- Acid-tolerant intermetallic cobalt-nickel silicides as noble metal-like catalysts for selective hydrogenation of phthalic anhydride to phthalide
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Chemoselective hydrogenation of phthalic anhydride is regarded as the most promising route for producing downstream high-performance phthalide. A series of intermetallic cobalt-nickel silicide catalysts embedded in a carbon matrix (CoxNi2-xSi@C) with acid-tolerance prepared by microwave-assisted chemical vapor deposition have been investigated in this reaction system. Activity measurements show a remarkable positive synergistic effect, forming a volcano-shaped plot over the nominal Co metal fraction for CoxNi2-xSi@C catalysts with a peak at x = 1.5, which corresponds to a 4.5-fold enhancement of the yield of phthalide over Co2Si@C and a 2.0-fold enhancement over the Ni2Si@C monometallic silicide catalysts, which can be correlated with the interaction of cobalt-nickel and metal-silicon bonds. In addition, the cobalt-rich bimetallic silicide exhibits an equal activity to the reference noble metal catalysts (Au, Pd, and Pt) and a significantly higher activity than transition metal catalysts. Moreover, the bimetallic silicide as an intermetallic compound catalyst has demonstrated robust acid corrosion resistance compared to the corresponding metal catalysts.
- Zhang, Liangliang,Chen, Xiao,Chen, Yujing,Peng, Zhijian,Liang, Changhai
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- Porous chitosan-MnO2 nanohybrid: A green and biodegradable heterogeneous catalyst for aerobic oxidation of alkylarenes and alcohols
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A porous chitosan-manganese dioxide (PC-MnO2) nanohybrid was synthesized using an in situ reduction method, in which potassium permanganate solution and nanoporous chitosan acted as precursor and reducing agent. The chemical and structural properties of PC-MnO2 were characterized using scanning and transmission electron microscopies, X-ray diffraction, thermogravimetric analysis and Fourier transform infrared spectroscopy. Highly dispersed MnO2 nanoparticles in a matrix of porous chitosan showed high catalytic activity for selective aerobic oxidation of alkylarenes and alcohols without using any bases or expensive oxidants. Short reaction time, ease of product separation by filtration and recyclability of the catalyst make it environmentally and economically favoured for the synthesis of versatile aldehydes and ketones.
- Shaabani, Ahmad,Borjian Boroujeni, Mahmoud,Laeini, Mohmmad Sadegh
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- Catalytic enantioselective intramolecular Tishchenko reaction ofmeso-dialdehyde: synthesis of (S)-cedarmycins
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The first successful example of a catalytic enantioselective intramolecular Tishchenko reaction of ameso-dialdehyde in the presence of a chiral iridium complex is described. Chiral lactones were obtained in good yields with up to 91% ee. The obtained enantioenriched lactones were utilized for the first synthesis of (S)-cedarmycins A and B.
- Ismiyarto,Kishi, Nobuki,Adachi, Yuki,Jiang, Rui,Doi, Takahiro,Zhou, Da-Yang,Asano, Kaori,Obora, Yasushi,Suzuki, Takayoshi,Sasai, Hiroaki,Suzuki, Takeyuki
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- Carbon monoxide as a One Carbon Component in Palladium Catalysed Cycloaddition Reactions
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Pd(0), generated in-situ, in combination with TlOAc promotes a range of catalytic bi- and tri-molecular cycloadditions of aryl/heteroaryl iodides in which carbon monoxide (1 atm) functions as a one carbon component furnishing 5-7 membered rings in good yield.
- Grigg, Ronald,Khalil, Hashim,Levett, Philip,Virica, Julia,Sridharan, Visuvanathar
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- Efficient conversion of dimethyl phthalate to phthalide over CuO in aqueous media
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An efficient conversion of dimethyl phthalate (DMP) to phthalide (PHT) over CuO in aqueous media was investigated. Among the catalysts we tested, various metals or metal oxides were effective for the conversion of DMP to PHT in water, and CuO showed excellent catalytic activity and gave the best result. The PHT yield of 85% was achieved when Zn acted as a reductant. Mechanism study for the conversion of DMP suggested that an intermediate 2-hydroxymethyl benzoic acid was produced in the process. The present study provides a useful route for the production of PHT from DMP.
- Fu, Jun,Ren, Dezhang,Li, Lu,Liu, Yunjie,Jin, Fangming,Huo, Zhibao
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- Strong base catalysis of sulfated mesoporous alumina for the Tishchenko reaction in supercritical carbon dioxide
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Heterogeneous strong base catalysis for the Tishchenko reaction in acidic scCO2 solvent has been realized with mesoporous alumina modified with SO42-, while a conventional solid base like CaO showed almost no catalytic performance in scCO2. Copyright
- Seki, Tsunetake,Onaka, Makoto
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- Au/FeOx-TiO2 as an efficient catalyst for the selective hydrogenation of phthalic anhydride to phthalide
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Au/FeOx-TiO2, prepared by deposition-precipitation method, is an efficient and stable catalyst for the liquid phase selective hydrogenation of phthalic anhydride to phthalide under mild reaction conditions.
- Liu, Ying Xin,Xing, Tie Feng,Luo, Yi Ming,Li, Xiao Nian,Yan, Wei
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- An efficient carbonylation of aryl halides catalysed by palladium complexes with phosphite ligands in supercritical carbon dioxide
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The carbonylation of aryl halides catalysed by CO2 soluble Pd complexes with trialkyl or triaryl phosphite ligands proceeds rapidly in scCO2, in which the rate of the reaction is higher than those attained in solution phase reactions.
- Kayaki, Yoshihito,Noguchi, Yushi,Iwasa, Seiji,Ikariya, Takao,Noyori, Ryoji
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- (Diacetoxyiodo)benzene-mediated oxygenation of benzylic C(sp3)-H bonds with N-hydroxyamides at room temperature
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A new, metal-free method for the formation of C(sp3)-O bonds was established by PhI(OAc)2-mediated oxygenation of benzylic C(sp3)-H bonds with N-hydroxyamides at room temperature, in which the C(sp3)-H oxidation is activated by a polyflurophenylamide group.
- Qian, Peng-Cheng,Liu, Yu,Song, Ren-Jie,Hu, Ming,Yang, Xu-Heng,Xiang, Jian-Nan,Li, Jin-Heng
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- Mechanistic insight into the synergistic Cu/Pd-catalyzed carbonylation of aryl iodides using alcohols and dioxygen as the carbonyl source
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Pd-catalyzed carbonylation, as an efficient synthetic approach to the installation of carbonyl groups in organic compounds, has been one of the most important research fields in the past decade. Although elegant reactions that allow highly selective carbonylations have been developed, straightforward routes with improved reaction activity and broader substrate scope remain long-term challenges for new practical applications. Here, we show a new type of synergistic Cu/Pd-catalyzed carbonylation reaction using alcohols and dioxgen as the carbonyl sources. A broad range of aryl iodides and alcohols are compatible with this protocol. The reaction is concise and practical due to the ready availability of the starting materials and the scalability of the reaction. In addition, the reaction affords lactones and lactams in an intermolecular fashion. Moreover, DFT calculations have been performed to study the detailed mechanisms. [Figure not available: see fulltext.]
- Li, Junxuan,Zhou, Jinlei,Wang, Yumei,Yu, Yue,Liu, Qiang,Yang, Tilong,Chen, Huoji,Cao, Hua
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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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- Covalent Organic Frameworks toward Diverse Photocatalytic Aerobic Oxidations
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Photoactive two-dimensional covalent organic frameworks (2D-COFs) have become promising heterogenous photocatalysts in visible-light-driven organic transformations. Herein, a visible-light-driven selective aerobic oxidation of various small organic molecules by using 2D-COFs as the photocatalyst was developed. In this protocol, due to the remarkable photocatalytic capability of hydrazone-based 2D-COF-1 on molecular oxygen activation, a wide range of amides, quinolones, heterocyclic compounds, and sulfoxides were obtained with high efficiency and excellent functional group tolerance under very mild reaction conditions. Furthermore, benefiting from the inherent advantage of heterogenous photocatalysis, prominent sustainability and easy photocatalyst recyclability, a drug molecule (modafinil) and an oxidized mustard gas simulant (2-chloroethyl ethyl sulfoxide) were selectively and easily obtained in scale-up reactions. Mechanistic investigations were conducted using radical quenching experiments and in situ ESR spectroscopy, all corroborating the proposed role of 2D-COF-1 in photocatalytic cycle.
- Liu, Shuyang,Tian, Miao,Bu, Xiubin,Tian, Hua,Yang, Xiaobo
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supporting information
p. 7738 - 7744
(2021/05/07)
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- Cu2O-CuO/Chitosan Composites as Heterogeneous Catalysts for Benzylic C?H Oxidation at Room Temperature
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Recently, in catalysis, chitosan has been exploited as a macrochelating ligand for metal active species due to the presence of various functional groups in its structure. Moreover, copper-based catalysts are classified as one of the most environmentally friendly catalytic systems and their use for the oxidation of alkylarene has not been established much. Therefore, in this work, the hydrothermal synthesis of copper oxide-chitosan composites as heterogeneous catalysts for the benzylic C?H oxidation of alkylarene was investigated. Characterization results reveal mixed phases of CuO and Cu2O, inferring the ability of chitosan to act as a reducing sugar under the hydrothermal condition. The pre-existing interaction between copper species and chitosan as well as the co-existence of the Cu2O and CuO structures give rise to the efficient performance of the catalysts. The synthesized composites exhibit high activity for the oxidation of fluorene to 9-fluorenone at room temperature and small catalyst loading (1 mol % of Cu, >90 % conversion and 100 % selectivity). Superior TOF was observed, and a good scope of substrates can be converted to corresponding ketones in 48–97 % yields with these copper oxide-chitosan catalysts. In addition, the catalysts can be used for up to nine cycles without significant decrease of the activity.
- Kanarat, Jurin,Bunchuay, Thanthapatra,Klysubun, Wantana,Tantirungrotechai, Jonggol
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p. 4833 - 4840
(2021/10/07)
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- Rational Construction of an Artificial Binuclear Copper Monooxygenase in a Metal-Organic Framework
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Artificial enzymatic systems are extensively studied to mimic the structures and functions of their natural counterparts. However, there remains a significant gap between structural modeling and catalytic activity in these artificial systems. Herein we report a novel strategy for the construction of an artificial binuclear copper monooxygenase starting from a Ti metal-organic framework (MOF). The deprotonation of the hydroxide groups on the secondary building units (SBUs) of MIL-125(Ti) (MIL = Matériaux de l'Institut Lavoisier) allows for the metalation of the SBUs with closely spaced CuI pairs, which are oxidized by molecular O2 to afford the CuII2(μ2-OH)2 cofactor in the MOF-based artificial binuclear monooxygenase Ti8-Cu2. An artificial mononuclear Cu monooxygenase Ti8-Cu1 was also prepared for comparison. The MOF-based monooxygenases were characterized by a combination of thermogravimetric analysis, inductively coupled plasma-mass spectrometry, X-ray absorption spectroscopy, Fourier-transform infrared spectroscopy, and UV-vis spectroscopy. In the presence of coreductants, Ti8-Cu2 exhibited outstanding catalytic activity toward a wide range of monooxygenation processes, including epoxidation, hydroxylation, Baeyer-Villiger oxidation, and sulfoxidation, with turnover numbers of up to 3450. Ti8-Cu2 showed a turnover frequency at least 17 times higher than that of Ti8-Cu1. Density functional theory calculations revealed O2 activation as the rate-limiting step in the monooxygenation processes. Computational studies further showed that the Cu2 sites in Ti8-Cu2 cooperatively stabilized the Cu-O2 adduct for O-O bond cleavage with 6.6 kcal/mol smaller free energy increase than that of the mononuclear Cu sites in Ti8-Cu1, accounting for the significantly higher catalytic activity of Ti8-Cu2 over Ti8-Cu1.
- Feng, Xuanyu,Song, Yang,Chen, Justin S.,Xu, Ziwan,Dunn, Soren J.,Lin, Wenbin
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supporting information
p. 1107 - 1118
(2021/01/25)
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- The Origin of Catalytic Benzylic C?H Oxidation over a Redox-Active Metal–Organic Framework
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Selective oxidation of benzylic C?H compounds to ketones is important for the production of a wide range of fine chemicals, and is often achieved using toxic or precious metal catalysts. Herein, we report the efficient oxidation of benzylic C?H groups in a broad range of substrates under mild conditions over a robust metal–organic framework material, MFM-170, incorporating redox-active [Cu2II(O2CR)4] paddlewheel nodes. A comprehensive investigation employing electron paramagnetic resonance (EPR) spectroscopy and synchrotron X-ray diffraction has identified the critical role of the paddlewheel moiety in activating the oxidant tBuOOH (tert-butyl hydroperoxide) via partial reduction to [CuIICuI(O2CR)4] species.
- Carter, Joseph H.,Day, Sarah J.,Han, Xue,Kang, Xinchen,Kimberley, Louis,Li, Jiangnan,McInnes, Eric J. L.,Schr?der, Martin,Sheveleva, Alena M.,Smith, Gemma L.,Tang, Chiu C.,Tuna, Floriana,Yang, Sihai
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supporting information
p. 15243 - 15247
(2021/06/08)
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- Sodium organoaluminate containing bidentate pyrrolyl ligand: Synthesis, structure, and catalytic activity for the Tishchenko reaction
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An novel sodium organoaluminate containing bidentate pyrrolyl ligand [C4H3NH(2-CH2NHtBu)] was efficiently synthesized and characterized by X-ray crystallography. The molecular structure shows it is a monodimensional infinite chain structures with linear arrangements. Its basic repeat unit comprises the Al atom bonded to two deprotonated pyrrole rings and Na atom coordinated to of nitrogen atoms of –NtBu fragment, which undergoes further to coordinates a pyrrolyl ring of an adjacent molecule in a ?2-fasion. Furthermore, this sodium organoaluminate exhibited high catalytic activities for Tishchenko reaction.
- Liu, Yu,Guo, Zhiqiang,Wang, Yakong
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- Visible Light-Promoted Magnesium, Iron, and Nickel Catalysis Enabling C(sp3)-H Lactonization of 2-Alkylbenzoic Acids
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A mild and practical C(sp3)-H lactonization protocol has been achieved by merging photocatalysis and magnesium (iron, nickel) catalysis. A diverse range of 2-alkylbenzoic acids with a variety of substitution patterns could be transformed into the corresponding phthalide products. Based on the mechanistic experimentation and reported prior studies, a possible mechanism for the benzylic oxidative lactonization reaction was proposed with the hypothetic photoactive ternary complex formed between the 2-alkylbenzoic acid substrate, magnesium ion, and bromate anion.
- Li, Sasa,Su, Mincong,Sun, Jie,Hu, Kunjun,Jin, Jian
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supporting information
p. 5842 - 5847
(2021/07/31)
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- Aniline-Type Hypervalent Iodine(III) for Intramolecular Cyclization via C?H Bond Abstraction of Hydrocarbons Containing N- and O-Nucleophiles
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We developed a method for the preparation of (diacetoxyiodo)-2-(N-alkylamido)benzene as an aniline-type hypervalent iodine(III). We also achieved direct cyclizations via C?H bond abstraction, such as the Hofmann-L?ffler-Freytag reaction, a direct amination, and a direct lactonization, using the aniline-type hypervalent iodine(III) to obtain corresponding products in high yields. (Figure presented.).
- Nishiguchi, Yuna,Moriyama, Katsuhiko
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supporting information
p. 3354 - 3358
(2021/05/17)
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- Squaramide-catalyzed asymmetric intramolecular oxa-michael reaction of α,β-unsaturated carbonyls containing benzyl alcohol: Construction of chiral 1-substituted phthalans
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Organocatalytic enantioselective intramolecular oxa-Michael reactions of benzyl alcohol bearing α,β-unsaturated carbonyls as Michael acceptors are presented herein. Using cinchona squaramide-based organocatalyst, enones as well as α,βunsaturated esters containing benzyl alcohol provided their corresponding 1,3-dihydroisobenzofuranyl-1-methylene ketones and 1,3-dihydroisobenzofuranyl-1-methylene esters in excellent yields with high enantioselectivities. In addition, enantioenriched 1,3-dihydroisobenzofuranyl-1-methylene ketone could be obtained from the Wittig/oxa-Michael reaction cascade of 1,3-dihydro-2-benzofuran-1-ol.
- Son, Eun Chae,Kim, Seung Yeon,Kim, Sung-Gon
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p. 6826 - 6839
(2021/05/29)
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- Enantioselective synthesis of 3-aryl-phthalides through a nickel-catalyzed stereoconvergent cross-coupling reaction
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A nickel-catalyzed asymmetric Suzuki-Miyaura cross-coupling of racemic 3-bromo-phthalides and arylboronic acids was realized for the synthesis of diverse chiral 3-aryl-phthalides in moderate to excellent reaction yields. The reaction proceeded in a stereoconvergent manner and high enantioselectivities were observed for most examined examples. A number of functional groups like aldehyde, ester and bromide were well tolerated. Heteroaromatic boronic acids were also competent coupling partners in this reaction.
- Feng, Chen-Guo,Xu, Si-Yu,Zhang, Rui,Zhang, Shu-Sheng
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supporting information
p. 4492 - 4496
(2021/05/31)
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- Organocatalytic enantioselective synthesis of phthalans via Wittig/oxa-Michael cascade reaction
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An enantioselective synthetic method for 1-substituted phthalans has been developed. The organocatalytic reaction between 1,3-dihydro-2-benzofuran-1-ols and Wittig reagents using cinchona squaramide-based organocatalyst proceeded with sequential Wittig reaction followed by an enantioselective intramolecular oxa-Michael reaction, yielding enantioenriched phthalans with moderate to good enantioselectivities.
- Son, Eun Chae,No, Jaeeun,Kim, Sung-Gon
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p. 1473 - 1480
(2021/09/25)
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- Azolium Control of the Osmium-Promoted Aromatic C-H Bond Activation in 1,3-Disubstituted Substrates
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The hexahydride complex OsH6(PiPr3)2 promotes the C-H bond activation of the 1,3-disubstituted phenyl group of the [BF4]- and [BPh4]- salts of the cations 1-(3-(isoquinolin-1-yl)phenyl)-3-methylimidazolium and 1-(3-(isoquinolin-1-yl)phenyl)-3-methylbenzimidazolium. The reactions selectively afford neutral and cationic trihydride-osmium(IV) derivatives bearing κ2-C,N- or κ2-C,C-chelating ligands, a cationic dihydride-osmium(IV) complex stabilized by a κ3-C,C,N-pincer group, and a bimetallic hexahydride formed by two trihydride-osmium(IV) fragments. The metal centers of the hexahydride are separated by a bridging ligand, composed of κ2-C,N- and κ2-C,C-chelating moieties, which allows electronic communication between the metal centers. The wide variety of obtained compounds and the high selectivity observed in their formation is a consequence of the main role of the azolium group during the activation and of the existence of significant differences in behavior between the azolium groups. The azolium role is governed by the anion of the salt, whereas the azolium behavior depends upon its imidazolium or benzimidazolium nature. While [BF4]- inhibits the azolium reactions, [BPh4]- favors the azolium participation in the activation process. In contrast to benzimidazolylidene, the imidazolylidene resulting from the deprotonation of the imidazolium substituent coordinates in an abnormal fashion to direct the phenyl C-H bond activation to the 2-position. The hydride ligands of the cationic dihydride-osmium(IV) pincer complex display intense quantum mechanical exchange coupling. Furthermore, this salt is a red phosphorescent emitter upon photoexcitation and displays a noticeable catalytic activity for the dehydrogenation of 1-phenylethanol to acetophenone and of 1,2-phenylenedimethanol to 1-isobenzofuranone. The bimetallic hexahydride shows catalytic synergism between the metals, in the dehydrogenation of 1,2,3,4-tetrahydroisoquinoline and alcohols.
- Cancela, Lara,Esteruelas, Miguel A.,Oliván, Montserrat,O?ate, Enrique
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p. 3979 - 3991
(2021/12/02)
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- A Proton-Responsive Pyridyl(benzamide)-Functionalized NHC Ligand on Ir Complex for Alkylation of Ketones and Secondary Alcohols
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A Cp*Ir(III) complex (1) of a newly designed ligand L1 featuring a proton-responsive pyridyl(benzamide) appended on N-heterocyclic carbene (NHC) has been synthesized. The molecular structure of 1 reveals a dearomatized form of the ligand. The protonation of 1 with HBF4 in tetrahydrofuran gives the corresponding aromatized complex [Cp*Ir(L1H)Cl]BF4 (2). Both compounds are characterized spectroscopically and by X-ray crystallography. The protonation of 1 with acid is examined by 1H NMR and UV-vis spectra. The proton-responsive character of 1 is exploited for catalyzing α-alkylation of ketones and β-alkylation of secondary alcohols using primary alcohols as alkylating agents through hydrogen-borrowing methodology. Compound 1 is an effective catalyst for these reactions and exhibits a superior activity in comparison to a structurally similar iridium complex [Cp*Ir(L2)Cl]PF6 (3) lacking a proton-responsive pendant amide moiety. The catalytic alkylation is characterized by a wide substrate scope, low catalyst and base loadings, and a short reaction time. The catalytic efficacy of 1 is also demonstrated for the syntheses of quinoline and lactone derivatives via acceptorless dehydrogenation, and selective alkylation of two steroids, pregnenolone and testosterone. Detailed mechanistic investigations and DFT calculations substantiate the role of the proton-responsive ligand in the hydrogen-borrowing process.
- Kaur, Mandeep,U Din Reshi, Noor,Patra, Kamaless,Bhattacherya, Arindom,Kunnikuruvan, Sooraj,Bera, Jitendra K.
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supporting information
p. 10737 - 10748
(2021/06/15)
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- Uranyl(VI) Triflate as Catalyst for the Meerwein-Ponndorf-Verley Reaction
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Catalytic transformation of oxygenated compounds is challenging in f-element chemistry due to the high oxophilicity of the f-block metals. We report here the first Meerwein-Ponndorf-Verley (MPV) reduction of carbonyl substrates with uranium-based catalysts, in particular from a series of uranyl(VI) compounds where [UO2(OTf)2] (1) displays the greatest efficiency (OTf = trifluoromethanesulfonate). [UO2(OTf)2] reduces a series of aromatic and aliphatic aldehydes and ketones into their corresponding alcohols with moderate to excellent yields, using iPrOH as a solvent and a reductant. The reaction proceeds under mild conditions (80 °C) with an optimized catalytic charge of 2.3 mol % and KOiPr as a cocatalyst. The reduction of aldehydes (1-10 h) is faster than that of ketones (>15 h). NMR investigations clearly evidence the formation of hemiacetal intermediates with aldehydes, while they are not formed with ketones.
- Kobylarski, Marie,Monsigny, Louis,Thuéry, Pierre,Berthet, Jean-Claude,Cantat, Thibault
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supporting information
p. 16140 - 16148
(2021/11/01)
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- Chiral Bicyclic Imidazole-Catalyzed Acylative Dynamic Kinetic Resolution for the Synthesis of Chiral Phthalidyl Esters
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Utilizing a chiral bicyclic imidazole organocatalyst and adopting a continuous injection process, an alternative route has been developed for the efficient synthesis of chiral phthalidyl ester prodrugs via dynamic kinetic resolution of 3-hydroxyphthalides through enantioselective acylation (up to 99 % ee). The computational studies suggest a general base catalytic mechanism differing from the widely accepted nucleophilic catalytic mechanism. The structure analysis of the key transition states shows that the CH-π interactions and not the previously considered cation/π-π interactions between the catalyst and substrate is the dominant factor giving rise to the observed stereocontrol.
- Zhou, Muxing,Gridneva, Tatiana,Zhang, Zhenfeng,He, Ende,Liu, Yangang,Zhang, Wanbin
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supporting information
p. 1641 - 1645
(2020/11/30)
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- Conversion of Aryl Aldehydes to Benzyl Iodides and Diarylmethanes by H3PO3/I2
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For the first time, H3PO3 was used as both the reducing reagent and the promotor in the reductive benzylation reactions with aryl aldehydes. By using a H3PO3/I2 combination, various aromatic aldehydes underwent iodination reactions and Friedel-Crafts type reactions with arenes via benzyl iodide intermediates, readily producing benzyl iodides and diarylmethanes in good yields. Intramolecular cyclization reactions also took place, giving the corresponding cyclic compounds. This new strategy features easy-handling, low-cost, and metal-free conditions.
- Lv, Fang,Xiao, Jing,Xiang, Junchun,Guo, Fengzhe,Tang, Zi-Long,Han, Li-Biao
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p. 3081 - 3088
(2021/02/01)
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- Efficient hydrogenation of levulinic acid catalysed by spherical NHC-Ir assemblies with atmospheric pressure of hydrogen
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A practical, efficient, and mild hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) under 1 atm H2was realized by single-sited 3D porous self-supported N-heterocyclic carbene iridium catalysts. Quantitative yields and selectivities were achieved at 0.02 mol% catalyst loading, and the catalyst could be reused for 9 runs without obvious loss of selectivity or activity.
- Liu, Yaoqi,Lu, Zeye,Shen, Lingyun,Tu, Tao,Wu, Jiajie,Zheng, Qingshu
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supporting information
p. 5037 - 5042
(2021/07/29)
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- Metal-Free Cascade Formation of Intermolecular C-N Bonds Accessing Substituted Isoindolinones under Cathodic Reduction
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An electrochemical protocol for the construction of substituted isoindolinones via reduction/amidation of 2-carboxybenzaldehydes and amines has been realized. Under metal-free and external-reductant-free electrolytic conditions, the reaction achieves the cascade formation of intermolecular C-N bonds and provides a series of isoindolinones in moderate to good yields. The deuterium-labeling experiment proves that the hydrogen in the methylene of the product is mainly provided by H2O in the system.
- Zou, Zirong,Cai, Genuo,Chen, Weihao,Zou, Canlin,Li, Yamei,Wu, Hongting,Chen, Lu,Hu, Jinhui,Li, Yibiao,Huang, Yubing
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p. 15777 - 15784
(2021/11/17)
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- Redox deracemization of α-substituted 1,3-dihydroisobenzofurans
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Chiral α-substituted 1,3-dihydroisobenzofurans are key scaffolds in a number of bioactive natural products and synthetic pharmaceuticals. However, catalytic asymmetric approaches have been rarely developed. Here, a redox deracemization technology is adopted to address the catalytic asymmetric synthesis. A broad range of α-aryl substituted 1,3-dihydroisobenzofurans are effectively deracemized in high efficiency with excellent ee. α-Alkynyl substituted ethers were also compatible with the deracemization technology.
- Chen, Xiaohan,Zhao, Ran,Liu, Ziqiang,Sun, Shutao,Ma, Yingang,Liu, Qingyun,Sun, Xia,Liu, Lei
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supporting information
p. 2305 - 2308
(2021/03/08)
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- Palladium-Catalyzed Distal m-C-H Functionalization of Arylacetic Acid Derivatives
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Herein, we present m-C-H olefination on derivatives of phenylacetic acids by tethering with a simple nitrile-based template through palladium catalysis. Notably, the versatility of the method is evaluated with a wide range of phenylacetic acid derivatives for obtaining the meta-olefination products in fair to excellent yields with outstanding selectivities under mild conditions. Significantly, the present strategy is successfully exemplified for the synthesis of drugs/natural product analogues (naproxen, ibuprofen, paracetamol, and cholesterol).
- Srinivas, Dasari,Satyanarayana, Gedu
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supporting information
p. 7353 - 7358
(2021/10/01)
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- α-Angelica lactone catalyzed oxidation of benzylic sp3C-H bonds of isochromans and phthalans
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A metal-free organocatalytic system has been developed for highly efficient benzylic C-H oxygenations of cyclic ethers using oxygen as an oxidant. This oxidation reaction utilizes α-angelica lactone as a low cost/low molecular weight catalyst. The optimized reaction conditions allow the synthesis of valued isocoumarins and phthalides from readily available precursors in good yields. Mechanistic studies indicate that the reaction pathway likely involves a radical processviaa peroxide intermediate.
- Das, Utpal,Deepake, Siddharth K.,Kumar, Pawan,Thatikonda, Thanusha
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supporting information
p. 4046 - 4050
(2020/06/09)
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- Green Organic Solvent-Free Oxidation of Alkylarenes with tert-Butyl Hydroperoxide Catalyzed by Water-Soluble Copper Complex
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Different benzylic compounds were efficiently oxidized to the corresponding ketones with aqueous 70% tert-butyl hydroperoxide (TBHP) and the catalytic system composed of CuCl2.2H2O and 2,2'-biquinoline-4,4'-dicarboxylic acid dipotassium salt (BQC). The catalytic system CuCl2/BQC/TBHP allows obtaining high yields at room temperature under organic solvent-free conditions. The interest of this system lies in its cost effectiveness and its benign nature towards the environment. Benzylic tertbutylperoxy ethers and benzylic alcohols were observed and suggested as the reaction intermediates. Analysis of organic products by atomic absorption did not show any contamination with copper metal. In terms of efficiency, CuCl2/BQC system is comparable or superior to the most of the catalytic systems described in the literature and which are based on toxic organic solvent.
- Ajjou, Abdelaziz Nait,Rahman, Ateeq
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p. 165 - 174
(2020/04/15)
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- Selective aerobic oxidation of cyclic ethers to lactones over Au/CeO2 without any additives
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Selective oxidation of ethers to lactones with O2 as a benign oxidant using Au/CeO2 as the catalyst has been developed. The oxygen vacancies and Au0 species on the surface of CeO2 contribute to the activation of O2. The excellent selectivity of lactones is due to the adsorption of ethers and activation of the C(sp3)-H bond on Au/CeO2.
- Liu, Shulin,Li, Shaopeng,Shen, Xiaojun,Wang, Yanyan,Du, Juan,Chen, Bingfeng,Han, Buxing,Liu, Huizhen
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supporting information
p. 2638 - 2641
(2020/03/10)
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- Palladium aminopyridine complexes catalyzed selective benzylic C-H oxidations with peracetic acid
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Four palladium(ii) complexes with tripodal ligands of the tpa family (tpa = tris(2-pyridylmethyl)amine) have been synthesized and X-ray characterized. These complexes efficiently catalyze benzylic C-H oxidation of various substrates with peracetic acid, affording the corresponding ketones in high yields (up to 100%), at 1 mol% catalyst loadings. Complex [(tpa)Pd(OAc)](PF6) with the least sterically demanding ligand tpa demonstrates the highest substrate conversions and ketone selectivities. Preliminary mechanistic data provide evidence in favor of metal complex-mediated rate-limiting benzylic C-H bond cleavage by an electron-deficient oxidant.
- Bryliakov, Konstantin P.,Lubov, Dmitry P.,Lyakin, Oleg Yu.,Rybalova, Tatyana V.,Samsonenko, Denis G.,Talsi, Evgenii P.
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supporting information
p. 11150 - 11156
(2020/09/02)
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- Novel HDAC/tubulin dual inhibitor: Design, synthesis and docking studies of α-phthalimidochalcone hybrids as potential anticancer agents with apoptosis-inducing activity
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Introduction: In order to develop novel anticancer HDAC/tubulin dual inhibitors, a novel series of α-phthalimido-substituted chalcones-based hybrids was synthesized and characterized by IR,1H NMR,13C NMR, mass spectroscopy and X-ray analysis. Methods: All the synthesized compounds were evaluated for their in vitro anticancer activity against MCF-7 and HepG2 human cancer cell lines using MTT assay. To explore the mechanism of action of the synthesized compounds, in vitro β-tubulin polymerization and HDAC 1 and 2 inhibitory activity were measured for the most potent anticancer hybrids. Further, cell cycle analysis was also evaluated. Results: The trimethoxy derivative 7j showed the most potent anticancer activity, possessed the most potent β-tubulin polymerase and HDAC 1 and 2 inhibitory activity and efficiently induced cell cycle arrest at both G2/M and preG1phases in the MCF-7 cell line.
- Jones, Peter G.,Mourad, Ahmed A E.,Mourad, Mai A E.
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p. 3111 - 3130
(2020/08/07)
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- Enhancing insulin sensitivity by dual PPARγ partial agonist, β-catenin inhibitor: Design, synthesis of new αphthalimido-o-toluoyl2-aminothiazole hybrids
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Aims: Partial PPARγ agonists attracted substantially heightened interest as safer thiazolidinediones alternatives. On the other hand, Wnt/β-catenin antagonists have been highlighted as promising strategy for type 2 diabetes management via up-regulating PPARγ gene expression. We aimed at synthesizing novel partial PPARγ agonists with β-catenin inhibitory activity which could enhance insulin sensitivity and avoid the side effects of full PPARγ agonists. Main methods: We synthesized novel series of α-phthlimido-o-toluoyl-2-aminothiazoles hybrids for evaluating their antidiabetic activity and discovering its mechanistic pathway. We assessed effect of the new hybrids on PPARγ activation using a luciferase reporter assay system. Moreover, intracellular triglyceride levels, gene levels of c/EBPα, PPARγ and PPARγ targets including GLUT4, adiponectin, aP2 were measured in 3T3-L1 cells. Uptake of 2-DOG together with PPARγ and β-catenin protein levels were evaluated in 3T3-L1cells. In addition, molecular docking studies with PPARγ LBD, physicochemical properties and structure activity relationship of the novel hybrids were also studied. Key findings: Three of the synthesized hybrids showed partial PPARγ agonistic activity and distinct PPARγ binding pattern. These compounds modulated PPARγ gene expression and PPARγ target genes; and increased glucose uptake in 3T3-L1 and slightly induced adipogenesis compared to rosiglitazone. Moreover, these compounds reduced β-catenin protein level which reflected in increased both PPARγ gene and protein levels that leads to improved insulin sensitivity and increased GLUT4 and adiponectin gene expression. Significance: Our synthesized compounds act as novel partial PPARγ agonists and β-catenin inhibitors that have potent insulin sensitizing activity and mitigate the lipogenic side effects of TZDs.
- Mourad, Ahmed A. E.,Mourad, Mai A. E.
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- Method for preparing o-toluic acid and phthalide from phthalic anhydride
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The invention provides a method for preparing o-toluic acid and phthalide from phthalic anhydride. The method comprises the following steps: carrying out a hydrogenation reaction on hydrogen and phthalic anhydride in the presence of a hydrogenation catalyst to prepare o-toluic acid and phthalide, wherein the reaction temperature is 120-180 DEG C, the reaction pressure is 1-6 MPa, and the mass ratio of the phthalic anhydride to the hydrogenation catalyst is (1:0.01)-(1:0.15). According to the method provided by the invention, selectivity of products of o-toluic acid and phthalide can be effectively controlled through control of reaction conditions.
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Paragraph 0054-0085
(2020/02/14)
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- Ligand-enabled pd(ii)-catalyzed c(sp3)-h lactonization using molecular oxygen as oxidant
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Pd(II)-catalyzed C-H lactonization of o-methyl benzoic acid substrates has been achieved using molecular oxygen as the oxidant. This finding provides a rare example of C-H oxygenation through Pd(II)/Pd(0) catalysis as well as a method to construct biologically important benzolactone scaffolds. The use of a gas mixture of 5% oxygen in nitrogen demonstrated the possibility for its application in pharmaceutical manufacturing.
- Qian, Shaoqun,Li, Zi-Qi,Li, Minyan,Wisniewski, Steven R.,Qiao, Jennifer X.,Richter, Jeremy M.,Ewing, William R.,Eastgate, Martin D.,Chen, Jason S.,Yu, Jin-Quan
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supporting information
p. 3960 - 3963
(2020/05/22)
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- Ruthenium-Catalyzed Dehydrogenation of Alcohols with Carbodiimide via a Hydrogen Transfer Mechanism
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Ruthenium-catalyzed oxidative dehydrogenation of alcohols using carbodiimide as an efficient hydrogen acceptor has been developed. The protocol exhibits wide substrate scope with good to excellent yields. The results of the kinetic analysis indicated that the reaction mechanism includes the hydrogen transfer process and that the addition of carbodiimide is essential for the reaction system, and the resulting amidine also could react as a hydrogen acceptor.
- Sueki, Shunsuke,Matsuyama, Mizuki,Watanabe, Azumi,Kanemaki, Arata,Katakawa, Kazuaki,Anada, Masahiro
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p. 4878 - 4885
(2020/06/02)
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- (Cyclopentadienone)iron-Catalyzed Transfer Dehydrogenation of Symmetrical and Unsymmetrical Diols to Lactones
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Air-stable iron carbonyl compounds bearing cyclopentadienone ligands with varying substitution were explored as catalysts in dehydrogenative diol lactonization reactions using acetone as both the solvent and hydrogen acceptor. Two catalysts with trimethylsilyl groups in the 2- A nd 5-positions, [2,5-(SiMe3)2-3,4-(CH2)4(δ4-C4C= O)]Fe(CO)3 (1) and [2,5-(SiMe3)2-3,4-(CH2)3(δ4-C4C= O)]Fe(CO)3 (2), were found to be the most active, with 2 being the most selective in the lactonization of diols containing both primary and secondary alcohols. Lactones containing five-, six-, and seven-membered rings were successfully synthesized, and no over-oxidations to carboxylic acids were detected. The lactonization of unsymmetrical diols containing two primary alcohols occurred with catalyst 1, but selectivity was low based on alcohol electronics and modest based on alcohol sterics. Evidence for a transfer dehydrogenation mechanism was found, and insight into the origin of selectivity in the lactonization of 1°/2° diols was obtained. Additionally, spectroscopic evidence for a trimethylamine-ligated iron species formed in solution during the reaction was discovered.
- Tang, Yidan,Meador, Rowan I. L.,Malinchak, Casina T.,Harrison, Emily E.,McCaskey, Kimberly A.,Hempel, Melanie C.,Funk, Timothy W.
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p. 1823 - 1834
(2020/02/04)
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- Cyclometalated Ruthenium Pincer Complexes as Catalysts for the α-Alkylation of Ketones with Alcohols
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Ruthenium PNP pincer complexes bearing supplementary cyclometalated C,N-bound ligands have been prepared and fully characterized for the first time. By replacing CO and H? as ancillary ligands in such complexes, additional electronic and steric modifications of this topical class of catalysts are possible. The advantages of the new catalysts are demonstrated in the general α-alkylation of ketones with alcohols following a hydrogen autotransfer protocol. Herein, various aliphatic and benzylic alcohols were applied as green alkylating agents for ketones bearing aromatic, heteroaromatic or aliphatic substituents as well as cyclic ones. Mechanistic investigations revealed that during catalysis, Ru carboxylate complexes are predominantly formed whereas neither the PNP nor the CN ligand are released from the catalyst in significant amounts.
- Piehl, Patrick,Amuso, Roberta,Alberico, Elisabetta,Junge, Henrik,Gabriele, Bartolo,Neumann, Helfried,Beller, Matthias
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p. 6050 - 6055
(2020/03/13)
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- Electron-rich phenoxyl mediators improve thermodynamic performance of electrocatalytic alcohol oxidation with an iridium pincer complex
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Electron-rich phenols, including α-rac-tocopherol Ar1OH, 2,4,6,-tri-tert-butylphenol Ar3OH, and butylated hydroxy-toluene Ar4OH, are effective electrochemical mediators for the electrocatalytic oxidation of alcohols by an iridium amido dihyride complex (PNP)Ir(H)2 (IrN 1, PNP = bis[2-diisopropylphosphino)ethyl]amide). Addition of phenol mediators leads to a decrease in the onset potential of catalysis from -0.65 V vs Fc+/0 under unmediated conditions to -1.07 V vs Fc+/0 in the presence of phenols. Mechanistic analysis suggests that oxidative turnover of the iridium amino trihydride (PNHP)Ir(H)3 (IrH 2, PNHP = bis[2-diisopropylphosphino)ethyl]amine) to IrN 1 proceeds through two successive hydrogen atom transfers (HAT) to 2 equiv of phenoxyl that are generated transiently at the anode. Isotope studies and comparison to known systems are consistent with initial homolysis of an Ir-H bond being rate-determining. Turnover frequencies up to 14.6 s-1 and an average Faradaic efficiency of 93% are observed. The mediated system shows excellent chemoselectivity in bulk oxidations of 2-propanol and 1,2-benzenedimethanol in THF and is also viable in neat 2-propanol.
- Galvin, Conor M.,Waymouth, Robert M.
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supporting information
p. 19368 - 19378
(2020/12/01)
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- Metal-Free Direct Deoxygenative Borylation of Aldehydes and Ketones
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Direct conversion of aldehydes and ketones into alkylboronic esters via deoxygenative borylation represents an unknown yet highly desirable transformation. Herein, we present a one-step and metal-free method for carbonyl deoxy-borylation under mild conditions. A wide range of aromatic aldehydes and ketones are tolerated and successfully converted into the corresponding benzylboronates. By the same deoxygenation manifold with aliphatic aldehydes and ketones, we also enable a concise synthesis of 1,1,2-tris(boronates), a family of compounds that currently lack efficient synthetic methods. Given its simplicity and versatility, we expect that this novel borylation approach could show great promise in organoboron synthesis and inspire more carbonyl deoxygenative transformations in both academic and industrial settings.
- Huang, Chia-Yu,Li, Chao-Jun,Li, Jianbin,Qiu, Zihang,Wang, Haining
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supporting information
p. 13011 - 13020
(2020/09/01)
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- DIELS-ALDER REACTION WITH FURANICS TO OBTAIN AROMATICS
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The present invention is directed to the preparation of phthalic anhydride compounds and the intermediate phthalide compounds. In particular, the invention is directed to an improved bio-based route from furanic compounds to phthalic anhydride compounds by reacting furfuryl alcohol (i.e. 2-hydroxymethylfuran) or an analogue thereof having a nucleophilic atom on the 2-methyl, with a dienophile comprising an α,β-unsaturated carbonyl comprising an α'-leaving group. The inventions further involved preparation of phthalic anhydride compounds, phthalic acid compounds and reduction products of the intermediate phthalide compounds.
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Page/Page column 15-16
(2020/03/23)
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- Manganese catalyzed selective hydrogenation of cyclic imides to diols and amines
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Herein we report the selective hydrogenation of cyclic imides to diols and amines, homogeneously catalyzed for the first time by a complex of an earth-abundant metal, a manganese pincer complex. A plausible catalytic cycle is proposed based on informative mechanistic experiments.
- Das, Uttam Kumar,Janes, Trevor,Kumar, Amit,Milstein, David
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supporting information
p. 3079 - 3082
(2020/06/19)
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- Method for synthesizing 3 - n -butyl - l (3H)-isobenzofuranone (by machine translation)
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The invention discloses a method for synthesizing 3 - n -butyl - l (3H)-isobenzofuranone, firstly mixing Grignard reagent with Lewis acid, adjusting pH to acidity by an acid reagent, extracting with an organic solvent, concentrating and removing an organic solvent to obtain 3 - n -butyl - l (3H)-isobenzofuranone. (by machine translation)
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Paragraph 0044-0052; 0056; 0057
(2020/07/24)
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- Synthesis of 3-Unsubstituted Phthalides from Aryl Amides and Paraformaldehyde via Ruthenium(II)-Catalyzed C–H Activation
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A straightforward and convenient route has been developed for the synthesis of 3-unsubstituted phthalide derivatives from aryl amides and paraformaldehyde by ruthenium(II)-catalyzed C–H activation. The reaction proceeds through tandem ortho-hydroxymethylation of aryl amide and subsequent intramolecular lactonization.
- Zhou, Chao,Zhao, Junqi,Chen, Wenkun,Imerhasan, Mukhtar,Wang, Jun
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supporting information
p. 6485 - 6488
(2020/10/02)
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- Dynamic Trapping as a Selective Route to Renewable Phthalide from Biomass-Derived Furfuryl Alcohol
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A novel route for the production of the versatile chemical building block phthalide from biorenewable furfuryl alcohol and acrylate esters is presented. Two challenges that limit sustainable aromatics production via Diels–Alder (DA) aromatisation—an unfavourable equilibrium position and undesired regioselectivity when using asymmetric addends—were addressed using a dynamic kinetic trapping strategy. Activated acrylates were used to speed up the forward and reverse DA reactions, allowing for one of the four DA adducts to undergo a selective intramolecular lactonisation reaction in the presence of a weak base. The adduct is removed from the equilibrium pool, pulling the system completely to the product with a fixed, desired regiochemistry. A single 1,2-regioisomeric lactone product was formed in up to 86 % yield and the acrylate activating agent liberated for reuse. The lactone was aromatised to give phthalide in almost quantitative yield in the presence of Ac2O and a catalytic amount of strong acid, or in 79 % using only catalytic acid.
- Lancefield, Christopher S.,F?lker, Bart,Cioc, Razvan C.,Stanciakova, Katarina,Bulo, Rosa E.,Lutz, Martin,Crockatt, Marc,Bruijnincx, Pieter C. A.
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supporting information
p. 23480 - 23484
(2020/10/19)
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- Aqueous Flow Hydroxycarbonylation of Aryl Halides Catalyzed by an Amphiphilic Polymer-Supported Palladium-Diphenylphosphine Catalyst
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An aqueous continuous-flow reaction system is developed for the palladium-catalyzed hydroxycarbonylation of aryl halides. Flow hydroxycarbonylation of aryl halides in aqueous solution proceeds efficiently in a flow reactor containing a palladium-diphenylphosphine complex immobilized on an amphiphilic polystyrene-poly(ethylene glycol) resin to give the corresponding benzoic acids in excellent yields.
- Osako, Takao,Kaiser, Reinhard,Torii, Kaoru,Uozumi, Yasuhiro
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p. 961 - 966
(2019/05/10)
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- Cu(I)-Based Metal-Organic Frameworks as Efficient and Recyclable Heterogeneous Catalysts for Aqueous-Medium C-H Oxidation
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The enantioselective transformation of ubiquitous C-H bonds into valuable C-O bonds offers an efficient synthetic approach to construct carbonyl functionalized molecules. However, the grand obstacles in the reaction are the selectivity issues and side reactions under the harsh reaction conditions. In order to overcome the limits, two Cu(I)-based MOFs {(NEt4)0.5[Cu3(TTPB)0.75(CN)0.5(H2O)]·H2O}n (1) and {[Cu2(TTPB)0.5]·DMF·2H2O}n (2) were synthesized (H4TTPB = 5,5′-(4′,5′-bis(4-(1H-tetrazol-5-yl)phenyl)-[1,1′:2′,1′′-terphenyl]-4,4′′-diyl) bis(1H-tetrazole)) under hydrothermal conditions with (triethylamine (TEA) and ethyldiisopropylamine (DIPEA) as structure-directing agents, respectively. Of these, 1 shows an anionic three-dimensional (3D) framework composed of two kinds of cagelike micropores with 7 × 17 ? and 10 × 17 ?, respectively. In comparison, 2 exhibits a 3D framework with open channels (14 × 8 ?). The stability studies showed that the crystallinity of 1 and 2 could remain in a series of organic solvents (ethanol, N,N-dimethylformamide, chloroform, dioxane, toluene) and acid and alkali aqueous solutions (pH = 1-13) at room temperature for 48 h. 1 and 2 with coordinatively unsaturated Cu(I) sites were applied as heterogeneous catalysts for the oxidation of arylacycloalkanes in aqueous medium and exhibited excellent catalytic activities, selectivities, and recyclabilities. Moreover, free-radical reaction mechanism and reversible valence-tautomeric conversions of central copper were confirmed during the process by control experiment.
- Gao, Kuan,Huang, Chao,Yang, Yisen,Li, Hong,Wu, Jie,Hou, Hongwei
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p. 976 - 982
(2019/02/15)
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- Functional Porous Organic Polymers Comprising a Triaminotriphenylazobenzene Subunit as a Platform for Copper-Catalyzed Aerobic C-H Oxidation
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Developing functional porous materials as a platform for the heterogeneous catalytic oxidation reaction provides a good way to solve the high environmental issues resulted by traditional oxidation processes in the industry. This article reported a design and facile synthesis of N-rich functional porous organic polymers with mesopores such as Azo-POP-4, Azo-POP-5, and Azo-POP-6 based on the triaminotriphenylazobenzene subunit for the first time. The nitrogen-rich POPs with the triaminotriphenylazobenzene subunit was found to remove 85% of copper ions from water within 30 min. The as-synthesized Cu@Azo-POP-4 demonstrated high catalytic reactivity and selectivity in aerobic C-H bond oxidation to afford the desired ketones in high yield. In addition, the catalyst could be reused easily five times without decreasing the reactivity, which will help to design catalysts reducing environmental pollution and advance the chemical technology.
- Liu, Xiangxiang,Luo, Xian-Sheng,Deng, Han-Lin,Fan, Wenhao,Wang, Shuifeng,Yang, Chaojie,Sun, Xiao-Yu,Chen, Shi-Lu,Huang, Mu-Hua
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p. 5421 - 5430
(2019/08/20)
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- Co(ii)-cluster-based metal-organic frameworks as efficient heterogeneous catalysts for selective oxidation of arylalkanes
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To explore metal-organic frameworks (MOFs) based on Co-clusters as heterogeneous catalysts to selectively catalyze the reaction of C-H bond oxidation of aromatic alkanes to their corresponding ketones, three MOFs {[Co5(pmbcd)2(μ3-OH)2(H2O)4(DMF)2]·4DMF}n (MOF 1), {[Co2(pmbcd)(bpea)2]·2H2O·2DMF}n (MOF 2), and {[Co2(pmbcd)(dpp)2]·3H2O·2DMF}n (MOF 3) (H4pmbcd = 9,9′-(1,4-phenylenebis(methylene))bis(9H-carbazole-3,6-dicarboxylic acid), bpea = 1,2-bis(4-pyridyl)ethane, dpp = 1,3-di(4-pyridyl)propane) were successfully synthesized and structurally characterized. MOF 1 was constructed from a pentanuclear Co(ii) cluster and exhibited a porous framework with channels of 8 × 10 ?2 along the b axis. MOF 2 was constructed from [Co2(CO2)4] units and presented a porous three-dimensional (3D) framework with channels of 11 × 13 ?2 along the b axis and of 10 × 12 ?2 along the c axis. MOF 3 was a flat two-dimensional (2D) layer based on binuclear Co(ii) units when dpp as an auxiliary ligand was introduced. The Co5-cluster-based MOF 1 exhibited excellent catalytic activity for the direct C-H bond activation of arylalkanes to ketones in H2O under room temperature because of its high density of Lewis acidic sites within the frameworks and suitable channel size to access the catalytic sites. It also presented the spatial confinement effect and catalyzed the reaction with high regioselectivity, forming mono-ketones as the sole products. Easy product separation, simple reaction procedures, and recyclability of these catalysts make the catalytic system attractive. Our work highlights the superiority of the MOF-based materials as heterogeneous catalysts.
- Fan, Yanru,Li, Xiao,Gao, Kuan,Liu, Yu,Meng, Xiangru,Wu, Jie,Hou, Hongwei
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p. 1666 - 1673
(2019/03/07)
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- Cercosporin-bioinspired selective photooxidation reactions under mild conditions
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The development of an efficient system for selective oxidation of organic compounds to generate more valuable compounds with molecular oxygen is a significant challenge in industrial chemistry. Bioinspired by the ability of naturally occurring perylenequinonoid pigments (PQPs) to generate reactive oxygen species (ROS) upon photoirradiation, here we report that cercosporin, one of the perylenequinonoid pigments, can function as a cost-effective and environmentally friendly photocatalyst for a wide range of selective oxidations, including benzylic C-H bonds to carbonyls, amines to aldehydes, and sulfides to sulfoxides. All of the representative reactions proceeded smoothly with high efficiency under mild conditions. Owing to the use of inexpensive metal-free visible light-driven photocatalyst produced from microbial fermentation with cheap glucose as the starting material and the ease of handling, we expect that this developed method will be particularly attractive for many more applications in synthetic transformation.
- Li, Jia,Bao, Wenhao,Tang, Zhaocheng,Guo, Baodang,Zhang, Shiwei,Liu, Haili,Huang, Shuping,Zhang, Yan,Rao, Yijian
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supporting information
p. 6073 - 6081
(2019/11/20)
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- A g-C3N4-based heterogeneous photocatalyst for visible light mediated aerobic benzylic C-H oxygenations
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A metal-free heterogeneous photocatalytic system has been developed for highly efficient benzylic C-H oxygenations using oxygen as an oxidant. This visible light mediated oxidation reaction utilizes graphitic carbon nitride (g-C3N4) as a recyclable, nontoxic and low cost photocatalyst. Mild reaction conditions allow for the generation of synthetically and biologically valued isochromannones, phthalides, isoquinolinones, isoindolinones and xanthones from readily accessible alkyl aromatic precursors in good yields. The heterogeneous nature of the g-C3N4 catalytic system enables easy recovery and recycling as well as the use in multiple runs without loss of activity. The synthetic utility of this "green" methodology was further demonstrated by applying in bioactive and drug valued target syntheses.
- Geng, Pengxin,Tang, Yurong,Pan, Guanglong,Wang, Wentao,Hu, Jinchuan,Cai, Yunfei
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supporting information
p. 6116 - 6122
(2019/11/20)
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- Thiyl radical promoted iron-catalyzed-selective oxidation of benzylic sp3 C-H bonds with molecular oxygen
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A ligand-free iron-catalyzed method for the oxygenation of benzylic sp3 C-H bonds by molecular oxygen (1 atm) using a thiyl radical as a cocatalyst has been developed. This transformation provides a facile access to amides, esters and ketones from readily accessible corresponding amines, ethers and alkanes. It features high regioselectivity, mild oxidative conditions and excellent functional group compatibility, providing good opportunities to the site-selective functionalization of complex molecules. Preliminary mechanistic studies suggest that this reaction may not undergo a benzylic cation intermediate pathway and the carbonyl oxygen atom in the products may be derived from molecular oxygen.
- Geng, Shasha,Xiong, Baojian,Zhang, Yun,Zhang, Juan,He, Yun,Feng, Zhang
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supporting information
p. 12699 - 12702
(2019/10/28)
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- Photochemical Reaction of o-Phthalaldehyde with Fullerene C60: The Stimulus for the Phthalide Additions to C60
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A new, simple, and rapid photochemical reaction of o-phthalaldehyde with C60 has been disclosed. This reaction afforded exclusively the unanticipated C60-phthalide derivative 11 in good yield. The formation of this product is consistent with the intervention of a key free-radical intermediate –a benzylic radical– in the course of the reaction. The structure of 11 has been determined by the combined use of experimental and theoretical NMR studies. In the course of this study we further disclosed a new mode of radical reactivity of C60 with a series of substituted phthalides (2, 15–17) catalyzed by tetrabutylammonium decatungstate.
- Tzirakis, Manolis D.,Malliaros, Nikitas G.,Orfanopoulos, Michael
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p. 6961 - 6967
(2019/11/13)
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- Organoaluminum cations for carbonyl activation
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In search of stable, yet reactive aluminum Lewis acids, we have isolated an organoaluminum cation, [(Me2NC6H4)2Al(C4H8O)2]+, coordinated with two labile tetrahydrofuran ligands. Its catalytic performance in aldehyde dimerization reveals turn-over frequencies reaching up to 6000 h-1, exceeding that of the reported main group catalysts. The cation is further demonstrated to catalyze hydroelementation of ketones. Mechanistic investigations reveal that aldehyde dimerization and ketone hydrosilylation occur through carbonyl activation.
- Kannan, Ramkumar,Chambenahalli, Raju,Kumar, Sandeep,Krishna, Athul,Andrews, Alex P.,Jemmis, Eluvathingal D.,Venugopal, Ajay
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supporting information
p. 14629 - 14632
(2019/12/11)
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- Platinum-on-Carbon-Catalyzed Aqueous Oxidative Lactonization of Diols by Using Molecular Oxygen
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A lactonization of various diols catalyzed by platinum on carbon (Pt/C) in water under an atmosphere of molecular oxygen was developed. Derivatives of 1,4- 1,5- and 1,6-diols were transformed into the corresponding five-, six-, and seven-membered lactones by the present oxidative lactonization method.
- Ban, Kazuho,Sajiki, Hironao,Sawama, Yoshinari,Takakura, Ryoya
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supporting information
p. 1919 - 1923
(2019/09/30)
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