- Manganese dioxide supported on aluminum silicate: A new reagent for oxidation of alcohols under heterogeneous conditions
-
Manganese dioxide supported on aluminum silicate, under heterogeneous conditions at reflux, selectively oxidized aromatic primary and secondary alcohols into the corresponding aldehydes and ketones, respectively, in yields of 87-96%. The present method failed to oxidize aliphatic alcohols.
- Huang, Li-Hong,Ma, Yi-Chun,Zhang, Changhe,Wang, Qiang,Zou, Xiao-Nan,Lou, Ji-Dong
-
-
Read Online
- Chromium(VI) Oxidation of Alkanol Components of Sodium Dodecyl Sulfate Reverse Micelles
-
Oxidation with potassium dichromate in perchloric acid medium of the alkanols 1-butanol, 1-hexanol, and 1-octanol, components of sodium dodecyl sulfate reverse micelles in alkanols, has been studied.The reaction rate is first-order with respect to Cr(VI) and depends linearly on the HClO4 concentration in the aqueous phase, but the reaction rate decreases with the amount of alcohol in the reverse micelles.To explain the kinetic results it is necessary to consider the intermicellar exchange of the reactants, which could depend on the thickness of the layer where the surfactant and the alcohol are located.
- Rodenas, E.,Perez-Benito, E.
-
-
Read Online
- Supported Au-Cu bimetallic alloy nanoparticles: An aerobic oxidation catalyst with regenerable activity by visible-light irradiation
-
Rejuvenating sunlight: Supported Au-Cu bimetallic alloy nanoparticles promote aerobic oxidation at room temperature under visible light (λ>450 nm) irradiation with little deactivation by the oxidation of surface Cu atoms by oxygen. This is achieved through the reduction of oxidized surface Cu atoms by the surface Au atoms, a process which is activated by visible-light irradiation, even by sunlight. Copyright
- Sugano, Yoshitsune,Shiraishi, Yasuhiro,Tsukamoto, Daijiro,Ichikawa, Satoshi,Tanaka, Shunsuke,Hirai, Takayuki
-
-
Read Online
- FATTY ACID HYDROPEROXIDE LYASE IN TOBACCO CELLS CULTURED IN VITRO
-
Fatty acid hydroperoxide lyase (HPO lyase) was found in green and non-green tobacco cells cultured in vitro.The HPO lyase activity in non-green cells was 1/3-1/2 of that in green cells.When the cells were transferred from the light to dark conditions or vice versa, cells turned non-green or green according to the light conditions.The HPO lyase activity also changed according to the light conditions, but the changes in HPO lyase activities were not proportional to the changes in chlorophyll contents.These results suggest that at least two types of HPO lyases are present in the green cells.One type of HPO lyase is perhaps common both to the green and non-green cells; another one is chloroplastic.The fatty acid compositions of cells and substrate specificities of HPO lyase differed between green and non-green cells.Key Word Index - Nicotiana tabacum; Solanaceae; cultured tobacco cells; green cells; fatty acid hydroperoxide lyase; linoleic acid; linolenic acid; C6-aldehydes.
- Sekiya, Jiro,Tanigawa, Satoru,Kajiwara, Tadahiko,Hatanaka, Akikazu
-
-
Read Online
- Functionalized-1,3,4-oxadiazole ligands for the ruthenium-catalyzed Lemieux-Johnson type oxidation of olefins and alkynes in water
-
Three arene-ruthenium(II) complexes bearing alkyloxy(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethylphenyl)methyl ligands were quantitatively obtained through the reaction of (E)-1-(4-trifluoromethylphenyl)-N-(5-phenyl-1,3,4-oxadiazol-2-yl)-methanimine with the ruthenium precursor [RuCl2(η6-p-cymene)]2 in a mixture of the corresponding alcohol and CH2Cl2 at 50 °C. The obtained complexes were fully characterized by elemental analysis, infrared, NMR and mass spectrometry. Solid-state structures confirmed the coordination of the 1,3,4-oxadiazole moiety to the ruthenium center via their electronically enriched nitrogen atom at position 3 in the aromatic ring. These complexes were evaluated as precatalysts in the Lemieux-Johnson type oxidative cleavage of olefins and alkynes in water at room temperature with NaIO4 as oxidizing agent. Good to full conversions of olefins into the corresponding aldehydes were measured, but low catalytic activity was observed in the case of alkynes. In order to get more insight into the mechanism, three analogue arene-ruthenium complexes were synthesized and tested in the oxidative cleavage of styrene. The latter tests clearly demonstrated the importance of the hemilabile alkyloxy groups, which may form more stable (N,O)-chelate intermediates and increase the efficiency of the cis-dioxo-ruthenium(VI) catalyst.
- Hkiri, Shaima,Touil, Soufiane,Samarat, Ali,Sémeril, David
-
-
- One-Pot Bioelectrocatalytic Conversion of Chemically Inert Hydrocarbons to Imines
-
Petroleum hydrocarbons are our major energy source and an important feedstock for the chemical industry. With the exception of combustion, the deep conversion of chemically inert hydrocarbons to more valuable chemicals is of considerable interest. However, two challenges hinder this conversion. One is the regioselective activation of inert carbon-hydrogen (C-H) bonds. The other is designing a pathway to realize this complicated conversion. In response to the two challenges, a multistep bioelectrocatalytic system was developed to realize the one-pot deep conversion from heptane to N-heptylhepan-1-imine under mild conditions. First, in this enzymatic cascade, a bioelectrocatalytic C-H bond oxyfunctionalization step based on alkane hydroxylase (alkB) was applied to regioselectively convert heptane to 1-heptanol. By integrating subsequent alcohol oxidation and bioelectrocatalytic reductive amination steps based on an engineered choline oxidase (AcCO6) and a reductive aminase (NfRedAm), the generated 1-heptanol was successfully converted to N-heptylhepan-1-imine. The electrochemical architecture provided sufficient electrons to drive the bioelectrocatalytic C-H bond oxyfunctionalization and reductive amination steps with neutral red (NR) as electron mediator. The highest concentration of N-heptylhepan-1-imine achieved was 0.67 mM with a Faradaic efficiency of 45% for C-H bond oxyfunctionalization and 70% for reductive amination. Hexane, octane, and ethylbenzene were also successfully converted to the corresponding imines. Via regioselective C-H bond oxyfunctionalization, intermediate oxidation, and reductive amination, the bioelectrocatalytic hydrocarbon deep conversion system successfully realized the challenging conversion from inert hydrocarbons to imines that would have been impossible by using organic synthesis methods and provided a new methodology for the comprehensive conversion and utilization of inert hydrocarbons.
- Chen, Hui,Tang, Tianhua,Malapit, Christian A.,Lee, Yoo Seok,Prater, Matthew B.,Weliwatte, N. Samali,Minteer, Shelley D.
-
p. 4047 - 4056
(2022/02/10)
-
- Spectroscopic Characterization of a Reactive [Cu2(μ-OH)2]2+ Intermediate in Cu/TEMPO Catalyzed Aerobic Alcohol Oxidation Reaction
-
CuI/TEMPO (TEMPO=2,2,6,6-tetramethylpiperidinyloxyl) catalyst systems are versatile catalysts for aerobic alcohol oxidation reactions to selectively yield aldehydes. However, several aspects of the mechanism are yet unresolved, mainly because o
- Warm, Katrin,Tripodi, Guilherme,Andris, Erik,Mebs, Stefan,Kuhlmann, Uwe,Dau, Holger,Hildebrandt, Peter,Roithová, Jana,Ray, Kallol
-
supporting information
p. 23018 - 23024
(2021/09/09)
-
- Highly ordered mesoporous hybrid silica functionalized with ionic liquid framework supported copper and its application in the oxidation of alcohols
-
A highly ordered organic-inorganic hybrid nanomaterial containing copper N-heterocyclic carbene complex (Cu-NHC@Pyrm-OMS) was synthesized and characterized using various techniques including FTIR, MAS NMR, XRD, TGA, SEM, and TEM. Cu-NHC@Pyrm-OMS nanomaterial is highly efficient heterogeneous system towards the selective oxidation of primary and secondary alcohols to corresponding aldehydes and ketones under mild conditions. Moreover, the supported copper nanocatalyst exhibited outstanding stability and could be reused at least ten times, remaining almost unchanged from initial activity. This work has focused on sustainable and green chemistry that use recoverable nanocatalyst, clean oxidant and aqueous media.
- Rajabi, Fatemeh,Bahrami, Nazli,Vessally, Esmail,Luque, Rafael
-
-
- Solvent-free selective oxidation of alcohols with tert-butyl hydroperoxide catalyzed by palladium(II) isatin Schiff base complex supported into three-dimensional mesoporous silica KIT-6
-
In this work, the catalytic activity of a palladium(II) isatin Schiff base complex immobilized into mesoporous silica KIT-6 (Pd-isatin Schiff base@KIT-6) was studied for the oxidation of different alcohols with tert-butyl hydroperoxide (TBHP, 70% aqueous solution) as an oxidant under solvent-free conditions. To find the suitable reaction conditions, the effect of essential factors including the solvent, temperature, catalyst amount and kind of oxidant on the oxidation of benzyl alcohol was explored. The results showed that in this catalytic system, the corresponding aldehydes and ketones were obtained with high to excellent yields at 50?°C without the formation of carboxylic acids as by-products. The catalyst was easily recovered by simple filtration and reused in five subsequent reaction cycles without any significant loss in the catalytic activity. Moreover, the comparison of the Fourier transform infrared (FT-IR) spectrum, X-ray diffraction (XRD) pattern, scanning and transmission electron microscopy (SEM and TEM) images of the used catalyst with a fresh one showed that the structure of the Pd-isatin Schiff base@KIT-6 catalyst remained intact after five times of reuse.
- Mousavi, Davoud,Ardakani, Mehdi Hatefi,Saeednia, Samira,Sabet, Mohammad
-
p. 1105 - 1121
(2020/11/17)
-
- DIBALH: From known fundamental to an unusual reaction; Chemoselective partial reduction of tertiary amides in the presence of esters
-
This study presents a quick and reliable approach to the chemoselective partial reduction of tertiary amides to aldehydes in the presence of readily reducible ester groups using commercial DIBALH reagent. Moreover, the developed method was also extended to multi-functional molecules bearing ester moieties, which were successfully chemoselectively reduced to the corresponding aldehydes. This journal is
- An, Duk Keun,Heo, Yu Jin,Jaladi, Ashok Kumar,Kim, Hyun Tae
-
p. 33809 - 33813
(2021/12/09)
-
- Multicatalytic approach to one-pot stereoselective synthesis of secondary benzylic alcohols
-
One-pot procedures bear the potential to rapidly build up molecular complexity without isolation and purification of consecutive intermediates. Here, we report multicatalytic protocols that convert alkenes, unsaturated aliphatic alcohols, and aryl boronic acids into secondary benzylic alcohols with high stereoselectivities (typically >95:5 er) under sequential catalysis that integrates alkene cross-metathesis, isomerization, and nucleophilic addition. Prochiral allylic alcohols can be converted to any stereoisomer of the product with high stereoselectivity (>98:2 er, >20:1 dr).
- Casnati, Alessandra,Lichosyt, Dawid,Lainer, Bruno,Veth, Lukas,Dydio, Pawe?
-
supporting information
p. 3502 - 3506
(2021/05/10)
-
- Green, homogeneous oxidation of alcohols by dimeric copper(II) complexes
-
Three pyrazole derivatives, 3,5-dimethyl-1H-pyrazole (DMPz) (I), 3-methyl-5-phenyl-1H-pyrazole (MPPz) (II), and 3,5-diphenyl-1H-pyrazole (DPPz) (III), were prepared via reacting semicarbazide hydrochloride with the acetylacetone, 1-phenylbutane-1,3-dione, and 1,3-diphenylpropane-1,3-dione, respectively. Complexes 1–3 were isolated by reacting CuCl2·2H2O with I–III, respectively, and characterized by CHNS elemental analyses, FT-IR, UV-Vis, 1H and 13C NMR, EPR spectra, and TGA/DTA. Molecular structures of the pyrazole derivatives I–III and copper(II) complexes 2 and 3 were studied through single-crystal XRD analysis to confirm their molecular structures. Overlapping of hyperfine splitting in the EPR spectra of the dimeric copper(II) complexes 1–3 indicates that both copper centers do not possess the same electronic environment in solution. The copper(II) complexes are dimeric in solid state as well as in solution and catalyze the oxidation of various primary and secondary alcohols selectively. Catalysts 1–3 show more than 92% product selectivity toward ketones during the oxidation of secondary alcohols. Surprisingly primary alcohols, which are relatively difficult to oxidize, produce carboxylic acid as a major product (48%–90% selectivity) irrespective of catalytic systems. The selectivity for carboxylic acid rises with decreasing the carbon chain length of the alcohols. An eco-friendly and affordable catalytic system for oxidation of alcohols is developed by the utilization of H2O2, a green oxidant, and water, a clean and greener solvent, which is a notable aspect of the study.
- Maurya, Abhishek,Haldar, Chanchal
-
p. 885 - 904
(2020/12/18)
-
- Synthesis of TEMPO radical decorated hollow porous aromatic frameworks for selective oxidation of alcohols
-
A bottom-up approach was developed to prepare TEMPO radical decorated hollow aromatic frameworks (HPAF-TEMPO) by using TEMPO radical functionalized monomers and SiO2nanospheres as templates. The accessible inner layer, high density of TEMPO sites, and hybrid micro-/mesopores of the HPAF-TEMPO enable the aerobic oxidation of a broad range of alcohols with high efficiency and excellent selectivity.
- Shen, Yan-Ming,Xue, Yun,Yan, Mi,Mao, Hui-Ling,Cheng, Hu,Chen, Zhuo,Sui, Zhi-Wei,Zhu, Shao-Bin,Yu, Xiu-Jun,Zhuang, Jin-Liang
-
supporting information
p. 907 - 910
(2021/02/06)
-
- Solvent-free oxidation of straight-chain aliphatic primary alcohols by polymer-grafted vanadium complexes
-
Oxidovanadium(IV) complexes [VO(tertacac)2] (1), [VO(dipd)2] (2), and [VO(phbd)2] (3) were synthesized by reacting [VO(acac)2] with 2,2,6,6-tetramethyl-3,5-hepatanedione, 1,3-diphenyl-1,3-propanedione, and 1-phenyl-1,3-butanedione, respectively. Imidazole-modified Merrifield resin was used for the heterogenization of complexes 1–3. During the process of heterogenization, the V4+ center in complex 2 converts into V5+, whereas the other two complexes 1 and 3 remain in the oxidovanadium(IV) state in the polymer matrix. Theoretically, calculated IPA values of 1–3 suggest that 2 is prone to oxidation compared with 1 and 3, which was also supported by the absence of EPR lines in 5. Polymer-supported complexes Ps-Im-[VIVO(tertacac)2] (4), Ps-Im-[VVO2(dipd)2] (5), and Ps-Im-[VIVO(phbd)2] (6) were applied for the solvent-free heterogenous oxidation of a series of straight-chain aliphatic alcohols in the presence of H2O2 at 60°C and showed excellent substrate conversion specially for the alcohols with fewer carbon atoms. Higher reaction temperature improves the substrate conversion significantly for the alcohols containing more carbon atoms such as 1-pentanol, 1-hexanol, and 1-heptanol while using optimized reaction conditions. However, alcohols with fewer carbon atoms seem less affected by reaction temperatures higher than the optimized temperature. A decreasing trend in the selectivity(%) of carboxylic acid was observed with increasing carbon atoms among the examined alcohols, whereas the selectivity towards aldehydes increased. The order of efficiency of the supported catalysts is 4 > 6 > 5 in terms of turnover frequency (TOF) values and substrate conversion, further supported by theoretical calculations.
- Chaudhary, Nikita,Haldar, Chanchal,Kachhap, Payal
-
-
- Catalyst composition containing bidentate phosphine ligand and application thereof
-
The catalyst composition comprises a bidentate phosphine ligand and a rhodium complex, wherein the skeleton of the bidentate phosphine ligand not only has C. 2 The symmetry and the appropriate rigidity, and the phosphine ligand derived based on the skeleton can provide effective steric hindrance around the catalyst center metal, so that the selectivity of the catalyst can be remarkably improved, the aldehyde yield is not lower 92% when the catalyst combination is applied to the hydroformylation reaction, and the selectivity of n-aldehyde is not lower 90%. In addition, the raw materials olefins with different structures can obtain outstanding reaction rate and normal aldehyde selectivity as compared with the existing catalyst systems, and can be suitable for the hydroformylation reaction of more types of olefins.
- -
-
Paragraph 0068; 0081-0084
(2021/11/03)
-
- Expanding the Biocatalytic Toolbox with a New Type of ene/yne-Reductase from Cyclocybe aegerita
-
This study introduces a new type of ene/yne-reductase from Cyclocybe aegerita with a broad substrate scope including aliphatic and aromatic alkenes/alkynes from which aliphatic C8-alkenones, C8-alkenals and aromatic nitroalkenes were the preferred substrates. By comparing alkenes and alkynes, a ~2-fold lower conversion towards alkynes was observed. Furthermore, it could be shown that the alkyne reduction proceeds via a slow reduction of the alkyne to the alkene followed by a rapid reduction to the corresponding alkane. An accumulation of the alkene was not observed. Moreover, a regioselective reduction of the double bond in α,β-position of α,β,γ,δ-unsaturated alkenals took place. This as well as the first biocatalytic reduction of different aliphatic and aromatic alkynes to alkanes underlines the novelty of this biocatalyst. Thus with this study on the new ene-reductase CaeEnR1, a promising substrate scope is disclosed that describes conceivably a broad occurrence of such reactions within the chemical landscape.
- Karrer, Dominik,Gand, Martin,Rühl, Martin
-
p. 2191 - 2199
(2021/02/26)
-
- Method for synthesizing fluorescent dye intermediate aldehyde by hydroformylation of 1,3-diene compound
-
The invention discloses a method for synthesizing a fluorescent dye intermediate aldehyde by hydroformylation of 1,3-diene compound. The method comprises the following steps: S1, sequentially adding 0.01 mmol (1 mol%) of [Rh(cod)Cl]2, 0.1 mmol of a phosphine ligand(P/Rh=10/1) and 1 mmol of diene into a reaction flask, adding 1 ml of a solvent DMF, putting the reaction flask into a high-pressure reaction kettle, after the reaction is finished, transferring a mixed solution into a 25 mL glass bottle with 200 microliters of n-tridecane as an internal standard by using a rubber head dropper, and detecting; and S2, determining the product yield and the structure through a gas chromatograph and a nuclear magnetic resonance spectrum, wherein the obtained olefin conversion rate is larger than 99%, the aldehyde yield ranges from 61% to 99%, and the regioselectivity of the product aldehyde ranges from 70/30 to 100/0. According to the method disclosed by the invention, the separation and purification steps of aldehyde products are simplified, and the substrate of the dialkene hydroformylation reaction is excellent in universality.
- -
-
Paragraph 0053-0054; 0056-0057
(2021/08/07)
-
- Chemo- And regioselective hydroformylation of alkenes with CO2/H2over a bifunctional catalyst
-
As is well known, CO2 is an attractive renewable C1 resource and H2 is a cheap and clean reductant. Combining CO2 and H2 to prepare building blocks for high-value-added products is an attractive yet challenging topic in green chemistry. A general and selective rhodium-catalyzed hydroformylation of alkenes using CO2/H2 as a syngas surrogate is described here. With this protocol, the desired aldehydes can be obtained in up to 97% yield with 93/7 regioselectivity under mild reaction conditions (25 bar and 80 °C). The key to success is the use of a bifunctional Rh/PTA catalyst (PTA: 1,3,5-triaza-7-phosphaadamantane), which facilitates both CO2 hydrogenation and hydroformylation. Notably, monodentate PTA exhibited better activity and regioselectivity than common bidentate ligands, which might be ascribed to its built-in basic site and tris-chelated mode. Mechanistic studies indicate that the transformation proceeds through cascade steps, involving free HCOOH production through CO2 hydrogenation, fast release of CO, and rhodium-catalyzed conventional hydroformylation. Moreover, the unconventional hydroformylation pathway, in which HCOOAc acts as a direct C1 source, has also been proved to be feasible with superior regioselectivity to that of the CO pathway.
- Hua, Kaimin,Liu, Xiaofang,Wei, Baiyin,Shao, Zilong,Deng, Yuchao,Zhong, Liangshu,Wang, Hui,Sun, Yuhan
-
supporting information
p. 8040 - 8046
(2021/11/01)
-
- Cyclohexene Promoted Efficient Biomimetic Oxidation of Alcohols to Carbonyl Compounds Catalyzed by Manganese Porphyrin under Mild Conditions?
-
Selective oxidation of alcohols to corresponding carbonyl compounds is one of the most important processes both in academic and application research. As a kind of biomimetic catalyst, metalloporphyrins-catalyzed aerobic oxidation of alcohols with aldehyde as hydrogen donator is gathering much attention. However, using olefins as another kind hydrogen donator for aerobic oxidation of alcohols has not been reported. In this study, a system comprising managenese porphyrin and cyclohexene for biomimetic aerobic oxidation of alcohols to carbonyl compounds was developed. The catalytic system exhibited excellent catalytic performance and selectivity towards the corresponding products for most primary and secondary alcohols under mild conditions. Based on the results obtained from experiments as well as in situ EPR (electron paramagnetic resonance) and UV-vis spectroscopy, the role of cyclohexene was demonstrated.
- Ji, Hong-Bing,Liu, Xiao-Hui,Xue, Can,Yu, Hai-Yang,Zhou, Xian-Tai
-
-
- Solvent-free, microwave assisted oxidation of alcohols with 4-hydroxypyridinium chlorochromate functionalized silica gel
-
4-Hydroxypyridinium chlorochromate functionalized silica gel was found to be an efficient and reusable oxidant for the very fast oxidation of primary and secondary alcohols to the corresponding carbonyl compounds under solventfree conditions and microwave irradiation in excellent yields.
- AHMADI, Sayed Ali,GHALEHBANDI, Shermineh Sadat,GHAZANFARI, Dadkhoda,SHEIKHHOSSEINI, Enayatollah
-
p. 283 - 289
(2020/10/06)
-
- Tungstate ion (WO42-) confined in hydrophilic/hydrophobic nanomaterials functionalized br?nsted acidic ionic liquid as highly active catalyst in the selective aerobic oxidation of alcohols in water
-
A Br?nsted acidic Ionic Liquid containing tungstate anion functionalized polysiloxane network (PMO-IL-WO42-) was synthesized by simple self-condensation of tungstic acid and zwitterionic organosilane precursor possessing both imidazolium and sulfonate groups. Characterization by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), thermal gravimetric analysis TGA, nitrogen porosimetry, solid-state NMR spectroscopy and elemental analysis confirmed that both imidazolium cation and tungstate anion of zwitterion are successfully incorporated inside the organosilica framework. The catalytic activity of resulting hybrid PMO-IL- WO42- material was studied in the selective aerobic oxidation of primary and secondary alcohols using an atmospheric pressure of air in pure water. Due to the ionic liquid-based charged surface containing hydrophilic sulfonic acid and tungstate group, the synergistic hydrophilic/hydrophobic and redox effect of PMO-IL-WO42- as water-friendly catalyst facilitates and enhances the activity and selectivity toward the target oxidative products in water and proved to have a particularly broad substrate scope for reliable aerobic oxidation reaction. Furthermore, the catalyst showed outstanding stability and could be easily separated and reused at least ten reactions run under the same conditions as fresh catalyst without any loss of catalytic activity and product selectivity.
- Luque, Rafael,Nafe, Mostafa,Rajabi, Fatemeh,Rezanejad Bardajee, Ghasem
-
-
- Selective TEMPO-Oxidation of Alcohols to Aldehydes in Alternative Organic Solvents
-
The TEMPO-catalyzed oxidation of alcohols to aldehydes has emerged to one of the most widely applied methodologies for such transformations. Advantages are the utilization of sodium hypochlorite, a component of household bleach, as an oxidation agent and the use of water as a co-solvent. However, a major drawback of this method is the often occurring strict limitation to use dichloromethane as an organic solvent in a biphasic reaction medium with water. Previous studies show that dichloromethane cannot easily be substituted because a decrease of selectivity or inhibition of the reaction is observed by using alternative organic solvents. Thus, up to now, only a few examples are known in which after a tedious optimization of the reaction dichloromethane could be replaced. In order to overcome the current limitations, we were interested in finding a TEMPO-oxidation method in alternative organic solvents, which is applicable for various alcohol oxidations. As a result, we found a method for N-oxyl radical-catalyzed oxidation using sodium hypochlorite as an oxidation agent in nitriles as an organic solvent component instead of dichloromethane. Besides the oxidation of aromatic primary alcohols also aliphatic primary alcohols, secondary alcohols as well as dialcohols were successfully converted when using this method, showing high selectivity towards the carbonyl compound and low amounts of the acid side-product.
- Hinzmann, Alessa,Stricker, Michael,Busch, Jasmin,Glinski, Sylvia,Oike, Keiko,Gr?ger, Harald
-
p. 2399 - 2408
(2020/04/29)
-
- PROCESS FOR THE PREPARATION OF A FATTY ALDEHYDE
-
The present invention relates to a process for the preparation of a fatty aldehyde which process comprises (a) providing a fatty acid, and (b) contacting the fatty acid with a zerovalent metal catalyst to reduce the fatty acid to the fatty aldehyde, wherein the zerovalent metal catalyst is in the form of solid particles.
- -
-
Page/Page column 9-11
(2021/01/23)
-
- Method for preparing aldehyde by olefin hydroformylation
-
The invention relates to a method for preparing aldehyde through olefin hydroformylation. The method comprises the steps: enabling alpha-olefin and synthesis gas to enter a hydroformylation reactor; carrying out a contact reaction on alpha-olefin and synthesis gas with a catalyst to generate an aldehyde-containing product, wherein the catalyst comprises a main catalyst and a co-catalyst, the maincatalyst is a complex catalyst and comprises a rhodium complex and a phosphine ligand, the phosphine ligand is tris[2,4-di-tert-butylphenyl]phosphite, and the co-catalyst is a nickel-palladium bimetallic phosphinate. The method has the advantages of high normal-to-abnormal ratio in the product, good selectivity and yield, mild reaction conditions and the like.
- -
-
Paragraph 0032-0034; 0035-0039
(2020/07/15)
-
- Aqueous extract of Shikakai; a green solvent for deoximation reaction: Mechanistic approach from experimental to theoretical
-
This article describes a green method for regeneration of carbonyl compounds from various types of oxime compounds under microwave radiation using I2 and aqueous saponin solution isolated from Shikakai. Effect of saponin concentration on yield percentage of regenerated different types of carbonyl compounds has been discussed. A correlation has been established between saponin concentration and yield percentage of carbonyl compounds. Mechanism of interaction between oxime and saponin is established on the basis of density functional theory. In addition, the quantum chemical parameters for saponin have been determined. Furthermore, electrostatic surface analysis of the saponin is carried out to confirm the mechanism of interaction between saponin and oximes.
- Das, Debadutta,Kudrat-E-Zahan, Md.,Mahal, Ahmed,Mohapatra, Ranjan K.,Parhi, Pankaj K.,Sahu, Raghaba,Sarangi, Ashish K.
-
-
- Recycling of two molecular catalysts in the hydroformylation/aldol condensation tandem reaction using one multiphase system
-
Tandem reactions are of great importance to efficiently execute multiple conversions in one synthesis step. Herein we present a multiphase system for the hydroformylation/aldol condensation, which is able to recycle both optimized catalysts multiple times. The system consists of an organometallic rhodium/sulfoXantphos hydroformylation catalyst and basic NaOH as aldol condensation initiator, which are both immobilized in a polyethylene glycol phase. Under reaction conditions, NaOH is converted to sodium formate, which is still able to catalyse the aldol condensation. The reaction and recycling are demonstrated by the conversion of 1-pentene to the corresponding aldol product in a recycling experiment. During nine consecutive runs, no significant loss of activity is found with an overall TON of 8700 in regard to the rhodium catalyst and an average rhodium leaching of only of 0.07% per run is observed.
- Leitner, Walter,Strohmann, Marc,Vorholt, Andreas J.,Vossen, Jeroen T.
-
p. 8444 - 8451
(2021/01/01)
-
- 9,10-Dihydroanthracene auto-photooxidation efficiently triggered photo-catalytic oxidation of organic compounds by molecular oxygen under visible light
-
The development of mild and efficient process for the selective oxidation of organic compounds by molecular oxygen (O2) can be one of the key technologies for synthesizing oxygenates. This paper discloses an efficient and mild synthesis protocol for the O2-involved ethylbenzene (EB) photooxidation triggered by 910-dihydroanthracene (DHA) auto- photooxidation in acetone under visible light illumination, which can achieve 87.7 percent EB conversion and 99.5 percent acetylacetone (ACP) selectivity under ambient conditions. Also, 62.9 percent EB conversion and 96.3 percent ACP selectivity is obtained in air atmosphere. Furthermore, this protocol has a good adaptability for the photooxidation of other organic substrates such as tetrahydronaphthalene, diphenylmethane, toluene, cyclohexane, cyclohexene, alcohol, methylfuran and thioether to their corresponding oxygenates. A series of control and quenching tests, combined with EPR spectra, suggest that the photo-excited DHA can transfer its photo-electron to O2 to yield a superoxide radical anion (O2??), then DHA is preferentially oxidized to anthraquinone (AQ) by the active O2?? owing to its high reactivity. Finally, the in situ generated AQ as an active photo-catalyst can achieve the photooxidation of EB and other organic compounds by O2. The present photo-autoxidation protocol gives a good example for the O2-based selective oxidation of inert hydrocarbons under mild conditions.
- Chen, Mengke,Deng, Youer,Fu, Zaihui,Hu, Wenwei,Jiang, Dabo,Liu, Yachun,Mao, Feng,Su, Anqun,Yang, Bo,Zhang, Chao
-
-
- Biosynthesis of Mycotoxin Fusaric Acid and Application of a PLP-Dependent Enzyme for Chemoenzymatic Synthesis of Substituted l -Pipecolic Acids
-
Fusaric acid (FA) is a well-known mycotoxin that plays an important role in plant pathology. The biosynthetic gene cluster for FA has been identified, but the biosynthetic pathway remains unclarified. Here, we elucidated the biosynthesis of FA, which features a two-enzyme catalytic cascade, a pyridoxal 5′-phosphate (PLP)-dependent enzyme (Fub7), and a flavin mononucleotide (FMN)-dependent oxidase (Fub9) in synthesizing the picolinic acid scaffold. FA biosynthesis also involves an off-line collaboration between a highly reducing polyketide synthase (HRPKS, Fub1) and a nonribosomal peptide synthetase (NRPS)-like carboxylic acid reductase (Fub8) in making an aliphatic α,β-unsaturated aldehyde. By harnessing the stereoselective C-C bond-forming activity of Fub7, we established a chemoenzymatic route for stereoconvergent synthesis of a series of 5-alkyl-, 5,5-dialkyl-, and 5,5,6-trialkyl-l-pipecolic acids of high diastereomeric ratio.
- Hai, Yang,Chen, Mengbin,Huang, Arthur,Tang, Yi
-
supporting information
p. 19668 - 19677
(2020/12/01)
-
- Engineering a nicotinamide mononucleotide redox cofactor system for biocatalysis
-
Biological production of chemicals often requires the use of cellular cofactors, such as nicotinamide adenine dinucleotide phosphate (NADP+). These cofactors are expensive to use in vitro and difficult to control in vivo. We demonstrate the development of a noncanonical redox cofactor system based on nicotinamide mononucleotide (NMN+). The key enzyme in the system is a computationally designed glucose dehydrogenase with a 107-fold cofactor specificity switch toward NMN+ over NADP+ based on apparent enzymatic activity. We demonstrate that this system can be used to support diverse redox chemistries in vitro with high total turnover number (~39,000), to channel reducing power in Escherichia coli whole cells specifically from glucose to a pharmaceutical intermediate, levodione, and to sustain the high metabolic flux required for the central carbon metabolism to support growth. Overall, this work demonstrates efficient use of a noncanonical cofactor in biocatalysis and metabolic pathway design.
- Black, William B.,Zhang, Linyue,Mak, Wai Shun,Maxel, Sarah,Cui, Youtian,King, Edward,Fong, Bonnie,Sanchez Martinez, Alicia,Siegel, Justin B.,Li, Han
-
-
- Novel nickel nanoparticles stabilized by imidazolium-amidinate ligands for selective hydrogenation of alkynes
-
The main challenge in the hydrogenation of alkynes into (E)- or (Z)-alkenes is to control the selective formation of the alkene, avoiding the over-reduction to the corresponding alkane. In addition, the preparation of recoverable and reusable catalysts is of high interest. In this work, we report novel nickel nanoparticles (Ni NPs) stabilized by three different imidazolium-amidinate ligands (ICy·(Ar)NCN; L1: Ar = p-tol, L2: Ar = p-anisyl and L3: Ar = p-ClC6H4). The as-prepared Ni NPs were fully characterized by (HR)-TEM, XRD, WASX, XPS and VSM. The nanocatalysts are active in the hydrogenation of various substrates. They present a remarkable selectivity in the hydrogenation of alkynes towards (Z)-alkenes, particularly in the hydrogenation of 3-hexyne into (Z)-3-hexene under mild reaction conditions (room temperature, 3% mol Ni and 1 bar H2). The catalytic behaviour of Ni NPs was influenced by the electron donor/acceptor groups (-Me, -OMe, -Cl) in the N-aryl substituents of the amidinate moiety of the ligands. Due to the magnetic character of the Ni NPs, recycling experiments were successfully performed after decantation in the presence of an external magnet, which allowed us to recover and reuse these catalysts at least 3 times preserving both activity and chemoselectivity.
- López-Vinasco, Angela M.,Martínez-Prieto, Luis M.,Asensio, Juan M.,Lecante, Pierre,Chaudret, Bruno,Cámpora, Juan,Van Leeuwen, Piet W. N. M.
-
p. 342 - 350
(2020/02/04)
-
- Aerobic photooxidative hydroxylation of boronic acids catalyzed by anthraquinone-containing polymeric photosensitizer
-
We report herein the synthesis of a polymeric photosensitizer and its application in aerobic photooxidative hydroxylation of boronic acids. The polymeric photosensitizer was synthesized by the condensation of anthraquinone-2-carbonyl chloride (AQ-2-COCl) with poly (2-hydroxyethyl methacrylate) (PHEMA). The photo-oxidative hydroxylation of boronic acids using anthraquinone-containing-poly (2-hydroxyethyl methacrylate) (AQ-PHEMA) was then explored and shown to exhibit high efficiency and broad scope. Moreover, AQ-PHEMA could be easily recovered and reused for more than 20 times without significant loss of the catalytic activity.
- Chen, Yang,Ding, Aishun,Hu, Jianhua
-
p. 7927 - 7932
(2020/03/11)
-
- Direct conversion of terminal alkenes to aldehydes via ozonolysis reaction in rotating zigzag bed
-
In this study, continuous ozonolysis of terminal alkenes in a rotating zigzag bed was developed. Rotating zigzag bed is a new type high gravity unit relative to the previous rotating packed bed and can intensify mass transfer remarkably. The rotating zigzag bed takes advantage of centrifugal force to mix liquid and gas phase effectively. The H2O in acetone acts as an in situ reducing agent for the carbonyl oxide intermediate, providing aldehydes directly from the reaction mixture. Critical factors were investigated and achieved optimum reaction conditions. Under these conditions, the yields of series aldehydes ranged from 72.3 to 95.8percent. The discrepancy in product yields among different olefin substrates likely originates from the electronic stability of the carbonyl oxide intermediate, which is longer lived for aryl olefines with electron donor group and longer carbon chain alkene (CnH2n, n ≥ 10).
- Liang, Zhengyong,Wei, Tong,Xie, Jun,Li, Hua,Liu, Hui
-
p. 2379 - 2384
(2020/05/25)
-
- Homogeneous catalytic oxidation of alkenes employing mononuclear vanadium complex with hydrogen peroxide
-
Abstract: Homogeneous liquid-phase oxidation of alkenes (allylbenzene, cis-cyclooctene, 4-chlorostyrene, styrene, 2-norbornene, 1-methyl cyclohexene, indene, lemonine, and 1-hexene) were catalyzed by using vanadium complex [VO(hyap)(acac)2] in existence of H2O2. The complex [VO(hyap)(acac)2] was formed as a crystal by the reaction of [VO(acac)2] and 2-hydroxyacetophenone (hyap) in the presence of methanol by refluxing the reaction mixture. Various analytical and spectroscopic techniques, namely FTIR, ESI–MS, UV–Vis, single-crystal XRD, and EPR, were used to analyze and optimize the structure of the complexes. Graphic abstract: [Figure not available: see fulltext.].
- Maurya, Abhishek
-
p. 3261 - 3269
(2020/07/14)
-
- The formyloxyl radical: Electrophilicity, C-H bond activation and anti-Markovnikov selectivity in the oxidation of aliphatic alkenes
-
In the past the formyloxyl radical, HC(O)O, had only been rarely experimentally observed, and those studies were theoretical-spectroscopic in the context of electronic structure. The absence of a convenient method for the preparation of the formyloxyl radical has precluded investigations into its reactivity towards organic substrates. Very recently, we discovered that HC(O)O is formed in the anodic electrochemical oxidation of formic acid/lithium formate. Using a [CoIIIW12O40]5- polyanion catalyst, this led to the formation of phenyl formate from benzene. Here, we present our studies into the reactivity of electrochemically in situ generated HC(O)O with organic substrates. Reactions with benzene and a selection of substituted derivatives showed that HC(O)O is mildly electrophilic according to both experimentally and computationally derived Hammett linear free energy relationships. The reactions of HC(O)O with terminal alkenes significantly favor anti-Markovnikov oxidations yielding the corresponding aldehyde as the major product as well as further oxidation products. Analysis of plausible reaction pathways using 1-hexene as a representative substrate favored the likelihood of hydrogen abstraction from the allylic C-H bond forming a hexallyl radical followed by strongly preferred further attack of a second HC(O)O radical at the C1 position. Further oxidation products are surmised to be mostly a result of two consecutive addition reactions of HC(O)O to the CC double bond. An outer-sphere electron transfer between the formyloxyl radical donor and the [CoIIIW12O40]5- polyanion acceptor forming a donor-acceptor [D+-A-] complex is proposed to induce the observed anti-Markovnikov selectivity. Finally, the overall reactivity of HC(O)O towards hydrogen abstraction was evaluated using additional substrates. Alkanes were only slightly reactive, while the reactions of alkylarenes showed that aromatic substitution on the ring competes with C-H bond activation at the benzylic position. C-H bonds with bond dissociation energies (BDE) ≤ 85 kcal mol-1 are easily attacked by HC(O)O and reactivity appears to be significant for C-H bonds with a BDE of up to 90 kcal mol-1. In summary, this research identifies the reactivity of HC(O)O towards radical electrophilic substitution of arenes, anti-Markovnikov type oxidation of terminal alkenes, and indirectly defines the activity of HC(O)O towards C-H bond activation.
- Iron, Mark A.,Khenkin, Alexander M.,Neumann, Ronny,Somekh, Miriam
-
p. 11584 - 11591
(2020/11/23)
-
- Efficient and selective oxidation of alcohols to carbonyl compounds at room temperature by a ruthenium complex catalyst and hydrogen peroxide
-
In this study, convenient and selective oxidation of alcohols using aqueous hydrogen peroxide to yield carbonyl compounds was studied. Using the ruthenium-(4-methylphenyl-2,6-bispydinyl) pyridinedicarboxylate complex [Ru(mpbp)(pydic)] as a catalyst, primary and secondary alcohols were oxidized to aldehydes and ketones at room temperature with a satisfactory yield and excellent selectivity. The influence of various reaction parameters, such as solvent, catalyst and oxidant amount on both the activity and selectivity was also evaluated. Kinetic studies showed that the oxidation of alcohol was first order in terms of the substrate and hydrogen peroxide, and was second order in terms of the catalyst. A plausible mechanism involving ruthenium-oxo species with electrophilic character was proposed based on the in situ UV-vis spectroscopy studies and Hammett plots.
- Wang, Jie-Xiang,Zhou, Xian-Tai,Han, Qi,Guo, Xiao-Xuan,Liu, Xiao-Hui,Xue, Can,Ji, Hong-Bing
-
p. 19415 - 19421
(2019/12/24)
-
- Efficient selective oxidation of alcohols to aldehydes catalyzed by a morpholinone nitroxide
-
Efficient chemoselective oxidation of primary alcohols to the corresponding aldehydes is described. The transformation is promoted by a catalytic morpholinone nitroxide radical catalyst which can be easily synthesized. A broad range of substrates includin
- Dong, Zhenhua,Gao, Pengwei,Xiao, Yongmei
-
p. 3380 - 3388
(2019/11/05)
-
- An Efficient Eco-friendly Modified Palladium, Immobilized on Imidazolium Supported Bi-functionalized Ionic Liquid for Selective Oxidation of Alcohols
-
An efficient method for the oxidation of primary and secondary alcohols to aldehydes and ketones, respectively, with hydrogen peroxide under ambient temperature has been achieved. By applying catalytic amount of palladium-bifunctional ionic liquid in the presence of solvent-free condition, a variety of substrates were selectively oxidized without the formation of ester by-products. The material also exhibited reusability as well as reaction time stability properties desired for industrial applications.
- Ashok, R. Francis Nicholas,Balan, A. Maria Kulandai Raja,Vasanthi, M.
-
-
- Europium-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes/Ketones and Photoluminescence Tracking
-
Europium is a lanthanide rare-earth metal and is known as a key element in luminophore development. Since europium has two relatively stable oxidation states, Eu2+ and Eu3+, which is exceptional among the various lanthanide elements, we have developed a europium-catalyzed aerobic oxidation with external oxidants utilizing the redox cycle of Eu2+/Eu3+. The reaction was performed under mild conditions with a wide substrate scope. The photoluminescence spectra clearly demonstrate the oxidation state changes that occur during the presented europium-catalyzed aerobic oxidation. (Figure presented.).
- Kim, Seongwoo,Kim, Youngik,Jin, Hyomin,Park, Myung Hwan,Kim, Youngjo,Lee, Kang Mun,Kim, Min
-
supporting information
(2019/02/05)
-
- Selective oxidation of exogenous substrates by a bis-Cu(III) bis-oxide complex: Mechanism and scope
-
Cu(III)2(μ-O)2 bis-oxides (O) form spontaneously by direct oxygenation of nitrogen-chelated Cu(I) species and constitute a diverse class of versatile 2e?/2H+ oxidants, but while these species have attracted attention as biomimetic models for dinuclear Cu enzymes, reactivity is typically limited to intramolecular ligand oxidation, and systems exhibiting synthetically useful reactivity with exogenous substrates are limited. OTMPD (TMPD = N1, N1, N3, N3-tetramethylpropane-1,3-diamine) presents an exception, readily oxidizing a diverse array of exogenous substrates, including primary alcohols and amines selectively over their secondary counterparts in good yields. Mechanistic and DFT analyses suggest substrate oxidation proceeds through initial axial coordination, followed by rate-limiting rotation to position the substrate in the Cu(III) equatorial plane, whereupon rapid deprotonation and oxidation by net hydride transfer occurs. Together, the results suggest the selectivity and broad substrate scope unique to OTMPD are best attributed to the combination of ligand flexibility, limited steric demands, and ligand oxidative stability. In keeping with the absence of rate-limiting C–H scission, OTMPD exhibits a marked insensitivity to the strength of the substrate Cα–H bond, readily oxidizing benzyl alcohol and 1-octanol at near identical rates.
- Large, Tao A.G.,Mahadevan, Viswanath,Keown, William,Stack, T. Daniel P.
-
p. 782 - 792
(2019/01/03)
-
- Fe3O4@SiO2@Im[Cl]Mn(III)-complex as a highly efficient magnetically recoverable nanocatalyst for selective oxidation of alcohol to imine and oxime
-
An efficient and environmentally friendly oxidation process for the one-pot preparation of oxime, imine and carbonyl compounds through alcohol oxidation in the presence of H2O2 and/or O2 have been developed by a melamine-Mn(III) Schiff base complex supported on Fe3O4@SiO2–Cl nanoparticles, named as Fe3O4@SiO2@Im[Cl]Mn(III)-complex nanocomposite, at room temperature. Direct oxidation of alcohol to carboxylic acid was performed using the catalyst in the presence of molecular O2 at room temperature in a different approach. The oxidation products were obtained with excellent yields and high TOFs. The properties of the catalyst were characterized by Fourier transform infrared spectroscopy (FTIR), elemental analysis (C, H, N), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), inductive coupled plasma (ICP), cyclic voltammetry (CV), nuclear magnetic resonance (1H & 13C NMR), vibration sample magnetometer (VSM), Brunauer– Emmett–Teller (BET) and differential pulse voltammetry (DPV) analyses. The mechanism of the oxidation processes was investigated for the both H2O2 and O2 oxidants. The role of the imidazolium moiety in the catalyst as a secondary functionality was investigated. Chemoselectivity behavior of the catalyst was studied by some combinations. The catalyst could be recycled from the reaction mixture by a simple external magnet and reused for several times without any considerable reactivity loss.
- Kazemnejadi, Milad,Alavi, Seyyedeh Ameneh,Rezazadeh, Zinat,Nasseri, Mohammad Ali,Allahresani, Ali,Esmaeilpour, Mohsen
-
p. 230 - 249
(2019/03/28)
-
- A new strategy for the selective oxidation of alcohols catalyzed by a polyoxometalate-based hybrid surfactant in biphasic systems
-
A hybrid surfactant with catalytic oxidation activity and interfacial activity was prepared via a combination of the polyoxometalate [PW11O39]7? anion and an alkoxysilane by a covalent bond. The organic-inorganic hybrid surfactant can effectively emulsify an alcohol/water biphase system, promote the alcohol oxidation reaction by increasing the oil-water interface area, and exhibit better catalytic oxidation activity than the homogeneous polyoxometallate. The demulsification of the emulsion can be achieved by increasing the temperature, and the catalyst can be recycled several times with no apparent loss of catalytic performance.
- Bai, Xueli,Huang, Xin,Wen, Liang,Song, Nianze,Zhang, Jian,Zhang, Yue,Zhao, Yongxiang
-
supporting information
p. 3598 - 3601
(2019/03/26)
-
- Chiral geminal disilyl alkane compound, synthesis method and applications thereof
-
The present invention discloses a chiral geminal disilyl alkane compound, which is represented by a formula V, wherein * represents a chiral carbon atom in the formula V. The invention discloses a synthesis method of the chiral geminal disilyl alkane compound, wherein the synthesis method comprises: carrying out a reaction in the presence of a reducing agent by using alkyne represented by a formula I, dihydrosilane represented by a formula II and trihydrosilane represented by a formula III as raw materials and using Xantphos-CoBr2 and a chiral CoX2-OIP complex as catalysts under an inert gas to prepare the chiral geminal disilyl alkane compound represented by the formula V. According to the present invention, the method has characteristics of mild reaction condition, simple operation, highatomic economy, no requirement of the addition of any other toxic transition metals (such as ruthenium, rhodium, palladium and the like) salts, high yield and high enantioselectivity, and has great practical value in the synthesis of drugs and materials, wherein the yield is generally 50-85%, and the enantioselectivity is generally 93-99%. The formulas I, II, III and V are defined in the specification.
- -
-
Paragraph 0204; 0205; 0206; 0207; 0209
(2019/01/14)
-
- Phosphine-free cobalt catalyst precursors for the selective hydrogenation of olefins
-
Cobalt(ii) complexes bearing phosphine-free tridentate NNS ligands were prepared. Depending on the ligand, dimeric or monomeric complexes were isolated. Monomeric Co(NNMeS)Cl2 selectively catalysed the hydrogenation of olefins in the presence of reducible moieties such as ketones. Further investigation showed that this complex functions as a nanoparticle precursor under the reaction conditions.
- Puylaert, Pim,Dell'Acqua, Andrea,El Ouahabi, Fatima,Spannenberg, Anke,Roisnel, Thierry,Lefort, Laurent,Hinze, Sandra,Tin, Sergey,De Vries, Johannes Gerardus
-
-
- Novel Old Yellow Enzyme Subclasses
-
Many drug candidate molecules contain at least one chiral centre, and consequently, the development of biocatalytic strategies to complement existing metal- and organocatalytic approaches is of high interest. However, time is a critical factor in chemical process development, and thus, the introduction of biocatalytic steps, even if more suitable, is often prevented by the limited availability of off-the-shelf enzyme libraries. To expand the biocatalytic toolbox with additional ene reductases, we screened 19 bacterial strains for double bond reduction activity by using the model substrates cyclohexanone and carvone. Overall, we identified 47 genes coding for putative ene reductases. Remarkably, bioinformatic analysis of all genes and the biochemical characterization of four representative novel ene reductases led us to propose the existence of two new Old Yellow Enzyme subclasses, which we named OYE class III and class IV. Our results demonstrate that although, on a DNA level, each new OYE subclass features a distinct combination of sequence motifs previously known from the classical and the thermophilic-like group, their substrate scope more closely resembles the latter subclass.
- Peters, Christin,Frasson, David,Sievers, Martin,Buller, Rebecca
-
p. 1569 - 1577
(2019/05/15)
-
- Chiral geminal disilicide alkane compound containing four silicon-hydrogen bonds as well as synthesis method and application thereof
-
The invention discloses a chiral geminal disilicide alkane compound containing four silicon-hydrogen bonds, shown as a formula VI, and discloses a synthesis method of the chiral geminal disilicide alkane compound. For the first method, in inert gas, a vinyl silane type compound shown as a formula V and silane trihydride shown as a formula IV are used as raw materials; a chiral CoX2-IIP complex compound is used as a catalyst; under the existence of reducing agents, reaction is performed to prepare VI. For the second method, in the inert gas, alkyne shown as a formula I, silane trihydride shownas a formula II and silane trihydride shown as a formula IV are used as raw materials; CoY2, bi(2-diphenyl phosphenyl) ether and a chiral CoX2-IIP complex compound are used as catalysts; under the existence of reducing agents, reaction is performed to prepare a formula VI. The method has the advantages of mild reaction conditions, operation simplicity and convenience, high atom economy, excellentproductive rate (57 to 84 percent), high regioselectivity (greater than 19:1) and high enantioselectivity (91.6 to 98.8 percent ee). The formulas are shown in description.
- -
-
-
- Racemic gem disilyl alkane compound containing four silicon-hydrogen bonds, and sybthesis method and application of compound
-
The invention discloses a racemic gem disilyl alkane compound containing four silicon-hydrogen bonds. The compound is as shown in a formula IV. The invention further discloses a synthesis method of the racemic gem disilyl alkane compound. The synthesis method comprises the following step of carrying out a reaction by taking alkyne as shown in a formula I and trihydrosilane as shown in a formula IIas raw materials and taking a chiral CoX-IIP complex as a catalyst in the presence of a reducing agent to obtain the racemic gem disilyl alkane compound containing four silicon-hydrogen bonds, wherein the compound is as shown in the formula IV. The method disclosed by the invention has mild reaction conditions, is simple and convenient to operate and has high atom economy. In addition, the reaction does not need addition of any salts of toxic transition metals (such as ruthenium, rhodium, palladium and the like), and the method has a relatively large practical application value in synthesis of medicines and materials. In addition, the reaction has a medium to excellent yield (51-99%) and high area selectivity (10:1-19:1, most parts larger than 19:1).
- -
-
-
- Production and testing of technical catalysts based on MnO2 for the abatement of aromatic volatile compounds at the laboratory and pilot plant scales
-
Shaping is a crucial step to produce technical catalysts that remains as some sort of dark art for catalytic researchers in academia. This contribution discusses aspects concerning the fabrication of technical catalysts based on MnO2 powders ai
- Baldovino-Medrano, Víctor Gabriel,Kartheuser, Beno?t,Gaigneaux, Eric M.
-
-
- A Supramolecular Strategy for Selective Catalytic Hydrogenation Independent of Remote Chain Length
-
Performing selective transformations on complex substrates remains a challenge in synthetic chemistry. These difficulties often arise due to cross-reactivity, particularly in the presence of similar functional groups at multiple sites. Therefore, there is a premium on the ability to perform selective activation of these functional groups. We report here a supramolecular strategy where encapsulation of a hydrogenation catalyst enables selective olefin hydrogenation, even in the presence of multiple sites of unsaturation. While the reaction requires at least one sterically nondemanding alkene substituent, the rate of hydrogenation is not sensitive to the distance between the alkene and the functional group, including a carboxylate, on the other substituent. This observation indicates that only the double bond has to be encapsulated to effect hydrogenation. Going further, we demonstrate that this supramolecular strategy can overcome the inherent allylic alcohol selectivity of the free catalyst, achieving supramolecular catalyst-directed regioselectivity as opposed to directing-group selectivity.
- Bender, Trandon A.,Bergman, Robert G.,Raymond, Kenneth N.,Toste, F. Dean
-
p. 11806 - 11810
(2019/08/22)
-
- A Redox Strategy for Light-Driven, Out-of-Equilibrium Isomerizations and Application to Catalytic C-C Bond Cleavage Reactions
-
We report a general protocol for the light-driven isomerization of cyclic aliphatic alcohols to linear carbonyl compounds. These reactions proceed via proton-coupled electron-transfer activation of alcohol O-H bonds followed by subsequent C-C β-scission of the resulting alkoxy radical intermediates. In many cases, these redox-neutral isomerizations proceed in opposition to a significant energetic gradient, yielding products that are less thermodynamically stable than the starting materials. A mechanism is presented to rationalize this out-of-equilibrium behavior that may serve as a model for the design of other contrathermodynamic transformations driven by excited-state redox events.
- Ota, Eisuke,Wang, Huaiju,Frye, Nils Lennart,Knowles, Robert R.
-
supporting information
p. 1457 - 1462
(2019/01/25)
-
- Enzymatic One-Step Reduction of Carboxylates to Aldehydes with Cell-Free Regeneration of ATP and NADPH
-
The direct generation of aldehydes from carboxylic acids is often a challenging synthetic task but undoubtedly attractive in view of abundant supply of such feedstocks from nature. Though long known, biocatalytic carboxylate reductions are at an early stage of development, presumably because of their co-factor requirement. To establish an alternative to whole-cell-based carboxylate reductions which are limited by side reactions, we developed an in vitro multi-enzyme system that allows for quantitative reductions of various carboxylic acids with full recycling of all cofactors and prevention of undesired over-reductions. Regeneration of adenosine 5′-triphosphate is achieved through the simultaneous action of polyphosphate kinases from Meiothermus ruber and Sinorhizobium meliloti and β-nicotinamide adenine dinucleotide 2′-phosphate is reduced by a glucose dehydrogenase. Under these conditions and in the presence of the carboxylate reductases from Neurospora crassa or Nocardia iowensis, various aromatic, heterocyclic and aliphatic carboxylic acids were quantitatively reduced to the respective aldehydes.
- Strohmeier, Gernot A.,Eitelj?rg, Inge C.,Schwarz, Anna,Winkler, Margit
-
p. 6119 - 6123
(2019/04/13)
-
- Ruthenium Nanoparticles Immobilized on Nano-silica Functionalized with Thiol-Based Dendrimer: A Nanocomposite Material for Oxidation of Alcohols and Epoxidation of Alkenes
-
Abstract: In this work, ruthenium nanoparticles were immobilized on thiol-based dendrimer functionalized nano-silica and its catalytic activity was investigated in the oxidation reactions. To do this, silica nanoparticles were functionalized with a thiol-
- Haghshenas Kashani, Sara,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
-
p. 1110 - 1123
(2018/02/22)
-
- Polyoxometalate-based Gemini ionic catalysts for selective oxidation of benzyl alcohol with hydrogen peroxide in water
-
Keggin-type phosphotungstic acid (H3PW12O40, HPW)-based di-imidazolium ionic liquid (IL) hybrids were prepared by exchanging the protons of HPW with PEG-bridged di-imidazolium cations in water. Characterization results sug
- Hao, Pengbo,Zhang, Mingjie,Zhang, Wei,Tang, Zhiyang,Luo, Ni,Tan, Rong,Yin, Donghong
-
p. 4463 - 4473
(2018/09/11)
-
- Copper diisobutyl-t-butoxyaluminum hydride: A novel reagent for chemoselective reduction of tertiary amides over esters
-
We demonstrate that copper diisobutyl-t-butoxyaluminum hydride, readily prepared from lithium diisobutyl-t-butoxyaluminum hydride and CuI, effectively and chemoselectively reduces tertiary amides over esters at ambient temperature, affording the corresponding aldehydes in excellent yields.
- Im, So Hee,Shin, Won Kyu,Jaladi, Ashok Kumar,An, Duk Keun
-
p. 2335 - 2340
(2018/05/16)
-
- Nickel boride mediated chemoselective deprotection of 1,1-diacetates to aldehydes and deprotection with concomitant reduction to alcohols at ambient temperature
-
A variety of 1,1-diacetates have been chemoselectively and efficiently deprotected to the corresponding aldehydes as well as deprotected and concomitantly reduced to the corresponding alcohols in high yields at ambient temperature with nickel boride generated in situ using different molar ratios of sodium borohydride and nickel (II) chloride in methanol at room temperature. Deprotection and reduction of a variety of aromatic, aliphatic and heterocyclic acylals have been achieved efficiently. Mild reaction conditions, easy work-up, high yields and chemoselectivity demonstrate the efficiency of this new method.
- Bartwal, Gaurav,Saroha, Mohit,Khurana, Jitender.M.
-
-