics, acidity, and catalytic activity is observed.
- El-Sharkawy,Al-Shihry, Shar S.
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- Liquid Phase Oxidation of p-cymene by (VO)2P2O 7 and VO(PO3)2 Catalysts
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Vanadium phosphate oxide (VPO) catalysts derived from VOHPO 4?0.5H2O and VO(H2PO4) 2 precursors showed improved rates in the catalysed liquid phase oxidation of p-cymene. Both catalysts showed high performance with conversions of up to 30% achieved within 3 h with a selectivity towards the tertiary cymene hydroperoxide (TCHP) of 75-80% when compared to lower conversions and poorer TCHP selectivity in the non-catalysed industrial oxidation processes that takes about 8-12 h reaction time. The temperature dependent structural changes during activation within the catalysts were studied by in situ XRD and TGA-MS. The in situ XRD showed that the VO(H2PO4)2 form mainly an amorphous phase at temperature up to 600 °C while above 650-750 °C a stable VO(PO3)2 phase was obtained. The in situ XRD studies of the (VO)2P2O7 phase derived from VOHPO4?0.5H2O showed to became more crystalline with increasing temperature from 400 to 750 °C. No formation of VOPO4 phases were observed in the activated (VO)2P2O7 catalyst even at high temperature under the in situ XRD conditions. Graphical Abstract: VPO catalysts derived from VOHPO4?0.5H2O and VO(H2PO4)2 precursors improve oxidation rates and improved tert-cymene hydroperoxide selectivity during the liquid-phase oxidation of p-cymene compared to non-catalyzed oxidations. [Figure not available: see fulltext.]
- Makgwane, Peter R.,Ferg, Ernst E.,Billing, David G.,Zeelie, Ben
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- Hierarchical zeolite Beta: An efficient and eco-friendly nanocatalyst for the Friedel-Crafts acylation of toluene
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P-Methyacetophenone, the acylated product of toluene finds a wide range of applications in the flavors and fragrance industry. It is typically produced on an industrial scale by Friedel-Crafts acylation of toluene with acetic anhydride using homogeneous, corrosive and polluting acid catalysts such as aluminium chloride. The pollution problems related to this process such as the disposal of catalyst and treatment of acidic effluent needs to be replaced by a green process. The current work reports on the activity of hierarchical zeolite Beta in the liquid phase acylation of toluene with acetic anhydride. The liquid phase reactions were carried out in the temperature range of 60-140 °C in an autoclave. The effect of various reaction parameters such as time-on-stream (TOS), mole ratio of reactants, catalyst loading, and reaction temperature on the rates of reaction has been investigated. Under the optimum reaction conditions the performance of hierarchical zeolite Beta was compared with nanocrystalline zeolite Beta. It was found that hierarchical zeolite Beta catalyst exhibit higher activity, which is due to the hierarchical porosity and to the nano size of the Beta zeolite catalyst particles allows faster diffusion of the products out of the catalyst. Copyright
- Selvin, Rosilda,Roselin, L. Selva,Khayyat, Suzan A.,Umar, Ahmad
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- Efficient photodecarboxylation of 3- and 4-acetylphenylacetic acids in aqueous solution
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The photochemistry of 3- and 4-acetylphenylacetic acids (6 and 7) has been studied in aqueous solution. This work is a continuation of research efforts aimed at understanding the structural effects on the efficacy for benzyl carbanion photogeneration via photodecarboxylation. The nitro group (at the 3- and 4-positions) is known to be an exceptionally good activating group on the benzene ring - because of its enhanced electron-withdrawing effect in the excited triplet state - for photodecarboxylation and the related photo-retro-aldol type process. It is shown in this work that the acetyl group is an equally good activating group for the photodecarboxylation. Thus, the photochemistry of 6 and 7 parallels much of what was observed for the corresponding nitrophenylacetic acids 1 and 2. Both 6 and 7 photodecarboxylate efficiently (Φd = 0.60 and 0.22, respectively, at pH 7) via the carboxylate form, to give observable (by laser flash photolysis) benzyl carbanion or related intermediates. The meta isomer 6 displays an acid-catalyzed pathway for photodecarboxylation at pH 3 and along with its enhanced overall reactivity, is consistent with a meta effect of the acetyl group. Triplet state reactivity is inferred from sensitization and laser flash photolysis experiments. Based on the results of this work, the acetyl group may now be viewed as an "enhanced" electron-withdrawing group (in the excited state) when attached to a benzene ring (i.e., in acetophenone derivatives) that is capable of inducing ionic reactions, which is not the traditional photochemistry that is expected from such compounds.
- Huck, Lawrence A.,Xu, Musheng,Forest, Kaya,Wan, Peter
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- Surface Coordination of Multiple Ligands Endows N-Heterocyclic Carbene-Stabilized Gold Nanoclusters with High Robustness and Surface Reactivity
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Deciphering the molecular pictures of the multi-component and non-periodic organic-inorganic interlayer is a grand technical challenge. Here we show that the atomic arrangement of hybrid surface ligands on metal nanoparticles can be precisely quantified through comprehensive characterization of a novel gold cluster, Au44(iPr2-bimy)9(PA)6Br8 (1), which features three types of ligands, namely, carbene (1,3-diisopropylbenzimidazolin-2-ylidene, iPr2-bimy), alkynyl (phenylacetylide, PA), and halide (Br), respectively. The delicately balanced stereochemical effects and bonding capabilities of the three ligands give rise to peculiar geometrical and electronic structures. Remarkably, despite its complex and highly distorted surface structure, cluster 1 exhibits unusual catalytic properties and yet it is highly stable, both chemically and thermally. Moreover, rich reactive sites on the cluster surface raise the prospect of bio-compatibility (as it can be functionalized to yield water-soluble derivatives) and bio-applications.
- Shen, Hui,Xu, Zhen,Hazer, Maryam Sabooni Asre,Wu, Qingyuan,Peng, Jian,Qin, Ruixuan,Malola, Sami,Teo, Boon K.,H?kkinen, Hannu,Zheng, Nanfeng
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- Mechanism of the nucleophilic substitution of acyl electrophiles using lithium organocuprates
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The mechanism of nucleophilic substitution reaction at an sp2 carbon center of a thioester or an acid chloride with a lithium organocuprate reagent has been investigated. Density functional calculations indicated that the thioester undergoes oxidative addition of the C-S bond to the copper(I) atom through a three-centered transition state to afford an organocopper(III) intermediate, which gives the product through reductive elimination of the alkyl and the acyl groups. On the other hand, the acid chloride loses a chloride anion very easily when it interacts with the cuprate, because the chloride anion is captured by a lithium(I) cation rather than a copper(I) atom. 13C kinetic isotope effect (KIE) experiments showed excellent agreement with computational predictions for the thioester reaction, but suggested that the nucleophilic displacement transition state of the acid chloride occurs much more advanced than the calculations predict.
- Yoshikai, Naohiko,Iida, Ryoko,Nakamura, Eiichi
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- Intramolecular selectivity in the side-chain oxidation of alkylbenzenes under Gif(IV) conditions
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The intramolecular selectivity in the side-chain oxidation of alkylbenzenes, under the Gif(IV) conditions, has been determined. The 1°-C: 2°-C: 3°-C reactivity ratios are 1:5:9.3 and little difference in reactivity is exhibited by methyl groups para and meta to a chloro substituent. It has also been found that these selectivities result from the operation of two competing oxidations pathways, one of which not requiring catalysis by Fe(III). The catalyzed pathway is particularly effective towards secondary positions, as expected in Gif(IV)-promoted oxidations.
- Baciocchi,Muraglia,Sleiter
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- NOVEL TYPES OF TRANSFORMATIONS OF α-AZIDOSTYRENE DERIVATIVES AND 3-ARYL-2H-AZIRINES IN THE PRESENCE OF HEXACARBONYLMOLYBDENUM
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The reaction of α-azidostyrene derivatives with hexacarbonylmolybdenum was found to give 2,5-diarylpyrroles and acetophenone derivatives via a complexed 1-arylvinylnitrene intermediate, while that of 3-aryl-2H-azirines gave 2,4-diarylpyrroles in addition to acetophenone derivatives and 2,5-diarylpyrazines.
- Nitta, Makoto,Kobayashi, Tomoshige
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- The "kinetic capture" of an acylium ion from live aluminum chloride promoted Friedel-Crafts acylation reactions
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AlCl3 promoted Friedel-Crafts acylation between 4-tert-butylbenzoyl chloride and mesitylene was investigated. The donor-acceptor complex was observed as the major species. Kinetic investigation demonstrated that the reaction was first-order on the donor-acceptor complex and zero-order on ArH, suggesting that the donor-acceptor complex was not the true reactive species. However, the acylium ion was almost invisible with a fairly low concentration under live reaction conditions. It was approved as the true reactive species through kinetic data ("kinetic capture") in the AlCl3 promoted Friedel-Crafts acylation reaction.
- Huang, Zhiliang,Jin, Liqun,Han, Heyou,Lei, Aiwen
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- An efficient oxidation of alcohols by aqueous H2O2 with 1,3-dibromo-5,5-dimethylhydantoin
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An efficient protocol is described for the oxidation of alcohols to the corresponding aldehydes or ketones with 1,3-dibromo-5,5-dimethylhydantoin in the presence of aqueous H2O2.
- Lee, Jieun,Lee, Jong Chan
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- Palladium-catalyzed cross-methylation of haloarenes possessing active hydrogen atoms by intramolecularly stabilized dimethylindium and dimethylaluminum reagents
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While the intramolecularly stabilized aluminum complex [(CH3)2AlOCH2CH2 N(CH3)2]2 (2a) reacts readily with 4-bromophenol to give methane and [(4-BrC6H4O)su
- Jaber, Nimer,Gelman, Dmitri,Schumann, Herbert,Dechert, Sebastian,Blum, Jochanan
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- Synthesis of ketones with alkyl phosphonates and nitriles as acyl cation equivalent: Application of dephosphonylation reaction of β-functionalized phosphonate with hydride
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The preparation of several α-substituted ketones is performed in a one-pot procedure with alkyl phosphonates and aromatic nitriles by subsequent treatment of LiAlH4. A new method for nitriles used as an acyl cation equivalent is described.
- Jang, Won Bum,Shin, Won Suk,Hong, Jong Eun,Lee, Shi Yong,Oh, Dong Young
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- Dehydrogenative oxidation of alcohols in aqueous media catalyzed by a water-soluble dicationic iridium complex bearing a functional N-heterocyclic carbene ligand without using base
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A dicationic iridium complex bearing a bidentate ligand that comprises N-heterocyclic carbene and α-hydroxypyridine moieties has been designed and synthesized. The complex exhibited high catalytic performance in aqueous media for the dehydrogenative oxidation of secondary alcohols to ketones accompanying the evolution of hydrogen. Furthermore, dehydrogenative transformation of primary alcohols to the carboxylic acids in aqueous media was also catalyzed by the complex without using base.
- Fujita, Ken-Ichi,Tamura, Ryuichi,Tanaka, Yuhi,Yoshida, Masato,Onoda, Mitsuki,Yamaguchi, Ryohei
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- Nanocrystalline magnesium oxide-stabilized molybdenum: An efficient heterogeneous catalyst for the aerobic oxidation of alcohols to carbonyl compounds
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A nanocrystalline magnesium oxide-stabilized molybdenum(VI) complex catalyzed the oxidation of primary and secondary alcohols to carbonyl compounds in excellent yields using molecular oxygen as stoichiometric oxidant. The nanomaterials with their three-dimensional structure and defined size and shape act as suitable supports for metal complexes. The catalyst can be reused for four runs without any significant loss of activity.
- Kantam, M. Lakshmi,Yadav, Jagjit,Laha, Soumi,Sreedhar, Bojja,Bhargava, Suresh
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- Nitration of Halterman porphyrin: A new route for fine tuning chiral iron and manganese porphyrins with application in epoxidation and hydroxylation reactions using hydrogen peroxide as oxidant
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A methodology is reported for the regioselective nitration of the phenyl groups of Halterman porphyrin, using NaNO2. These nitro-porphyrins can be reduced to aminoporphyrins and then N-dimethylated to give new optically active porphyrins. Applications to the asymmetric epoxidation of styrene derivatives by H2O2 to give optically active epoxides (ee up to 60%) and hydroxylation of alkanes to give optically active secondary alcohols (ee up to 69%) were carried out in organic solvents (dichloromethane/methanol) using chiral iron and manganese porphyrins as catalysts.
- Amiri, Nesrine,Le Maux, Paul,Srour, Hassan,Nasri, Habib,Simonneaux, Gérard
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- Friedel-crafts acylation reactions in pyridinium based ionic liquids
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The Friedel-Crafts acylations of representative aromatic compounds with acetic anhydride in pyridinium based ionic liquids (ILs) were investigated. The effect of factors such as reactant composition, catalyst-IL composition, catalyst dosage and reaction temperature were studied. The reactions were found to proceed under relatively mild conditions with excellent conversions; and a simple product isolation procedure was achieved. ILs could also be recycled and reused effectively, thus rendering green characteristic to this reaction.
- Xiao, Ying,Malhotra, Sanjay V.
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- A facile approach to constructing Pd@PCN-Se nano-composite catalysts for selective alcohol oxidation reactions
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By using selenium as the structure-directing agent, Se-incorporated polymeric carbon nitride (PCN-Se) was prepared for the first time and could be used as a superexcellent support for Pd nanoparticles (NPs). A trace amount of Se dopant (0.01 wt%) was found to play an unexpectedly vital role in increasing the materials' surface area and total mesoporous volume by 4.5 and 2 times respectively, so the Pd@PCN-Se catalyst might contain even more active sites than its simple PCN and Pd@PCN counterparts, and a strong interaction between Se(0) and Pd(ii) was also built-in, affording a dramatically improved catalytic activity as well as good recycling stability in selective catalytic alcohol oxidation reactions.
- Cao, Kuanhong,Deng, Xin,Chen, Tian,Zhang, Qitao,Yu, Lei
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- ESI-MS detection of proposed reaction intermediates in the air-promoted and ligand-modulated oxidative heck reaction
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Electrospray ionization mass spectrometry (ESI-MS) and subsequent MS/MS analyses were used to directly detect palladium-containing cationic reaction intermediates in a ligand controlled palladium(II)-catalyzed oxidative Heck arylation. All potential intermediates were observed as dmphen-ligated palladium(II) species, suggesting that the dmphen bidentate ligand is attached to the metal center during the entire catalytic cycle. The study supports previous mechanistic propositions and provides new information regarding the composition of aryl-containing Pd(II) complexes in an ongoing oxidative Heck reaction. In addition, sodium acetate was found to be a useful base alternative to previously used tertiary amines.
- Enquist, Per-Anders,Nilsson, Peter,Sjoeberg, Per,Larhed, Mats
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- Temperature dependent solvent effects in photochemistry of 1-phenylpentan-1-ones
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Temperature dependent solvent effects have been investigated on the Norrish Type II reaction of 1-phenylpentan-1-one and its p-methyl derivative. Efficiencies of the photoreaction were studied in terms of solvent polarity and base addition as a function of temperature. Such a small structure change as the p-methyl substitution in 1-phenylpentan-1-one altered the temperature dependent photoreactivity in presence of weak bases. The experimental results suggest that the hydrogen bonding between the Type II biradical intermediate OH group and the solvent is weaker for 1-(4-methylphenyl)pentan-1-one than that for 1-phenylpentan-1-one at 20°C but the interactions probably vanish in both cases at 80°C.
- Klan, Petr,Literak, Jaromir
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- Sulfur and nitrogen-doped porous cobalt carbon catalyst for high efficient aerobic oxidation of hydrocarbons
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The selective oxidation of hydrocarbons to corresponding ketones under green reaction conditions is of more and more important in chemical processes due to environmental and economic pressure. In this respect, we successfully prepared high efficient sulfur and nitrogen-doped porous cobalt carbon catalyst through a simple but efficient one-pot method. Potassium thiocyanate (KSCN) is using as sulfur source and complexing agent, what's more, KSCN also acts as pore-forming agent to create larger specific surface area. In addition, the as-obtained catalyst shows high catalytic performance for oxidation of hydrocarbons under solvent-free and oxygen as oxidant conditions, especially for ethylbenzene, the conversion is up to 82% with 88% of selectivity for acetophenone, which is an exciting result due to the relative low activity of oxygen in comparison with tert-butyl hydroperoxide as oxidant. This is due to structure defect and Co4S3 by the doping of KSCN in CoNC catalysts, which may result in the improvement of the catalytic performance of the catalysts.
- Lin, Xiu,Jie, Shanshan,Liu, Zhigang
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- In situ synthesis of highly dispersed Co-N-C catalysts with carbon-coated sandwich structures based on defect anchoring
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Highly dispersed Co-N-C catalysts were successfully prepared via a defect strategy to anchor metal atoms with a carbon coating. The catalysts showed remarkable catalytic performance under mild conditions (a yield of 97.0% for ethylbenzene oxidation). Meanwhile, BET, TEM, XRD, Raman spectroscopy and XPS studies were employed to investigate the as-prepared catalysts. The results revealed that the unique structure was conducive to producing more defects in carbon, increasing the number of active sites and enhancing the dispersion of cobalt. The outstanding catalytic performance of the catalysts was attributed to the synergy effect of the special structure and the Co-N, pyridine nitrogen and graphite nitrogen species.
- Li, Suisheng,Zhang, Lushuang,Jie, Shanshan,Liu, Zhigang
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- Ester Cleavage in Superacid Media Involving Diprotonated Gitonic Carboxonium Dications
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The reactivity of protonated and methylated methyl ester in superacidic media was investigated by experiment and theory.Protonated methyl acetate was found to undergo slow acyl oxygen cleavage at -78 deg C in FSO3H/SbF5/SO2 solution to give acetyl cation and methyloxonium ion. 1,1-Dimethoxyethyl cation (methylated methyl acetate) was found to undergo slow methyl exchange in CD3SO3F/SbF5 solution.The reaction of 1,1-dimethoxyethyl cation with toluene in the presence of trifluoromethanesulfonic acid at -78 deg C gave acylation in 4percent yield.Theoretical calculations at the MP4(SDTQ)/6-31G*//MP2/6-31G* level of theory were performed to find stationary points on the potential energy surface of the mono- and diactivated ester system.Based on the available evidence a new mechanism for the acid-catalyzed ester cleavage in superacidic media is proposed.
- Olah, George A.,Hartz, Nikolai,Rasul, Golam,Burrichter, Arwed,Prakash, G. K. Surya
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- Highly Enantioselective C?H Oxidation of Arylalkanes with H2O2 in the Presence of Chiral Mn-Aminopyridine Complexes
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Bioinspired chiral Mn-aminopyridine complexes [(S,S)-LMnII(OTf)2] and [(R,R)-LMnII(OTf)2] (where (S,S)-L=(2S,2S)-1,1-bis((3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl)methyl)-2,2-bipyrrolidine, and (R,R)-L=(2R,2R)-1,1-bis((3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl)methyl)-2,2-bipyrrolidine) have been shown to efficiently catalyze the benzylic C?H oxidation of arylalkanes with hydrogen peroxide in the presence of carboxylic acid additives, affording enantiomerically enriched 1-arylalkanols and the corresponding ketones. Optically pure additive N-Boc-(L)-proline, in combination with [(R,R)-LMnII(OTf)2] complex, affords 1-arylalkanols in up to 86 % ee, which is the highest reported enantioselectivity for direct benzylic hydroxylations with H2O2 in the presence of transition-metal catalysts. Oxidative kinetic resolution only slightly contributes to the increase of the observed enantiomeric excess over the reaction course. The observed kH/kD values (3.5–3.6 for the oxidation of ethylbenzene/d10-ethylbenzene) and competitive oxidation data are consistent with either a hydrogen-atom transfer/oxygen rebound or hydride transfer/oxygen rebound asymmetric hydroxylation mechanism.
- Talsi, Evgenii P.,Samsonenko, Denis G.,Ottenbacher, Roman V.,Bryliakov, Konstantin P.
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- Ruthenium carbonyl complexes with pyridylalkanol ligands: Synthesis, characterization and catalytic properties for aerobic oxidation of secondary alcohols
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Reaction of Ru3(CO)12 with pyridylalkanol ligands PyC(CH2)4OH (L1H), PyC(CH2)5OH (L2H) and PyCR1R2OH (R1 = R2 = CH3 (L3H); R1 = CH3, R2 = C6H5 (L4H); R1 = H, R2 = C6H5 (L5H); R1 = H, R2 = 4-CH3C6H4 (L6H); R1 = H, R2 = 4-OMeC6H4 (L7H); R1 = H, R2 = 4-ClC6H4 (L8H); R1 = H, R2 = 4-BrC6H4 (L9H); R1 = H, R2 = 4-CF3C6H4 (L10H)) in refluxing xylene afforded the bis-chelate ruthenium carbonyl complexes [(Ln)2Ru3(CO)8] (n = 1 (1a); n = 2 (1b); n = 3 (1c); n = 4 (1d); n = 5 (1e); n = 6 (1f); n = 7 (1g); n = 8 (1h); n = 9 (1i); n = 10 (1j)), respectively. All the novel ruthenium complexes were fully characterized by NMR, elemental analyses and IR spectra and the molecular structures of 1a, 1c, 1e, 1g and 1i were further determined by single crystal X-ray diffraction analysis. In the presence of TEMPO (TEMPO = 2,2,6,6-tetramethyl-1-piperidinyloxyl), these trirhenium carbonyl clusters displayed high reactivity for aerobic oxidation of secondary alcohols to give the corresponding ketonic compounds in good to excellent yield using ambient air as the source of oxidant.
- Hao, Zhiqiang,Li, Ning,Yan, Xinlong,Li, Ying,Zong, Siqi,Liu, Huating,Han, Zhangang,Lin, Jin
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Read Online
- Synthesis of a 2,7-dioxatricyclo[4.2.1.03,8]nonane: A model study for possible application in a synthesis of dictyoxetane
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A method for the synthesis of the 2,7-dioxatricyclo[4.2.1.03,8]nonane ring system characteristic of the marine diterpene dictyoxetane has been developed. This method utilizes a dipolar cycloaddition of a 3-oxidopyrylium salt to create the carbon skeleton and employs an intramolecular S(N)2 displacement to form the oxetane ring. The route described could easily be adapted to incorporate additional functionality, making it potentially useful in a total synthesis of dictyoxetane.
- Marshall,Mapp,Heathcock
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Read Online
- Acylation of Toluene with Acetic Anhydride over Beta Zeolites: Influence of Reaction Conditions and Physicochemical Properties of the Catalyst
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Acylation of toluene with acetic anhydride was carried out over Beta-type zeolites in a stainless steel autoclave. At low temperature, i.e., 150°C, and an arene/anhydride molar ratio 10-20, high yields of 4-methylacetophenone were obtained with selectivity close to 100%. The reaction is limited by the poisoning of the active sites by adsorption of the product and pore blockage due to coke -type products. Acid site accessibility is of paramount importance for this reaction, and the use of a nanocrystalline Beta zeolite as catalyst minimizes catalyst decay. This, combined with an optimum framework composition, allows the preparation of active and selective acylation catalysts based on Beta zeolite.
- Botella,Corma,Lopez-Nieto,Valencia,Jacquot
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Read Online
- Visible light-mediated, high-efficiency oxidation of benzyl to acetophenone catalyzed by fluorescein
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An environmentally friendly aerobic oxidation of benzyl C(sp3)-H bonds to ketones via selective oxidation catalysis was developed. Fluorescein is an efficient photocatalyst with excellent chemical selectivity. The reaction has a wide substrate scope, and a successful gram-scale experiment demonstrated its potential industrial utility.
- Geng, Haoxing,Liu, Xin,Zhu, Qing
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supporting information
(2021/12/20)
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- Using Data Science To Guide Aryl Bromide Substrate Scope Analysis in a Ni/Photoredox-Catalyzed Cross-Coupling with Acetals as Alcohol-Derived Radical Sources
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Ni/photoredox catalysis has emerged as a powerful platform for C(sp2)–C(sp3) bond formation. While many of these methods typically employ aryl bromides as the C(sp2) coupling partner, a variety of aliphatic radical sources have been investigated. In principle, these reactions enable access to the same product scaffolds, but it can be hard to discern which method to employ because nonstandardized sets of aryl bromides are used in scope evaluation. Herein, we report a Ni/photoredox-catalyzed (deutero)methylation and alkylation of aryl halides where benzaldehyde di(alkyl) acetals serve as alcohol-derived radical sources. Reaction development, mechanistic studies, and late-stage derivatization of a biologically relevant aryl chloride, fenofibrate, are presented. Then, we describe the integration of data science techniques, including DFT featurization, dimensionality reduction, and hierarchical clustering, to delineate a diverse and succinct collection of aryl bromides that is representative of the chemical space of the substrate class. By superimposing scope examples from published Ni/photoredox methods on this same chemical space, we identify areas of sparse coverage and high versus low average yields, enabling comparisons between prior art and this new method. Additionally, we demonstrate that the systematically selected scope of aryl bromides can be used to quantify population-wide reactivity trends and reveal sources of possible functional group incompatibility with supervised machine learning.
- Doyle, Abigail G.,Gandhi, Shivaani S.,Jiang, Shutian,Kariofillis, Stavros K.,Martinez Alvarado, Jesus I.,?urański, Andrzej M.
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supporting information
p. 1045 - 1055
(2022/01/19)
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- Selective Activation of Unstrained C(O)-C Bond in Ketone Suzuki-Miyaura Coupling Reaction Enabled by Hydride-Transfer Strategy
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A Rh(I)-catalyzed ketone Suzuki-Miyaura coupling reaction of benzylacetone with arylboronic acid is developed. Selective C(O)-C bond activation, which employs aminopyridine as a temporary directing group and ethyl vinyl ketone as a hydride acceptor, occurs on the alkyl chain containing a β-position hydrogen. A series of acetophenone products were obtained in yields up to 75%.
- Zhong, Jing,Zhou, Wuxin,Yan, Xufei,Xia, Ying,Xiang, Haifeng,Zhou, Xiangge
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supporting information
p. 1372 - 1377
(2022/02/23)
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- A Practically Unified Electrochemical Strategy for Ni-Catalyzed Decarboxylative Cross-Coupling of Aryl Trimethylammonium Salts
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By merging electrocatalysis and nickel catalysis, a unified strategy has been successfully applied to achieve the decarboxylative cross-coupling of four types of α-oxocarboxylic acids and their derivatives with aryl trimethylammonium salts under mild conditions. Our strategy provides a practical way for preparing aryl ketones, amides, esters, or aldehydes.
- Cao, Zhong-Yan,Chen, Xiaohui,Chen, Yiyi,Kong, Xianqiang,Lu, Zheng-Xuan,Ni, Shao-Fei,Wang, Wei
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supporting information
p. 2137 - 2142
(2022/04/07)
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- Electrochemical Aerobic Oxidative Cleavage of (sp3)C-C(sp3)/H Bonds in Alkylarenes
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An electrochemistry-promoted oxidative cleavage of (sp3)C-C(sp3)/H bonds in alkylarenes was developed. Various aryl alkanes can be smoothly converted into ketones/aldehydes under aerobic conditions using a user-friendly undivided cell setup. The features of air as oxidant, scalability, and mild conditions make them attractive in synthetic organic chemistry.
- Liu, Shuai,Liu, Zhong-Quan,Shen, Tong,Shen, Xu,Wang, Nengyong,Wu, Jintao,Yang, Le,Zhao, Jianyou
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p. 3286 - 3295
(2022/03/14)
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- Site-Specific Oxidation of (sp3)C-C(sp3)/H Bonds by NaNO2/HCl
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A site-specific oxidation of (sp3)C-C(sp3) and (sp3)C-H bonds in aryl alkanes by the use of NaNO2/HCl was explored. The method is chemical-oxidant-free, transition-metal-free, uses water as the solvent, and proceeds under mild conditions, making it valuable and attractive to synthetic organic chemistry.
- Zhao, Jianyou,Shen, Tong,Sun, Zhihui,Wang, Nengyong,Yang, Le,Wu, Jintao,You, Huichao,Liu, Zhong-Quan
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p. 4057 - 4061
(2021/05/26)
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- Integration of Earth-Abundant Photosensitizers and Catalysts in Metal-Organic Frameworks Enhances Photocatalytic Aerobic Oxidation
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We report here the construction of two metal-organic frameworks (MOFs), Zr6-Cu/Fe-1 and Zr6-Cu/Fe-2, by integrating earth-abundant cuprous photosensitizers (Cu-PSs) and Fe catalysts for photocatalytic aerobic oxidation. Site isolation and pore confinement stabilize both Cu-PSs and Fe catalysts, while the proximity between active centers facilitates electron and mass transfer. Upon visible light irradiation and using O2 as the only oxidant, Zr6-Cu/Fe-1 and Zr6-Cu/Fe-2 efficiently oxidize alcohols and benzylic compounds to afford corresponding carbonyl products with broad substrate scopes, high turnover numbers of up to 500 with a 9.4-fold enhancement over homogeneous analogues, and excellent recyclability in four consecutive runs. Control experiments, spectroscopic evidence, and computational studies revealed the photo-oxidation mechanism: Oxidative quenching of [Cu-PS]? by O2 affords [CuII-PS], which efficiently oxidizes FeIII-OH to generate a hydroxyl radical for substrate oxidation. This work highlights the potential of MOFs in promoting earth-abundant metal-based photocatalysis.
- Feng, Xuanyu,Pi, Yunhong,Song, Yang,Xu, Ziwan,Li, Zhong,Lin, Wenbin
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p. 1024 - 1032
(2021/01/26)
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- Exploration of highly electron-rich manganese complexes in enantioselective oxidation catalysis; A focus on enantioselective benzylic oxidation
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The direct enantioselective hydroxylation of benzylic C-H bonds to form chiral benzylic alcohols represents a challenging transformation. Herein, we report on the exploration of new biologically inspired manganese and iron complexes bearing highly electron-rich aminopyridine ligands containing 4-pyrrolidinopyridine moieties ((S,S)-1, (R,R)-1, 2 and 5) in combination with chiral bis-pyrrolidine and N,N-cyclohexanediamine backbones in enantioselective oxidation catalysis with aqueous H2O2. The current manganese complexes outperform the analogous manganese complexes containing 4-dimethylaminopyridine moieties (3 and 4) in benzylic oxidation reactions in terms of alcohol yield while keeping similar ee values (~60% ee), which is attributed to the higher basicity of the 4-pyrrolidinopyridine group. A detailed investigation of different carboxylic acid additives in enantioselective benzylic oxidation provides new insights into how to rationally enhance enantioselectivities by means of proper tuning of the environment around the catalytic active site, and has resulted in the selection of Boc-l-Tert-leucine as the preferred additive. Using these optimized conditions, manganese complex 2 was shown to be effective in the enantioselective benzylic oxidation of a series of arylalkane substrates with up to 50% alcohol yield and 62% product ee. A final set of experiments also highlights the use of the new 4-pyrrolidinopyridine-based complexes in the asymmetric epoxidation of olefins (up to 98% epoxide yield and >99% ee).
- Klein Gebbink, Robertus J. M.,Li, Fanshi,Lutz, Martin,Masferrer-Rius, Eduard
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p. 7751 - 7763
(2021/12/13)
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- Chiral Yolk-Shell MOF as an Efficient Nanoreactor for Asymmetric Catalysis in Organic-Aqueous Two-Phase System
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It remains a great challenge to introduce large and efficient homogeneous asymmetric catalysts into MOFs and other microporous materials as well as retain their degrees of freedom. Herein, a new heterogeneous strategy of homogeneous chiral catalysts is proposed, that is, to construct a yolk-shell MOFs-confined, large-size, and highly efficient homogeneous chiral catalyst, which can be used as a nanoreactor for asymmetric catalytic reactions.
- Shi, Shunli,Zhong, Yicheng,Hu, Zhuo,Wang, Lei,Yuan, Mingwei,Ding, Shunmin,Wang, Shuhua,Chen, Chao
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supporting information
p. 12714 - 12718
(2021/09/11)
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- Hydration of Alkynes to Ketones with an Efficient and Practical Polyoxomolybdate-based Cobalt Catalyst
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Hydration of alkynes to ketones is one of the most atom economical and universal methods for the synthesis of carbonyl compounds. However, the basic reaction usually requires organic ligand catalysts or harsh reaction conditions to insert oxygen into the C≡C bond. Here, we report an inorganic ligand supported cobalt (III) catalyst, (NH4)3[CoMo6O18(OH)6], which is supported by a central cobalt (III) mononucleus and a ring-shaped pure inorganic ligand composed of six MoVIO6 octahedrons to avoid the disadvantages of expensive and unrecyclable organic ligand catalysts or noble metal catalysts. Under mild conditions, the cobalt (III) catalyst can be used for the hydration of alkynes to ketones. The catalyst is non-toxic, green, and environment friendly. The catalyst can be recycled at least six times with high activity. According to control experiments, a reasonable mechanism is provided.
- Xie, Ya,Wang, Jingjing,Wang, Yunyun,Han, Sheng,Yu, Han
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p. 4985 - 4989
(2021/10/12)
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- Catalyst- and acid-free Markovnikov hydration of alkynes in a sustainable H2O/ethyl lactate system
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An efficient and sustainable protocol for the hydration of alkynes has been developed under metal/acid/catalyst/ligand-free conditions in a water/ethyl lactate mixture. The hydrogen-bond network in the ethyl lactate and water mixture plays a crucial and decisive role in activating the alkynes for hydration to afford the corresponding methyl ketones. This strategy gives the Markovnikov (ketone) addition product selectively over other possible products. The essential role of hydrogen bonding has been confirmed by experimental and theoretical techniques. A probable mechanism has been suggested by various control tests. The efficacy of the method has been further explored for the competent production of value-added α,β-unsaturated carbonyl compounds through the reaction of aldehydes with alkynes as ketonic surrogates. The environmentally benign hydration method takes place under mild conditions, has broad functional-group compatibility, and uses the ethyl lactate/water (1:3) medium as a “green alternative” in the absence of any hazardous, harmful, or expensive substances.
- Dandia, Anshu,Saini, Pratibha,Chithra,Vennapusa, Sivaranjana Reddy,Parewa, Vijay
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- Bismuth subnitrate-catalyzed markovnikov-type alkyne hydrations under batch and continuous flow conditions
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Bismuth subnitrate is reported herein as a simple and efficient catalyst for the atom-economical synthesis of methyl ketones via Markovnikov-type alkyne hydration. Besides an effective batch process under reasonably mild conditions, a chemically intensified continuous flow protocol was also developed in a packed-bed system. The applicability of the methodologies was demonstrated through hydration of a diverse set of terminal acetylenes. By simply switching the reaction medium from methanol to methanol-d4, valuable trideuteromethyl ketones were also prepared. Due to the ready availability and nontoxicity of the heterogeneous catalyst, which eliminated the need for any special additives and/or harmful reagents, the presented processes display significant advances in terms of practicality and sustainability.
- ?tv?s, Sándor B.,Fül?p, Ferenc,Szécsényi, Zsanett
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- Organotellurium-catalyzed oxidative deoximation reactions using visible-light as the precise driving energy
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Irradiated by visible light, the recyclable (PhTe)2-catalyzed oxidative deoximation reaction could occur under mild conditions. In comparison with the thermo reaction, the method employed reduced catalyst loading (1 mol% vs. 2.5 mol%), but afforded elevated product yields with expanded substrate scope. This work demonstrated that for the organotellurium-catalyzed reactions, visible light might be an even more precise driving energy than heating because it could break the Te–Te bond accurately to generate the active free radical catalytic intermediates without damaging the fragile substituents (e.g., heterocycles) of substrates. The use of O2 instead of explosive H2O2 as oxidant affords safer reaction conditions from the large-scale application viewpoint.
- Deng, Xin,Qian, Rongrong,Zhou, Hongwei,Yu, Lei
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supporting information
p. 1029 - 1032
(2020/10/23)
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- PhSe(O)OH/NHPI-catalyzed oxidative deoximation reaction using air as oxidant
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A novel oxidative deoximation method was developed in this article. Compared with the reported organoselenium-catalyzed oxidative deoximation reaction, this reaction employed N-hydroxyphthalimide (NHPI) as the co-catalyst, so that the oxidative deoximation reaction could utilize air as oxidant in the green DMC solvent under mild reaction conditions. Control experiments and X-ray photoelectron spectroscopy (XPS) analysis results indicated that NHPI was essential for activating the catalytic organoselenium species. It could accelerate the activation of molecular oxygen in air to promote the reaction process. The reaction can avoid metal residues in product and is of potential application values in pharmaceutical industry due to the transition metal-free process.
- Shi, Yaocheng,Wang, Feng,Yang, Chenggen,Yu, Lei
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- Visible-Light-Driven Selective Air-Oxygenation of C?H Bond via CeCl3 Catalysis in Water
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Visible-light-induced C?H aerobic oxidation is an important chemical transformation that can be applied for the synthesis of aromatic ketones. High-cost catalysts and toxic solvents were generally needed in the present methodologies. Here, an efficient aqueous C?H aerobic oxidation protocol was reported. Through CeCl3-mediated photocatalysis, a series of aromatic ketones were produced in moderate to excellent yields. With air as the oxidant, this reaction could be performed under mild conditions in water and demonstrated high activity and functional group tolerance. This method is economical, highly efficient, and environmentally friendly, and it will provide inspiration for the development of aqueous photochemical synthesis reactions.
- Xie, Pan,Xue, Cheng,Shi, Sanshan,Du, Dongdong
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p. 2689 - 2693
(2021/05/07)
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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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- Selective electrochemical oxidation of aromatic hydrocarbons and preparation of mono/multi-carbonyl compounds
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A selective electrochemical oxidation was developed under mild condition. Various mono-carbonyl and multi-carbonyl compounds can be prepared from different aromatic hydrocarbons with moderate to excellent yield and selectivity by virtue of this electrochemical oxidation. The produced carbonyl compounds can be further transformed into α-ketoamides, homoallylic alcohols and oximes in a one-pot reaction. In particular, a series of α-ketoamides were prepared in a one-pot continuous electrolysis. Mechanistic studies showed that 2,2,2-trifluoroethan-1-ol (TFE) can interact with catalyst species and generate the corresponding hydrogen-bonding complex to enhance the electrochemical oxidation performance. [Figure not available: see fulltext.]
- Li, Zhibin,Zhang, Yan,Li, Kuiliang,Zhou, Zhenghong,Zha, Zhenggen,Wang, Zhiyong
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p. 2134 - 2141
(2021/09/29)
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- Selective Electrochemical Oxygenation of Alkylarenes to Carbonyls
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An efficient electrochemical method for benzylic C(sp3)-H bond oxidation has been developed. A variety of methylarenes, methylheteroarenes, and benzylic (hetero)methylenes could be converted into the desired aryl aldehydes and aryl ketones in moderate to excellent yields in an undivided cell, using O2 as the oxygen source and lutidinium perchlorate as an electrolyte. On the basis of cyclic voltammetry studies, 18O labeling experiments, and radical trapping experiments, a possible single-electron transfer mechanism has been proposed for the electrooxidation reaction.
- Li, Xue,Bai, Fang,Liu, Chaogan,Ma, Xiaowei,Gu, Chengzhi,Dai, Bin
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supporting information
p. 7445 - 7449
(2021/10/02)
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- An efficient and practical aerobic oxidation of benzylic methylenes by recyclable: N -hydroxyimide
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An efficient and practical benzylic aerobic oxidation catalyzed by cheap and simple N-hydroxyimide organocatalyst has been achieved with high yields and broad substrate scope. The organocatalyst used can be recycled and reused by simple workup and only minute amount (1 mol% in most cases) of simple iron salt is used as promoter. Phenyl substrates with mild and strong electron-withdrawing group could also be oxygenated in high yields as well as other benzylic methylenes. Influence of substituents, gram-scale application, catalysts decay and general mechanism of this methodology has also been discussed. This journal is
- Wang, Jian,Zhang, Cheng,Ye, Xiao-Qing,Du, Wenting,Zeng, Shenxin,Xu, Jian-Hong,Yin, Hong
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p. 3003 - 3011
(2021/01/28)
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- Synergistic Catalytic?Effect?of N-Hydroxyphthalimide/Cobalt Tetraamide Phthalocyanine and Its Application for Aerobic Oxidation of Hydrocarbons and Alcohols
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Abstract: The activation of oxygen?for?selective?oxidation?of?organic molecules, such as hydrocarbons and alcohols, remains a major catalytic?challenge. We have developed a catalytic system combining N-hydroxyphthalimide (NHPI) with cobalt tetraamide phthalocyanine [CoPc(CONH2)4] for the oxidation of hydrocarbons and alcohols at 75?°C under an oxygen atmosphere. CoPc(CONH2)4 was synthesized by trimellitic anhydride-urea method, and its structure was confirmed by FT-IR, UV–Vis and XRD. This catalyst, in synergy with NHPI/O2 system, exhibited excellent catalytic ability and high selectivity in the oxidation of hydrocarbons and alcohols. Based on the experimental results, a reasonable reaction mechanism was proposed for the oxidation of alkanes and alcohols, respectively. Graphic Abstract: Cobalt tetraamide phthalocyanine (CoPc(CONH2)4) was synthesized by a simple solid-thermal method, and the synergistic catalysis oxidation of NHPI and CoPc(CONH2)4 was studied. A synergistic catalysis system for the aerobic oxidation of hydrocarbons and alcohols by N-hydroxyphthalimide combined with cobalt tetraamide phthalocyanine has been developed.[Figure not available: see fulltext.]
- Li, Fei,Tang, Shuo,Tang, Zhilin,Ye, Lingjun,Li, Hehua,Niu, Fanfan,Sun, Xiaoling
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- A Copper-Containing Polyoxometalate-Based Metal-Organic Framework as an Efficient Catalyst for Selective Catalytic Oxidation of Alkylbenzenes
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A copper-containing polyoxometalate-based metal-organic framework (POMOF), CuI12Cl2(trz)8[HPW12O40] (HENU-7, HENU = Henan University; trz = 1,2,4-triazole), has been successfully synthesized and well-characterized. In addition, the excellent catalytic ability of HENU-7 has been proved by the selective oxidation of diphenylmethane. Under the optimal conditions, the diphenylmethane conversion obtained over HENU-7 is 96%, while the selectivity to benzophenone is 99%, which outperforms most noble-metal-free POM-based catalysts. Moreover, HENU-7 is stable to reuse for five runs without an obvious loss in activity and also can catalyze the oxidation of different benzylic C-H with satisfactory conversions and selectivities, which implied the significant catalytic activity and recyclability.
- Xu, Baijie,Xu, Qian,Wang, Quanzhong,Liu, Zhen,Zhao, Ruikun,Li, Dandan,Ma, Pengtao,Wang, Jingping,Niu, Jingyang
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p. 4792 - 4799
(2021/04/09)
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- Bifunctional Metal-Organic Layers for Tandem Catalytic Transformations Using Molecular Oxygen and Carbon Dioxide
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Tandem catalytic reactions improve atom- and step-economy over traditional synthesis but are limited by the incompatibility of the required catalysts. Herein, we report the design of bifunctional metal-organic layers (MOLs), HfOTf-Fe and HfOTf-Mn, consisting of triflate (OTf)-capped Hf6 secondary building units (SBUs) as strong Lewis acidic centers and metalated TPY ligands as metal active sites for tandem catalytic transformations using O2 and CO2 as coreactants. HfOTf-Fe effectively transforms hydrocarbons into cyanohydrins via tandem oxidation with O2 and silylcyanation whereas HfOTf-Mn converts styrenes into styrene carbonates via tandem epoxidation and CO2 insertion. Density functional theory calculations revealed the involvement of a high-spin FeIV (S = 2) center in the challenging oxidation of the sp3 C-H bond. This work highlights the potential of MOLs as a tunable platform to incorporate multiple catalysts for tandem transformations.
- Jiang, Xiaomin,Lan, Guangxu,Lin, Wenbin,Ni, Kaiyuan,Quan, Yangjian,Shi, Wenjie,Song, Yang,Wang, Cheng
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supporting information
p. 16718 - 16724
(2021/10/21)
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- Dimensional Reduction of Eu-Based Metal-Organic Framework as Catalysts for Oxidation Catalysis of C(sp3)–H Bond
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Developing new catalysts for highly selectivity and conversion of saturated C(sp3)–H bonds is of great significance. In order to obtain catalysts with high catalytic performance, six Eu-based MOFs with different structural characteristics were obtained by using europium ions and different organic acid ligands, namely Eu-1~Eu-6. Eu-1, Eu-2 and Eu-3 featured three-dimensional structures, while Eu-4 and Eu-5 featured two-dimensional structures. Differently, a one-dimensional chain structure of Eu-6 was obtained by changing the ligand. All the six MOFs were applied to the catalytic reaction of C(sp3)–H bond, and it was found that the catalytic effect was gradually enhanced with the decrease of dimension and the increase of the size of channels. As expected, Eu-6 showed the highest selectivity (~99%) and conversion (~99%). Moreover, catalytic cycling and stability tests showed Eu-6 can be a reliable catalyst.
- Yan, Jun,Yu, Wei-Dong,Zhang, Yin,Zhao, Cai-Feng
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- Polyoxometalate-Incorporated Framework as a Heterogeneous Catalyst for Selective Oxidation of C-H Bonds of Alkylbenzenes
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Developing new catalysts for highly efficient and selective oxidation of saturated C-H bonds is significant due to their thermodynamic strength. Via incorporation of PW12O403-, pyridine-2,5-dicarboxylic acids (pydc), and Fe(III) ions into one framework, a new polyoxometalate-based metal-organic framework, [HFe4O2(H2O)4(pydc)3PW12O40]·10.5H2O (FeW-PYDC), was successfully prepared by a hydrothermal method. Interestingly, FeW-PYDC features a three-dimensional porous structure with {Fe4O2} interconnecting with PW12O403- units. FeW-PYDC displayed excellent performance in the selective oxidation of C-H bonds of alkylbenzenes with high conversion (95.7%) and selectivity (96.6%). As an effective heterogeneous catalyst, FeW-PYDC demonstrates good reusability and structural stability.
- Hu, Xin,Ma, Pengtao,Niu, Jingyang,Wang, Hui,Wang, Jingping,Wang, Quanzhong,Wang, Yingyue,Xu, Baijie
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p. 7753 - 7761
(2021/06/27)
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- An Artificial Light-Harvesting System with Tunable Fluorescence Color in Aqueous Sodium Dodecyl Sulfonate Micellar Systems for Photochemical Catalysis
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In the present work, an artificial light-harvesting system with fluorescence resonance energy transfer (FRET) is successfully fabricated in aqueous sodium dodecyl sulfonate (SDS) micellar systems. Since the tight and orderly arrangement of dodecyl in the SDS micelles is hydrophobic, tetra-(4-pyridylphenyl)ethylene (4PyTPE) can be easily encapsulated into the hydrophobic layer of SDS micelles through noncovalent interaction, which exhibits aggregation-induced emission (AIE) phenomenon and can be used as energy donor. By using amphoteric sulforhodamine 101 (SR101) fluorescent dye attached to the negatively charged surface of SDS micelles through electrostatic interaction as energy acceptor, the light-harvesting FRET process can be efficiently simulated. Through the steady-state emission spectra analysis in the micelle-mediated energy transfer from 4PyTPE to SR101, the fluorescence emission can be tuned and white light emission with CIE coordinates of (0.31, 0.29) can be successfully achieved by tuning the donor/acceptor ratio. More importantly, to better mimic natural photosynthesis, the SDS micelles with 4PyTPE and SR101 FRET system showed enhanced catalytic activity in photochemical catalysis for dehalogenation of α-bromoacetophenone in aqueous solution and the photocatalytic reaction could be extended to gram levels.
- Li, Xinglong,Wang, Ying,Song, Ao,Zhang, Minghui,Chen, Mengning,Jiang, Man,Yu, Shengsheng,Wang, Rongzhou,Xing, Lingbao
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supporting information
p. 2725 - 2730
(2021/08/03)
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- Engineering the large pocket of an (S)-selective transaminase for asymmetric synthesis of (S)-1-amino-1-phenylpropane
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Amine transaminases offer an environmentally benign chiral amine asymmetric synthesis route. However, their catalytic efficiency towards bulky chiral amine asymmetric synthesis is limited by the natural geometric structure of the small pocket, representing a great challenge for industrial applications. Here, we rationally engineered the large binding pocket of an (S)-selective ?-transaminase BPTA fromParaburkholderia phymatumto relieve the inherent restriction caused by the small pocket and efficiently transform the prochiral aryl alkyl ketone 1-propiophenone with a small substituent larger than the methyl group. Based on combined molecular docking and dynamic simulation analyses, we identified a non-classical substrate conformation, located in the active site with steric hindrance and undesired interactions, to be responsible for the low catalytic efficiency. By relieving the steric barrier with W82A, we improved the specific activity by 14-times compared to WT. A p-p stacking interaction was then introduced by M78F and I284F to strengthen the binding affinity with a large binding pocket to balance the undesired interactions generated by F44. T440Q further enhanced the substrate affinity by providing a more hydrophobic and flexible environment close to the active site entry. Finally, we constructed a quadruple variant M78F/W82A/I284F/T440Q to generate the most productive substrate conformation. The 1-propiophenone catalytic efficiency of the mutant was enhanced by more than 470-times in terms ofkcat/KM, and the conversion increased from 1.3 to 94.4% compared with that of WT, without any stereoselectivity loss (ee > 99.9%). Meanwhile, the obtained mutant also showed significant activity improvements towards various aryl alkyl ketones with a small substituent larger than the methyl group ranging between 104- and 230-fold, demonstrating great potential for the efficient synthesis of enantiopure aryl alkyl amines with steric hindrance in the small binding pocket.
- Liu, He,Wang, Hualei,Wei, Dongzhi,Xie, Youyu,Xu, Feng,Xu, Xiangyang,Yang, Lin
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p. 2461 - 2470
(2021/04/22)
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- Decatungstate-mediated solar photooxidative cleavage of CC bonds using air as an oxidant in water
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With the increasing attention for green chemistry and sustainable development, there has been much interest in searching for greener methods and sources in organic synthesis. However, toxic additives or solvents are inevitably involved in most organic transformations. Herein, we first report the combination of direct utilization of solar energy, air as the oxidant and water as the solvent for the selective cleavage of CC double bonds in aryl olefins. Various α-methyl styrenes, diaryl alkenes as well as terminal styrenes are well tolerated in this green and sustainable strategy and furnished the desired carbonyl products in satisfactory yields. Like heterogeneous catalysis, this homogeneous catalytic system could also be reused and it retains good activity even after repeating three times. Mechanism investigations indicated that both O2- and 1O2 were involved in the reaction. Based on these results, two possible mechanisms, including the electron transfer pathway and the energy transfer pathway, were proposed.
- Du, Dongdong,Luo, Junfei,Shi, Sanshan,Xie, Pan,Xue, Cheng
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p. 5936 - 5943
(2021/08/23)
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- Selective oxidation of alkenes to carbonyls under mild conditions
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Herein, a practical and sustainable method for the synthesis of aldehydes, ketones, and carboxylic acids from an inexpensive olefinic feedstock is described. This transformation features very sustainable and mild conditions and utilizes commercially available and inexpensive tetrahydrofuran as the additive, molecular oxygen as the sole oxidant and water as the solvent. A wide range of substituted alkenes were found to be compatible, providing the corresponding carbonyl compounds in moderate-to-good yields. The control experiments demonstrated that a radical mechanism is responsible for the oxidation reaction.
- Huo, Jie,Xiong, Daokai,Xu, Jun,Yue, Xiaoguang,Zhang, Pengfei,Zhang, Yilan
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supporting information
p. 5549 - 5555
(2021/08/16)
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- Oxidative Cleavage of Alkenes by O2with a Non-Heme Manganese Catalyst
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The oxidative cleavage of C═C double bonds with molecular oxygen to produce carbonyl compounds is an important transformation in chemical and pharmaceutical synthesis. In nature, enzymes containing the first-row transition metals, particularly heme and non-heme iron-dependent enzymes, readily activate O2 and oxidatively cleave C═C bonds with exquisite precision under ambient conditions. The reaction remains challenging for synthetic chemists, however. There are only a small number of known synthetic metal catalysts that allow for the oxidative cleavage of alkenes at an atmospheric pressure of O2, with very few known to catalyze the cleavage of nonactivated alkenes. In this work, we describe a light-driven, Mn-catalyzed protocol for the selective oxidation of alkenes to carbonyls under 1 atm of O2. For the first time, aromatic as well as various nonactivated aliphatic alkenes could be oxidized to afford ketones and aldehydes under clean, mild conditions with a first row, biorelevant metal catalyst. Moreover, the protocol shows a very good functional group tolerance. Mechanistic investigation suggests that Mn-oxo species, including an asymmetric, mixed-valent bis(μ-oxo)-Mn(III,IV) complex, are involved in the oxidation, and the solvent methanol participates in O2 activation that leads to the formation of the oxo species.
- Bennett, Elliot L.,Brookfield, Adam,Guan, Renpeng,Huang, Zhiliang,Mcinnes, Eric J. L.,Robertson, Craig M.,Shanmugam, Muralidharan,Xiao, Jianliang
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supporting information
p. 10005 - 10013
(2021/07/19)
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- Hydroxyl radical-mediated oxidative cleavage of CC bonds and further esterification reaction by heterogeneous semiconductor photocatalysis
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A hydroxyl radical-mediated aerobic cleavage of alkenes and further sequence esterification reaction for the preparation of carbonyl compounds have been developed by using tubular carbon nitride (TCN) as a general heterogeneous photocatalyst under an oxygen atmosphere with visible light irradiation. This protocol has an excellent substrate scope and gives the desired aldehydes, ketones and esters in moderate to high yields. Importantly, this metal-free procedure employed photogenerated hydroxyl radicals in situ as green oxidation active species, avoiding the present additional initiators. The reaction could be carried out under solar light irradiation and was applicable to large-scale reactions. Furthermore, the recyclable TCN catalyst could be used several times without a significant loss of activities.
- Hong, Mei,Jia, Rui,Miao, Hongyan,Ni, Bangqing,Niu, Tengfei,Wang, Hui
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p. 6591 - 6597
(2021/09/10)
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- Photo-induced oxidative cleavage of C-C double bonds for the synthesis of biaryl methanoneviaCeCl3catalysis
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A Ce-catalyzed strategy is developed to produce biaryl methanonesviaphotooxidative cleavage of C-C double bonds at room temperature. This reaction is performed under air and demonstrates high activity as well as functional group tolerance. A synergistic Ce/ROH catalytic mechanism is also proposed based on the experimental observations. This protocol should be the first successful Ce-catalyzed photooxidation reaction of olefins with air as the oxidant, which would provide inspiration for the development of novel Ce-catalyzed photochemical synthesis processes.
- Xie, Pan,Xue, Cheng,Du, Dongdong,Shi, SanShan
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supporting information
p. 6781 - 6785
(2021/08/20)
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- Visible-Light-Driven Oxidative Cleavage of Alkenes Using Water-Soluble CdSe Quantum Dots
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The oxidative cleavage of C=C bonds is an important chemical reaction, which is a popular reaction in the photocatalytic field. However, high catalyst-loading and low turnover number (TON) are general shortcomings in reported visible-light-driven reactions. Herein, the direct oxidative cleavage of C=C bonds through water-soluble CdSe quantum dots (QDs) is described under visible-light irradiation at room temperature with high TON (up to 3.7×104). Under the same conditions, water-soluble CdSe QDs could also oxidize sulfides to sulfoxides with 51–84 % yields and TONs up to 3.4×104. The key features of this photocatalytic protocol include high TONs, wide substrates scope, low catalyst loadings, simple and mild reaction conditions, and molecular O2 as the oxidant.
- Li, Jianing,Zhao, Jingnan,Ma, Cunfei,Yu, Zongyi,Zhu, Hongfei,Yun, Lei,Meng, Qingwei
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p. 4985 - 4992
(2021/10/16)
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- Palladium-Aminopyridine Catalyzed C?H Oxygenation: Probing the Nature of Metal Based Oxidant
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A mechanistic study of direct selective oxidation of benzylic C(sp3)?H groups with peracetic acid, catalyzed by palladium complexes with tripodal amino-tris(pyriylmethyl) ligands, is presented. The oxidation of arylalkanes having secondary and tertiary benzylic C?H groups, predominantly yields, depending on the substrate and conditions, either the corresponding ketones or alcohols. One of the three 2-pyriylmethyl moieties, which is pending in the starting catalyst, apparently, facilitates the active species formation and takes part in stabilization of the high-valent Pd center in the active species, occupying the axial coordination site of palladium. The catalytic, as well as isotopic labeling experiments, in combination with ESI-MS data and DFT calculations, point out palladium oxyl species as possible catalytically active sites, operating essentially via C?H abstraction/oxygen rebound pathway. For the ketones formation, O?H abstraction/в-scission mechanism has been proposed.
- Lubov, Dmitry P.,Bryliakova, Anna A.,Samsonenko, Denis G.,Sheven, Dmitriy G.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
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p. 5109 - 5120
(2021/11/10)
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- Lewis Acidic Boranes, Lewis Bases, and Equilibrium Constants: A Reliable Scaffold for a Quantitative Lewis Acidity/Basicity Scale
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A quantitative Lewis acidity/basicity scale toward boron-centered Lewis acids has been developed based on a set of 90 experimental equilibrium constants for the reactions of triarylboranes with various O-, N-, S-, and P-centered Lewis bases in dichloromethane at 20 °C. Analysis with the linear free energy relationship log KB=LAB+LBB allows equilibrium constants, KB, to be calculated for any type of borane/Lewis base combination through the sum of two descriptors, one for Lewis acidity (LAB) and one for Lewis basicity (LBB). The resulting Lewis acidity/basicity scale is independent of fixed reference acids/bases and valid for various types of trivalent boron-centered Lewis acids. It is demonstrated that the newly developed Lewis acidity/basicity scale is easily extendable through linear relationships with quantum-chemically calculated or common physical–organic descriptors and known thermodynamic data (ΔH (Formula presented.)). Furthermore, this experimental platform can be utilized for the rational development of borane-catalyzed reactions.
- Mayer, Robert J.,Hampel, Nathalie,Ofial, Armin R.
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supporting information
p. 4070 - 4080
(2021/01/29)
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- Scalable Negishi Coupling between Organozinc Compounds and (Hetero)Aryl Bromides under Aerobic Conditions when using Bulk Water or Deep Eutectic Solvents with no Additional Ligands
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Pd-catalyzed Negishi cross-coupling reactions between organozinc compounds and (hetero)aryl bromides have been reported when using bulk water as the reaction medium in the presence of NaCl or the biodegradable choline chloride/urea eutectic mixture. Both C(sp3)-C(sp2) and C(sp2)-C(sp2) couplings have been found to proceed smoothly, with high chemoselectivity, under mild conditions (room temperature or 60 °C) in air, and in competition with protonolysis. Additional benefits include very short reaction times (20 s), good to excellent yields (up to 98 %), wide substrate scope, and the tolerance of a variety of functional groups. The proposed novel protocol is scalable, and the practicability of the method is further highlighted by an easy recycling of both the catalyst and the eutectic mixture or water.
- Dilauro, Giuseppe,Azzollini, Claudia S.,Vitale, Paola,Salomone, Antonio,Perna, Filippo M.,Capriati, Vito
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supporting information
p. 10632 - 10636
(2021/04/09)
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- Mizoroki-Heck type reactions and synthesis of 1,4-dicarbonyl compounds by heterogeneous organic semiconductor photocatalysis
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We report the synthesis of 1,4-dicarbonyl compounds and substituted alkenes (Mizoroki-Heck type coupling) starting from secondary and tertiary alkyl halides and vinyl acetate or styrene derivatives using visible-light photocatalysis. The protocol uses mesoporous graphitic carbon nitride (mpg-CN) as a heterogeneous organic semiconductor photocatalyst and Ni(ii) salts as Lewis acid catalysts. Detailed post-characterization of the heterogeneous material has been carried out to support the proposed catalytic cycle. Apart from high functional-group tolerance, mild reaction conditions, scalability as well as easy recovery and reuse of the mpg-CN photocatalyst provide a practical solution to these widespread transformations in terms of sustainability and efficiency and this methodology is recommended for applications in academic and industrial synthesis.
- Khamrai, Jagadish,Das, Saikat,Savateev, Aleksandr,Antonietti, Markus,K?nig, Burkhard
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supporting information
p. 2017 - 2024
(2021/03/26)
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- To Rebound or...Rebound? Evidence for the "alternative Rebound" mechanism in Ca'H Oxidations by the systems nonheme Mn Complex/H2O2/carboxylic acid
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In this work, it has been shown that aliphatic Ca'H oxidations by bioinspired catalyst systems Mn aminopyridine complex/H2O2/carboxylic acid in acetonitrile afford predominantly a mixture of the corresponding alcohol and the ester. The alcohol/ester ratio is higher for catalysts bearing electron-donating groups at the aminopyridine core. Isotopic labeling studies witness that the oxygen atom of the alcohol originates from the H2O2molecule, while the ester oxygen comes exclusively from the acid. Oxidation of ethylbenzene in the presence of acetic acid affords enantiomerically enriched 1-phenylethanol and 1-phenyl acetate, with close enantioselectivities and the same sign of absolute chirality. Experimental data and density functional theory calculations provide evidence in favor of the rate-limiting benzylic H atom abstraction by the high-spin (S = 1) [LMnV(O)OAc]2+active species followed by competitive OH/OC(O)R rebound. This mechanism has been unprecedented for Ca'H oxidations catalyzed by bioinspired Mn complexes. The trends governing the alcohol/ester ratios have been rationalized in terms of steric properties of the catalyst, acid, and substrate. copy; 2021 American Chemical Society.
- Ottenbacher, Roman V.,Bryliakova, Anna A.,Shashkov, Mikhail V.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
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p. 5517 - 5524
(2021/05/31)
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- Iron-catalyzed domino decarboxylation-oxidation of α,β-unsaturated carboxylic acids enabled aldehyde C-H methylation
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A practical and general iron-catalyzed domino decarboxylation-oxidation of α,β-unsaturated carboxylic acids enabling aldehyde C-H methylation for the synthesis of methyl ketones has been developed. This mild, operationally simple method uses ambient air as the sole oxidant and tolerates sensitive functional groups for the late-stage functionalization of complex natural-product-derived and polyfunctionalized molecules.
- Gong, Pei-Xue,Xu, Fangning,Cheng, Lu,Gong, Xu,Zhang, Jie,Gu, Wei-Jin,Han, Wei
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supporting information
p. 5905 - 5908
(2021/06/18)
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- METHOD FOR OXIDATIVE CLEAVAGE OF COMPOUNDS WITH UNSATURATED DOUBLE BOND
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A method for oxidative cleavage of a compound with an unsaturated double bond is provided. The method includes the steps of: (A) providing a compound (I) with an unsaturated double bond, a trifluoromethyl-containing reagent, and a catalyst; wherein, the catalyst is represented by Formula (II): M(O)mL1yL2z??(II);wherein, M, L1, L2, m, y, z, R1, R2 and R3 are defined in the specification; and(B) mixing the compound with an unsaturated double bond and the trifluoromethyl-containing reagent to perform an oxidative cleavage of the compound with the unsaturated double bond by using the catalyst in air or under oxygen atmosphere condition to obtain a compound represented by Formula (III):
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Paragraph 0071
(2021/07/10)
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- Nitrosoarene-Catalyzed HFIP-Assisted Transformation of Arylmethyl Halides to Aromatic Carbonyls under Aerobic Conditions
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A rare metal-free nucleophilic nitrosoarene catalysis accompanied by highly hydrogen-bond-donor (HBD) solvent, 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), organocatalytically converts arylmethyl halides to aromatic carbonyls. This protocol offers an effective means to access a diverse array of aromatic carbonyls with good chemoselectivity under mild reaction conditions. The activation of arylmethyl halides by HFIP to generate stable carbocation and autoxidation of in situ generated hydroxylamine to nitrosoarene in the presence of atmospheric O2 are the keys to success.
- Pradhan, Suman,Sharma, Vishali,Chatterjee, Indranil
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supporting information
p. 6148 - 6152
(2021/08/03)
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- The Reactivity of α-Fluoroketones with PLP Dependent Enzymes: Transaminases as Hydrodefluorinases
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A chemical method for the treatment of harmful halogenated compounds that has recently become of interest is the reductive dehalogenation of carbon-halogen bonds. In the case of a fluorine atom, this process is called hydrodefluorination. While many transition metal-based approaches now exist to reductively defluorinate aromatic fluoroarenes, the cleavage of C?F bonds in aliphatic compounds is not so well-developed. Here we propose a biocatalytic approach exploiting a promiscuous activity exhibited by transaminases (TAs). Hence, a series of α-fluoroketones have been defluorinated with excellent conversions using Chromobacterium violaceum and Arthrobacter sp. TAs under mild conditions and in aqueous medium, using a stoichiometric amount of an amine (e. g. 2-propylamine) as reagent and formally releasing its oxidized form (e. g. acetone), with ammonia and hydrogen fluoride as by-products. It is also demonstrated that this process can be performed in a regio- or stereoselective fashion.
- García-Ramos, Marina,Cuetos, Aníbal,Kroutil, Wolfgang,Grogan, Gideon,Lavandera, Iván
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p. 3967 - 3972
(2021/08/09)
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- Method for oxidative cracking of compound containing unsaturated double bonds
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The invention relates to a method for oxidative cracking of a compound containing unsaturated double bonds. The method comprises the following steps: (A) providing a compound (I) containing unsaturated double bonds, a trifluoromethyl-containing reagent and a catalyst, wherein the catalyst is shown as a formula (II): M(O)mL1yL2z (II), M, L1, L2, m, y, z, R1, R2 and R3 being defined in the specification; and (B) mixing the compound containing the unsaturated double bonds and the trifluoromethyl-containing reagent, and performing an oxidative cracking reaction on the compound containing the unsaturated double bonds in the presence of air or oxygen by using the catalyst to obtain a compound represented by formula (III),.
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Paragraph 0108-0114; 0134-0139
(2021/07/09)
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- METHOD FOR OXIDATIVE CLEAVAGE OF COMPOUNDS WITH UNSATURATED DOUBLE BOND
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A method for oxidative cleavage of a compound with an unsaturated double bond is provided. The method comprises the following step: (A) providing a compound (I) with an unsaturated double bond, a reagent with trifluoromethyl, and a catalyst; wherein the catalyst is represented by the following formula (II): M(O)mL1yL2z (II); wherein, M, L1, L2, m, y, z, R1, R2 and R3 are defined in the specification; and (B) mixing the compound with an unsaturated double bond and the reagent with a trifluoromethyl to perform an oxidation of the compound with the unsaturated double bond by using the catalyst at air or an oxygen condition to get a compound presented as formula (III):
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Paragraph 0053-0056
(2021/03/19)
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- Photoinduced Acetylation of Anilines under Aqueous and Catalyst-Free Conditions
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A green and efficient visible-light induced functionalization of anilines under mild conditions has been reported. Utilizing nontoxic, cost-effective, and water-soluble diacetyl as photosensitizer and acetylating reagent, and water as the solvent, a variety of anilines were converted into the corresponding aryl ketones, iodides, and bromides. With advantages of environmentally friendly conditions, simple operation, broad substrate scope, and functional group tolerance, this reaction represents a valuable method in organic synthesis.
- Yang, Yu-Ming,Yan, Wei,Hu, Han-Wei,Luo, Yimin,Tang, Zhen-Yu,Luo, Zhuangzhu
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p. 12344 - 12353
(2021/09/02)
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- Promoting charge separation in donor-acceptor conjugated microporous polymers: Via cyanation for the photocatalytic reductive dehalogenation of chlorides
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Conjugated microporous polymers (CMPs) have emerged as promising heterogeneous photocatalysts for organic transformations owing to their structural designability and functional versatility. However, limited by the insufficient separation of the photo-generated excitons, their photocatalytic efficiency falls far short of expectations. Herein, we demonstrate a cyanation strategy to promote charge carrier separation in CMPs by selectively incorporating carbazole and cyano groups as electron-donating and electron-withdrawing units, respectively. The resulting CMPs feature π-extended donor (D)-acceptor (A) conjugation structures endowing them with distinct semiconducting properties, in which the efficient charge separation and transfer and wide visible-light absorption are facilitated. Compared to the cyano-free counterpart, the cyano-functionalized CMPs showed superior photocatalytic efficiency as exemplified by photocatalytic reductive dehalogenation of chlorides. More prominently, full recyclability of the designed CMPs as well as catalytic activity for at least ten runs without the loss of catalytic performance in photocatalytic reductive dehalogenation of chlorides demonstrated their robustness and sustainability. This journal is
- Deng, Jiyong,Fang, Zhengjun,Lan, Donghui,Liao, Yunfeng,Liu, Qingquan,Zhang, Weijie,Zhou, Xiang
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p. 7151 - 7159
(2021/11/17)
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- Acceptorless and Base-Free Dehydrogenation of Alcohols Mediated by a Dipyridylamine-Iridium(III) Catalyst
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Several dipyridylamine-IrIII and dipyridylamine-RuII complexes have been evaluated in the acceptorless dehydrogenation of alcohols in the absence of base additives. Iridium catalysts were found superior to ruthenium complexes, and the nature of the bridging nitrogen in dipyridylamine ligands was also evidenced as a key parameter. Catalytic reactions were conducted in toluene, but more sustainable solvents such as anisole and p-cymene were found suitable for this transformation.
- Bruneau, Christian,Fischmeister, Cédric,Guo, Liwei,Jayaprakash, Harikrishnan,Wang, Shengdong
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- Photochemical oxidation of benzylic primary and secondary alcohols utilizing air as the oxidant
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A mild and green photochemical protocol for the oxidation of alcohols to aldehydes and ketones was developed. Utilizing thioxanthenone as the photocatalyst, molecular oxygen from air as the oxidant and cheap household lamps or sunlight as the light source, a variety of primary and secondary alcohols were converted into the corresponding aldehydes or ketones in low to excellent yields. The reaction mechanism was extensively studied.
- Nikitas, Nikolaos F.,Tzaras, Dimitrios Ioannis,Triandafillidi, Ierasia,Kokotos, Christoforos G.
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supporting information
p. 471 - 477
(2020/02/13)
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- Amine-functionalized metal-organic framework-based Pd nanoparticles: Highly efficient multifunctional catalysts for base-free aerobic oxidation of different alcohols
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A palladium (Pd) nanoparticle containing a metal organic framework (MOF) is described as a highly efficient multifunctional catalyst for the aerobic oxidation of different aliphatic, aromatic and heteroaromatic alcohols in toluene. The catalytic efficienc
- Taher, Abu,Susan, Md. Abu Bin Hasan,Begum, Noorjahan,Lee, Ik-Mo
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p. 19113 - 19121
(2020/11/23)
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