- CuII-salan compounds: Synthesis, characterization and evaluation of their potential as oxidation catalysts
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We report the synthesis and characterization of several salan-type Cu II complexes. Suitable crystals suitable for X-ray diffraction were obtained for several of the CuII complexes, including a half-salen compound, revealing square-planar coordination environments common to d9 species. The CuII-salan complexes are tested as catalysts in sulfoxidation, alkene oxidation, and oxidative naphthol coupling. At room temperature the compounds exhibit low to moderate catalytic activity in sulfoxidations and alkene oxidations, but no activity in oxidative naphthol coupling. The saturated coordination environments around the Cu centers probably are the main reason for the lower catalytic activities compared to the Ti- and V-salan analogs. Spectroscopic and mass spectrometry studies revealed that the CuII-salan complexes decompose, in the presence of H2O2, significantly faster at 40 °C than at room temperature. The catalytic activity observed is probably due to the CuII-salan degradation products, observed in the mass spectrometry studies, and not to the original CuII-salan precursors.
- Ad?o, Pedro,Barroso, Sónia,Avecilla, Fernando,Oliveira, M. Concei??o,Pessoa, Jo?o Costa
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- Syntheses of U3O8 nanoparticles form four different uranyl complexes: Their catalytic performance for various alcohol oxidations
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Two dinuclear complexes namely [(UO2)2(L1)2(DMSO)2] (1) and [(UO2)2(L2)2(DMSO)2] (2) of two Schiff base ligands 2-[(2-hydroxy-3-methoxy-benzylidene)-amino]-2-hydroxymethyl propane-1,3-diol (HL1) and 2-[(3,5-dichloro-2-hydroxy-benzylidene)-amino]-2-hydroxymethyl-propane-1,3-diol (HL2) obtained by condensation of the aldehydes 2-hydroxy-3-methoxy-benzaldehyde and 3, 5-dichloro salicylaldehyde with tris(hydroxymethyl)aminomethane ammine, have been synthesized. On the other hand, when the two aldehydes were treated with uranyl nitrate two mononuclear complexes, [(UO2)(L3)2(DMSO)2] (3) and [(UO2)(L4)2(DMSO)2] (4), are obtained. The complexes are then heated at 800?°C in open atmosphere to obtain the U3O8 nanomaterials as the final product. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed to characterize the so obtained the U3O8 nanoparticles. Studies shows the synthesized U3O8 nanoparticles obtained from different complexes were different as far as morphology and size are concerned. All four different U3O8 nanoparticles explored as oxidising catalyst to oxidize alcohols where morphology of the nanoparticles controls the catalytic efficiency.
- Majumder, Ishani,Chatterjee, Sourav,Fischer, Roland C.,Neogi, Swarup Kumar,Mautner, Franz A.,Chattopadhyay, Tanmay
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- One-pot synthesis of silica gel confined functional ionic liquids: Effective catalysts for deoximation under mild conditions
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Several acid-functional ionic liquids were physically confined into the silica gel through a sol-gel process and used as effective catalysts for deoximation reactions, which proceeded under ambient temperatures without addition of any co-catalysts or oxidizing and reducing agents.
- Li, Dongmei,Shi, Feng,Guo, Shu,Deng, Youquan
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- Synthesis and biological activity of hydroxylated analogs of RCAI-80
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RCAI-80 is one of the ester analogs of KRN7000 (α-galactosylceramide) . This compound released mainly T helper 2 (Th2) cytokines, such as IL-4 rather than T helper 1 (Th1) cytokines, such as IFNγ from the invariant natural killer T (iNKT) cells. In addition, it has been known that some of the hydroxylated derivatives of KRN7000 make the cytokine secretion bias to Th2 by decreasing the IFNγ production to almost zero. This time, the three compounds having these two characteristic properties, namely an ester group and also some extra hydroxy groups existing on the ester side chain and/or on the 2-acyloxy-3,4-dihydroxyoctadecyl main chain of RCAI-80, were synthesized to examine the biological activities. As a result, it was found that these compounds made the cytokine secretion skew to Th2. Therefore, their effectiveness for experimental autoimmune encephalomyelitis (EAE) was examined. It was recognized that one of them showed moderate suppression of EAE symptom.
- Shiozaki, Masao,Tashiro, Takuya,Koshino, Hiroyuki,Shigeura, Tomokuni,Watarai, Hiroshi,Taniguchi, Masaru,Mori, Kenji
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- Nanostructured rutile TiO2 for selective photocatalytic oxidation of aromatic alcohols to aldehydes in water
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Selective photocatalytic oxidation of aromatic alcohols to aldehydes was performed in water in the presence of TiO2 rutile photocatalysts that exhibited a low degree of crystallinity. The nanostructured rutile samples, prepared ex TiCl4 at very low temperature, ensured a selectivity toward the aldehyde 3 to 4-fold higher than the commercial rutile tested (Sigma-Aldrich). Copyright
- Yurdakal, Sedat,Palmisano, Giovanni,Loddo, Vittorio,Augugliaro, Vincenzo,Palmisano, Leonardo
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- Synthesis, characterization and catalytic activity of new Cr(III) complex in oxidation of primary alcohols to aldehydes
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New mononuclear complex of chromium(III), [Cr(bp)(N3)(CH 3OH)]·2CH3OH has been synthesized where H 2bp is N,N-bis(2-hydroxy-3,5-di-tert-butylbenzyl)-N',N'- dimethylethylene-1,2-diamine. The complex was character
- Noshiranzadeh, Nader,Bikas, Rahman,?lepokura, Katarzyna,Mayeli, Mina,Lis, Tadeusz
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- Gold nanoparticle-modified TiO2/SBA-15 nanocomposites as active plasmonic photocatalysts for the selective oxidation of aromatic alcohols
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The catalytic performance of noble-metal on mesoporous silica hosts has been widely investigated because the effects of surface plasmon resonance can open new avenues for the improvement of catalytic performance under light irradiation. In this study, a s
- Chen, Yu,Li, Weizun,Wang, Jingyu,Yang, Qian,Hou, Qidong,Ju, Meiting
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- A ceric ammonium nitrate based oxidative cleavage pathway for the asymmetric aldol adducts of oxadiazinones derived from (1R,2S)-N-p-methoxybenzylnorephedrine
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An N4-p-methoxybenzyloxadiazinone has been prepared from (1R,2S)-norephedrine through a process of reductive amination, N-nitrosation, reduction, and cyclization. The oxadiazinone was acylated and employed in the asymmetric aldol addition reaction with aromatic and aliphatic aldehydes to yield aldol adducts in isolated yields ranging from 54% to 90%. Selected aldol adducts were treated with ceric ammonium nitrate in aqueous acetonitrile to afford the desired β-hydroxycarboxylic acids through a tandem process of oxidative cleavage of the N4-p-methoxybenzyl group and acidic hydrolysis of the N3-acyl side chain. The β-hydroxycarboxylic acids were recovered in high diastereomeric purity as determined by 500 MHz 1H NMR spectroscopy and the absolute configuration was confirmed by polarimetry. The chiral auxiliary unit, the 3,4,5,6-tetrahydro-2H-1,3,4-oxadiazin-2-one (oxadiazinone), was converted into its corresponding 3,6-dihydro-2H-1,3,4-oxadiazin-2-one (oxadiazinone) through an oxidative pathway promoted by the ceric ammonium nitrate.
- Leise, Austin R.,Comas, Nicole,Harrison, Doug,Patel, Dipak,Whitemiller, Eileen G.,Wilson, Jennifer,Timms, Jacob,Golightly, Ian,Hamaker, Christopher G.,Hitchcock, Shawn R.
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- Lewis acid-catalyzed reactions of ethyl diazoacetate with aldehydes. Synthesis of α-formyl esters by a sequence of aldol reaction and 1,2- nucleophilic rearrangement
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Ethyl diazoacetate reacts with a variety of aldehydes in the presence of a Lewis acid catalyst to give either β-keto esters or α-formyl esters, the types of products mainly depending upon the nature of Lewis acid catalysts employed. Reactions catalyzed by Lewis acids such as SnCl2 and SnCl4 provide β-keto esters via nucleophilic 1,2-hydride migration, while those catalyzed by trimethylsilyl triflate give α-formyl esters via migration of the substituent of the aldehyde. Reaction mechanisms are discussed.
- Kanemasa, Shuji,Kanai, Toshio,Araki, Takahiro,Wada, Eiji
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- New oligostilbenes having a benzofuran from Vitis vinifera 'Kyohou'
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Three new oligostilbenes having a benzofuran moiety, viniferifuran, (+)- vitisifuran A and (-)-vitisifuran B, were isolated from Vitis vinifera 'Kyohou'. The structures of these oligostilbenes including the absolute configuration were elucidated by spectroscopic and chemical methods. Furthermore, these were chemically transformed from (+)-ε-viniferin, (+)- vitisin A and (-)-vitisin B, respectively, whose absolute configurations are known.
- Ito, Junko,Takaya, Yoshiaki,Oshima, Yoshiteru,Niwa, Masatake
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- 9,10-Dicyanoanthracene-sensitized Photo-oxygenation of trans-1,2-Di(carbazol-9-yl)cyclobutane via Electron-transfer
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9,10-Dicyanoanthracene-sensitized photo-oxygenation of trans-1,2-di(carbazol-9-yl)cyclobutane in acetonitrile efficiently affords 3,6-di(carbazol-9-yl)-1,2-dioxan.
- Mizuno, Kazuhiko,Murakami, Kazuhiro,Kamiyama, Nobuhiro,Otsuji, Yoshio
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- Facile one-pot synthesis of anisaldehyde
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At room temperature, anisaldehyde (4-methoxybenzaldehyde) is synthesized based on the ozonolysis of anethole (1-methoxy-4-(1-propenyl)-benzene) in a novel and environmentally friendly system composed of water and ethyl acetate. In the presence of water, ozonolysis of anethole results in the direct formation of anisaldehyde, avoiding the isolation or decomposition of ozonide.
- Yu, Jing,Shen, Minmin,Deng, Lianli,Gan, Lu,Ha, Chengyong
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- A biomimetic approach to the synthesis of rocaglamide based on a photochemical [2 + 2] cycloaddition of a cinnamate unit to a flavone
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In attempting a biomimetic synthesis of rocaglamide, we have discovered the first examples of photochemically induced cycloaddition reactions involving a flavone system.
- Hailes,Raphael,Staunton
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- A DyP-type peroxidase of pleurotus sapidus with alkene cleaving activity
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Alkene cleavage is a possibility to generate aldehydes with olfactory properties for the fragrance and flavor industry. A dye-decolorizing peroxidase (DyP) of the basidiomycete Pleurotus sapidus (PsaPOX) cleaved the aryl alkene trans-anethole. The PsaPOX was semi-purified from the mycelium via FPLC, and the corresponding gene was identified. The amino acid sequence as well as the predicted tertiary structure showed typical characteristics of DyPs as well as a non-canonical Mn2+-oxidation site on its surface. The gene was expressed in Komagataella pfaffii GS115 yielding activities up to 142 U/L using 2,20-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) as substrate. PsaPOX exhibited optima at pH 3.5 and 40 ?C and showed highest peroxidase activity in the presence of 100 μM H2O2 and 25 mM Mn2+. PsaPOX lacked the typical activity of DyPs towards anthraquinone dyes, but oxidized Mn2+ to Mn3+. In addition, bleaching of β-carotene and annatto was observed. Biotransformation experiments verified the alkene cleavage activity towards the aryl alkenes (E)-methyl isoeugenol, α-methylstyrene, and trans-anethole, which was increased almost twofold in the presence of Mn2+. The resultant aldehydes are olfactants used in the fragrance and flavor industry. PsaPOX is the first described DyP with alkene cleavage activity towards aryl alkenes and showed potential as biocatalyst for flavor production.
- Berger, Ralf G.,Ersoy, Franziska,Krahe, Nina-Katharina
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- Alkene cleavage by white-rot Trametes hirsuta: Inducing enzyme activity by a fungicide
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Alkene cleavage is a widely employed oxidation reaction in organic chemistry. An enzyme preparation of the wood degrading fungus Trametes hirsuta is known to cleave the CC double bond adjacent to an aromatic ring to give the corresponding carbonyl compound at the expense of molecular oxygen as the sole oxidant. Lab-grown fungus cultures displayed varied activity and lost their alkene cleavage activity over generations of growth. t-Anethole, which is the best accepted substrate by the enzyme, is described as a major component of essential oils produced by certain plants with powerful fungicidal property. We could now show that the alkene cleaving activity was improved by the addition of the fungicide t-anethole during culture growth which represented to be an efficient method to produce cells possessing a consistent level of high alkene cleavage activity.
- Rajagopalan, Aashrita,Seisser, Birgit,Mutti, Francesco G.,Schober, Markus,Kroutil, Wolfgang
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- Aminolysis of 6-[1-(2,6-difluorophenyl)cyclopropyl]-5-methyl-2-(nitroamino)pyrimidin-4(3H)-one
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The aminolysis of 6-[1-(2,6-difluorophenyl)cyclopropyl]-5-methyl-2-(nitroamino)pyrimidin-4(3H)-one with various amines in butan-1-ol and under solvent-free conditions is successful when the amino group in the reagent is sterically unshielded and the reaction medium is characterized by a high dielectric permittivity. Reactions of the title compound with sterically shielded amines are accompanied by alcoholysis where the amine acts as a base catalyst.
- Novakov,Brunilina,Vernigora,Kirillov,Mkrtchyan,Navrotskii,Sheikin,Yablokov,Ruchko,Kachala
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- Rate and equilibrium constants for hydrolysis and isomerization of (E)- and (Z)-p-methoxybenzaldehyde oximes
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The interconversion and hydrolysis of (E)- and (Z)-oximes of p-methoxybenzaldehyde in aqueous solutions of perchloric acid have been studied in the acid concentration range from pH 3 to UM. Kinetic measurements confirm that isomerization and hydrolysis proceed through a common tetrahedral intermediate TQ. At low acid concentrations, attack of water on the protonated oxime is rate-determining in the hydrolysis reaction and no separate isomerization is observable. However, as the acid concentration increases the attack of water becomes faster than loss hydroxylamine from T0 and E to Z isomerization is observable as a faster reaction in competition with hydrolysis. From kinetic and equilibrium measurements a comprehensive set of rate and equilibrium constants for protonation, hydrolysis and hydration of (E)- and (Z)-oximes is derived. For the neutral oximes KT = [E]/[Z] = 8 and for the protonated oximes pKa = -0.55 and 0.80 for the E and Z isomers, respectively. By combining these values with measurements of oxime formation from p-methoxybenzaldehyde and hydroxylamine, including Kadd = [T0]/ [aldehyde][NH2OH] = [T2]/[oxime] = 1.8, values of pKR = -3.65 and -5.90 and KH2O = 6.3 × 10-5 and 7.9 × 10-6 for (Z)- and (Z)-oximes may also be derived. The values of pKa, pKR and KH2O for the oximes are compared with corresponding values for p-methoxybenzaldehyde and its hydrate (≡T0). Copyright 2004 John Wiley & Sons, Ltd. Additional material for this paper is available in Wiley Interscience.
- O'Ferrall, Rory A. More,O'Brien, Deirdre
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- Hydrogen evolution using the visible-light-induced metal-to-polyoxometalate multiple electron transfer
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A tetranuclear cerium-containing polyoxometalate, TBA6-[{Ce(H2O)}2{Ce(CH3CN)}2(μ4-O)(γ-SiW10O36)2] (I, TBA: tetra-n-butylammonium), showed a unique intramolecular multiple electron transfer (Ce3+-to-POM(W6+)) on irradiation of visible light (λ > 400 nm). This could induce hydrogen (H2) evolution using alcohols as the electron donors, and a high turnover number (TON) of 1960 was achieved. Moreover, I could be reused without an appreciable loss in its catalytic performance.
- Suzuki, Kosuke,Tang, Fei,Kikukawa, Yuji,Yamaguchi, Kazuya,Mizuno, Noritaka
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- Copper-Catalyzed Cleavage of Unstrained C-C Bonds for the Synthesis of 1-Acyloxy-2,2,6,6-tetramethylpiperidines from Cyclic or Acyclic Ketones
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A copper-catalyzed approach for the synthesis of 1-acyloxy-2,2,6,6-tetramethylpiperidines through the C-C bond cleavage of cyclic or acyclic ketones was developed. In this chemistry, a combination of CuCl 2 ·2H 2 O, 1,10-phenanthroline monohydrate, and aniline was crucial for the formation of the desired products by the reaction of ketones with TEMPO. This research provides a new strategy for the further transformation of α-aryl cyclic or acyclic ketones.
- Jiang, Qijian,Yang, Luo,Zhou, Wang
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- Nitrogen dioxide-catalyzed aerobic oxidation of benzyl alcohols under cocatalyst and acid-free conditions
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Nitrogen dioxide is usually considered as a mediator between dioxygen and the catalysts for the aerobic oxidation of alcohols. Here, we report that nitrogen dioxide has an ability to catalyze this reaction, which not only avoids the use of the cocatalysts or the acids in traditional approaches, but also reveals a method for the present transformation with a single component catalyst. A series of primary and secondary benzyl alcohols underwent this transformation to give the targeted products in low to high yields.
- Ren, Fangping,Tian, Xinzhe,Ren, Yun-Lai,Zhao, Shuang,Wang, Jianji,Zhao, Bo
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- Zeolite-supported chromium(VI) oxide: A mild, efficient, and inexpensive reagent for oxidative deprotection of trimethylsilyl ethers under microwave irradiation
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Primary and secondary trimethylsilyl ethers are efficiently converted, to the corresponding carbonyl compounds using HZSM-5 zeolite-supported CrO 3 under microwave irradiation in solventless system.
- Heravi, Majid M.,Hydarzadeh, Fereshteh,Farhangi, Yahya,Ghassemzadeh, Mitra
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- Synthesis of a stereoisomer of wortmannilactone C - failure and success
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Abstract A diastereomer of wortmannilactone C was synthesized according to a versatile strategy from tert-butyl 3-hydroxypropanoate and ethyl (R)-3-hydroxybutanoate, by using versatile organometallic reagents to control four stereogenic centers out of five. The successful strategy consists of the construction of the C13-C17 triene by using a Liebeskind coupling and the construction of the C2-C7 triene by utilizing a Horner-Wadsworth-Emmons reaction to form the macrocycle.
- Dittoo, Aurélia,Brandt, Damien,Bellosta, Véronique,Cossy, Janine
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- Synthesis of α-CF3 ketones from alkenes and electrophilic trifluoromethylating reagents by visible-light driven photoredox catalysis
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α-Trifluoromethyl ketones are important fluorinated intermediates and products in chemical synthesis and medicinal development. Herein, visible light-catalyzed photoredox trifluoromethylation of 1-aryl-2-alkyl substituted alkenes using an electrophilic tr
- Li, Lun,Chen, Qing-Yun,Guo, Yong
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- Copper(II) catalyzed selective oxidation of primary alcohols to aldehydes with atmospheric oxygen
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Copper(II) complex 1 selectively catalyzes the oxidation of primary alcohols to aldehydes in high yields by atmospheric oxygen in the presence of TEMPO. This procedure does not require an additive and the catalyst 1 is recyclable without loss of activity.
- Velusamy, Subbarayan,Srinivasan, Arumugam,Punniyamurthy
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- The oxidation of sulfides by chromium(V)
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The mechanism for the oxidation of sulfides by [(me4-salen)CrV(O)(pyO)]CF3SO3, where me4-salen is 8,8,8',8'-tetramethylsalen and pyO is pyridine N-oxide, has been investigated. Results from Hammett correlations on the rates of oxidation of substituted thioanisoles, frontier molecular orbital calculations, and product studies are consistent with a mechanism that is initiated by a single electron transfer to give a radical cation intermediate.
- Lepage, Carmela R. Jackson,Mihichuk, Lynn,Lee, Donald G.
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- The activation of C-H bonds using an EmimAc/MWCNTs composite: A comparison of the composite used as electrolyte and electrode in aqueous media
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An EmimAc/MWCNTs composite was prepared and characterized through SEM and TEM. The MWCNTs were well dispersed after combining with alkaline EmimAc. The activity of the composite was demonstrated by CV and controlled potential electrolysis. The composite could be used independently as electrolyte or electrode and showed excellent activity toward the electro-oxidation of the C-H bond of benzylic systems, and did so at a lower oxidation potential than when using EmimAc or MWCNTs. After modification, the pH value of the composite was adjusted to the acid range, and the yield of aldehyde adducts obtained through electro-oxidation improved.
- Zhu, Yinghong,Chen, Ziying,Zhang, Jianqing,Wu, Qianqian,Ma, Chun'An,Little, R. Daniel
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- Detailed Mechanistic Study of the Non-enzymatic Formation of the Discoipyrrole Family of Natural Products
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Discoipyrroles A-D (DPA-DPD) are recently discovered natural products produced by the marine bacterium Bacillus hunanensis that exhibit anticancer properties in vitro. Initial biosynthetic studies demonstrated that DPA is formed in the liquid fermentation medium of B. hunanensis from three secreted metabolites through an unknown but protein-independent mechanism. The increased identification of natural products that depend on non-enzymatic steps creates a significant need to understand how these different reactions can occur. In this work, we utilized 15N-labeled starting materials and continuous high-sensitivity 1H-15N HMBC NMR spectroscopy to resolve scarce reaction intermediates of the non-enzymatic discoipyrrole reaction as they formed in real time. This information guided supplemental experiments using 13C- and 18O-labeled materials to elucidate the details of DPA's non-enzymatic biosynthesis, which features a highly concerted pyrrole formation and necessary O2-mediated oxidation. We have illustrated a novel way of using isotopically enhanced two-dimensional NMR spectroscopy to interrogate reaction mechanisms as they occur. In addition, these findings add to our growing knowledge of how multicomponent non-enzymatic reactions can occur through inherently reactive bacterial metabolites.
- Colosimo, Dominic A.,Macmillan, John B.
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- Chemoselective Henry Condensations Catalyzed by Artificial Carboligases
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The promiscuity of de novo designed enzymes provides a privileged platform for diverse abiological reactions. In this work, we report the first example of a nitroolefin synthase that catalyzes the Henry condensation between aromatic aldehydes and nitromethane. Significant catalytic activity was discovered in the computationally designed and evolved carboligase RA95.5-8, and mutations around the active site were shown to improve the reaction rate, demonstrating the potential to optimize the enzyme by directed evolution. This novel nitroolefin synthase could participate in complex biological cascades, whereby the highly tunable chemoselectivity could afford useful synthetic building blocks.
- Garrabou, Xavier,Macdonald, Duncan Stuart,Hilvert, Donald
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- Highly selective electrocatalytic dehydrogenation at low applied potential catalyzed by an Ir organometallic complex
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A homogeneous organometallic Ir complex was shown to catalyze the electro-oxidation of 4-methoxybenzyl alcohol to p-anisaldehyde at a very low applied potential with remarkably high selectivity and Faradaic efficiency. In the chemical catalysis, when stoi
- Bonitatibus, Peter J.,Rainka, Matthew P.,Peters, Andrea J.,Simone, Davide L.,Doherty, Mark D.
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- Ostensible enzyme promiscuity: Alkene cleavage by peroxidases
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Enzyme promiscuity is generally accepted as the ability of an enzyme to catalyse alternate chemical reactions besides the 'natural' one. In this paper peroxidases were shown to catalyse the cleavage of a C=C double bond adjacent to an aromatic moiety for selected substrates at the expense of molecular oxygen at an acidic pH. It was clearly shown that the reaction occurs due to the presence of the enzyme; furthermore, the reactivity was clearly linked to the hemin moiety of the peroxidase. Comparison of the transformations catalysed by peroxidase and by hemin chloride revealed that these two reactions proceed equally fast; additional experiments confirmed that the peptide backbone was not obligatory for the reaction and only a single functional group of the enzyme was required, namely in this case the prosthetic group (hemin). Consequently, we propose to define such a promiscuous activity as 'ostensible enzyme promiscuity'. Thus, we call an activity that is catalysed by an enzyme 'ostensible enzyme promiscuity' if the reactivity can be tracked back to a single catalytic site, which on its own can already perform the reaction equally well in the absence of the peptide backbone.
- Mutti, Francesco G.,Lara, Miguel,Kroutil, Markus,Kroutil, Wolfgang
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- A hydrophilic covalent organic framework for photocatalytic oxidation of benzylamine in water
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The highly hydrophilic COF material (TFPT-BMTH) was constructed by pore surface functionalizing strategy, and exhibited excellent porosity, high crystallinity, and good thermal and chemical stability. The resulting COF exhibits significant catalytic activity and recyclability together with environmental benignity in photocatalytic oxidation of benzylamine in water under ambient conditions.
- Liu, Ziqian,Su, Qing,Ju, Pengyao,Li, Xiaodong,Li, Guanghua,Wu, Qiaolin,Yang, Bing
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- Tetra-porphyrin molecular tweezers: Two binding sites linked: Via a polycyclic scaffold and rotating phenyl diimide core
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The synthesis of a tetra-porphyrin molecular tweezer with two binding sites is described. The bis-porphyrin binding sites are aligned by a polycyclic scaffold and linked via a freely rotating phenyl diimide core. Synthesis was achieved using a divergent approach employing a novel coupling method for linking two polycyclic units to construct the core, with a copper(ii)-mediated phenyl boronic acid coupling found to extend to our polycyclic imide derivative. We expect this chemistry to be a powerful tool in accessing functional polycyclic supramolecular architectures in applications where north/south reactivity and/or directional interactions between modules are important. Porphyrin receptor functionalisation was undertaken last, by a four-fold ACE coupling reaction on the tetra-epoxide derivative of the core.
- Murphy,Norman,White,Perkins,Johnston
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- A convenient deprotection of 1,3-dithiane derivatives with ferric nitrate under heterogeneous conditions
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1,3-Dithianes derived from aromatic, aliphatic, and alicyclic ketones or aldehydes can be conveniently converted to the parent carbonyl compounds with a combination of ferric nitrate and silica gel in hexane in excellent to quantitative yields.
- Hirano, Masao,Ukawa, Ken,Yakabe, Shigetaka,Morimoto, Takashi
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- Manganese(III) corrole catalyzed selective oxidation of alcohols to carbonyl compounds by tert-butyl hydroperoxide under mild condition
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Mild oxidation of alcohols has been achieved with tert-butylhydroperoxide catalyzed by electron deficient manganese(III) corroles at room temperature. The catalysts used in this study showed high activity in the oxidation of benzylic alcohols to the corre
- Bose, Suranjana,Pariyar, Anand,Biswas, Achintesh Narayan,Das, Purak,Bandyopadhyay, Pinaki
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- Nascent-HBr-Catalyzed Removal of Orthogonal Protecting Groups in Aqueous Surfactants
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Organic reactions in the aqueous environment have recently emerged as a promising research area. The generation of nascent-HBr from the slow hydrolysis of the dispersed catalyst, benzyl bromide, with the interior water present in the hydrophobic core of the confined micellar medium in aqueous surfactant is described for the first time. The sustained-release nascent-HBr enabled the chemoselective cleavages of acid-sensitive orthogonal functionalities present in carbohydrates, amino alcohols, and hydroxylated acyclic compounds in good to excellent yields.
- Bera, Smritilekha,Gupta, Shilpi,Mondal, Dhananjoy
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- An Electrochemical Evidence for the Participation of Iron(IV) Porphyrin Species in the C-C Bond Cleavage of 1,2-Diaryl-1,2-ethanediol
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Cyclic voltammogram of as mixture of tetraphenylporphrinatoiron(III) and 1,2-bis(4-methoxyphenyl)ethane-1,2-diol in dichloromethane showed a catalytic wave at the potential corresponding to the oxidation of Fe(III) to Fe(IV).The rate of reaction of Fe(IV) with the diol following the electrochemical process was determined.
- Okamoto, Tadashi,Sasaki, Ken,Takano, Mikio,Oka, Shinzaburo
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- Outstanding response of carbon nitride photocatalysts for selective synthesis of aldehydes under UV-LED irradiation
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The photocatalytic conversion of alcohols into the corresponding aldehydes constitutes an important reaction in organic synthesis. Optical semiconductors based on carbon nitride were prepared by thermal condensation of dicyandiamide followed by a thermal
- Lopes, Joana C.,Sampaio, Maria J.,Fernandes, Raquel A.,Lima, Maria J.,Faria, Joaquim L.,Silva, Cláudia G.
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- The Oxidation of Akoxytributylstannanes with Copper(II) Bromide
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The oxidation of alkoxytributylstannanes with copper(II) bromide in the presence of lithium bromide and t-butoxytributylstannane gave the corresponding carbonyl compounds in good yields under mild reaction conditions.
- Yamaguchi, Jun-ichi,Takeda, Takeshi
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- Transition metal-free and substrate-selective oxidation of alcohols using water as an only solvent in the presence of β-cyclodextrin
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A facile, substrate-selective and transition metal-free oxidation of benzylic and allylic alcohols catalyzed by β-cyclodextrin with NaOCl oxidant using water as an only solvent was developed.
- Ji, Hong-Bing,Shi, Dong-Po,Shao, Ming,Li, Zhong,Wang, Le-Fu
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- Aerobic dehydrogenative imination in complete aqueous media catalyzed by poly(aniline sulfonic acid)/gold nanoparticles
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Dehydrogenative imination in aqueous media was achieved using poly(2-methoxyaniline-5-sulfonic acid) (PMAS)/gold nanoparticles, where PMAS worked as a redox mediator.
- Amaya, Toru,Ito, Tsubasa,Hirao, Toshikazu
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- Chemoselective aerobic oxidation of primary alcohols catalyzed by a ruthenium complex
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In the presence of secondary alcohols, primary alcohols are selectively oxidized to aldehydes under aerobic conditions by using a (nitrosyl)Ru(salen) complex as catalyst.
- Miyata, Atsushi,Murakami, Masakazu,Irie, Ryo,Katsuki, Tsutomu
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- One-pot conversion of activated alcohols into 1,1-dibromoalkenes and terminal alkynes using tandem oxidation processes with manganese dioxide
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Approaches to the preparation of C1-homologated dibromoalkenes and terminal alkynes from activated alcohols using one-pot tandem oxidation processes (TOPs) with manganese dioxide are outlined. The conversion of alcohols into dibromoalkenes is described using dibromomethyltriphenylphosphonium bromide and the formation of terminal alkynes was achieved via a sequential one-pot, two-step process utilising the Bestmann-Ohira reagent.
- Quesada, Ernesto,Raw, Steven A.,Reid, Mark,Roman, Estelle,Taylor, Richard J.K.
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- Thermotropic phase transitions in 5,15-bis(4-alkoxyphenyl)octaalkylporphyrins
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Nineteen novel alkyl substituted porphyrins have been synthesized and their thermal phase behaviour has been investigated in detail. Twelve compounds showed a reversible phase transition below the isotropization temperature. From time resolved microwave conductivity (TRMC) measurements and powder X-ray diffractometry it was concluded that the molecular packing does not change significantly at the lower phase transition temperature and that the porphyrin cores occupy isolated positions. Single X-ray diffraction measurements showed that the porphyrins are arranged in a layered structure and that the space between the layers is occupied by the alkyl substituents of the pyrrole units. The phase transitions at the lower temperature were therefore identified as changes in the crystal ordering of the porphyrins.
- Sudhoelter, Ernst J. R.,Van Dijk, Marinus,Teunis, Cees J.,Sanders, Georgine M.,Harkema, Sybolt,Van De Velde, Gerrit M. H.,Schouten, Pieter G.,Warman, John M.
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- Total Synthesis of Biselyngbyaside
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The first total synthesis of biselyngbyaside, an 18-membered macrolide glycoside, was achieved. The glycoside bond was introduced using the Schmidt method before construction of the 18-membered ring due to the instability of the conjugated diene and the β
- Sato, Eisuke,Sato, Miho,Tanabe, Yurika,Nakajima, Naoya,Ohkubo, Akifumi,Suenaga, Kiyotake
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- Optimization of a biocatalytic single-step alkene cleavage of aryl alkenes
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The oxidative cleavage of a C{double bond, long}C double bond adjacent to an aryl moiety was achieved in the presence of a protein preparation of Trametes hirsuta G FCC 047 to yield the corresponding aldehydes. Molecular oxygen was the only oxidant required. All positive substrates had a C{double bond, long}C bond conjugated to an aromatic system, all other compounds tested not fulfilling this requirement were non-substrates. The optimum reaction conditions are 20 °C, pH 6-6.5, 15% v/v ethanol as co-solvent at an apparent oxygen pressure of 2 bar.
- Mang, Harald,Gross, Johannes,Lara, Miguel,Goessler, Christian,Schoemaker, Hans E.,Guebitz, Georg M.,Kroutil, Wolfgang
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- Metal Ion-Driven Constitutional Adaptation in Dynamic Covalent C=C/C=N Organo-Metathesis
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Knoevenagel barbiturate derivatives and imines are able to undergo efficient component recombination through dynamic covalent C=C/C=N organo-metathesis in absence of a catalyst. A [2×2] dynamic covalent library (DCL) containing two Knoevenagel derivatives Kn1 and Kn2 and two imines A1 and A2 has been established and its adaptive features in response to the addition of metal cations have been investigated. Addition of Cu(I) triflate as an effector, induces fast and remarkable constitutional selection of the DCL towards amplification of the Cu(I)-A2 complex and its agonist Kn1. This adaptation process could be reversed by addition of neocuproine as a competitive Cu(I) ligand. Furthermore, separate addition of five other metal cations as input agents, i. e. Ag(I), Fe(II), Zn(II), Cu(II) and Li(I), led to the generation of cation-specific distribution patterns as outputs, showing the ability of the present DCL to recognize different effectors.
- Gu, Ruirui,Lehn, Jean-Marie
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- Functionalized-1,3,4-oxadiazole ligands for the ruthenium-catalyzed Lemieux-Johnson type oxidation of olefins and alkynes in water
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Three arene-ruthenium(II) complexes bearing alkyloxy(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethylphenyl)methyl ligands were quantitatively obtained through the reaction of (E)-1-(4-trifluoromethylphenyl)-N-(5-phenyl-1,3,4-oxadiazol-2-yl)-methanimine with the ruthenium precursor [RuCl2(η6-p-cymene)]2 in a mixture of the corresponding alcohol and CH2Cl2 at 50 °C. The obtained complexes were fully characterized by elemental analysis, infrared, NMR and mass spectrometry. Solid-state structures confirmed the coordination of the 1,3,4-oxadiazole moiety to the ruthenium center via their electronically enriched nitrogen atom at position 3 in the aromatic ring. These complexes were evaluated as precatalysts in the Lemieux-Johnson type oxidative cleavage of olefins and alkynes in water at room temperature with NaIO4 as oxidizing agent. Good to full conversions of olefins into the corresponding aldehydes were measured, but low catalytic activity was observed in the case of alkynes. In order to get more insight into the mechanism, three analogue arene-ruthenium complexes were synthesized and tested in the oxidative cleavage of styrene. The latter tests clearly demonstrated the importance of the hemilabile alkyloxy groups, which may form more stable (N,O)-chelate intermediates and increase the efficiency of the cis-dioxo-ruthenium(VI) catalyst.
- Hkiri, Shaima,Touil, Soufiane,Samarat, Ali,Sémeril, David
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- A DFT and experimental study of the spectroscopic and hydrolytic degradation behaviour of some benzylideneanilines
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The spectroscopic and hydrolytic degradation behaviour of some N-benzylideneanilines are investigated experimentally and theoretically via high quality density function theoretical (DFT) modelling techniques. Their absorption and vibrational spectra, accurately predicted by DFT calculations, are highly dependent on the nature of the substituents on the aromatic rings, hence, though some of their spectroscopic features are similar, energetic differences exist due to differences in their electronic structures. Whereas the o-hydroxy aniline derived adducts undergo hydrolysis via two pathways, the most energetically economical of which is initiated by a fast enthalpy driven hydration, over a conservative free energy (ΔG?) barrier of 53 kJ mol?1, prior to the rate limiting entropy controlled lysis step which occurs via a conservative barrier of ca.132 kJ mol?1, all other compounds hydrolyse via a slower two-step pathway, limited by the hydration step. Barriers heights for both pathways are controlled primarily by the structure and hence, stability of the transition states, all of which are cyclic for both pathways.
- Nelson, Peter N.,Robertson, Tahjna I.
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- Lessons from an Array: Using an Electrode Surface to Control the Selectivity of a Solution-Phase Chemical Reaction
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Electrochemistry offers a variety of novel means by which selectivity can be introduced into synthetic organic transformations. In the work reported, it is shown how methods used to confine chemical reactions to specific sites on a microelectrode array can also be used to confine a preparative reaction to the surface of an electrode inserted into a bulk reaction solution. In so doing, the surface of a modified electrode can be used to introduce new selectivity into a preparative reaction that is not observed in the absence of either the modified electrode surface or the effort to confine the reaction to that surface. The observed selectivity can be optimized in the same way that confinement is optimized on an array and is dependent on the nature of the functionalized surface.
- Feng, Enqi,Jing, Qiwei,Moeller, Kevin D.
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supporting information
(2022/01/26)
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- Visible-Light-Induced Selective C-C Bond Cleavage Reactions of Dimeric β-O-4 and β-1 Lignin Model Substrates Utilizing Amine-Functionalized Fullerene
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Finding a selective and efficient fragmentation process under ambient conditions is pivotal for the generation of fuels and chemical feedstocks from lignoceullosic biomass. In the present study, visible-light and amine-functionalized fullerene-based photocatalyst-promoted photodegradation reactions of dimeric β-O-4 and β-1 lignin model compounds, containing varying numbers of methoxy substituents on the arene ring, were explored to find and develop mild, eco-friendly photochemical techniques for efficient delignification. The results showed that, in contrast to well-known organic photoredox catalysts, amine-functionalized fullerene photocatalyst promoted photochemical reactions of lignin model compounds could lead to more efficient lignin fragmentation reactions through a pathway involving a selective Cα-Cβ bond cleavage process, and in addition, Cα-hydroxyl moiety in lignin model compounds played a significant role in the success of the Cα-Cβ bond cleavage reaction of lignin model substrates.
- Cho, Dae Won,Jang, Hannara,Kim, Min-Ji,Kim, Young-Il,Lim, Dong Hyun,Lim, Suk Hyun,Wee, Kyung-Ryang
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p. 2289 - 2300
(2022/02/07)
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- Highly atom efficient synthesis of 2,2,4,5-tetrasubstituted 3(2H)-furanones having both hydroxyl and amino substituents
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We have developed a highly atom efficient synthesis of tetrasubstituted 3(2H)-furanones from easily accessible starting materials such as C,N-diarylaldonitrones and dibenzoylacetylene. Control experiments revealed that reaction of aldonitrones having electron-withdrawing groups on the C-aryl substituent in polar aprotic solvents exhibited high product selectivity while reaction temperature has only a negligible effect on product yield and selectivity.
- Antony, Jesna,Mathai, Sindhu,Natarajan, Rakesh,P. Musthafa, Sumi,Rappai, John P.,S. Devaky, Karakkattu
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supporting information
(2022/02/25)
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- One-Pot Biocatalytic In Vivo Methylation-Hydroamination of Bioderived Lignin Monomers to Generate a Key Precursor to L-DOPA
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Electron-rich phenolic substrates can be derived from the depolymerisation of lignin feedstocks. Direct biotransformations of the hydroxycinnamic acid monomers obtained can be exploited to produce high-value chemicals, such as α-amino acids, however the reaction is often hampered by the chemical autooxidation in alkaline or harsh reaction media. Regioselective O-methyltransferases (OMTs) are ubiquitous enzymes in natural secondary metabolic pathways utilising an expensive co-substrate S-adenosyl-l-methionine (SAM) as the methylating reagent altering the physicochemical properties of the hydroxycinnamic acids. In this study, we engineered an OMT to accept a variety of electron-rich phenolic substrates, modified a commercial E. coli strain BL21 (DE3) to regenerate SAM in vivo, and combined it with an engineered ammonia lyase to partake in a one-pot, two whole cell enzyme cascade to produce the l-DOPA precursor l-veratrylglycine from lignin-derived ferulic acid.
- Birmingham, William R.,Galman, James L.,Parmeggiani, Fabio,Seibt, Lisa,Turner, Nicholas J.
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- Controlled reduction of activated primary and secondary amides into aldehydes with diisobutylaluminum hydride
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A practical method is disclosed for the reduction of activated primary and secondary amides into aldehydes using diisobutylaluminum hydride (DIBAL-H) in toluene. A wide range of aryl and alkyl N-Boc, N,N-diBoc and N-tosyl amides were converted into the corresponding aldehydes in good to excellent yields. Reduction susceptible functional groups such as nitro, cyano, alkene and alkyne groups were found to be stable. Broad substrate scope, functional group compatibility and quick conversions are the salient features of this methodology.
- Azeez, Sadaf,Kandasamy, Jeyakumar,Sabiah, Shahulhameed,Sureshbabu, Popuri
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supporting information
p. 2048 - 2053
(2022/03/31)
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- Urchin-like Nb2O5 hollow microspheres enabling efficient and selective photocatalytic C–C bond cleavage in lignin models under ambient conditions
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Selective cleavage of robust C?C bonds to harvest value-added aromatic oxygenates is an intriguing but challenging task in lignin depolymerization. Photocatalysis is a promising technology with the advantages of mild reaction conditions and strong sustainability. Herein, we show a novel urchin-like Nb2O5 hollow microsphere (U-Nb2O5 HM), prepared by one-pot hydrothermal method, are highly active and selective for Cα?Cβ bond cleavage of lignin β-O-4 model compounds under mild conditions, achieving 94% substrate conversion and 96% C?C bond cleavage selectivity. Systematic experimental studies and density functional theory (DFT) calculations revealed that the superior performance of U-Nb2O5 HMs arises from more exposed active sites, more efficient free charge separation and the active (001) facet, which facilitates the activation of Cβ?H bond of lignin models and generate key Cβ radical intermediates by photogenerated holes, further inducing the Cα?Cβ bond cleavage to produce aromatic oxygenates. This work could provide some suggestions for the fabrication of hierarchical photocatalysts in the lignin depolymerization system.
- Chen, Huan,Hong, Donghui,Long, Donghui,Niu, Bo,Wan, Kun,Wang, Junjie,Zhang, Yayun
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- CuO-catalyzed conversion of arylacetic acids into aromatic nitriles with K4Fe(CN)6 as the nitrogen source
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Readily available CuO was demonstrated to be effective as the catalyst for the conversion of arylacetic acids to aromatic nitriles with non-toxic and inexpensive K4Fe(CN)6 as the nitrogen source via the complete cleavage of the C[tbnd]N triple bond. The present method allowed a series of arylacetic acids including phenylacetic acids, naphthaleneacetic acids, 2-thiopheneacetic acid and 2-furanacetic acid to be converted into the targeted products in low to high yields.
- Ren, Yun-Lai,Shen, Zhenpeng,Tian, Xinzhe,Xing, Ai-Ping,Zhao, Zhe
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- Electro-Oxidative Selective Esterification of Methylarenes and Benzaldehydes
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A mild and green electro-oxidative protocol to construct aromatic esters from methylarenes and alcohols is herein reported. Importantly, the reaction is free of metals, chemical oxidants, bases, acids, and operates at room temperature. Moreover, the design of the electrolyte was found critical for the oxidation state and structure of the coupling products, a rarely documented effect. This electro-oxidative coupling process also displays exceptional tolerance of many fragile easily oxidized functional groups such as hydroxy, aldehyde, olefin, alkyne, as well as neighboring benzylic positions. The enantiomeric enrichment of some chiral alcohols is moreover preserved during this electro-oxidative coupling reaction, making it overall a promising synthetic tool.
- Yu, Congjun,?zkaya, Bünyamin,Patureau, Frederic W.
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supporting information
p. 3682 - 3687
(2021/02/01)
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- Method for synthesizing P-methoxybenzaldehyde by taking anethole as raw material
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The invention discloses a method for synthesizing p-methoxybenzaldehyde by taking anethole as a raw material, and the method comprises the following steps: taking 1 part of POL-PPh3@PdCl2 catalyst, 15-20 parts of anethole and 300-500 parts of methylbenzene, uniformly stirring, then adding 150-300 parts of 30% hydrogen peroxide aqueous solution, and carrying out catalytic oxidation reaction at normal temperature for 0.5-1.5 hours; filtering the reaction solution through an adsorbent, standing for layering, washing an organic phase with water, performing dehydrating, performing drying, and carrying out vacuum fractionation to obtain p-methoxybenzaldehyde. The p-methoxybenzaldehyde is synthesized by taking anethole as a raw material and taking methylbenzene as a solvent under the catalysis of POL-PPh3@PdCl2 and the oxidation of hydrogen peroxide. The synthesis method has the advantages of high yield, mild reaction conditions, high production efficiency, simple process, low production cost, readily available raw materials, less emission of three wastes and the like, has good social, ecological and economic benefits, and provides an effective way for industrial production of p-methoxybenzaldehyde.
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Paragraph 0018-0024
(2021/05/01)
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- Preparation method of anisic aldehyde
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The invention discloses a preparation method of anisic aldehyde, and the method comprises the following steps of: S1, adding natural anise camphor and water into a bubbling reactor, introducing ozoneat 15-27DEG C to carry out ozone oxidation reaction for 200-300min, standing the reaction solution after the reaction is finished, carrying out phase splitting, and performing separation to remove thewater phase to obtain an organic phase for later use; S2, adding a reducing agent aqueous solution into the organic phase obtained in the S1, carrying out reduction reaction for 40-60min at the temperature of 70-80DEG C, and adding alkali liquor for neutralization so as to obtain an anisic aldehyde crude product; and S3, carrying out reduced pressure distillation on the anisic aldehyde crude product obtained in the S2, and collecting fractions with a pressure of 120-220Pa and a temperature of 120-170DEG C to obtain the anisic aldehyde finished product. The method is simple in process, mild inreaction condition, high in yield and high in raw material utilization rate, the total yield is 68-75%, the green and environment-friendly process requirements are met, and industrial production is facilitated.
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Paragraph 0030-0053
(2021/02/24)
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- Rapid, chemoselective and mild oxidation protocol for alcohols and ethers with recyclable N-chloro-N-(phenylsulfonyl)benzenesulfonamide
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Chlorine is the 20th most abundant element on the earth compared to bromine, iodine, and fluorine, a sulfonimide reagent, N-chloro-N-(phenylsulfonyl)benzenesulfonamide (NCBSI) was identified as a mild and selective oxidant. Without activation, the reagent was proved to oxidize primary and secondary alcohols as well as their symmetrical and mixed ethers to corresponding aldehydes and ketones. With recoverable PS-TEMPO catalyst, selective oxidation over chlorination of primary and secondary alcohols and their ethers with electron-donating substituents was achieved. The reagent precursor of NCBSI was recovered quantitatively and can be reused for synthesizing NCBSI.
- Badani, Purav,Chaturbhuj, Ganesh,Ganwir, Prerna,Misal, Balu,Palav, Amey
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supporting information
(2021/06/03)
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- Co-Oxidative Transformation of Piperine to Piperonal and 3,4-Methylenedioxycinnamaldehyde by a Lipoxygenase from Pleurotus sapidus
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The valuable aroma compound piperonal with its vanilla-like olfactory properties is of high interest for the fragrance and flavor industry. A lipoxygenase (LOXPsa1) of the basidiomycete Pleurotus sapidus was identified to convert piperine, the abundant pungent principle of black pepper (Piper nigrum), to piperonal and a second volatile product, 3,4-methylenedioxycinnamaldehyde, with a vanilla-like odor through an alkene cleavage. The reaction principle was co-oxidation, as proven by its dependence on the presence of linoleic or α-linolenic acid, common substrates of lipoxygenases. Optimization of the reaction conditions (substrate concentrations, reaction temperature and time) led to a 24-fold and 15-fold increase of the piperonal and 3,4-methylenedioxycinnamaldehyde concentration using the recombinant enzyme. Monokaryotic strains showed different concentrations of and ratios between the two reaction products.
- Krahe, Nina-Katharina,Berger, Ralf G.,Kahlert, Lukas,Ersoy, Franziska
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p. 2857 - 2861
(2021/06/12)
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- Nickel catalyzed hydrosilane reduction of (het)arenecarboxylic acids into aldehydes
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Nickel-catalyzed reduction of (het)arenecarboxylic acids with hydrosilanes in the presence of dimethyl dicarbonate as the activator affords the corresponding aldehydes. The role of the activator is the conversion of the acids into their anhydrides undergoing C–O cleavage. The good yields were achieved in case of substrates bearing electron-donating and electron-neutral groups.
- Wang, Liang,Wang, Yaoyao,Tao, Yu,Zhang, Nana,Li, Shubai
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p. 271 - 273
(2021/05/04)
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- Metal-free selective reduction of acid chlorides to aldehydes using 1-hydrosilatrane
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This work uses 1-hydrosilatrane – an accessible and easy-to-handle reducing reagent – to selectively reduce acid chlorides to aldehydes. This metal-free reduction proceeds rapidly at ambient temperature in the presence of N-methylpyrrolidine, efficiently producing aldehydes in up to 54% yield and with the balance largely remaining as starting material. No over-reduced alcohol product is observed.
- Adler, Marc J.,Azam, Fawwaz,Raveenthrarajan, David
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supporting information
(2021/10/29)
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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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- 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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- Ferric ion concentration-controlled aerobic photo-oxidation of benzylic C–H bond with high selectivity and conversion
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A Fe(III)-promoted highly selective photo-oxidation of benzylic C–H bond delivering relative carbonyl products is reported. By altering the concentration of ferric salt, methylarenes can be selectively oxidized under UV irradiation to furnish aromatic aldehydes or acids, respectively. By this protocol, the oxidation of ethylarenes provides the corresponding acetophenones. The reaction is inferred to involve divergent pathways in different concentrations of catalyst for the alternative selectivity between aldehydes and aicds. The reusable catalyst, high conversion and selectivity make this oxidation a green and economic protocol for the synthesis of aromatic carbonyl compounds.
- Bu, Hongzhong,Gu, Jiefan,Li, Yufeng,Ma, Hongfei,Wan, Yuting,Wu, Zheng-Guang,Zhang, Weijian,Zhou, Ying'ao,Zhu, Hongjun
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- Metal- And additive-free C-H oxygenation of alkylarenes by visible-light photoredox catalysis
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A metal- and additive-free methodology for the highly selective, photocatalyzed C-H oxygenation of alkylarenes under air to the corresponding carbonyls is presented. The process is catalyzed by an imide-acridinium that forms an extremely strong photooxidant upon visible light irradiation, which is able to activate inert alkylarenes such as toluene. Hence, this is an easy to perform, sustainable and environmentally friendly oxidation that provides valuable carbonyls from abundant, readily available compounds.
- García Manche?o, Olga,Kuhlmann, Jan H.,Pérez-Aguilar, María Carmen,Piekarski, Dariusz G.,Uygur, Mustafa
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supporting information
p. 3392 - 3399
(2021/05/21)
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- SBA-15 Supported Silver Catalyst for the Efficient Aerobic Oxidation of Toluene Under Solvent-Free Conditions
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The efficient SBA-15 supported silver catalysts(Ag/SBA-15) were prepared and characterized by ICP-OES, XRD, TEM, SEM, XPS and N2 adsorption–desorption techniques. The catalysts exhibited an excellent catalytic activity for the aerobic oxidation of toluene to benzaldehyde under solvent-free conditions. Conversion of toluene and selectivity of benzaldehyde were 50% and 89% respectively over catalyst with 9.1 wt% Ag loading (10Ag/SBA-15). A wide range of substrates were tolerated under the selected reaction conditions. The kinetic study shows that the oxidation of toluene over 10Ag/SBA-15 is pseudo-first-order reaction and the activation energy Ea is 45.1?kJ/mol. A plausible mechanism involving oxygen free radicals was proposed for the aerobic oxidation reaction. Compared with the traditional method, the newly designed heterogeneous catalytic system shows better economic applicability, environmental friendliness and broader application prospects. Graphical abstract: [Figure not available: see fulltext.]
- Chen, Lei,Chen, Yanjiao,Dai, Xuan,Guo, Jiaming,Peng, Xinhua
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- Core-shell Co-MOF-74@Mn-MOF-74 catalysts with Controllable shell thickness and their enhanced catalytic activity for toluene oxidation
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A series of core-shell Co-MOF-74@Mn-MOF-74 samples with different shell thicknesses were prepared by the seed growth method, which were characterized by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), inductively coupled plasma mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy, nitrogen adsorption-desorption and scanning electron microscopy (SEM). The shell thickness of these MOF samples were successfully controlled by adjusting the mass ratio between MnCl2·4H2O and Co-MOF-74. On this basis, these MOFs were applied to the catalytic oxidation of toluene. The results showed that with the growth of Mn-MOF-74 in the outer layer of Co-MOF-74, the oxidative selectivity of the substrate to benzaldehyde was greatly improved for the synergy between the core layer and shell layer. The conversion of toluene was 22.4%, and the selectivity of benzaldehyde was 98.1%. In addition, the catalyst can transform various substituted toluene into the corresponding aldehydes in highly selectivity and still keep good stability after four catalytic cycles. The selectivity of the corresponding aldehyde is generally above 80%.
- Gu, Xiangyu,Huang, Cheng,Xu, Zengchuang,Wu, Hao,Dong, Ruilan,Liu, Rui,Chen, Jing,Zhu, Hongjun
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- Oxidation/ MCR domino protocol for direct transformation of methyl benzene, alcohol, and nitro compounds to the corresponding tetrazole using a three-functional redox catalytic system bearing TEMPO/Co(III)-porphyrin/ Ni(II) complex
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A redox catalytic system for oxidation-reduction reactions and the domino preparation of tetrazole compounds from nitro and alcohol precursors was designed, prepared and characterized by UV–vis, GPC, TGA, XRD, EDX, XPS, VSM, FE-SEM, TEM, DLS, BET, NMR, and ICP analyses. The catalyst was prepared via several successive steps by demetalation of chlorophyll b, copolymerization with acrylated TEMPO monomers, complexation with Ni and Co metals (In two different steps), then immobilized on magnetic nanoparticles. The presence of three functional groups including TEMPO, coordinated cobalt, and coordinated nickel in the catalyst, allowed the oxidation of various types of alcohols, alkyl benzenes as well as the reduction of nitro compounds by a single catalyst. All reactions yielded up to 97 % selectivity for oxidation and reduction reactions. Next, the ability of the catalyst to successfully convert alcohol, methyl benzenes and nitro to their corresponding tetrazoles was studied.
- Mahmoudi, Boshra,Rostami, Amin,Kazemnejadi, Milad,Hamah-Ameen, Baram Ahmed
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- C70Fullerene Catalyzed Photoinduced Aerobic Oxidation of Benzylamines to Imines and Aldehydes
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C70 fullerene catalyzed photoinduced oxidation of benzylic amines at ambient conditions has been explored here. The developed strategy's main feature includes the additive/oxidant-free conversion of benzylic amine to corresponding imine and aldehydes. The reaction manifests broad substrate scope with excellent function group leniency and is applicable up to the gram scale. Further, symmetrical secondary amines can also be synthesized from benzylic amine in a one-pot two-step process. Various experiments and density functional theory studies revealed that the current reaction involves the generation of reactive oxygen species, single electron transfer reaction, and benzyl radical formation as key steps under photocatalytic conditions.
- Kumar, Inder,Kumar, Rakesh,Gupta, Shiv Shankar,Sharma, Upendra
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supporting information
p. 6449 - 6457
(2021/05/29)
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- One-Pot Direct Oxidation of Primary Amines to Carboxylic Acids through Tandem ortho-Naphthoquinone-Catalyzed and TBHP-Promoted Oxidation Sequence
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Biomimetic oxidation of primary amines to carboxylic acids has been developed where the copper-containing amine oxidase (CuAO)-like o-NQ-catalyzed aerobic oxidation was combined with the aldehyde dehydrogenase (ALDH)-like TBHP-mediated imine oxidation protocol. Notably, the current tandem oxidation strategy provides a new mechanistic insight into the imine intermediate and the seemingly simple TBHP-mediated oxidation pathways of imines. The developed metal-free amine oxidation protocol allows the use of molecular oxygen and TBHP, safe forms of oxidant that may appeal to the industrial application.
- Kim, Hun Young,Oh, Kyungsoo,Si, Tengda
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supporting information
p. 18150 - 18155
(2021/12/09)
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- Molybdenum-Catalyzed Deoxygenation Coupling of Lignin-Derived Alcohols for Functionalized Bibenzyl Chemicals
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With the growing demand for sustainability and reducing CO2 footprint, lignocellulosic biomass has attracted much attention as a renewable, carbon-neutral and low-cost feedstock for the production of chemicals and fuels. To realize efficient utilization of biomass resource, it is essential to selectively alter the high degree of oxygen functionality of biomass-derivates. Herein, we introduced a novel procedure to transform renewable lignin-derived alcohols to various functionalized bibenzyl chemicals. This strategy relied on a short deoxygenation coupling pathway with economical molybdenum catalyst. A well-designed H-donor experiment was performed to investigate the mechanism of this Mo-catalyzed process. It was proven that benzyl carbon-radical was the most possible intermediate to form the bibenzyl products. It was also discovered that the para methoxy and phenolic hydroxyl groups could stabilize the corresponding radical intermediates and then facilitate to selectively obtain bibenzyl products. Our research provides a promising application to produce functionalized aromatics from biomass-derived materials.
- Jiang, Huifang,Lu, Rui,Luo, Xiaolin,Si, Xiaoqin,Xu, Jie,Lu, Fang
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supporting information
p. 1292 - 1296
(2020/12/09)
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- Catalytic alcohol oxidation using cationic Schiff base manganeseIII complexes with flexible diamino bridge
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Four Schiff base manganese(III) complexes with derivatives of [(R,R)-N,N’-bis(salicy1idene)-1,2-cyclohexanediaminato)] including substituents on salicylaldehyde such as 3-methoxy, 3,5-di-tert-butyl and 3,5-chloro were synthesized and characterized using a combination of IR, UV–Vis, and HR ESI-MS techniques. The catalytic activity of these complexes was tested in the oxidation of 1-phenylethanol to acetophenone, revealing very good performances for all of the four manganese complexes. The catalytic reactions were carried out in the presence of tert-butyl hydroperoxide (TBHP) as oxidant and imidazole as co-catalyst. Complex Mn-4, bearing electron withdrawing [(R,R)-N,N’-bis(3,5-di-chloro-salicylidene)-1,2-cyclohexanediaminato)] ligand was found to be the most stable of the tested Mn(III) complexes and was selected for the oxidation of several primary and secondary alcohols.
- Kakavand, Meysam,Mastrorilli, Piero,Mesto, Ernesto,Neshat, Abdollah,Osanlou, Farzane,Schingaro, Emanuela,Todisco, Stefano
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- Combining photoredox catalysis and oxoammonium cations for the oxidation of aromatic alcohols to carboxylic acids
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A methodology is reported for converting alcohols to the corresponding carboxylic acids. A dual catalytic system involving a merger of photoredox catalysis and 4-acetamido-TEMPO is employed to carry out this oxidation process.
- Nandi, Jyoti,Hutcheson, Ellen L.,Leadbeater, Nicholas E.
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supporting information
(2020/12/25)
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- Soluble/MOF-Supported Palladium Single Atoms Catalyze the Ligand-, Additive-, and Solvent-Free Aerobic Oxidation of Benzyl Alcohols to Benzoic Acids
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Metal single-atom catalysts (SACs) promise great rewards in terms of metal atom efficiency. However, the requirement of particular conditions and supports for their synthesis, together with the need of solvents and additives for catalytic implementation, often precludes their use under industrially viable conditions. Here, we show that palladium single atoms are spontaneously formed after dissolving tiny amounts of palladium salts in neat benzyl alcohols, to catalyze their direct aerobic oxidation to benzoic acids without ligands, additives, or solvents. With this result in hand, the gram-scale preparation and stabilization of Pd SACs within the functional channels of a novel methyl-cysteine-based metal-organic framework (MOF) was accomplished, to give a robust and crystalline solid catalyst fully characterized with the help of single-crystal X-ray diffraction (SCXRD). These results illustrate the advantages of metal speciation in ligand-free homogeneous organic reactions and the translation into solid catalysts for potential industrial implementation.
- Tiburcio, Estefanía,Greco, Rossella,Mon, Marta,Ballesteros-Soberanas, Jordi,Ferrando-Soria, Jesús,López-Haro, Miguel,Hernández-Garrido, Juan Carlos,Oliver-Meseguer, Judit,Marini, Carlo,Boronat, Mercedes,Armentano, Donatella,Leyva-Pérez, Antonio,Pardo, Emilio
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p. 2581 - 2592
(2021/02/16)
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- PhIO-Mediated oxidative dethioacetalization/dethioketalization under water-free conditions
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Treatment of thioacetals and thioketals with iodosobenzene in anhydrous DCM conveniently afforded the corresponding carbonyl compounds in high yields under water-free conditions. The mechanistic studies indicate that this dethioacetalization/dethioketalization process does not need water and the oxygen of the carbonyl products comes from the hypervalent iodine reagent.
- Du, Yunfei,Ouyang, Yaxin,Wang, Xi,Wang, Xiaofan,Yu, Zhenyang,Zhao, Bingyue,Zhao, Kang
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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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- 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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- Heterogeneous vanadium-catalyzed oxidative cleavage of olefins for sustainable synthesis of carboxylic acids
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The development of green and sustainable processes to synthesize active pharmaceutical ingredients and key starting materials is a priority for the pharmaceutical industry. A green and sustainable protocol for the oxidative cleavage of olefins to produce pharmaceutically and biologically valuable carboxylic acids is achieved. The developed protocol involves 70% aq. TBHP as an oxidant over a heterogeneous vanadium catalyst system. Notably, the synthesis of industrially important azelaic acid from various renewable vegetable oils is accomplished. The catalyst could be recycled for up to 5 cycles without significant loss in yield and the protocol was successfully demonstrated at the gram-scale.
- Upadhyay, Rahul,Rana, Rohit,Sood, Aakriti,Singh, Vikash,Kumar, Rahul,Srivastava, Vimal Chandra,Maurya, Sushil K.
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supporting information
p. 5430 - 5433
(2021/06/09)
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- V2O5@TiO2 Catalyzed Green and Selective Oxidation of Alcohols, Alkylbenzenes and Styrenes to Carbonyls
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The versatile application of different functional groups such as alcohols (1° and 2°), alkyl arenes, and (aryl)olefins to construct carbon-oxygen bond via oxidation is an area of intense research. Here, we report a reusable heterogeneous V2O5@TiO2 catalyzed selective oxidation of various functionalities utilizing different mild and eco-compatible oxidants under greener reaction conditions. The method was successfully applied for the alcohol oxidation, oxidative scission of styrenes, and benzylic C?H oxidation to their corresponding aldehydes and ketones. The utilization of mild and eco-friendly oxidizing reagents such as K2S2O8, H2O2 (30 % aq.), TBHP (70 % aq.), broad substrate scope, gram-scale synthesis, and catalyst recyclability are notable features of the developed protocol.
- Upadhyay, Rahul,Kumar, Shashi,Maurya, Sushil K.
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p. 3594 - 3600
(2021/07/02)
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- Method for generating benzaldehyde by catalyzing alpha-monosubstituted styrene to be oxidized by N-hydroxyphthalimide
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The invention discloses a method for generating benzaldehyde by catalyzing alpha-mono-substituted styrene to be oxidized through N-hydroxyphthalimide. According to the method, N-hydroxyphthalimide isused as a catalyst, oxygen is used as an oxidizing agent, and an alpha mono-substituted styrene compound is oxidized in an organic solvent to obtain the benzaldehyde derivative. The method has the advantages of simple reaction operation, low cost, mild conditions, high yield, no heavy metal pollution and the like.
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Paragraph 0033-0035
(2021/01/24)
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- Aryl aldiketone and synthesis method thereof
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The invention discloses an aryl aldehyde ketone and a synthesis method thereof, wherein an aryl aldehyde is synthesized from cheap olefin as a raw material. A commercially available inexpensive olefin is used as a raw material, ether is used as an additive, molecular oxygen serves as a sole oxidizing agent, water is used as a solvent, and the aldehyde and ketone are synthesized by column chromatography under a photocatalytic condition. The invention has the advantages of mild reaction conditions, green and environmental protection, simple experimental operation, good reaction selectivity, high product yield and the like.
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Paragraph 0014; 0036-0042
(2021/09/26)
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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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- 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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- Aerobic oxidative C?C bond cleavage of aromatic alkenes by a high valency iron-containing perovskite catalyst
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High valency iron-containing perovskite catalyst BaFeO3-dcould efficiently promote the additive-free oxidative C?C bond cleavage of various aromatic alkenes to the corresponding aldehydes or ketones using O2as the sole oxidant. This system was applicable to the gram-scale oxidation of 1,1-diphenylethylene, in which 2.71 g (75% yield) of the analytically pure ketone could be isolated.
- Shibata, Satomi,Kamata, Keigo,Hara, Michikazu
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p. 2369 - 2373
(2021/04/22)
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- Thiol-initiated photocatalytic oxidative cleavage of the C=C bond in olefins and its extension to direct production of acetals from olefins
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The oxidative cleavage of olefins to produce aldehydes/ketones is an important reaction in organic syntheses. In this manuscript, a mild and operationally simple protocol for the aerobic oxidation of olefins to produce carbonyl compounds was realized over ZnIn2S4under visible light, using air as the oxidant and a thiol as the initiator. It was proposed that the photogenerated holes over ZnIn2S4attack the thiol to produce thiyl radicals, which initiate the oxidative cleavage of the C=C bond in olefins to produce aldehydes/ketones. By further coupling with the condensation between the as-obtained aldehydes/ketones and alcohols, this strategy can also be applied to the production of different acetals directly from the olefins. This study demonstrates a new pathway to realize the oxidative cleavage of olefins to produce aldehydes/ketones, and also provides a new protocol for the production of acetals directly from the olefins.
- Wang, Xinglin,Li, Yuanyuan,Li, Zhaohui
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p. 1000 - 1006
(2021/02/26)
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- g-C3N4@Ce-MOF Z-scheme heterojunction photocatalyzed cascade aerobic oxidative functionalization of styrene
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A special composite of the cerium-based metal-organic framework (Ce-UiO-66) modified with graphitic carbon nitride nanosheets (g-C3N4) has been synthesized. In order to make a comparison, a series of composites comprising g-C3N4and Ce-MOF were synthesized as well. Their structural features were investigated using Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), sorption of nitrogen (BET and BJH), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), X-ray fluorescence spectroscopy (XRF) and diffuse reflectance UV-Vis spectroscopy (UV-Vis DRS) and electron spin resonance (ESR) techniques. According to the obtained results, it was found that nanosheets of mesoporous g-C3N4act as linkers between the cerium sites, playing a critical role in the formation of composites. In fact, the embedded g-C3N4nanoparticles in the Ce-MOF cause a new kind of meso-porosity. Moreover, the coordination of nitrogen atoms in the graphitic carbon nitride structure to cerium atoms of the crystal brings about substantial changes in the optical properties, increasing the photoreactivity. On the other hand, since there is a physical contact between Ce-UiO-66 and g-C3N4in the composite, the unaltered pore volume and optical properties lead to the formation of a physical mixture rather than a composite. The g-C3N4@Ce-MOF as a photocatalyst was employed in photocatalytic aerobic oxidative Hantzsch pyridine synthesis of styrene and indicated high performance under visible light. The stability and reusability of g-C3N4@Ce-MOF were also examined and showed high efficiency up to the 5th run. Besides, the PXRD and FT-IR analyses taken from the retrieved g-C3N4@Ce-MOF nanocomposite confirmed the catalyst stability after the completion of the cascade aerobic oxidative reaction. Despite the photocatalytic performance, the synergistic effect of open metal sites in the MOF as Lewis acid and nitrogen in g-C3N4have greatly improved the efficiency of the catalyst. Moreover, the study of the reaction mechanism using ESR indicates the positive effect of composite formation on the performance of the photocatalytic aerobic oxidation reaction by the superoxide radical (O2˙—), as a selective oxidant species.
- Karimia, Meghdad,Sadeghia, Samira,Gavinehroudi, Reza Ghahremani,Mohebali, Haleh,Mahjoub, Alireza,Heydari, Akbar
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p. 6671 - 6681
(2021/04/22)
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- A highly stable metal-organic framework with cubane-like clusters for the selective oxidation of aryl alkenes to aldehydes or ketones
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Triazine derivatives, a class of electron-deficient π-conjugated molecules with high photochemical activity and excellent luminescent characteristics, have been utilized as a kind of electron-acceptor for the construction of molecular cages, luminescent and photochromic materials. In this paper, a novel and highly stable MOF with cubane-like clusters, [Co4(SO4)3(F)3(tpt)2(tatb)] (1) (tpt = 2,4,6-tris-(4-pyridyl)-1,3,5-triazine, H3tatb = 4,4′,4′′-(1,3,5-triazine-2,4,6-triyl)tribenzoic acid), has been successfully synthesized based on a triazine derivative, and possesses unprecedented sulfate- and fluoride-bridged cubane-type tetranuclear cobalt clusters and a 3D + 3D → 3D open framework. Compound1shows a rather high BET surface area and exhibits excellent thermal stability and high chemical stability in common solvents and even in acidic or basic solutions (in a pH range from 4 to 12). Moreover, catalytic measurements show that compound1is an excellent heterogeneous catalyst for the selective oxidation of aryl alkenes to aldehydes or ketones with conversions of 97%.
- He, Chixian,Liu, Jiaming,Liu, Jian-Jun,Liu, Teng,Shen, Xianfu,Shen, Xiang
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p. 4667 - 4673
(2021/07/11)
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- Method for preparing aldehyde compounds by oxidative cleavage of carbon-carbon bonds of terminal alkene compounds
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The invention discloses a method for preparing aldehyde compounds by oxidizing and breaking carbon-carbon bonds of terminal alkene compounds. The method comprises the following steps: adding an alkene-terminated compound, an additive and a nitrogen-doped mesoporous carbon-loaded monatomic catalyst into a fatty primary alcohol solvent, putting into a pressure container, sealing, introducing oxygen source gas with a certain pressure, controlling the pressure of the oxygen source gas to be 0.1-1MPa and the reaction temperature to be 80-150 DEG C, and obtaining a reaction product, namely the aldehyde compound. The nitrogen-doped mesoporous carbon-loaded monatomic catalyst adopted by the invention is high in activity, the highest separation yield of the aldehyde compound as a reaction product reaches 99%, the method is wide in application range, the reaction conditions are easy to control, the catalyst can be recycled, the post-treatment is simple, and the method is suitable for industrial production.
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Paragraph 0047-0048; 0089-0090
(2021/06/06)
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- Fe-S Catalyst Generated in Situ from Fe(III)- And S3?--Promoted Aerobic Oxidation of Terminal Alkenes
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An iron-sulfur complex formed by the simple mixture of FeCl3 with S3?- generated in situ from K2S is developed and applied to selective aerobic oxidation of terminal alkenes. The reaction was carried out under an atmosphere of O2 (balloon) and could proceed on a gram scale, expanding the application of S3?- in organic synthesis. This study also encourages us to explore the application of an Fe-S catalyst in organic reactions.
- Ai, Jing-Jing,Huang, Cheng-Mi,Li, Jian,Liu, Bei-Bei,Rao, Weidong,Wang, Fei,Wang, Shun-Yi
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supporting information
p. 4705 - 4709
(2021/06/28)
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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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- DIBALH: From known fundamental to an unusual reaction; Chemoselective partial reduction of tertiary amides in the presence of esters
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This study presents a quick and reliable approach to the chemoselective partial reduction of tertiary amides to aldehydes in the presence of readily reducible ester groups using commercial DIBALH reagent. Moreover, the developed method was also extended to multi-functional molecules bearing ester moieties, which were successfully chemoselectively reduced to the corresponding aldehydes. This journal is
- An, Duk Keun,Heo, Yu Jin,Jaladi, Ashok Kumar,Kim, Hyun Tae
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p. 33809 - 33813
(2021/12/09)
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- New method for promoting photosensitive oxidation to remove 1, 2-mercaptoethanol acetal protecting group by utilizing visible light irradiation
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The invention discloses a new method for removing a 1, 2-mercaptoethanol acetal protecting group, and belongs to the field of organic synthetic chemistry. The method comprises the following steps of:under a room-temperature open system, adding a substrate 2-substituted-1, 3-oxo-thio-cyclopentane and a catalytic amount of a photosensitizer Eosin Y into a proper amount of acetonitrile; and performing irradiating with a blue LED lamp for 3 hours while stirring to obtain the corresponding aldehyde compound with favorable yield. The method has the advantages of mild operation conditions, greenness, environmental protection, no harsh water and oxygen removal operation and device, realization of the reaction at room temperature, high substrate conversion rate, simple and easy post-treatment, andprovides a good method for removing the 1, 2-mercaptoethanol acetal protecting group at present.
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Paragraph 0014-0016
(2021/01/30)
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- Dual utility of a single diphosphine-ruthenium complex: A precursor for new complexes and, a pre-catalyst for transfer-hydrogenation and Oppenauer oxidation
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The diphosphine-ruthenium complex, [Ru(dppbz)(CO)2Cl2] (dppbz = 1,2-bis(diphenylphosphino)benzene), where the two carbonyls are mutually cis and the two chlorides are trans, has been found to serve as an efficient precursor for the synthesis of new complexes. In [Ru(dppbz)(CO)2Cl2] one of the two carbonyls undergoes facile displacement by neutral monodentate ligands (L) to afford complexes of the type [Ru(dppbz)(CO)(L)Cl2] (L = acetonitrile, 4-picoline and dimethyl sulfoxide). Both the carbonyls in [Ru(dppbz)(CO)2Cl2] are displaced on reaction with another equivalent of dppbz to afford [Ru(dppbz)2Cl2]. The two carbonyls and the two chlorides in [Ru(dppbz)(CO)2Cl2] could be displaced together by chelating mono-anionic bidentate ligands, viz. anions derived from 8-hydroxyquinoline (Hq) and 2-picolinic acid (Hpic) via loss of a proton, to afford the mixed-tris complexes [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], respectively. The molecular structures of four selected complexes, viz. [Ru(dppbz)(CO)(dmso)Cl2], [Ru(dppbz)2Cl2], [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], have been determined by X-ray crystallography. In dichloromethane solution, all the complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the complexes shows redox responses within 0.71 to -1.24 V vs. SCE. [Ru(dppbz)(CO)2Cl2] has been found to serve as an excellent pre-catalyst for catalytic transfer-hydrogenation and Oppenauer oxidation.
- Mukherjee, Aparajita,Bhattacharya, Samaresh
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p. 15617 - 15631
(2021/05/19)
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