- Silica-embedded tert-butyldimethylsilyltrifluoromethanesulfonate catalysts as new solid acid catalysts
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Silica-embedded tert-butyldimethylsilyltrifluoromethanesulfonate catalysts were synthesized by a sol-gel method in acidified CCl4, using hexadecyltrimethyl-ammonium bromide as a surfactant. The catalysts were characterized by nitrogen adsorption-desorption isotherms at 77 K; TG-DTA; 1H, 13C, and 29Si solid state MAS/NMR; XRD; XPS; Raman spectroscopy; and FTIR after adsorption of NH3. The characterization data indicated mesoporous solids in which most of the silyl-triflate derivative keeps its integrity. The catalytic tests performed with the methyl ester of 1-cyclopentenylacetic acid in various solvents showed that the reaction selectively leads to 3-methylbenzaldehyde and is sensitive to the solvent accepting ability.
- Parvulescu,Gagea,Alifanti,Parvulescu,Parvulescu,Nae,Razus,Poncelet,Grange
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Read Online
- The decomposition of methyl hemiacetals of benzaldehyde in aqueous solution: A study of the effect of aromatic substitution
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The acid-base catalysed decomposition of hydrates and hemiacetals of carbonyl compounds are classical examples of reactions where (slow) proton transfer is coupled with heavy atom reorganization, i.e., C - O bond breaking and solvent reorganization. We have studied the influence of m- and p-substitution in the carbonyl electrophile on the kinetics of the acid and base catalysis of the decomposition of methyl hemiacetals of benzaldehyde. The experimental data are well described by three-dimensional More O'Ferrall - Jencks energy contour diagrams according to principles developed by Jencks (the BEMA HAPOTHLE). Thus, for acid catalysis, a Cordes cross-interaction coefficient pxy′ = ?ρ/?pKa = 0.15 indicates the coupled nature of the rate-limiting step in a class e mechanism, similar to conclusions reached from systematic substitution in the nucleophile. Our more extensive set of data for base catalysis permits a more rigorous analysis according to the BEMA HAPOTHLE. The data are consistent with a class n mechanism as also suggested earlier on the basis of substitution in the nucleophile. A slight upward curvature observed in the Hammett plots for the various catalysts is described by the direct correlation parameter py = ?ρ/?σ = -0.11. This second derivative demonstrates the concerted nature of the C - O bond cleavage and O-H formation in the transition state, which changes with changing substituent. A class n mechanism for base catalysis is also supported by the observation of a Cordes cross-interaction parameter pxy = ?ρ/?pKa = -?β/?σ = 0.03, which describes the experimentally observed decrease in Hammett ρ with increasing pKa of the catalyst. This change may be rationalized by the movement of a saddle point on a diagonal reaction coordinate in the energy contour diagram, as a resultant of shifts parallel and perpendicular to the coordinate, when the energy along one side of the diagram is changed. It is concluded that observed rate changes as a result of substitution in the electrophile are consistent with and present further confirmation of earlier suggested mechanisms of hemiacetal decomposition reactions.
- Engell, Karen M.,McClelland, Robert A.,Sorensen, Poul E.
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- A novel and active catalyst Ag/ZnO for oxidant-free dehydrogenation of alcohols
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Nano Ag/ZnO catalysts were prepared by varying load of Ag on ZnO supports using a new and very simple method. The structure of nano Ag/ZnO has been confirmed by various techniques. The Ag/ZnO with 7.4 × 10-5 mol% of Ag has pore size distribution about 2.74 nm and this nano Ag/ZnO is found to be the best catalyst for oxidation of primary and secondary benzyl alcohols into corresponding aldehydes and ketones in oxidant-free at the atmospheric pressure. The influence of various parameters such as: solvent, base, temperature, time of reaction, etc. has been systematically studied on nano Ag/ZnO catalyst.
- Hosseini-Sarvari, Mona,Ataee-Kachouei, Tahereh,Moeini, Fatemeh
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Read Online
- Selective Encapsulation and Unusual Stabilization of cis-Isomers by a Spherical Polyaromatic Cavity
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To explore new cavity functions, we herein employed cis-trans stereoisomers with a N=N, C=C, or C=N unit as guest indicators for a polyaromatic capsule. Thanks to the rigid, spherical cavity with a diameter of ～1 nm, azobenzene and stilbene derivatives ar
- Yuasa, Mana,Sumida, Ryuki,Tanaka, Yuya,Yoshizawa, Michito
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supporting information
(2022/02/02)
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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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- 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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- Gold Catalysts Can Generate Nitrone Intermediates from a Nitrosoarene/Alkene Mixture, Enabling Two Distinct Catalytic Reactions: A Nitroso-Activated Cycloheptatriene/Benzylidene Rearrangement
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Gold-catalyzed reactions of cycloheptatrienes with nitrosoarenes yield nitrone derivatives efficiently. This reaction sequence enables us to develop gold-catalyzed aerobic oxidations of cycloheptatrienes to afford benzaldehyde derivatives using CuCl and nitrosoarenes as co-catalysts (10-30 mol %). Our density functional theory calculations support a novel nitroso-activated rearrangement, tropylium → benzylidene. With the same nitrosoarenes, we developed their gold-catalyzed [2 + 2 + 1]-annulations between nitrosobenzene and two enol ethers to yield 5-alkoxyisoxazolidines using 1,4-cyclohexadienes as hydrogen donors.
- Cheng, Mu-Jeng,Kardile, Rahul Dadabhau,Kuo, Tung-Chun,Liu, Rai-Shung,More, Sayaji Arjun
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supporting information
p. 5506 - 5511
(2021/07/31)
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- The: In situ fabrication of ZIF-67 on titania-coated magnetic nanoparticles: A new platform for the immobilization of Pd(ii) with enhanced catalytic activity for organic transformations
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Considering the outstanding characteristics of metal organic frameworks (MOFs) and magnetic nanoparticles, herein we report a facile approach for the synthesis of a magnetic zeolitic-imidazolate-framework-supported palladium(ii) catalyst. In brief, zeolitic imidazolate framework-67 (ZIF-67) was successfully incorporated onto the surface of titania-coated magnetic nanoparticles using ethane-1,2-diamine as a linker, and then Pd(ii) was immobilized onto this. The resulting Pd@ZIF-67-Fe3O4-TiO2 catalyst possesses a high surface area (205 m2 g-1), a large pore volume (0.10 cm3 g-1), good magnetic responsivity (10.71 emu g-1), and high stability. A comparative analysis of Pd@ZIF-67-Fe3O4-TiO2 and Pd@Fe3O4-TiO2 catalysts for the oxidation, reduction, and oxidative deprotection of oximes was done to investigate the effects of ZIF-67 on the catalytic performance of Pd species. Substantial differences in activity and stability were observed in the presence of ZIF-67, suggesting that ZIF-67 plays an important role in enhancing the activity of Pd(ii). This superior catalytic activity and stability arises due to a synergistic effect between well-dispersed palladium species and highly porous ZIF-67, which was confirmed via XPS analysis. Moreover, the catalyst retains its structure, chemical environment, and good magnetic response even after five catalytic runs, as confirmed via FTIR, XRD, XPS, and VSM studies of reused catalyst samples.
- Kaur, Manpreet,Paul, Satya,Sharma, Chandan,Sharma, Sukanya
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p. 20309 - 20322
(2021/11/22)
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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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- 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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- 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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- A TEMPO-Functionalized Ordered Mesoporous Polymer as a Highly Active and Reusable Organocatalyst
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The properties of high stability, periodic porosity, and tunable nature of ordered mesoporous polymers make these materials ideal catalytic nanoreactors. However, their application in organocatalysis has been rarely explored. We report herein for the first time the incorporation of a versatile organocatalyst, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), into the pores of an FDU-type mesoporous polymer via a pore surface engineering strategy. The resulting FDU-15-TEMPO possesses a highly ordered mesoporous organic framework and enhanced stability, and shows excellent catalytic activity in the selective oxidation of alcohols and aerobic oxidative synthesis of 2-substituted benzoxazoles, benzimidazoles and benzothiazoles. Moreover, the catalyst can be easily recovered and reused for up to 7 consecutive cycles.
- Guo, Ying,Wang, Wei David,Li, Shengyu,Zhu, Yin,Wang, Xiaoyu,Liu, Xiao,Zhang, Yuan
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supporting information
p. 3689 - 3694
(2021/09/29)
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- A new porous Co(ii)-metal-organic framework for high sorption selectivity and affinity to CO2and efficient catalytic oxidation of benzyl alcohols to benzaldehydes
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Herein, we report a new 3D porous Co(ii)-based metal-organic framework catalyst (Me2NH2)2[Co3(L)2(H2O)2]·2DMF (MOF I), which has been successfully prepared by using Co(ii) ions and rigid V-shaped 3,5-di(2,4-dicarboxylphenyl)pyridine (H4L) via the solvothermal reaction. Structural analysis reveals that I displays a porous structure with the pore size of 16.2 × 7.2 ?2 based on the trinuclear [Co3(COO)4(H2O)2N2] secondary building units (SBUs). Gas sorption experiments on the guest free sample I′ reveals a high capacity and selectivity to CO2 over CH4. And further, the catalytic explorations of the I′-catalyzed system (I′: 3 mol%; proline: 40 mol%; CH3CN: 2 mL) reveal that benzyl alcohols with different structures can be efficiently transformed into benzyl alcohols without by-products under mild conditions.
- Wu, Yun-Long,Yang, Rong-Rong,Yang, Guo-Ping,Yan, Yang-Tian,Su, Xiao-Lei,He, Xin-Hai,Song, Yan-Yan,Ma, Zheng-Sheng,Wang, Yao-Yu
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p. 3717 - 3723
(2021/05/31)
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- Magneto-structural properties and reliability of (Mn/Ni/Zn) substituted cobalt-copper ferrite heterogeneous catalyst for selective and efficient oxidation of aryl alcohols
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Herein, M2+ substituted CoCuFe2O4 (M2+ = Mn, Zn, Ni) ferrites have been synthesized using the sol-gel auto combustion method. The structural, morphological and magnetic studies confirm the phase formation of pure magnetic cubic spinel MCoCuFe2O4 (M2+ = Mn, Zn, Ni) ferrites. The substitution with Mn, Ni and Zn does not show large variation in binding energies obtained from XPS of Cu (2p) that specifies identical copper concentration (Cu0.5) and substitution of only cobalt (Co2+) in Mn-F, Ni-F and Zn-F catalysts. Interestingly, MCoCuFe2O4 magnetic catalysts were explored for selective oxidation of a series of substituted benzyl alcohols. Catalyst Mn-F showed 93% conversion of benzyl alcohol while, Ni-F showed 95% conversion of 4-nitrobenzyl alcohol. Whereas, the catalyst Zn-F was showed 96% conversion for 4-methoxybenzyl alcohol. Additionally the results also indicate an efficient separation and recovery of the magnetic catalysts after four successive reuses without any considerable loss in its catalytic activity.
- Dhabbe, Rohant,Gaikwad, Pratapsingh,Kakade, Bhalchandra,Kamble, Prakash,Kurane, Rajnikant,Parase, Haridas,Sabale, Sandip
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- Synthesis, characterization, reactivity, and catalytic studies of heterobimetallic vanadium(V) complexes containing hydrazone ligands
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Six heterobimetallic alkali metal dioxidovanadium(V) coordination polymer complexes {[M6{VO(μ-O)}2(μ-OH)4(μ4-slox/nph)].n DMF}∞ where M = Na, K, and Cs; n = 1 for (1), 0 for (2)-(6) of two dihydrazone ligands, disalicylaldehydeoxaloyldihydrazone (H4slox) and bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone (H4nph) are reported. All the complexes have been characterized by various physicochemical techniques such as elemental analyses, molar conductance, IR, NMR, UV–vis, and cyclic voltammetry. The IR, 1HNMR, and 13CNMR spectral data suggest that the dihydrazones are coordinated through phenolate/naphtholate oxygen, enolate oxygen, and azine nitrogen atoms to the metal centres. The structure of complex {[Na6{VO(μ-O)}2(μ-OH)4(μ4-slox)].DMF}∞ (1) is also determined by single-crystal X-ray data, which revealed that the H4slox coordinated via all possible dative sites to metal centres as tetrabasic octadentate ligand. The vanadium metal centres adopted distorted square-pyramidal coordination geometries, and the sodium atoms are also in five coordination atmospheres. The electronic spectra of the complexes showed LMCT bands in addition to intra-ligand π → π* and n → π* transitions. As evident from the cyclic voltammetry, the complexes showed two metal-centred electron transfer reactions {[(VVVV(slox)2?/VVVIV(slox)3?] and [(VVVIV(slox)3?/VVVIV(slox)4?]}, in addition to the ligand centred electron transfer reactions. Further, bovine serum albumin (BSA interaction studies of the complexes {[Na6{VO(μ-O)}2(μ-OH)4(μ4-slox)].DMF}∞ (1) and [Na6{VO(μ-O)}2(μ-OH)4(μ4-nph)]∞ (4) revealed strong binding affinity. Moreover, the catalytic studies of the complexes (1) and (4) were found to be effective for the oxidation of alcohols into their corresponding aldehydes and ketones and bromination of some organic substrates in the presence of H2O2 as an oxidizing agent.
- Borthakur, Rosmita,Dhanpat, Shobha A.,Kumar, Arvind,Kurbah, Sunshine D.,Lal, Ram A.,Syiemlieh, Ibanphylla
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- Dioxido-vanadium(V) complex catalyzed oxidation of alcohols and tandem synthesis of oximes: a simple catalytic protocol for C–N bond formation
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We report the synthesis of a vanadium(V) complex characterized by FT-IR and 1H NMR spectroscopy. The structure of the complex was established by single crystal X-ray crystallography. We also carried out the catalytic oxidation of benzyl alcohol, hetero-aryl alcohols and propargylic alcohols. Tandem synthesis of oximes from alcohols were also carried out using our vanadium(V) complex. The newly synthesized complex acts as a catalyst for oxidation reactions and tandem synthesis of oxime from alcohols.
- Kurbah, Sunshine Dominic
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p. 905 - 918
(2021/02/03)
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- La(OH)3nanoparticles immobilized on Fe3O4@chitosan composites as novel magnetic nanocatalysts for sonochemical oxidation of benzyl alcohol to benzaldehyde
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This work introduces an eco-friendly method for immobilization of La(OH)3 nanoparticles on modified Fe3O4 nanoparticles. The structural and morphological characteristics of the nanocatalyst were determined by various analytical techniques including, FT-IR, EDS, FESEM, VSM and XRD. The catalytic efficiency of the Fe3O4@Cs/La(OH)3 composite as a heterogeneous nanocatalyst was evaluated by selective oxidation of benzylic alcohols to aldehydes. The optimum reaction conditions including time, temperature, nanocatalyst dosage, and solvent were investigated for ultrasound-assisted oxidation processes. Furthermore, the magnetic nanocatalyst was recovered up to seven times without considerable activity loss. Furthermore, the proposed nanocomposite had a remarkable effect on reducing the reaction time and enhancing the yield. This journal is
- Fadaeian, Manoochehr,Ghomi, Javad Safaei,Javidfar, Fereshteh
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p. 35988 - 35993
(2021/12/02)
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- Aerobic Alcohol Oxidation by a Zeolitic Octahedral Metal Oxide based on Iron Vanadomolybdates Under Mild Conditions
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Zeolitic octahedral metal oxides are fully-inorganic crystalline materials with the multi-component redox property and the intrinsic microporosity. The redox active zeolitic iron vanadomolybdate acts as a catalyst for aerobic oxidation of primary aromatic alcohols. Molecular oxygen is able to be activated in the material due to the confinement effect of the micropore and the unique redox property of the framework. Different primary aromatic alcohols are oxidized by the material, and high alcohol conversion and aldehyde selectivity are achieved. The material is stable and able to be reused for 5 times without loss of activity.
- Zhu, Qianqian,Yin, Shanshan,Zhou, Mengyuan,Wang, Jie,Chen, Chaomin,Hu, Panpan,Jiang, Xizhuo,Zhang, Zhenxin,Li, Yanshuo,Ueda, Wataru
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p. 1763 - 1771
(2021/02/26)
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- Radical induced disproportionation of alcohols assisted by iodide under acidic conditions
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The disproportionation of alcohols without an additional reductant and oxidant to simultaneously form alkanes and aldehydes/ketones represents an atom-economical transformation. However, only limited methodologies have been reported, and they suffer from a narrow substrate scope or harsh reaction conditions. Herein, we report that alcohol disproportionation can proceed with high efficiency catalyzed by iodide under acidic conditions. This method exhibits high functional group tolerance including aryl alcohol derivatives with both electron-withdrawing and electron-donating groups, furan ring alcohol derivatives, allyl alcohol derivatives, and dihydric alcohols. Under the optimized reaction conditions, a 49% yield of 5-methyl furfural and a 49% yield of 2,5-diformylfuran were obtained simultaneously from 5-hydroxymethylfurfural. An initial mechanistic study suggested that the hydrogen transfer during this redox disproportionation occurred through the inter-transformation of HI and I2. Radical intermediates were involved during this reaction.
- Huang, Yang,Jiang, Haiwei,Li, Teng,Peng, Yang,Rong, Nianxin,Shi, Hexian,Yang, Weiran
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supporting information
p. 8108 - 8115
(2021/10/29)
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- A Magnetically Recyclable Palladium-Catalyzed Formylation of Aryl Iodides with Formic Acid as CO Source: A Practical Access to Aromatic Aldehydes
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A magnetically recyclable palladium-catalyzed formylation of aryl iodides under CO gas-free conditions has been developed by using a bidentate phosphine ligand-modified magnetic nanoparticles-anchored- palladium(II) complex [2P-Fe 3O 4@SiO 2-Pd(OAc) 2] as catalyst, yielding a wide variety of aromatic aldehydes in moderate to excellent yields. Here, formic acid was employed as both the CO source and the hydrogen donor with iodine and PPh 3as the activators. This immobilized palladium catalyst can be obtained via a simple preparative procedure and can be facilely recovered simply by using an external magnetic field, and reused at least 9 times without any apparent loss of catalytic activity.
- You, Shengyong,Zhang, Rongli,Cai, Mingzhong
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p. 1962 - 1970
(2021/01/25)
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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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- 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 0057-0059
(2021/01/24)
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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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- 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 0039-0040; 0089-0090
(2021/06/06)
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- Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas
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The reductive carbonylation of aryl iodides to aryl aldehydes possesses broad application prospects. We present an efficient and facile Rh-based catalytic system composed of the commercially available Rh salt RhCl3·3H2O, PPh3 as phosphine ligand, and Et3N as the base, for the synthesis of arylaldehydes via the reductive carbonylation of aryl iodides with CO and H2 under relatively mild conditions with a broad substrate range affording the products in good to excellent yields. Systematic investigations were carried out to study the experimental parameters. We explored the optimal ratio of Rh salt and PPh3 ligand, substrate scope, carbonyl source and hydrogen source, and the reaction mechanism. Particularly, a scaled-up experiment indicated that the catalytic method could find valuable applications in industrial productions. The low gas pressure, cheap ligand and low metal dosage could significantly improve the practicability in both chemical researches and industrial applications.
- Chen, Suqing,Liu, Zhenghui,Mu, Tiancheng,Wang, Peng,Yan, Zhenzhong,Yu, Dongkun,Zhao, Xinhui
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p. 645 - 656
(2020/05/14)
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- A Strategy for Accessing Aldehydes via Palladium-Catalyzed C?O/C?N Bond Cleavage in the Presence of Hydrosilanes
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We report the catalytic reduction of both active esters and amides by selective C(acyl)?X (X=O, N) cleavage to access aldehyde functionality via a palladium-catalyzed strategy. Reactions are promoted by hydrosilanes as reducing reagents with good to excellent yields and with excellent chemoselectivity for C(acyl)?N and C(acyl)?O bond cleavage. Carboxylic acid C(acyl)?O bonds are activated by 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) to form triazine ester intermediates, which further react with hydrosilanes to yield aldehydes in one-pot two-step procedures. We demonstrate that C(acyl)?O cleavage/formylation offers higher yields and broader substrate scopes compared with C(acyl)?N cleavage under the same reaction conditions.
- He, Zhanyu,Liu, Tingting,Ru, Junxiang,Wang, Yulin,Wang, Zijia,Zeng, Zhuo
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p. 5794 - 5800
(2020/12/01)
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- Clean and Selective Oxidation of Alcohols with Oxone and Phase-Transfer Catalysts in Water
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Abstract: A new, simple, metal-free, and eco-friendly procedure has been proposed forthe oxidation of alcohols with Oxone (potassium peroxymonosulfate) in water inthe presence of six phase-transfer catalysts (PTC). Phase-transfer catalystswere found to display high catalytic activity in water solution. Furthermore,the oxidation of alcohols was also carried out with relatively good conversionand selectivity in water without any catalyst.
- An, X. Q.,Kang, M.,Ma, H. C.,Yang, Y. X.,Yang, Z. W.,Zeng, W.
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p. 1790 - 1794
(2020/12/01)
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- Reaction method for selectively synthesizing aromatic aldehyde or aromatic carboxylic acid
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The invention provides a reaction method for selectively synthesizing aromatic aldehyde or aromatic carboxylic acid. Toluene aromatic hydrocarbon without substituent or with substituent on a benzene ring is used as a raw material, an inorganic salt of ferric iron is used as a catalyst, air or oxygen is used as an oxidizing agent, a mixed solution of acetonitrile and water is used as a solvent, theraw material is oxidized by adjusting the dosage of the catalyst to obtain aromatic aldehyde or aromatic carboxylic acid, and the aromatic aldehyde or aromatic carboxylic acid is irradiated by ultraviolet light for 10-16 hours. Aromatic carboxylic acid obtained under the condition that the dosage of the catalyst is 5-50% mol of aromatic hydrocarbon is used as a main product, wherein the use amount of the catalyst is 70-200% mol of aromatic hydrocarbon. The reaction method provided by the invention has the characteristics of atom economy and high selectivity, uses the metal iron salt with richearth content for catalysis, and has the advantages of mild conditions, recyclable catalyst and solvent and the like.
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Paragraph 0029-0030
(2020/12/05)
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- Nickel complex containing meta-carborane triazole ligand and preparation method and application of nickel complex
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The invention relates to a nickel complex containing a meta-carborane triazole ligand and a preparation method and application of the nickel complex. The nickel complex is prepared by the following steps of: (1) dropwise adding an n-BuLi solution into a meta-carborane m-C2B10H12 solution, stirring and reacting; then adding 3-propargyl bromide for a reaction, and separating after the reaction is finished so as to obtain 1, 3-dipropargyl meta-carborane; and (2) carrying out a reaction between 1, 3-dipropargyl meta-carborane and aryl azide under the catalytic condition of a catalyst CuI, then adding NiCl2 into the reaction system, continuing the reaction, carrying out separation after the reaction is finished so as to obtain the nickel complex containing the meta-carborane triazole ligand. The nickel complex is applied to preparation of aldehyde by catalyzing partial oxidation of primary alcohol. Compared with the prior art, the preparation method is simple and green, the complex can efficiently catalyze partial oxidation of primary alcohol to prepare aldehyde, the reaction conditions are mild, the universality is good, the catalytic efficiency is high, and few byproducts are produced; and the catalyst has high stability and is not sensitive to air and water.
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Paragraph 0048; 0050-0052
(2020/08/07)
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- Simple synthesis of the novel Cu-MOF catalysts for the selective alcohol oxidation and the oxidative cross-coupling of amines and alcohols
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A novel porous metal–organic framework {Cu2(bbda)0.5(Hbbda)1.5(OAc)1.5.8H2O} (UoB-5) was synthesized under ultrasound irradiation by employing a new Schiff base ligand H2bbda (4,4'(1,4-phenylene bis (azanylylidene)) bis (methanylylidene))dibenzoic acid) and was fully characterized. The microporous nature of UoB-5 was confirmed by gas-sorption measurements. This framework acted as a highly effective heterogeneous catalyst for the alcohol oxidation reaction with tert-butyl hydroperoxide (t-BuOOH) as an oxidant. The presence of coordinatively unsaturated metal sites in UoB-5 could be the reason for high performance in this reaction. Furthermore, using the long linker with the free -NC group and uncoordinated -N atom on the wall of the pores created UoB-5 an excellent candidate for the catalytic activities without activation of the framework. It was confirmed with the heterogeneous catalytic experiments on the one-pot tandem synthesis of imines from benzyl alcohols and anilines. Eventually, the new Cu-MOF (UoB-5) could be an alternative catalyst as a more economically favorable and environmentally friendly in the catalysis field.
- Ghamari Kargar, Pouya,Aryanejad, Sima,Bagherzade, Ghodsieh
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- Solvent-free oxidation of benzyl alcohols catalysed by a tetrazole-saccharinate Zn(II) complex under microwave radiation: The role of the ligand and the reaction mechanism
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Herein we present an efficient methodology for the microwave-assisted peroxidative oxidation of benzyl alcohols to the corresponding aldehydes by using a novel and stable tetrazole-saccharinate zinc(II) catalyst, along with some insights into the reaction mechanism. This methodology is distinguished by the use of easily available and cheap reagents on the genesis of the zinc catalyst, mild reaction conditions, very short reaction periods (5–20 min) and no need to add an organic solvent. Furthermore, the use of TBHP (70percent. aq.) as oxidizing agent turn this protocol a convenient one for benzyl alcohol oxidation in yields up to 98percent.
- Cristiano, M. Lurdes S.,Fernandes, André L.,Frija, Luís M. T.,Pombeiro, Armando J. L.
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- Heterogeneous carbon nitride photocatalyst for C-C bond oxidative cleavage of vicinal diols in aerobic micellar medium
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A green and efficient visible-light promoted aerobic oxidative C-C bond cleavage of vicinal diols in micellar medium has been developed. This protocol used graphitic carbon nitride with nitrogen vacancies (CN620) as a metal-free recyclable photocatalyst and CTAB as surfactant in water. Control experiments and the ESR results indicated that superoxide radicals and valence band holes played an important role in the reaction. Further isotope experiments suggested both a β-scission/HAT pathway and an oxidation/hydrolysis/dehydration pathway for the reaction, which is different from previous reports. The semiconductor/micellar catalyst system can be recycled at least 10 times without a significant reduction in activity. Furthermore, this reaction could be carried out under solar light irradiation and was applicable to large-scale reactions with similar results.
- Chen, Jiayang,Chen, Shengjun,Dong, Xinyu,Hong, Mei,Ni, Bangqing,Niu, Tengfei,Zhang, Tianhao
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supporting information
p. 5042 - 5049
(2020/08/25)
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- Decarboxylative formylation of aryl halides with glyoxylic acid by palladium catalysis under oxygen
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A new free radical/palladium cooperative catalyzed formylation of aryl halides with glyoxylic acid as the formyl source under oxygen conditions has been developed. Various aromatic and heteroaromatic aldehydes were produced in medium to good yields.
- Cao, Hualiang,Pu, Weiwen,Zhang, Jie,Yan, Peijun,Zhang, Jun,Xu, Sheng
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supporting information
p. 1287 - 1290
(2020/08/21)
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- Continuous flow synthesis of aryl aldehydes by Pd-catalyzed formylation of phenol-derived aryl fluorosulfonates using syngas
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This communication describes the palladium-catalyzed reductive carbonylation of aryl fluorosulfonates (ArOSO2F) using syngas as an inexpensive and sustainable source of carbon monoxide and hydrogen. The conversion of phenols to aryl fluorosulfonates can be conveniently achieved by employing the inexpensive commodity chemical sulfuryl fluoride (SO2F2) and base. The developed continuous flow formylation protocol requires relatively low loadings for palladium acetate (1.25 mol%) and ligand (2.5 mol%). Good to excellent yields of aryl aldehydes were obtained within 45 min for substrates containing electron withdrawing substituents, and 2 h for substrates containing electron donating substituents. The optimal reaction conditions were identified as 120 °C temperature and 20 bar pressure in dimethyl sulfoxide (DMSO) as solvent. DMSO was crucial in suppressing Pd black formation and enhancing reaction rate and selectivity. This journal is
- Hanselmann, Paul,Hone, Christopher A.,Hu, Guixian,K?ckinger, Manuel,Kappe, C. Oliver
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p. 22449 - 22453
(2020/07/03)
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- Oxidative C-S Bond Cleavage of Benzyl Thiols Enabled by Visible-Light-Mediated Silver(II) Complexes
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The oxidative cleavage reaction of the C-S bond using singlet oxygen is challenging because of its uncontrollable nature. We have developed a novel method for the singlet-oxygen-mediated selective C-S bond cleavage reaction using silver(II)-ligand complexes. Visible-light-induced silver catalysis enables the controlled oxidative cleavage of benzyl thiols to afford carbonyl compounds, such as aldehydes or ketones, which are important synthetic components.
- Hong, Boseok,Aganda, Kim Christopher C.,Lee, Anna
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supporting information
p. 4395 - 4399
(2020/06/05)
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- FeCl3-catalyzed oxidative decarboxylation of aryl/heteroaryl acetic acids: Preparation of selected API impurities
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There is an ever-increasing demand for impurity compounds for use in impurity profiling as regulatory agencies seek information during registration. Herein, we report the FeCl3-catalyzed oxidative decarboxylation of aryl- and heteroaryl acetic acids to the corresponding carbonyl compounds. A variety of useful aldehydes and ketones were prepared in a simple one-pot transformation by employing an environmentally benign, low-cost, and readily available iron salt. The utility of this method has been demonstrated by preparing five valuable API impurities including a multi-gram-scale synthesis of ketorolac impurity B for the first time. This journal is
- Gangadurai, Chinnakuzhanthai,Illa, Giri Teja,Reddy, D. Srinivasa
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p. 8459 - 8466
(2020/11/05)
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- 1,1,1,3,3,3-Hexafluoroisopropanol as an efficient medium for the room temperature oxidation of styrenes to benzaldehydes
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A room temperature N-hydroxyphthalimide-catalyzed oxidation of styrene derivatives to the corresponding aldehydes has been developed. The use of 1,1,1,3,3,3-hexafluoroisopropanol as the solvent was determined as being key for efficient oxidation. The incorporated oxygen atom originates from molecular dioxygen.
- Zhang, Zhuyong,Chen, Weidong,Luo, Junfei
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supporting information
(2020/10/23)
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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 Deoximation Method for Deprotection of Ketones and Aldhydes Using a Graphene-Oxide-Based Co-catalysts System
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The deoximation of a wide range of ketoximes and aldoximes to their corresponding carbonyl compounds with high yields has been achieved using graphene oxide (GO) and sodium nitrite (NaNO2) as highly efficient catalysts and air as the green oxidant under mild conditions. The mechanism of deprotection and recycling use of catalyst were revealed in deep experiment. The carboxylic acid groups on the GO were essential for high catalytic activity. (Figure presented.).
- Tong, Qiaolin,Liu, Yang,Gao, Xuezhi,Fan, Zhanfang,Liu, Tianfu,Li, Bo,Su, Dangsheng,Wang, Qinghe,Cheng, Maosheng
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supporting information
p. 3137 - 3145
(2019/05/01)
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- Organosuperbase dendron manganese complex grafted on magnetic nanoparticles; heterogeneous catalyst for green and selective oxidation of ethylbenzene, cyclohexene and oximes by molecular oxygen
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Magnetic Fe3O4 nanoparticles as a support were modified with an amino-terminated organosilicon and cyanoric choloride ligands. The novel manganese complex was grafted on modified magnetic support (Mn(II)-Met@MMNPs). The nanocatalyst structure, particle size, morphology and surface properties was well characterized by elemental analysis, ICP-AES, AAS, EDS, FT-IR, SEM, TEM, DLS, VSM, TGA, XRD and XPS. In order to develop an effective heterogeneous nanocatalyst for eco-friendly aerobic, highly active and selective catalytic reactions, synthesized nanocatalyst was applied in oxidation of various organic compounds. The catalytic performance of the manganese nanocatalyst in the aerobic oxidation of ethylbenzene (EB), cyclohexene (CYHE) and various aldoximes and ketoxime were studied. Selective aerobic oxidation of EB and CYHE and various oximes were catalyzed by the Mn-nanocatalyst using N-hydroxyphthalimide (NHPI) with molecular oxygen as the green oxidant without the need of any reducing agent, and respectively the acetophenone (AcPO) as a benzylic product, 2-cyclohexene-1-one (CYHE[dbnd]O) as an allylic product and corresponding carbonyl compounds were obtained. The oxidation process has been optimized for Mn-nanocatalyst by considering the effect of different parameters such as the ratio and amount of Mn-nanocatalyst/NHPI, reaction time and solvent for achieving maximum conversion and selectivity to products. Due to their significant low cost, informal preparation, easy magnetically separation from reaction mixture, excellent catalytic performance, simple recovery and reusability without any metal leaching, the Mn-nanocatalyst has huge application prospect in selective and green oxidation process.
- Faraji, Ali Reza,Ashouri, Fatemeh,Hekmatian, Zahra,Heydari, Somayyeh,Mosazadeh, Sima
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- Efficient catalytic oxidation of methyl aromatic hydrocarbon with: N -alkyl pyridinium salts
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A series of N-alkyl pyridinium salts were synthesized and employed as metal-free catalyst for the selective oxidation of methyl aromatic hydrocarbon with molecular oxygen. The electronic effect of the substitutes was found to be an important factor for the catalytic performance. With the introduction of electron-donating substitute -N(CH3)2, the conversion of p-xylene and selectivity of p-toluic acid could be simultaneously increased. 1-Benzyl-4-N,N-dimethylaminopyridinium salt showed the highest catalytic activity, and 95% conversion with 84% of selectivity to p-toluic acid could be obtained for the selective oxidation of p-xylene. Several methyl aromatic hydrocarbons could all be efficiently oxidized with the reported catalyst at the absence of any metal species.
- Zhang, Qiaohong,He, Honghao,Wang, Huibin,Zhang, Zhan,Chen, Chen
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p. 38891 - 38896
(2019/12/11)
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- Development of a polymer embedded reusable heterogeneous oxovanadium(IV)catalyst for selective oxidation of aromatic alkanes and alkenes using green oxidant
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A new heterogeneous polymer supported solid phase oxovanadium(IV)catalyst was synthesized successfully. The designed catalyst furnished excellent results in the oxidation reactions of various aromatic alkanes, e.g. toluene, para-xylene, mesitylene. The polymer supported vanadium complex was proved also an efficient catalyst for the oxidation of aromatic alkenes, like substituted styrenes, trans-stilbene, etc. under mild reaction conditions. The supported catalyst was nicely elucidated by SEM-EDAX, TGA, FT-IR and UV–Vis spectral analysis. The catalytic activity was tested in the presence of an environment-friendly oxidant, 30% aqueous H2O2 during the oxidation of broad range of substrates. Another important fact is that the designed oxovanadium(IV)catalyst is heterogeneous in nature. Moreover, the newly synthesized oxovanadium(IV)complex exhibited a notable recoverability and it could be recycled up to six runs devoid of any prominent reduction in catalytic behavior.
- Paul, Priyanka,Ghosh, Aniruddha,Chatterjee, Sauvik,Bera, Apurba,Alam, Seikh Mafiz,Islam, Sk. Manirul
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p. 198 - 212
(2019/05/01)
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- Selective Visible Light Aerobic Photocatalytic Oxygenation of Alkanes to the Corresponding Carbonyl Compounds
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The aerobic, selective oxygenation of alkanes via C-H bond activation is an important research challenge. Photocatalysis offers the potential for the introduction of additional concepts for such reactions. Visible light photoactive semiconductors such as bismuth oxyhalides (BiOX, X = Cl and Br) used in this research typically oxidize organic compounds through photocatalyzed formation of strongly oxidizing holes. The reactive oxygen species formed react with organic compounds in one-electron processes, leading to radical intermediates and nonselective oxidation. Such oxidation reactions generally lead to total oxidation. Here, impregnation of BiOX with a polyoxometalate, H5PV2Mo10O40, as a strong electron acceptor changed the reactivity of BiOX, leading to Mars-van Krevelen-type reactivity, that is, photoactivated oxygen donation from BiOX to the organic substrate followed by reoxidation by O2 and catalysis. This conclusion was supported by mechanistic studies involving isotope labeling studies. In this way, ethane was selectively oxidized to acetaldehyde in a flow reactor with a turnover number (24 h) of 415.
- Somekh, Miriam,Khenkin, Alexander M.,Herman, Adi,Neumann, Ronny
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p. 8819 - 8824
(2019/09/30)
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- Facile synthesis of size-controlled Ag supported on WO3 nanorods and their application as novel and active catalyst in oxidant-free dehydrogenation of benzyl alcohols
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A new and simple strategy for the size-tunable synthesis of silver supported tungsten oxide nanoparticles (NPs) was reported. Polyethylene glycol (PEG) of molecular weights 400 and 4000 was used as surfactant to tune the size of nanoparticles. These as-sy
- Paul, Bappi,Sharma, Sachin,Purkayastha, Debraj D.,Dhar, Siddhartha S.,Bal, Rajaram
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- A novel nano-cotton-like bismuth oxyfluoride (NC-BiOF) and a novel nanosheet heterogeneous compound BiOF@ZIF-8 as catalyst for the selective and green oxidation of benzylic alcohols
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We describe here for the first time a new morphology of BiOF nanoparticles with a cotton-like structure, made using a hydrothermal synthesis method. We also prepared heterogeneous nanosheets of BiOF@ZIF-8 by a one-pot synthesis under hydrothermal conditions. We demonstrate that in this method the morphology of BiOF and one-pot synthesis conditions are the main factors for the preparation of the nanosheet BiOF@ZIF-8. Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), thermogravimetry-differential thermal analysis (TG-DTA), and BET surface area were used to characterize the samples prepared. XRD, SEM, and adsorption–desorption analysis showed that the structure of ZIF-8 and BiOF form intact only in one-pot synthesis of BiOF (with nano-cotton-like morphology) with Zn(NO3)3, while spectral techniques show the successful encapsulation of the sheet BiOF on ZIF-8. Nanosheet BiOF@ZIF-8 was found to be a highly efficient heterogeneous catalyst for the selective oxidation of alcohols. BiOF@ZIF-8 could be reused several times although it got less active with recycling.
- Ghayoumian, Narges,Aliyan, Hamid,Fazaeli, Razieh
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p. 363 - 370
(2018/10/26)
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- 3-BocNH-ABNO-catalyzed aerobic oxidation of alcohol at room temperature and atmospheric pressure
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A transition-metal-free catalytic system has been developed for selective transformation of alcohol to aldehydes or ketones. The reactions were performed with 3-(tert-butoxycarbonylamino)-9-azabicyclo[3.3.1]nonane N-oxyl (3-BocNH-ABNO) as the catalyst, NaNO2 as the co-catalyst, molecular oxygen as the terminal oxidant, and AcOH as the solvent under room temperature. This catalytic system exhibited broad functional group tolerance. A series of alcohol substrates, including primary and secondary benzylic alcohols, heteroaromatic analogues, primary and secondary aliphatic alcohols, could be converted into their corresponding aldehydes and ketones in good conversions and selectivities.
- Zhao, Yajing,Li, Yutong,Shen, Zhenlu,Hu, Xinquan,Hu, Baoxiang,Jin,Sun, Nan,Li, Meichao
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supporting information
(2019/08/06)
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- Efficient acceptorless photo-dehydrogenation of alcohols and: N -heterocycles with binuclear platinum(ii) diphosphite complexes
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Although photoredox catalysis employing Ru(ii) and Ir(iii) complexes as photocatalysts has emerged as a versatile tool for oxidative C-H functionalization under mild conditions, the need for additional reagents acting as electron donor/scavenger for completing the catalytic cycle undermines the practicability of this approach. Herein we demonstrate that photo-induced oxidative C-H functionalization can be catalysed with high product yields under oxygen-free and acceptorless conditions via inner-sphere atom abstraction by binuclear platinum(ii) diphosphite complexes. Both alcohols (51 examples), particularly the aliphatic ones, and saturated N-heterocycles (24 examples) can be efficiently dehydrogenated under light irradiation at room temperature. Regeneration of the photocatalyst by means of reductive elimination of dihydrogen from the in situ formed platinum(iii)-hydride species represents an alternative paradigm to the current approach in photoredox catalysis.
- Zhong, Jian-Ji,To, Wai-Pong,Liu, Yungen,Lu, Wei,Che, Chi-Ming
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p. 4883 - 4889
(2019/05/16)
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- Synthesis, crystal structure and reactivity of homobimetallic vanadium(V) complexes derived from oxaloyldihydrazone ligands
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Treatment of V2O5 with dihydrazone ligands (H4L) (disalicylaldehydeoxaloyldihydrazone (H4L1 = H4slox), bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone (H4L2 = H4nph) and bis(5-bromosalicylaldehyde)oxaloyldihydrazone (H4L3 = H4sloxBr)) in methanol leads to the formation of homobimetallic vanadium(V) complexes of the composition [(CH3)2NH2]2[(VO2)2(L)]·nH2O, where n = 2 (1, 2) and n = 4 (3). The reaction of complexes 1–3 with H2O2 results in the formation of bis(monooxidoperoxidovanadate(V)) complexes[{VO(O2)}2(L)]2? and the reaction with HCl leads to the formation of oxidohydroxido species of the composition [(VO(OH)(L)]2?. The complexes show great potential for the oxidation of alcohols and the oxidative bromination of some organic substrates.
- Syiemlieh, Ibanphylla,Asthana, Mrityunjaya,Kurbah, Sunshine D.,Lal, Ram A.
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p. 202 - 216
(2019/06/19)
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- UV light promoted 'Metal'/'Additive'-free oxidation of alcohols: Investigating the role of alcohols as electron donors
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UV light promoted selective oxidation of primary and secondary alcohols has been demonstrated under 'metal-free' and 'additive-free' conditions. Under the optimized conditions, a variety of aromatic, heteroaromatic, and alicyclic alcohols have been examined for their transformations to the corresponding carbonyl compounds. The mechanistic studies emphasize the important role of substrate (alcohol) and solvent (DMSO) in the generation of superoxide radical which is a vital intermediate for the transformation. This study also highlights the role of air as the oxidant in the oxidation process. Further, the practical application of the strategy has also been demonstrated for the oxidation of the alcoholic moiety in cholesterol.
- Walia, Preet Kamal,Sharma, Manik,Kumar, Manoj,Bhalla, Vandana
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p. 36198 - 36203
(2019/11/20)
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