- Regeneration of carbonyl compounds by oxidative cleavage of oximes with NBS in the presence of β-cyclodextrin in water
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The conversion of different oximes to the corresponding carbonyl compounds was carried out at room temperature in good to high yields with N-bromosuccinimide in water in the presence of β-cyclodextrin.
- Reddy, M. Somi,Narender,Rao, K. Rama
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- First example of water-soluble transition-metal catalysts for Oppenauer-type oxidation of secondary alcohols
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The first water-soluble transition-metal catalysts for Oppenauer-type oxidation of secondary alcohols have been developed. The catalytic system composed of [Ir(COD)Cl]2, 2,2'-biquinoline-4,4'-dicarboxylic acid dipotassium salt (BQC) and sodium carbonate is highly efficient for the selective oxidation of benzylic and aliphatic secondary alcohols to the corresponding ketones with catalyst/substrate ratios ranging from 0.4 to 2.5 percent. The substitution of [Ir(COD)Cl]2 by its rhodium analog [Rh(COD)Cl]2 generates a less active catalytic system. [Ir(COD)Cl]2/BQC was also found to be more active than its water-insoluble analog system [Ir(COD)Cl]2/2,2'-biquinoline (BC).
- Ajjou, Abdelaziz Nait
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- Nickel boride mediated cleavage of 1,3-oxathiolanes: A convenient approach to deprotection and reduction
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1,3-Oxathiolanes are rapidly cleaved by nickel boride allowing regeneration of corresponding carbonyl compounds. Optimum reaction conditions have also been defined to obtain alcohols exclusively by reduction of oxathiolanes. Reactions are rapid at room temperature and do not require protection from atmosphere. Mild reaction conditions, simple work up, and high yields are some of the major advantages of the procedure.
- Khurana, Jitender M.,Magoo, Devanshi,Dawra, Kiran
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- A Mild and Efficient Oxidation of Alcohols to Ketones with Iodosobenzene/(Salen) Manganese Complex
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An excellent method for the chemoselective oxidation of alcohols to ketones with C6H5IO catalyzed by (salen) manganese/4A MS in CH3CN has been devised. The reported procedure is fast, simple, and the yields are excellent (> 95%) in most cases.
- Kim, Sung Soo,Borisova, Galina
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- An efficient and practical aerobic oxidation of benzylic methylenes by recyclable: N -hydroxyimide
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An efficient and practical benzylic aerobic oxidation catalyzed by cheap and simple N-hydroxyimide organocatalyst has been achieved with high yields and broad substrate scope. The organocatalyst used can be recycled and reused by simple workup and only minute amount (1 mol% in most cases) of simple iron salt is used as promoter. Phenyl substrates with mild and strong electron-withdrawing group could also be oxygenated in high yields as well as other benzylic methylenes. Influence of substituents, gram-scale application, catalysts decay and general mechanism of this methodology has also been discussed. This journal is
- Wang, Jian,Zhang, Cheng,Ye, Xiao-Qing,Du, Wenting,Zeng, Shenxin,Xu, Jian-Hong,Yin, Hong
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- TEMPO-tert-butyl nitrite: An efficient catalytic system for aerobic oxidation of alcohols
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A metal-free catalytic system consisting of 2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO) and tert-butyl nitrite has been developed to activate molecular oxygen for the aerobic oxidation of alcohols. A variety of active and non-active alcohols were oxidized to their corresponding carbonyl compounds in high selectivity and yields.
- He, Xijun,Shen, Zhenlu,Mo, Weimin,Sun, Nan,Hu, Baoxiang,Hu, Xinquan
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- Stereoselective oxidation and reduction by immobilized Geotrichum candidum in an organic solvent
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Cells of the fungus, Geotrichwn candidum, were immobilized on a water-absorbing polymer and used for stereoselective oxidation and reduction in an organic solvent using cyclohexanone, cyclopentanol or alkan-2-ols as additive. Enantiomerically pure (.β)-1-arylethanols were obtained by the stereoselective oxidation of racemic 1-arylethanols, whereas enantiomerically pure (S)- 1-arylethanols were obtained by the reduction of the corresponding ketones, in contrast to reduction in water by the free cells in which (R)- or (S)- 1-arylethanols were produced in low ee. The reaction mechanism was investigated by measuring the partition of the substrates and products between the organic phase and aqueous phase in the polymer around which the cells were immobilized. Deuterated compounds were used to determine the role of the additives.
- Nakamura, Kaoru,Inoue, Yuko,Matsuda, Tomoko,Misawa, Ibuki
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- Enantiocomplementary C–H Bond Hydroxylation Combining Photo-Catalysis and Whole-Cell Biocatalysis in a One-Pot Cascade Process
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Enantiocomplementary hydroxylation of alkyl aromatics through a one-pot photo-biocatalytic cascade reaction is described. The photoredox process is implemented in aqueous phase with O2 as oxidant and the subsequent (R)- or (S)-selective bioreduction is performed by whole cell system without the addition of the expensive cofactor (NADPH). This mild, operationally simple protocol transforms a wide variety of readily available aromatic compounds into valuable chiral alcohols with high yield (up to 90 %) and stereoselectivity (up to 99 %), thereby displaying important potentials in organic synthesis.
- Peng, Yongzhen,Li, Danyang,Fan, Jiajie,Xu, Weihua,Xu, Jian,Yu, Huilei,Lin, Xianfu,Wu, Qi
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- Catalytic Friedel-Crafts acylation of alkoxybenzenes mediated by aluminum hydrogensulfate in solution and solvent-free conditions
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Friedel-Crafts acylation of alkoxybenzenes was achieved efficiently by a reaction with aliphatic acid anhydrides in the presence of catalytic amounts of aluminum hydrogensulfate, Al(HSO4)3, in nitromethane and under solvent-free conditions. Alkylbenzenes and aryl halides, as well as aromatic anhydrides, remained intact under these conditions.
- Salehi, Peyman,Khodaei, Mohammad Mehdi,Zolfigol, Mohammad Ali,Sirouszadeh, Sara
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- Liquid-phase oxidation of 1-isopropyl- and 1-ethyl-4-methoxybenzenes with oxygen to hydroperoxides
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A study was carried out on the kinetics of free-radical chain oxidation of 1-isopropyl-4-methoxybenzene (1a) and 1-ethyl-4-methoxybenzene (1b) with oxygen in the liquid phase to yield 1-methyl-1-(4-methoxyphenyl)ethyl hydroperoxide (2a) and 1-(4-methoxyphenyl)ethyl hydroperoxide (2b). The oxidizability of 1a and 1b was studied over the temperature range 50-100°C. Long-term oxidations of 1a and 1b to the corresponding hydroperoxides were carried out and the properties and thermal stability of 2a were established.
- Zawadiak, Jan,Stec, Zbigniew,Jakubowski, Bartlomiej,Orlinska, Beata
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- A Novel Catalyst System, Antimony(V) Chloride-Lithium Perchlorate (SbCl5-LiClO4), in the Friedel-Crafts Acylation Reaction
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A novel catalyst system consisting of antimony(V) chloride (SbCl5) and lithium perchlorate (LiClO4) effectively promotes the Friedel-Crafts acylation reaction of aromatic compounds with acid anhydrides.
- Mukaiyama, Teruaki,Suzuki, Kaoru,Han, Jeong Sik,Kobayashi, Shu
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- Efficient and recyclable rare earth-based catalysts for Friedel-Crafts acylations under microwave heating: Dendrimers show the way
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The catalytic system involving Sc(OTf)3 and a dendritic terpyridine ligand is able to promote the Friedel-Crafts acylation of a wide range of aromatics under microwave irradiation. The expected products are obtained in high yields after short reaction times and the nano-sized catalyst can be recovered and successfully used in 12 consecutive runs.
- Perrier, Arnaud,Keller, Michel,Caminade, Anne-Marie,Majoral, Jean-Pierre,Ouali, Armelle
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- A supported manganese complex with amine-bis(phenol) ligand for catalytic benzylic C(sp3)-H bond oxidation
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With regards to the importance of direct and selective activation of C-H bonds in oxidation processes, we develop a supported manganese amine bis(phenol) ligand complex as a novel catalyst with the aim of obtaining valuable products such as carboxylic acids and ketones that have an important role in life, industry and academic laboratories. We further analyzed and characterized the catalyst using the HRTEM, SEM, FTIR, TGA, VSM, XPS, XRD, AAS, and elemental analysis (CHN) techniques. Also, the catalytic evaluation of our system for direct oxidation of benzylic C-H bonds under solvent-free condition demonstrated that the heterogeneous form of our catalyst has high efficiency in comparison with homogeneous ones due to more stability of the supported complex. Furthermore, the structural and morphological stability of our efficient recyclable catalytic system has been investigated and all of the data proved that the complex was firmly anchored to the magnetite nanoparticles.
- Karimpour, Touraj,Safaei, Elham,Karimi, Babak
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- Palladium(II)-catalyzed desulfitative synthesis of aryl ketones from sodium arylsulfinates and nitriles: Scope, limitations, and mechanistic studies
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A fast and efficient protocol for the palladium(II)-catalyzed production of aryl ketones from sodium arylsulfinates and various organic nitriles under controlled microwave irradiation has been developed. The wide scope of the reaction has been demonstrated by combining 14 sodium arylsulfinates and 21 nitriles to give 55 examples of aryl ketones. One additional example illustrated that, through the choice of the nitrile reactant, benzofurans are also accessible. The reaction mechanism was investigated by electrospray ionization mass spectrometry and DFT calculations. The desulfitative synthesis of aryl ketones from nitriles was also compared to the corresponding transformation starting from benzoic acids. Comparison of the energy profiles indicates that the free energy requirement for decarboxylation of 2,6-dimethoxybenzoic acid and especially benzoic acid is higher than the corresponding desulfitative process for generating the key aryl palladium intermediate. The palladium(II) intermediates detected by ESI-MS and the DFT calculations provide a detailed understanding of the catalytic cycle. (Figure Presented).
- Skillinghaug, Bobo,Sk?ld, Christian,Rydfjord, Jonas,Svensson, Fredrik,Behrends, Malte,S?vmarker, Jonas,Sj?berg, Per J. R.,Larhed, Mats
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- N- Hydroxyphthalimide and transition metal salts as catalysts of the liquid-phase oxidation of 1-methoxy-4-(1-methylethyl)benzene with oxygen
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The oxidation process of 1-methoxy-4-(1-methylethyl)benzene catalysed by N-hydroxyphthalimide (NHPI) or NHPI in combination with Cu(II), Co(II), Mn(II) and Fe(II) salts was studied. The effects of the amount of catalyst and the temperature were determined
- Orlinska, Beata,Romanowska, Iwona
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- Clean and highly selective oxidation of alcohols in an ionic liquid by using an ion-supported hypervalent iodine(III) reagent
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Alcohol consumption: The Phl(OAc)2-derived hypervalent iodine reagent 1 acts as an oxidant in the conversion of primary and secondary alcohols 2 into carbonyl compounds 3 with good to excellent yields (see scheme). The bromide ion remaining from the preparation of [emim]+[BF 4]-(emim = 1-ethyl-3-methylimidazolium tetrafluoroborate) acts as a catalyst in the reaction. Primary alcohols are oxidized without any detectable overoxidation.
- Qian, Weixing,Jin, Erlei,Bao, Weiliang,Zhang, Yongmin
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- Solid state cleavage of oximes with potassium permanganate supported on alumina
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A manipulatively simple and rapid method for conversion of oximes to the corresponding carbonyl compounds is described. The reaction is conducted under solvent-less conditions using alumina-supported permanganate. According to the reaction system and conditions used, different ketones and aldehydes are obtained in moderate and good yields.
- Imanzadeh,Hajipour,Mallakpour
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- Metal Sulfonate Polymers as Catalysts for the Heterogeneous Acylation of Aromatic Derivatives
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A series of metal sulfonate salts attached to a poly(ether ether ketone) (PEEK) polymer were prepared by ultrasonic activation and then examined as heterogeneous catalysts in the Friedel–Crafts acylation of aromatic derivatives.
- Morizur, Vincent,Hector, Daphné,Olivero, Sandra,Desmurs, Jean Roger,Du?ach, Elisabet
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- p-Methoxyphenacyl Esters as Photodeblockable Protecting Groups for Phosphates
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p-Methoxyphenacyl esters of substituted phosphates have been found to be photosensitive protecting groups which may be useful in biologically important phosphate synthesis.
- Epstein, William W.,Garrossian, Massoud
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- Sur l'effet ipso du silicium lors de l'acylation du m-trimethylsilylanisole
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The acylation of m-trimethylsilylanisole which led to a significant amount of silylated acylanisoles was thoroughly investigated.This demonstrates with certainty that the ipso effect of the trimethylsilyl group generally admitted in this case is countered by the methoxy effect.
- Bennetau, B.,Krempp, M.,Dunogues, J.
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- Reactions of silica chloride (SiO2Cl)/DMSO, a heterogeneous system for the facile regeneration of carbonyl compounds from thioacetals and ring-expansion annelation of cyclic thioacetals
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Silica chloride (SiO2Cl)/DMSO, as a heterogeneous system, has been efficiently used for deprotection of thioacetals into aldehydes in dry CH2Cl2 at room temperature. Thioketals without enolizable hydrogens adjacent to a sulfur atom are converted easily to the corresponding ketones in high yields under similar reaction conditions. However, thioketals with enolizable methyl and methylene groups undergo ring-expansion reactions to afford 1,4-dithiepins and 1,4-dithiins in dry CH2Cl2 at room temperature in good yields.
- Firouzabadi, Habib,Iranpoor, Nasser,Hazarkhani, Hassan,Karimi, Babak
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- Sulfoximidations of Benzylic C?H bonds by Photocatalysis
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An efficient photocatalytic functionalization of compounds with benzylic C?H bonds by sulfoximidation in visible light is described. The mild reaction conditions allow the use of a broad array of substrates, including diarylmethane, alkyl arenes, arylacetonitrile, 2-arylacetate, and alkynyl aryl methanes. The sulfoximidation process is highly chemoselective and leads to the corresponding sulfoximines in generally good yields. Mechanistic investigations suggested the intermediacy of sulfoximidoyl radicals.
- Wang, Han,Zhang, Duo,Bolm, Carsten
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- VO(acac)2 catalyzed oxidative deprotection of oximes, hydrazones, and semicarbazones
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Oximes, hydrazones, and semicarbazones undergo facile deprotection in the presence of a catalytic amount of vanadyl acetylacetonate and hydrogen peroxide in acetone at room temperature.
- De, Surya Kanta
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- Acid-catalyzed hydration of alkynes in aqueous microemulsions
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Terminal aromatic alkynes are converted rapidly into ketones in a regioselective manner by treatment of their microemulsions with 0.33 M mineral acid between 80 and 140 °C. Internal and aliphatic acetylenes are likewise hydrated, but require longer reaction periods. The products are easily isolated from the reaction mixtures by phase separation. Replacement of H2O by D2O leads to the formation of trideuteriomethyl ketones. Copyright
- Nairoukh, Zackaria,Avnir, David,Blum, Jochanan
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- Biphasic copper-catalyzed C–H bond activation of arylalkanes to ketones with tert-butyl hydroperoxide in water at room temperature
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A facile C–H bond activation of arylalkanes to their corresponding ketones catalyzed by copper salts using tert-butyl hydroperoxide as an oxidant in water at room temperature is described. Easy product separation, simple reaction procedures (without using base or phase transfer catalysis), and catalyst recycling make the catalytic system attractive. It is also active beyond activated benzylic methylene positions and could tolerate factionalized arylalkanes with diverse groups.
- Hossain, Md. Munkir,Shyu, Shin-Guang
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- Oxidation of alcohols with molecular oxygen promoted by Nafion ionomer anchored pyrochlore composite at room temperature
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Nafion ionomer anchored ruthenium oxide pyrochlore composite has been demonstrated for selective oxidation of alcohols to aldehydes and ketones in good yields. In the absence of any additives, the reaction was achieved by atmospheric air or molecular oxygen at room temperature.
- Venkatesan,Kumar, A. Senthil,Zen
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- Three Pd-decavanadates with a controllable molar ratio of Pd to decavanadate and their heterogeneous aerobic oxidation of benzylic C-H bonds
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By the combination of Pd-complexes and [V10O28]6-, three Pd-decavanadate compounds [Pd(NH3)4]3[V10O28]·8H2O (1), [Pd(deta)(H2O)]2(NH4)2[V10O28]·2H2O (2) (deta = diethylenetriamine) and [Pd(dpa)2](Hdpa)2(Et3NH)2[V10O28]·2H2O (3) (dpa = 2,2′-dipyridylamine) have been successfully synthesized and thoroughly characterized using single X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), infrared spectroscopy (FT-IR) and elemental analyses (EA). Interestingly, in the three compounds, the molar ratios of Pd to decavanadate vary from 3:1 to 1:1 by changing N-ligands. The three Pd-decavanadates as heterogeneous catalysts are active in the aerobic oxidation of benzylic hydrocarbons under solvent-free conditions without adding any additives and co-catalysts. Moreover, compound 1 can be reused three times without losing its activity.
- Huang, Xianqiang,Li, Jikun,Shen, Guodong,Xin, Nana,Lin, Zhengguo,Chi, Yingnan,Dou, Jianmin,Li, Dacheng,Hu, Changwen
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- Non-heme iron catalysts for the benzylic oxidation: A parallel ligand screening approach
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Ethylbenzene and 4-ethylanisole were used as model substrates for benzylic oxidation with H2O2 or O2 using a range of non-heme iron catalysts following a parallel ligand screening approach. Effective oxidation was found fo
- Klopstra, Marten,Hage, Ronald,Kellogg, Richard M.,Feringa, Ben L.
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- Hydration of aromatic alkynes catalyzed by a self-assembled hexameric organic capsule
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The combination of a Br?nsted acid catalyst and a supramolecular organic capsule formed by the self-assembly of six resorcin[4]arene units efficiently promotes the mild hydration of aromatic alkynes to their corresponding ketones. The capsule provides a suitable nanoenvironment that favors protonation of the substrate and addition of water.
- La Sorella, Giorgio,Sperni, Laura,Ballester, Pablo,Strukul, Giorgio,Scarso, Alessandro
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- In Situ Preparation of Au-SH@SO3H-SBA-15 Catalyst with Enhanced Activity and Durability in Alkyne Hydration
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A facile approach was developed for synthesizing Au-SH@SO3H-SBA-15 with ordered mesoporous channels by reducing Au3+ to Au nanoparticles with SH-group bonded to silica support, followed by in situ coordinating Au with the unreacted SH-groups. This catalyst exhibited high efficiency in alkyne hydration owing to the high activity of uniformly dispersed ultrasmall Au nanoparticles, the diminished diffusion limit due to the mesoporous structure, and the promoting effect of acidic SO3H-groups resulting from oxidation of the SH-group by Au3+. Meanwhile, the catalyst could be easily recycled and displayed strong durability owing to the strong hydrothermal stability of mesoporous structure and the enhanced stability against Au leaching due to the Au-SH coordination bond.
- Zhu, Fengxia,Li, Hexing
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- Hydration of terminal alkynes catalyzed by a water-soluble salen-Co(III) complex
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A water-soluble salen-Co(III) complex was studied as catalyst for hydration of terminal alkynes to methyl ketones in the presence of H2SO4 as a co-catalyst. The products were obtained with excellent yields using relatively low catalyst loadings and a simple protocol. Notably, the products were easily separated from the catalyst after reaction by extraction, and the catalyst could be recovered and reused with only a slight loss of activity.
- Wang, Shoufeng,Miao, Chengxia,Wang, Wenfang,Lei, Ziqiang,Sun, Wei
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- Pd(II)-Catalyzed Denitrogenative and Desulfinative Addition of Arylsulfonyl Hydrazides with Nitriles
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A Pd(II)-catalyzed denitrogenative and desulfinative addition of arylsulfonyl hydrazides with nitriles has been successfully achieved under mild conditions. This transformation is a new method for the addition reaction to nitriles with arylsulfonyl hydrazides as arylating agent, thus providing an alternative synthesis of aryl ketones. The reported addition reaction is tolerant to many common functional groups, and works well in the presence of electron-donating and electron-withdrawing substituents. Notably, the reported denitrogenative and desulfinative addition was also appropriate for alkyl nitriles, making this newly developed transformation attractive.
- Meng, Mengting,Yang, Liangfeng,Cheng, Kai,Qi, Chenze
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- A well-defined complex for palladium-catalyzed aerobic oxidation of alcohols: Design, synthesis, and mechanistic considerations
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A breath of fresh air: A variety of alcohols are oxidized using 0.5-0.1 mol% of the catalyst, and in some cases the oxidation can simply be carried out open to the air (see scheme). Mechanistic insight into the mechanism is provided by a crystal structure that shows remarkable hydrogen bonds between the coordinated water and acetate ligands and an unprecedented large kinetic isotope effect.
- Jensen, David R.,Schultz, Mitchell J.,Mueller, Jaime A.,Sigman, Matthew S.
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- Novel anti-Markovnikov regioselectivity in the Wacker reaction of styrenes
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The Wacker reaction is one of the longest known palladium-catalysed organic transformations, and in the vast majority of cases proceeds with Markovnikov regioselectivity. Palladium(II)-mediated oxidation of styrenes was examined and in the absence of reoxidants was found to proceed in an anti-Markovnikov sense, giving aldehydes. Studies on the mechanism of this unusual transformation were carried out, and indicate the possible involvement of a η4-palladium-styrene complex. With a heteropolyacid as the terminal oxidant, oxidation of styrene to give the anti-Markovnikov aldehyde as the major product was found to be catalytic.
- Wright, Joseph A.,Gaunt, Matthew J.,Spencer, Jonathan B.
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- Identification of an ASE2 Mechanism in the Hydrolysis of Cyclic Thioacetals
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2-Phenyl-2-methyl-1,3-dithiane and its p-methoxy derivative undergo hydrolysis in concentrated aqueous perchloric acid via the ASE2 mechanism rather than via the A1 mechanism.
- Ali, Muhammad,Satchell, Derek P. N.
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- Photohydration of Styrenes and Phenylacetylenes. General Acid Catalysis and Broensted Relationship
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The acid-catalyzed photohydration of a series of substituted styrenes and phenylacetylenes have been investigated in aqueous buffer solutions.General acid catalysis was clearly detected in five cases with a range of catalysts, and approximately linear Broensted plots gave α values in the range 0.14-0.18.The rate enhancements caused by excitation from S0 to S1 were estimated from comparisons with thermal hydration data to be in the 1E11-1E15 range.Treatment of the dependence of the rate constants for general acid catalysis (kHA) on the buffer pKHA values with multiple regression analysis suggests that the Broensted plots are smoothly curved, as predicted by Eigen and by the Marcus equation.However, reliable values of the Broensted curvature could not be established.The possible catalytic reactivity analogous triplet states was examined with a series of nitrosubstituted analogues, but no general acid catalysis could be detected.The factors controlling the detection of general acid catalysis in these photoreactions are discussed.
- McEwen, John,Yates, Keith
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- Ruthenium carbonyl complexes with pyridine-alkoxide ligands: Synthesis, characterization and catalytic application in dehydrogenative oxidation of alcohols
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Several new trinuclear ruthenium carbonyl complexes chelated with 6-bromopyridine alcohol ligands, [6-bromopyC(CH2)4O]Ru3(CO)9 (1a), [6-bromopyC(CH2)5O]Ru3(CO)9 (1b), [6-bromopyC(Me)2O]Ru3(CO)9 (1c) and [6-bromopyCMeC6H5O]Ru3(CO)9 (1d), were synthesized by the reaction of Ru3(CO)12 with 6-bromopyC(CH2)4OH (L1H), 6-bromopyC(CH2)5OH (L2H), 6-bromopyC(Me)2OH (L3H) and 6-bromopyCMeC6H5OH (L4H) in refluxing THF, respectively. The free ligands L1H-L4H were synthesized by the nucleophilic reaction of lithium salt (generated from 2,6-dibromopyridine and n-BuLi) with the corresponding ketones. Furthermore, these pyridine-based ligands were characterized by NMR spectroscopy and elemental analyses. All the four ruthenium carbonyl complexes were well characterized by NMR, IR, single-crystal X-ray crystallography, etc. Complexes 1a-1d were found to exhibit high catalytic activities for the dehydrogenative oxidation of secondary alcohols to give their corresponding products in good to excellent yields.
- Hao, Zhiqiang,Yan, Xinlong,Liu, Kang,Yue, Xiaohui,Han, Zhangang,Lin, Jin
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- Metal/catalyst/reagent free hydration of alkynes up to gram scale under temperature and pressure controlled condition
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A new green water-mediated metal/catalyst/reagent-free methodology for hydration of alkyne is devised. The remarkable yields of various ketones were achieved when alkynes were heated at 150 °C under 11 bar pressure in an autoclave for 14 h in water-methanol solution. Outstanding functional group compatibility for both the terminal and internal alkynes was established. This methodology produces excellent yields up to gram scale under optimised reaction condition.
- Ali, Munsaf,Srivastava, Avinash K.,Joshi, Raj K.
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- Ruthenium-catalyzed oxidation of alkanes with tert-butyl hydroperoxide and peracetic acid
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The ruthenium-catalyzed oxidation of alkanes with tert-butyl hydroperoxide and peracetic acid gives the corresponding ketones and alcohols highly efficiently at room temperature. The former catalytic system, RuCl2(PPh3)3-t-BuOOH, is preferable to the oxidation of alkylated arenes to give aryl ketones. The latter system, Ru/C-CH3CO3H, is suitable especially for the synthesis of ketones and alcohols from alkanes. The ruthenium-catalyzed oxidation of cyclohexane with CH3CO3H in trifluoroacetic acid/CH2Cl2 at room temperature gave cyclohexyl trifluoroacetate and cyclohexanone with 90% conversion and 90% selectivity (85:15). The mechanistic study indicates that these catalytic oxidations of hydrocarbons involve oxo-ruthenium species as key intermediates.
- Murahashi,Komiya,Oda,Kuwabara,Naota
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- Rh- and Ru-complex-catalyzed dimerization of arylethynes Rylethynes in aqueous environment
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Complexes [RhCl(PPh3)3] and [Ru(CHPh)Cl 2(PCy3)2] efficiently catalyzed the dimerization of arylethynes to the corresponding 1,4-substituted enynes in aqueous environment in the presence of sodium dodecyl sulfate. The Rh catalyst exhibited almost exclusive preference for the formation of ￡-isomers, the Ru one exhibits strong preference for the formation of Z-isomers.
- Novak, Petr,Kotora, Martin
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- Microwave Heated Continuous Flow Palladium(II)-Catalyzed Desulfitative Synthesis of Aryl Ketones
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A protocol for Pd(II)-catalyzed desulfitative synthesis of aryl ketones from sodium aryl sulfinates and nitriles in continuous flow has been developed. The reactions proceed with microwave heating using microwave transparent tube reactors, affording the desired aryl ketones in fair to good yields. Microwave transparent aluminum oxide reactors were identified as a safe and thermostable alternative to borosilicate glass reactors.
- Skillinghaug, Bobo,Rydfjord, Jonas,S?vmarker, Jonas,Larhed, Mats
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- Light-driven carbon dioxide reduction coupled with conversion of acetylenic group to ketone by a functional Janus catalyst based on keplerate {Mo132}
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Catalysts enabling CO2 reduction coupled with another organic reaction are rare. In this study, we report such a catalyst keplerate {Mo132}, which catalyses photochemical carbon dioxide reduction to formic acid coupled with organic transformation, i.e., hydration of phenylacetylene to acetophenone in visible light. It initially oxidizes water and injects the reducing equivalents for reduction of carbon dioxide at the same time, converting acetylenic group to ketone. Our designed redox Janus catalyst provides an inexpensive pathway to achieve carbon dioxide reduction as well as conversion of phenylacetylene to acetophenone, which is an industrially important precursor.
- Lodh, Joyeeta,Mallick, Apabrita,Roy, Soumyajit
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- Clay supported ammonium nitrate 'Clayan': A mild and highly selective reagent for the deoximation of electron rich oximes
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A simple and convenient method for selective deoximation of electron rich oximes is described using Clay supported ammonium nitrate 'Clayan'. Self destroying nature of the reagent makes the procedure attractive and eco- friendly.
- Meshram,Reddy, Gondi Sudershan,Srinivas, Dale,Yadav
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- Highly efficient oxidation of alcohols catalyzed by a porphyrin-inspired manganese complex
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A novel strategy for catalytic oxidation of a variety of benzylic, allylic, propargylic, and aliphatic alcohols to the corresponding aldehydes or ketones by an in situ formed porphyrin-inspired manganese complex in excellent yields (up to 99%) has been successfully developed.
- Dai, Wen,Lv, Ying,Wang, Lianyue,Shang, Sensen,Chen, Bo,Li, Guosong,Gao, Shuang
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- Highly efficient AgBF4-catalyzed synthesis of methyl ketones from terminal alkynes
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A silver-catalyzed highly efficient synthesis of a wide range of methyl ketones from terminal alkynes is described. The reactions are conducted under convenient conditions and provide products with excellent regioselectivity in moderate to excellent yields, with broad substrate scope, including a variety of aromatic and aliphatic terminal alkynes.
- Chen, Zheng-Wang,Ye, Dong-Nai,Qian, Yi-Ping,Ye, Min,Liu, Liang-Xian
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- Enantioselective oxidation of racemic secondary alcohols catalyzed by chiral Mn(III)-salen complex with sodium hypochlorite as oxidant
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Chiral Mn(III)-salen complex catalyzed oxidative kinetic resolution (OKR) of secondary alcohols has been achieved with cheap and easily available sodium hypochlorite (NaClO) as oxidant. The novel protocol is very efficient for the OKR of a variety of secondary alcohols at room temperature.
- Zhang, Yuecheng,Zhou, Qiao,Ma, Wenchan,Zhao, Jiquan
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Read Online
- Photophysics of Perylene Diimide Dianions and Their Application in Photoredox Catalysis
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The two-electron reduced forms of perylene diimides (PDIs) are luminescent closed-shell species whose photochemical properties seem underexplored. Our proof-of-concept study demonstrates that straightforward (single) excitation of PDI dianions with green
- Li, Han,Wenger, Oliver S.
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supporting information
(2021/12/23)
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- Selective Activation of Unstrained C(O)-C Bond in Ketone Suzuki-Miyaura Coupling Reaction Enabled by Hydride-Transfer Strategy
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A Rh(I)-catalyzed ketone Suzuki-Miyaura coupling reaction of benzylacetone with arylboronic acid is developed. Selective C(O)-C bond activation, which employs aminopyridine as a temporary directing group and ethyl vinyl ketone as a hydride acceptor, occurs on the alkyl chain containing a β-position hydrogen. A series of acetophenone products were obtained in yields up to 75%.
- Zhong, Jing,Zhou, Wuxin,Yan, Xufei,Xia, Ying,Xiang, Haifeng,Zhou, Xiangge
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supporting information
p. 1372 - 1377
(2022/02/23)
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- Copper-Catalyzed Azide-Alkyne Cycloaddition of Hydrazoic Acid Formed in Situ from Sodium Azide Affords 4-Monosubstituted-1,2,3-Triazoles
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We report a copper-catalyzed cycloaddition of hydrogen azide (hydrazoic acid, HN3) with terminal alkynes to form 4-substituted-1H-1,2,3-triazoles in a sustainable manner. Hydrazoic acid was formed in situ from sodium azide under acidic conditions to react with terminal alkynes in a copper-catalyzed reaction. Using polydentate N-donor chelating ligands and mild organic acids, the reactions were realized to proceed at room temperature under aerobic conditions in a methanol-water mixture and with 5 mol % catalyst loadings to afford 4-substituted-1,2,3-triazoles in high yields. This method is amenable on a wide range of alkyne substrates, including unprotected peptides, showing diverse functional group tolerance. It is applicable for late-stage functionalization synthetic strategies, as demonstrated in the synthesis of the triazole analogue of losartan. The preparation of orthogonally protected azahistidine from Fmoc-l-propargylglycine was realized on a gram scale. The hazardous nature of hydrazoic acid has been diminished as it forms in situ in a reactive species in the copper-catalyzed reaction.
- Jankovi?, Dominik,Virant, Miha,Gazvoda, Martin
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p. 4018 - 4028
(2022/02/25)
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- A Mild Heteroatom (O -, N -, and S -) Methylation Protocol Using Trimethyl Phosphate (TMP)-Ca(OH) 2Combination
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A mild heteroatom methylation protocol using trimethyl phosphate (TMP)-Ca(OH)2combination has been developed, which proceeds in DMF, or water, or under neat conditions, at 80 °C or at room temperature. A series of O-, N-, and S-nucleophiles, including phenols, sulfonamides, N-heterocycles, such as 9H-carbazole, indole derivatives, and 1,8-naphthalimide, and aryl/alkyl thiols, are suitable substrates for this protocol. The high efficiency, operational simplicity, scalability, cost-efficiency, and environmentally friendly nature of this protocol make it an attractive alternative to the conventional base-promoted heteroatom methylation procedures.
- Tang, Yu,Yu, Biao
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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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- 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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- V2O5@TiO2 Catalyzed Green and Selective Oxidation of Alcohols, Alkylbenzenes and Styrenes to Carbonyls
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The versatile application of different functional groups such as alcohols (1° and 2°), alkyl arenes, and (aryl)olefins to construct carbon-oxygen bond via oxidation is an area of intense research. Here, we report a reusable heterogeneous V2O5@TiO2 catalyzed selective oxidation of various functionalities utilizing different mild and eco-compatible oxidants under greener reaction conditions. The method was successfully applied for the alcohol oxidation, oxidative scission of styrenes, and benzylic C?H oxidation to their corresponding aldehydes and ketones. The utilization of mild and eco-friendly oxidizing reagents such as K2S2O8, H2O2 (30 % aq.), TBHP (70 % aq.), broad substrate scope, gram-scale synthesis, and catalyst recyclability are notable features of the developed protocol.
- Upadhyay, Rahul,Kumar, Shashi,Maurya, Sushil K.
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p. 3594 - 3600
(2021/07/02)
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- Visible-light photocatalytic selective oxidation of C(sp3)-H bonds by anion-cation dual-metal-site nanoscale localized carbon nitride
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Selective oxidation of C(sp3)-H bonds to carbonyl groups by abstracting H with a photoinduced highly active oxygen radical is an effective method used to give high value products. Here, we report a heterogeneous photocatalytic alkanes C-H bonds oxidation method under the irradiation of visible light (λ= 425 nm) at ambient temperature using an anion-cation dual-metal-site modulated carbon nitride. The optimized cation (C) of Fe3+or Ni2+, with an anion (A) of phosphotungstate (PW123?) constitutes the nanoscale dual-metal-site (DMS). With a Fe-PW12dual-metal-site as a model (FePW), we demonstrate a A-C DMS nanoscale localized carbon nitride (A-C/g-C3N4) exhibiting a highly enhanced photocatalytic activity with a high product yield (86% conversion), selectivity (up to 99%), and a wide functional group tolerance (52 examples). The carbon nitride performs the roles of both the visible light response, and improves the selectivity for the oxidation of C(sp3)-H bonds to carbonyl groups, along with the function of A-C DMS in promoting product yield. Mechanistic studies indicate that this reaction follows a radical pathway catalyzed by a photogenerated electron and hole on A-C/g-C3N4that is mediated by thetBuO˙ andtBuOO˙ radicals. Notably, a 10 g scale reaction was successfully achieved for alkane photocatalytic oxidation to the corresponding product with a good yield (80% conversion), and high selectivity (95%) under natural sunlight at ambient temperature. In addition, this A-C/g-C3N4photocatalyst is highly robust and can be reused at least six times and the activity is maintained.
- Duan, Limei,Li, Peihe,Li, Wanfei,Liu, Jinghai,Liu, Ying,Liu, Zhifei,Lu, Ye,Sarina, Sarina,Wang, Jinghui,Wang, Yin,Wang, Yingying,Zhu, Huaiyong
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p. 4429 - 4438
(2021/07/12)
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- Selective electrochemical oxidation of aromatic hydrocarbons and preparation of mono/multi-carbonyl compounds
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A selective electrochemical oxidation was developed under mild condition. Various mono-carbonyl and multi-carbonyl compounds can be prepared from different aromatic hydrocarbons with moderate to excellent yield and selectivity by virtue of this electrochemical oxidation. The produced carbonyl compounds can be further transformed into α-ketoamides, homoallylic alcohols and oximes in a one-pot reaction. In particular, a series of α-ketoamides were prepared in a one-pot continuous electrolysis. Mechanistic studies showed that 2,2,2-trifluoroethan-1-ol (TFE) can interact with catalyst species and generate the corresponding hydrogen-bonding complex to enhance the electrochemical oxidation performance. [Figure not available: see fulltext.]
- Li, Zhibin,Zhang, Yan,Li, Kuiliang,Zhou, Zhenghong,Zha, Zhenggen,Wang, Zhiyong
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p. 2134 - 2141
(2021/09/29)
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- Gold complexes of bis-indazole-derived N-Heterocyclic carbene: Synthesis, structural characterizations, and catalysis
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A novel series of bis Indy-NHC gold complexes have been developed and investigated via a mild Ag-carbene transfer route. The obtained complexes were characterized by NMR spectroscopy and X-ray diffraction analysis. The catalytic property of these gold complexes was further evaluated in the oxidation of benzylic. The gold complex E1 showed a high catalytic activity in the oxidation of various benzylic substrates, resulting in the corresponding carbonyl compounds with excellent yields using TBHP as oxidant.
- Zhang, Hua,Xu, Ting,Li, Dongdong,Cheng, Tao,Chen, Jing,Zhou, Yang
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- Selective Oxidation of Benzylic sp3C-H Bonds using Molecular Oxygen in a Continuous-Flow Microreactor
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Selective aerobic oxidation of benzylic sp3 C-H bonds to generate the corresponding ketones was achieved under continuous-flow conditions. The catalysts N-hydroxyphthalimide (NHPI) and tert-butyl nitrite (TBN) as the precursor of the radical under aerobic conditions motivated this process. Flow microreactors operating under optimized conditions enabled this oxidation with higher efficiency and a shortened reaction time of 54 s (total time was 10 min), which was improved 466 times compared with the batch parallel reaction (7.0 h). Notably, the catalyst and solvent recycling (92.6 and 94.5%) and scale-up experiments (0.87 g h-1 in 28 h) demonstrated the practicability of the protocol. The high product selectivity and functional group tolerance of the process allowed the production of ketones in yields of 41.2 to 90.3%. To reveal the versatility and applicability of this protocol, the late-stage modification of an antiepileptic drug to obtain oxcarbazepine was further conducted.
- Ma, Cunfei,Meng, Qingwei,Tang, Xiaofei,Yu, Zongyi,Yun, Lei,Zhao, Jingnan
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p. 1612 - 1618
(2021/07/21)
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- Selective Electrochemical Oxygenation of Alkylarenes to Carbonyls
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An efficient electrochemical method for benzylic C(sp3)-H bond oxidation has been developed. A variety of methylarenes, methylheteroarenes, and benzylic (hetero)methylenes could be converted into the desired aryl aldehydes and aryl ketones in moderate to excellent yields in an undivided cell, using O2 as the oxygen source and lutidinium perchlorate as an electrolyte. On the basis of cyclic voltammetry studies, 18O labeling experiments, and radical trapping experiments, a possible single-electron transfer mechanism has been proposed for the electrooxidation reaction.
- Li, Xue,Bai, Fang,Liu, Chaogan,Ma, Xiaowei,Gu, Chengzhi,Dai, Bin
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supporting information
p. 7445 - 7449
(2021/10/02)
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- 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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- HCl-Catalyzed Aerobic Oxidation of Alkylarenes to Carbonyls
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The construction of C?O bonds through C?H bond functionalization remains fundamentally challenging. Here, a practical chlorine radical-mediated aerobic oxidation of alkylarenes to carbonyls was developed. This protocol employed commercially available HCl as a hydrogen atom transfer (HAT) reagent and air as a sustainable oxidant. In addition, this process exhibited excellent functional group tolerance and a broad substrate scope without the requirement for external metal and oxidants. The mechanistic hypothesis was supported by radical trapping, 18O labeling, and control experiments.
- Ding, Ling,Liu, Yuxiu,Niu, Kaikai,Shi, Xiaodi,Song, Hongjian,Wang, Qingmin
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- Robust Photocatalytic Method Using Ethylene-Bridged Flavinium Salts for the Aerobic Oxidation of Unactivated Benzylic Substrates
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7,8-Dimethoxy-3-methyl-1,10-ethylenealloxazinium chloride (1a) was found to be a superior photooxidation catalyst among substituted ethylene-bridged flavinium salts (R=7,8-diMeO, 7,8-OCH2O-, 7,8-diMe, H, 7,8-diCl, 7-CF3 and 8-CF3). Selection was carried out based on structure vs catalytic activity and properties relationship investigations. Flavinium salt 1a proved to be robust enough for practical applications in benzylic oxidations/oxygenations, which was demonstrated using a series of substrates with high oxidation potential, i. e., 1-phenylethanol, ethylbenzene, diphenylmethane and diphenylmethanol derivatives substituted with electron-withdrawing groups (Cl or CF3). The unique capabilities of 1a can be attributed to its high photostability and participation via a relatively long-lived singlet excited state, which was confirmed using spectroscopic studies, electrochemical measurements and TD-DFT calculations. This allows the maximum use of the oxidation power of 1a, which is given by its singlet excited state reduction potential of +2.4 V. 7,8-Dichloro-3-methyl-1,10-ethylenealloxazinium chloride (1 h) can be used as an alternative photocatalyst for even more difficult substrates. (Figure presented.).
- Pokluda, Adam,Anwar, Zubair,Boguschová, Veronika,Anusiewicz, Iwona,Skurski, Piotr,Sikorski, Marek,Cibulka, Radek
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p. 4371 - 4379
(2021/04/02)
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- Efficient aerobic oxidation of ethylbenzene accelerated by cu species in hydrotalcite
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The simply prepared CuMgAl hydrotalcite (CuMgAl-LDH) has been developed as an efficient catalyst for the aerobic oxidation of ethylbenzene to acetophenone in the presence of N-Hydroxyphthalimide (NHPI). Various alkyl arenes could be tolerated under the selected reaction conditions. The kinetic study showed that the oxidation of ethylbenzene is a first-order reaction over CuMgAl-LDH. The mechanism study indicated that CuMgAl-LDH could accelerate not only the conversion of ethylbenzene, but also the transformation of the alcohol intermediate to ketone. The positive effect of surface basicity of the catalyst on the reaction has been observed in the aerobic oxidation of the ethylbenzene.
- Dai, Xuan,Jiang, Ou,Li, Xingyan,Peng, Xinhua,Tang, Shuangling,Zheng, Xuegen
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- A Copper-Containing Polyoxometalate-Based Metal-Organic Framework as an Efficient Catalyst for Selective Catalytic Oxidation of Alkylbenzenes
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A copper-containing polyoxometalate-based metal-organic framework (POMOF), CuI12Cl2(trz)8[HPW12O40] (HENU-7, HENU = Henan University; trz = 1,2,4-triazole), has been successfully synthesized and well-characterized. In addition, the excellent catalytic ability of HENU-7 has been proved by the selective oxidation of diphenylmethane. Under the optimal conditions, the diphenylmethane conversion obtained over HENU-7 is 96%, while the selectivity to benzophenone is 99%, which outperforms most noble-metal-free POM-based catalysts. Moreover, HENU-7 is stable to reuse for five runs without an obvious loss in activity and also can catalyze the oxidation of different benzylic C-H with satisfactory conversions and selectivities, which implied the significant catalytic activity and recyclability.
- Xu, Baijie,Xu, Qian,Wang, Quanzhong,Liu, Zhen,Zhao, Ruikun,Li, Dandan,Ma, Pengtao,Wang, Jingping,Niu, Jingyang
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p. 4792 - 4799
(2021/04/09)
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- 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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- Single-atom cobalt-fused biomolecule-derived nitrogen-doped carbon nanosheets for selective oxidation reactions
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Non-noble metal single-atom catalysts hold great promise in selective oxidation reactions, although the progress is still unsatisfactory because of the synthesis challenge and the lack of mechanistic interpretations. Herein, we develop a biomolecule-based strategy to synthesize isolated Co single atom site catalysts by one-step pyrolysis of guanosine and Co precursors. Due to the abundant hydrogen bonding and π-π interaction of guanosine, the as-synthesized Co-N-C catalysts present a hierarchical porous two-dimensional (2D) nanostructure with an ultrahigh specific surface area, large pore volume, and high density of cobalt single atoms. Aberration-corrected electron microscopy and X-ray photoelectron spectroscopy reveal that Co species are present as isolated single sites and stabilized by nitrogen-doped carbon nanosheets. These characteristics make Co-GS-900 suitable as an efficient catalyst for selective oxidation of aromatic alkanes. For oxidation of ethylbenzene, Co-GS-900 exhibits a superior performancefwith 91% conversion and 98% selectivity of acetophenone.
- Huang, Haitao,Wei, Qiao-Hua,Xia, Miao,Xie, Zailai,Zhang, Xuefei
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p. 14276 - 14283
(2021/07/13)
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- Protein powder derived nitrogen-doped carbon supported atomically dispersed iron sites for selective oxidation of ethylbenzene
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Atomically dispersed Fe species embedded in the nitrogen-containing carbon supports (Fe1/NC) are successfully synthesized using a ball milling approach, with commercial protein powder as the nitrogen source. The catalyst exhibits outstanding performance in the oxidation of aromatic compounds containing saturated C-H bonds into corresponding ketones under ambient conditions, which is superior to those of a nanoparticle catalyst (Fen/NC) and a metal-free catalyst (NC).
- Cheng, Yujie,Gan, Tao,He, Qian,He, Xiaohui,Huang, Liyun,Ji, Hongbing,Shi, Shaolin,Sun, Qingdi,Wang, Pengbo,Zhang, Hao,Zhang, Xingcong,Zhang, Ying
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supporting information
p. 11711 - 11715
(2021/09/06)
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- Synthetic method of etoricoxib intermediate 4 - methylsulfonyl acetophenone
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The synthesis method comprises the following steps: adding anhydrous 4 - aluminum trichloride to a dichloromethane system; adding acetyl chloride to obtain the reaction solution; and adding the chloride to obtain the reaction solution. Step II: The reaction solution is added dropwise to the reaction solution; and the reaction solution is added dropwise to the reaction solution. The aqueous phase is extracted with dichloromethane, the organic phase is combined, and the combined organic phases are washed with 10% sodium hydrogen carbonate aqueous solution. Step IV: The organic phase after washing is evaporated to dryness, n-heptane is added, the crystals are washed and dried to obtain the acetyl benzyl thioether. The method comprises the following steps: adding the acetoxymethylsulfide obtained in the step to the acetone system, further reacting to obtain 4 - methylsulfonyl acetophenone. Or to the acetic acid system, the obtained acetoxymethylsulfide is added, and the mixture is stirred and dissolved to obtain the reaction mixture. A further reaction gave 4 - methylsulfonylacetophenone. It reduces the energy consumption, and the reaction is more stable, and the benefit is high.
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Paragraph 0041-0048; 0052-0058; 0062-0081
(2021/08/25)
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- Compound with cinnamon fragrance as well as preparation method and application thereof
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The invention relates to a compound with cinnamon fragrance as well as a preparation method and application thereof. The compound has the following structural formula, wherein the structural formula can be named as 2-decenoic acid-2-(4-methoxy)-phenyl-2-butyl ester. The provided compound has the advantages of obvious cinnamon aroma, rich aroma, lasting aroma and good stability, and enriches the sources of cinnamon aroma. When the essence is prepared in different periods, the compound has consistent cinnamon aroma, so that the required aroma can be accurately mastered.
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Paragraph 0104-0108; 0126-0129; 0137-0138; 0141-0142; 0145
(2021/04/10)
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- Cobalt-Catalyzed Aerobic Oxidative Cleavage of Alkyl Aldehydes: Synthesis of Ketones, Esters, Amides, and α-Ketoamides
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A widely applicable approach was developed to synthesize ketones, esters, amides via the oxidative C?C bond cleavage of readily available alkyl aldehydes. Green and abundant molecular oxygen (O2) was used as the oxidant, and base metals (cobalt and copper) were used as the catalysts. This strategy can be extended to the one-pot synthesis of ketones from primary alcohols and α-ketoamides from aldehydes.
- Li, Tingting,Hammond, Gerald B.,Xu, Bo
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supporting information
p. 9737 - 9741
(2021/05/31)
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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 preparing carbonyl compound through oxidative cleavage of visible light excitation aqueous solution quantum dot catalytic olefin compound
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The invention provides a method for preparing carbonyl compounds through oxidative cleavage of a visible light excitation aqueous solution quantum dot catalytic olefin compound. Belong to photocatalysis synthesis technical field. To the method, an aqueous solution quantum dot is used as a photocatalyst, and an aqueous solution quantum dot activated molecular oxygen catalytic oxidation aromatic alkene compound is excited by visible light to be cracked to prepare a carbonyl compound. Low-loading capacity is used, a simple aqueous solution quantum dot is used as a catalyst, the yield of the carbonyl compound is high, TON more than ten millions are obtained. The reaction conditions are mild, water serves as a main solvent for the reaction, and the carbonyl compound can be obtained by catalytic olefin compound oxidation cracking without addition of a cocatalyst or the like. The method is simple to operate, wide in substrate range and low in cost.
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Paragraph 0034
(2021/11/10)
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- Aryl aldiketone and synthesis method thereof
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The invention discloses an aryl aldehyde ketone and a synthesis method thereof, wherein an aryl aldehyde is synthesized from cheap olefin as a raw material. A commercially available inexpensive olefin is used as a raw material, ether is used as an additive, molecular oxygen serves as a sole oxidizing agent, water is used as a solvent, and the aldehyde and ketone are synthesized by column chromatography under a photocatalytic condition. The invention has the advantages of mild reaction conditions, green and environmental protection, simple experimental operation, good reaction selectivity, high product yield and the like.
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Paragraph 0021
(2021/09/26)
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- Photo-induced oxidative cleavage of C-C double bonds of olefins in water
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The carbonyl compounds, synthesized by the oxidative cleavage of their corresponding olefins, are of great significance in organic synthesis, especially aryl ketones. We have developed a gentle and effective protocol, using acid red 94 as the organic metal-free photocatalyst, O2 as the oxidant, and water as the solvent. Under visible light irradiation, aryl ketone derivatives were obtained in moderate to excellent yields, showing good economic and environmental advantages.
- Zhang, Yilan,Yue, Xiaoguang,Liang, Chenfeng,Zhao, Jianming,Yu, Wenbo,Zhang, Pengfei
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supporting information
(2021/08/27)
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- Decatungstate-mediated solar photooxidative cleavage of CC bonds using air as an oxidant in water
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With the increasing attention for green chemistry and sustainable development, there has been much interest in searching for greener methods and sources in organic synthesis. However, toxic additives or solvents are inevitably involved in most organic transformations. Herein, we first report the combination of direct utilization of solar energy, air as the oxidant and water as the solvent for the selective cleavage of CC double bonds in aryl olefins. Various α-methyl styrenes, diaryl alkenes as well as terminal styrenes are well tolerated in this green and sustainable strategy and furnished the desired carbonyl products in satisfactory yields. Like heterogeneous catalysis, this homogeneous catalytic system could also be reused and it retains good activity even after repeating three times. Mechanism investigations indicated that both O2- and 1O2 were involved in the reaction. Based on these results, two possible mechanisms, including the electron transfer pathway and the energy transfer pathway, were proposed.
- Du, Dongdong,Luo, Junfei,Shi, Sanshan,Xie, Pan,Xue, Cheng
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p. 5936 - 5943
(2021/08/23)
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- Photo-induced oxidative cleavage of C-C double bonds for the synthesis of biaryl methanoneviaCeCl3catalysis
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A Ce-catalyzed strategy is developed to produce biaryl methanonesviaphotooxidative cleavage of C-C double bonds at room temperature. This reaction is performed under air and demonstrates high activity as well as functional group tolerance. A synergistic Ce/ROH catalytic mechanism is also proposed based on the experimental observations. This protocol should be the first successful Ce-catalyzed photooxidation reaction of olefins with air as the oxidant, which would provide inspiration for the development of novel Ce-catalyzed photochemical synthesis processes.
- Xie, Pan,Xue, Cheng,Du, Dongdong,Shi, SanShan
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supporting information
p. 6781 - 6785
(2021/08/20)
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- Visible-Light-Driven Oxidative Cleavage of Alkenes Using Water-Soluble CdSe Quantum Dots
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The oxidative cleavage of C=C bonds is an important chemical reaction, which is a popular reaction in the photocatalytic field. However, high catalyst-loading and low turnover number (TON) are general shortcomings in reported visible-light-driven reactions. Herein, the direct oxidative cleavage of C=C bonds through water-soluble CdSe quantum dots (QDs) is described under visible-light irradiation at room temperature with high TON (up to 3.7×104). Under the same conditions, water-soluble CdSe QDs could also oxidize sulfides to sulfoxides with 51–84 % yields and TONs up to 3.4×104. The key features of this photocatalytic protocol include high TONs, wide substrates scope, low catalyst loadings, simple and mild reaction conditions, and molecular O2 as the oxidant.
- Li, Jianing,Zhao, Jingnan,Ma, Cunfei,Yu, Zongyi,Zhu, Hongfei,Yun, Lei,Meng, Qingwei
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p. 4985 - 4992
(2021/10/16)
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- Promoting charge separation in donor-acceptor conjugated microporous polymers: Via cyanation for the photocatalytic reductive dehalogenation of chlorides
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Conjugated microporous polymers (CMPs) have emerged as promising heterogeneous photocatalysts for organic transformations owing to their structural designability and functional versatility. However, limited by the insufficient separation of the photo-generated excitons, their photocatalytic efficiency falls far short of expectations. Herein, we demonstrate a cyanation strategy to promote charge carrier separation in CMPs by selectively incorporating carbazole and cyano groups as electron-donating and electron-withdrawing units, respectively. The resulting CMPs feature π-extended donor (D)-acceptor (A) conjugation structures endowing them with distinct semiconducting properties, in which the efficient charge separation and transfer and wide visible-light absorption are facilitated. Compared to the cyano-free counterpart, the cyano-functionalized CMPs showed superior photocatalytic efficiency as exemplified by photocatalytic reductive dehalogenation of chlorides. More prominently, full recyclability of the designed CMPs as well as catalytic activity for at least ten runs without the loss of catalytic performance in photocatalytic reductive dehalogenation of chlorides demonstrated their robustness and sustainability. This journal is
- Deng, Jiyong,Fang, Zhengjun,Lan, Donghui,Liao, Yunfeng,Liu, Qingquan,Zhang, Weijie,Zhou, Xiang
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p. 7151 - 7159
(2021/11/17)
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- Chitosan as a chiral ligand and organocatalyst: Preparation conditions-property-catalytic performance relationships
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Chitosan is an abundant and renewable chirality source of natural origin. The effect of the preparation conditions by alkaline hydrolysis of chitin on the properties of chitosan was studied. The materials obtained were used as ligands in the ruthenium-catalysed asymmetric transfer hydrogenation of aromatic prochiral ketones and oxidative kinetic resolution of benzylic alcohols as well as organocatalysts in the Michael addition of isobutyraldehyde to N-substituted maleimides. The degrees of deacetylation of the prepared materials were determined by 1H NMR, FT-IR and UV-vis spectroscopy, the molecular weights by viscosity measurements, their crystallinity by WAXRD, and their morphology by SEM and TEM investigations. The materials were also characterized by Raman spectroscopy. The biopolymers which have molecular weights in a narrow (200-230 kDa) range and appropriate (80-95%) degrees of deacetylation were the most efficient ligands in the enantioselective transfer hydrogenation, whereas in the oxidative kinetic resolution the activity of the complexes and the stereoselectivity increased with the degree of deacetylation. The chirality of the chitosan was sufficient to obtain enantioselection in the Michael addition of isobutyraldehyde to maleimides in the aqueous phase. Interestingly, the biopolymer afforded the opposite enantiomer in excess compared to the monomer, d-glucosamine. In this reaction, good correlation between the degree of deacetylation and the catalytic activity was found. These results are novel steps in the application of this natural, biocompatible and biodegradable polymer in developing environmentally benign methods for the production of optically pure fine chemicals.
- Kolcsár, Vanessza Judit,Sz?ll?si, Gy?rgy
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p. 7652 - 7666
(2021/12/13)
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- Electrochemical reactivity of S-phenacyl-O-ethyl-xanthates in hydroalcoholic (MeOH/H2O 4:1) and anhydrous acetonitrile media
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The electrochemical behavior of a series of S-phenacyl-O-ethyl-xanthates (O-ethyl-dithiocarbonate acetophenone derivatives) in hydroalcoholic (MeOH/H2O 4:1) and anhydrous media (ACN/TBAPF6) using carbon electrodes was studied. Cyclic voltammetry showed in hydroalcoholic media only two cathodic waves, whereas in ACN one anodic and two cathodic waves were present. The first cathodic wave corresponded to the reduction of the phenylketone group, whereas the first anodic was attributed to the xanthate unit. Macroelectrolysis on graphite and vitreous carbon at anodic and cathodic potentials, let us to explore the synthetic potential of this electrochemical reactions. With some compounds in hydroalcoholic media and using carbon electrodes, polymeric material was deposited on the electrode impeding the reaction; this deposit was characterized by AFM and SEM-EDS. The electroreduction on Ti electrode overcome this problem and gave the corresponding acetophenones (>95%). On the other hand, in ACN, small quantities of the dimeric 1,4-dicarbonyl compounds X-PhCOCH2CH2COPh-X (7–15%), as well as the corresponding acetophenones (ca. 50%) were isolated. Oxidation macroelectrolysis showed a very complicated transformation without synthetic value. The reaction mechanism for the reduction and the homolytic dissociation into the phenacyl radical was supported by DFT calculations.
- López-López, Ernesto Emmanuel,López-Jiménez, Sergio J.,Barroso-Flores, Joaquín,Rodríguez-Cárdenas, Esdrey,Tapia-Tapia, Melina,López-Téllez, Gustavo,Miranda, Luis D.,Frontana-Uribe, Bernardo A.
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- Interfacially synthesized 2D COF thin film photocatalyst: efficient photocatalyst for solar formic acid production from CO2and fine chemical synthesis
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The targeted synthesis of an efficient, visible light active, recyclable, freestanding covalent organic framework thin film photocatalyst for multi-faceted photocatalysis is the essence of the proposed work. A simple, scalable, reagent free synthesis of a thin film at the interface of 5,10,15,20-tetra-(4-aminophenyl)porphyrin, 2-vinylbenzene-1,4-dicarbaldehyde in nitrobenzene and aqueous glyoxal affords centimetre sized continuous 2D thin film with substantial stability, flexibility and efficient visible light activity. Strikingly different from the regular imine based COF, the incorporation of the glyoxal unit as a modulator helps in band gap tuning and induces flexibility within the thin film. An interplay between time and concentration helps in achieving a thin film photocatalyst with efficient photocatalytic activity for 1,4-NADH regeneration and selective formic acid formation from CO2. The optimum band edge position of the thin film photocatalyst also enables solar fine chemical synthesisviareductive dehalogenation under visible light illumination with excellent recyclability. The present work gives insight into visible light active thin film formation en route to metal-free sustainable photocatalysis.
- Yadav, Dolly,Kumar, Abhishek,Kim, Jae Young,Park, No-Joong,Baeg, Jin-Ook
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supporting information
p. 9573 - 9580
(2021/04/26)
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- Hydration of Alkynes to Ketones with an Efficient and Practical Polyoxomolybdate-based Cobalt Catalyst
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Hydration of alkynes to ketones is one of the most atom economical and universal methods for the synthesis of carbonyl compounds. However, the basic reaction usually requires organic ligand catalysts or harsh reaction conditions to insert oxygen into the C≡C bond. Here, we report an inorganic ligand supported cobalt (III) catalyst, (NH4)3[CoMo6O18(OH)6], which is supported by a central cobalt (III) mononucleus and a ring-shaped pure inorganic ligand composed of six MoVIO6 octahedrons to avoid the disadvantages of expensive and unrecyclable organic ligand catalysts or noble metal catalysts. Under mild conditions, the cobalt (III) catalyst can be used for the hydration of alkynes to ketones. The catalyst is non-toxic, green, and environment friendly. The catalyst can be recycled at least six times with high activity. According to control experiments, a reasonable mechanism is provided.
- Xie, Ya,Wang, Jingjing,Wang, Yunyun,Han, Sheng,Yu, Han
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p. 4985 - 4989
(2021/10/12)
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- Synthesis and Catalytic Applications of Multinuclear Gold(I)-1,2,3-Triazolylidene Complexes
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A series of mono- to trinuclear gold(I) complexes (1–3) supported by oxo-functionalized 1,2,3-triazolylidenes have been prepared. All new compounds were fully characterized by means of 1H and 13C NMR spectroscopy, elemental analyses, and in the case of complexes 1 and 2 by x-ray diffraction. The catalytic performance of the new triazolylidene gold complexes was tested in several hydroelementation and cyclization processes employing a variety of alkynes as starting materials. According to the overall results, the trinuclear complex 3 displayed the highest catalytic activity in all processes, providing good to excellent yields under mild reaction conditions.
- Rendón-Nava, David,álvarez-Hernández, Alejandro,Mendoza-Espinosa, Daniel
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supporting information
p. 840 - 847
(2021/02/26)
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- Catalyst- and acid-free Markovnikov hydration of alkynes in a sustainable H2O/ethyl lactate system
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An efficient and sustainable protocol for the hydration of alkynes has been developed under metal/acid/catalyst/ligand-free conditions in a water/ethyl lactate mixture. The hydrogen-bond network in the ethyl lactate and water mixture plays a crucial and decisive role in activating the alkynes for hydration to afford the corresponding methyl ketones. This strategy gives the Markovnikov (ketone) addition product selectively over other possible products. The essential role of hydrogen bonding has been confirmed by experimental and theoretical techniques. A probable mechanism has been suggested by various control tests. The efficacy of the method has been further explored for the competent production of value-added α,β-unsaturated carbonyl compounds through the reaction of aldehydes with alkynes as ketonic surrogates. The environmentally benign hydration method takes place under mild conditions, has broad functional-group compatibility, and uses the ethyl lactate/water (1:3) medium as a “green alternative” in the absence of any hazardous, harmful, or expensive substances.
- Dandia, Anshu,Saini, Pratibha,Chithra,Vennapusa, Sivaranjana Reddy,Parewa, Vijay
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- Bismuth subnitrate-catalyzed markovnikov-type alkyne hydrations under batch and continuous flow conditions
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Bismuth subnitrate is reported herein as a simple and efficient catalyst for the atom-economical synthesis of methyl ketones via Markovnikov-type alkyne hydration. Besides an effective batch process under reasonably mild conditions, a chemically intensified continuous flow protocol was also developed in a packed-bed system. The applicability of the methodologies was demonstrated through hydration of a diverse set of terminal acetylenes. By simply switching the reaction medium from methanol to methanol-d4, valuable trideuteromethyl ketones were also prepared. Due to the ready availability and nontoxicity of the heterogeneous catalyst, which eliminated the need for any special additives and/or harmful reagents, the presented processes display significant advances in terms of practicality and sustainability.
- ?tv?s, Sándor B.,Fül?p, Ferenc,Szécsényi, Zsanett
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- One-Pot Chemoenzymatic Conversion of Alkynes to Chiral Amines
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A one-pot chemoenzymatic sequential cascade for the synthesis of chiral amines from alkynes was developed. In this integrated approach, just ppm amounts of gold catalysts enabled the conversion of alkynes to ketones (>99%) after which a transaminase was used to catalyze the production of biologically valuable chiral amines in a good yield (up to 99%) and enantiomeric excess (>99%). A preparative scale synthesis of (S)-methylbenzylamine and (S)-4-methoxy-methylbenzylamine from its alkyne form gave a yield of 59 and 92%, respectively, withee> 99%.
- Mathew, Sam,Renn, Dominik,Rueping, Magnus,Sagadevan, Arunachalam
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p. 12565 - 12569
(2021/10/21)
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- p-Toluenesulfonic acid functionalized imidazole ionic liquids encapsulated into bismuth SBA-16 as high-efficiency catalysts for Friedel-Crafts acylation reaction
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Bismuth SBA-16 catalyst was synthesized by the hydrothermal method. Four kinds ofp-toluenesulfonic acid functionalized imidazole ionic liquids were prepared by a two-step method and their molecular structures were characterized by1H NMR and MS. The post-synthesis impregnation method was used to functionalize the Bi(10)-SBA-16 silicon mesoporous material with the ionic liquids and the obtained materials were characterized by FT-IR, XRD, BET, XPS, and TG. The results show that the volume and pore size of SBA-16 were changed by loading Bi and ionic liquids, while the three-dimensional cubic pore structure of SBA-16 was not destroyed. The composite catalyst was evaluated in Friedel-Crafts acylation of anisole with acetic anhydride. The effects of reaction temperature and the ratio of anisole and acylating agent on the acylation of anisole were investigated by experimental design. The results showed that 1.2ILc@Bi(10)-SBA-16 was used as the catalyst, the conversion of anisole was 85.41% and the yield of aromatic ketone was 69.19% under the conditions of a reaction temperature of 100 °C, a catalyst dosage of 0.5 g, a time period of 4 h and a molar ratio of 1?:?1.5. After 5 recycling runs, the reduction in the overall ratio of reactant conversion and product yield did not exceed 7.5%, indicating that 1.2ILc@Bi(10)-SBA-16 has good stability and reusability.
- Gao, Guofang,Zhao, Qian,Yang, Cheng,Jiang, Tingshun
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p. 5871 - 5882
(2021/05/10)
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- Catalytic activity and stability of sulfonic-functionalized UiO-66 and MIL-101 materials in friedel-crafts acylation reaction
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Sulfonic-containing UiO-66 and MIL-101 MOF materials, prepared by direct synthesis with a sulfonic acid-including benzene dicarboxylate (SO3H-BDC) linker, have been evaluated as acid catalysts in Friedel–Crafts acylation of anisole with acetic
- Calleja, Guillermo,Crespí, Neus,Leo, Pedro,Martín, Antonio,Martinez, Fernando,Orcajo, Gisela,Palomino, Carlos
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- PhSe(O)OH/NHPI-catalyzed oxidative deoximation reaction using air as oxidant
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A novel oxidative deoximation method was developed in this article. Compared with the reported organoselenium-catalyzed oxidative deoximation reaction, this reaction employed N-hydroxyphthalimide (NHPI) as the co-catalyst, so that the oxidative deoximation reaction could utilize air as oxidant in the green DMC solvent under mild reaction conditions. Control experiments and X-ray photoelectron spectroscopy (XPS) analysis results indicated that NHPI was essential for activating the catalytic organoselenium species. It could accelerate the activation of molecular oxygen in air to promote the reaction process. The reaction can avoid metal residues in product and is of potential application values in pharmaceutical industry due to the transition metal-free process.
- Shi, Yaocheng,Wang, Feng,Yang, Chenggen,Yu, Lei
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- Iron-Catalyzed Wacker-type Oxidation of Olefins at Room Temperature with 1,3-Diketones or Neocuproine as Ligands**
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Herein, we describe a convenient and general method for the oxidation of olefins to ketones using either tris(dibenzoylmethanato)iron(III) [Fe(dbm)3] or a combination of iron(II) chloride and neocuproine (2,9-dimethyl-1,10-phenanthroline) as catalysts and phenylsilane (PhSiH3) as additive. All reactions proceed efficiently at room temperature using air as sole oxidant. This transformation has been applied to a variety of substrates, is operationally simple, proceeds under mild reaction conditions, and shows a high functional-group tolerance. The ketones are formed smoothly in up to 97 % yield and with 100 % regioselectivity, while the corresponding alcohols were observed as by-products. Labeling experiments showed that an incorporated hydrogen atom originates from the phenylsilane. The oxygen atom of the ketone as well as of the alcohol derives from the ambient atmosphere.
- Kataeva, Olga,Kn?lker, Hans-Joachim,Linke, Philipp,Puls, Florian
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supporting information
p. 14083 - 14090
(2021/05/24)
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- Visible-Light Promoted C–O Bond Formation with an Integrated Carbon Nitride–Nickel Heterogeneous Photocatalyst
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Ni-deposited mesoporous graphitic carbon nitride (Ni-mpg-CNx) is introduced as an inexpensive, robust, easily synthesizable and recyclable material that functions as an integrated dual photocatalytic system. This material overcomes the need of expensive photosensitizers, organic ligands and additives as well as limitations of catalyst deactivation in the existing photo/Ni dual catalytic cross-coupling reactions. The dual catalytic Ni-mpg-CNx is demonstrated for C–O coupling between aryl halides and aliphatic alcohols under mild condition. The reaction affords the ether product in good-to-excellent yields (60–92 %) with broad substrate scope, including heteroaryl and aryl halides bearing electron-withdrawing, -donating and neutral groups. The heterogeneous Ni-mpg-CNx can be easily recovered from the reaction mixture and reused over multiple cycles without loss of activity. The findings highlight exciting opportunities for dual catalysis promoted by a fully heterogeneous system.
- Vijeta, Arjun,Casadevall, Carla,Roy, Souvik,Reisner, Erwin
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supporting information
p. 8494 - 8499
(2021/03/08)
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- Catalytic C(β)-O Bond Cleavage of Lignin in a One-Step Reaction Enabled by a Spin-Center Shift
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A challenge to the utilization of lignin as a feedstock for aromatic fine chemicals lies in selective cleavage of copious β-O-4 linkages. A photocatalytic strategy for the selective cleavage of the C(β)-O bonds of model substrates and natural lignin extracts is achieved by a redox-neutral, catalytic cycle that does not require stoichiometric reagents. Mechanistic studies reveal the generation of a thiyl radical, which is derived from a cystine-derived H-atom transfer catalyst, initiates a spin-center shift (SCS) that leads to C(β)-O bond cleavage. The SCS reactivity is reminiscent of the C(β)-O bond cleavage chemistry that occurs in the active site of ribonucleotide reductase.
- Zhu, Qilei,Nocera, Daniel G.
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p. 14181 - 14187
(2021/11/27)
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- A highly stable all-in-one photocatalyst for aryl etherification: The NiIIembedded covalent organic framework
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The efficient conversion of aryl bromides to the corresponding aryl alkyl ethers by dual nickel/photocatalysis has seen great progress, but difficulties of recycling the photosensitizer or nickel complexes cause problems of sustainability. Here, we report the design of a novel, highly stable vinyl bridge 2D covalent organic framework (COF) containing Ni, which combines the role of photosensitizer and reactive site. The as-prepared sp2c-COFdpy-Ni acts as an efficient heterogeneous photocatalyst for C-O cross coupling. The sp2c-COFdpy-Ni can be completely recovered and used repeatedly without loss of activity, overcoming the limitations of the prior methods. Preliminary studies reveal that strong interlayer electron transfer may facilitate the generation of the proposed intermediate sp2c-COFdpy-NiI in a bimolecular and self-sustained manner. This all-in-one heterogeneous photocatalyst exhibits good compatibility of substrates and tolerance of functional groups. The successful attempt to expand the 2D COFs with this new catalyst into photocatalytic organic transformation opens an avenue for photoredox/transition metal mediated coupling reactions.
- Chen, Hao,Dong, Wenbo,Hu, Jianxiang,Rao, Li,Wang, Pei,Wang, Shengyao,Xiang, Yonggang,Yang, Yi
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p. 5797 - 5805
(2021/08/23)
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- Nano WO3-Catalyzed One-Pot Process for Mild Oxidative Depolymerization of Lignin and its Model Compounds
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Despite challenges related to the robust and irregular structure of lignin, the valorization of this aromatic biopolymer has aroused great interest. However, the current methods exhibit problems such as harsh reaction conditions, complicated operation, and difficult recovery of catalyst. Herein we present a one-pot process for the mild oxidative depolymerization of lignin and lignin model compounds catalyzed by nano WO3, along with tert-butyl hydrogen peroxide (TBHP) as the oxidant and NaOH as the additive, which exhibits advantages of both homogeneous and heterogeneous catalysis. Under the optimized condition, it yielded 80.4 wt % of liquid oil from organosolv lignin with 7.6 wt % of vanillic acid as the main monomer product, accounting for 91.6 wt % monomeric selectivity. Mechanism studies on the model substrate suggest that the reaction proceeds via an oxidation of Cα?OH to C=O followed by C?O bond cleavage to afford phenol and ketone products which may undergo further oxidation to produce aromatic carboxylic acids. We have developed an operationally simple procedure for mild fragmentation of lignin and lignin model compounds with excellent yields, which provides the potential to expand the existing lignin usage from energy source to value-added commodity chemicals.
- Liang, Jing,Wang, Meng-Xiao,Zhao, Yun-Peng,Yan, Wei-Wei,Si, Xing-Gang,Yu, Guo,Cao, Jing-Pei,Wei, Xian-Yong
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p. 3836 - 3845
(2021/07/26)
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- LIGHT INDUCED CATALYTIC C-H OXYGENATION OF ALKANES
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A method of oxygenating a benzylic C-H bond is provided. The method comprises light induced activation of an initiator and subsequent reaction with oxygen, resulting in the formation of free radicals. Subsequently, free radicals catalyze the reaction of the benzylic C-H bond with oxygen, thereby forming an oxygenated compound.
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Paragraph 00201; 00207; 00218
(2021/04/02)
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