- Asymmetric Hydrogenation Cazalyzed by Bis(disubstitiuted glyoximato)cobalt(II)-Chiral Cocatalyst System. Effect of Structural Variation of Ligands and Hydrogen Pressure
-
The reaction rate was extremely enhanced by increasing the basicity of the axial ligand of and by increasing the hydrogen pressure without decreasing the enantioselectivity.Substituting one and two methyl groups of the dimethylglyoxime liga
- Ohgo, Yoshiaki,Tashiro, Yasuhisa,Takeuchi, Seiji
-
-
Read Online
- Synthesis and immobilization of amylose derivatives bearing a 4-terf-butylbenzoate group at the 2-position and 3,5-dichlorophenylcarbamate/3- (triethoxysilyl)propylcarbamate groups at 3- And 6-positions as chiral packing material for HPLC
-
Two novel amylose derivatives 2a and 2b bearing A-tertbutylbenzoate at the 2-position and 3,5-dichlorophenylcarbamate/3-(triethoxysilyl)propylcarbamate residues at 3- and 6positions were successfully synthesized and immobilized onto silica gel, and their chiral recognition abilities were evaluated as chiral packing materials (CPMs) for high-performance liquid chromatography. These immobilized CPMs exhibited recognition ability similar to conventional coated CPM, and for some racemates, comparable or better resolutions were observed even compared to commercial immobilized amylose- or cellulosebased columns.
- Shen, Jun,Ikai, Tomoyuki,Shen, Xiande,Okamoto, Yoshio
-
-
Read Online
- Benzaldehyde lyase (BAL)-catalyzed enantioselective CC bond formation in deep-eutectic-solvents-buffer mixtures
-
Deep-eutectic-solvents (DES) have emerged in the last decades as promising bio-based and biodegradable neoteric solvents for biocatalysis, with examples covering different enzymes (mostly hydrolases) and whole-cells (baker's yeast). This paper explores fo
- Maugeri, Zaira,Dominguez De Maria, Pablo
-
-
Read Online
- Asymmetric reduction of benzil to (S)-benzoin with Penicillium claviforme IAM 7294 in a liquid-liquid interface bioreactor (L-L IBR)
-
The asymmetric reduction of benzyl to (S)-benzoin with Penicillium claviforme IAM 7294 was applied to a liquid-liquid interface bioreactor (L-L IBR) using a unique polymeric material, ballooned microsphere (MS). The L-L IBR showed superior performance, as
- Oda, Shinobu,Isshiki, Kunio
-
-
Read Online
- A holoenzyme model of thiamin dependent enzyme; asymmetrical acyloin condensation using a lipid catalyst in a bilayer membrane
-
Within a DPPC bilayer membrane, the lipid catalyst 1, having a thiazolium salt unit in the head group, exhibited catalytic activity and enantioselectivity in the acyloin condensation of benzaldehyde. The activity and enantioselectivity were strongly depen
- Yamashita, Keiji
-
-
Read Online
- 105. A novel asymmetric benzoin reaction catalyzed by a chiral triazolium salt: Preliminary communication
-
Using the chiral triazolium salt 1 as catalyst, a novel asymmetric variant of the benzoin reaction is reported. For the first time, the scope of the method is extended to a broader range of aromatic aldehydes 2, affording the acyloins 3a-h in yields of 22
- Enders, Dieter,Breuer, Klaus,Teles, J. Henrique
-
-
Read Online
- Fungal deracemization of benzoin
-
An enzyme system of Rhizopus oryzae (ATCC 9363) catalyzes the inversion of the chirality of benzoin via a deracemization reaction and, depending on the pH of the medium, both enantiomers of benzoin are obtained in good yield and high ee starting from rac-
- Demir, Ayhan S,Hamamci, Haluk,Sesenoglu, Ozge,Neslihanoglu, Rahsan,Asikoglu, Beril,Capanoglu, Doga
-
-
Read Online
- Optimised dynamic kinetic resolution of benzoin by a chemoenzymatic approach in 2-MeTHF
-
Different influential parameters in the Dynamic Kinetic Resolution of racemic benzoin via lipase-ruthenium catalyst enantioselective transesterification have been improved in order to develop a more productive process. In this sense, 2-Methyltetrahydrofur
- Hoyos, Pilar,Quezada, M. Alberto,Sinisterra, Jose Vicente,Alcantara, Andres R.
-
-
Read Online
- SmI2-(Chiral Auxiliary)-Induced Asymmetric Reduction
-
Benzyl was reduced to benzoin with 56.2 percent ee by a system of SmI2-THF-HMPA in the presence of quinidine.
- Takeuchi, Seiji,Ohgo, Yoshiaki
-
-
Read Online
- Asymmetric Reactions. X. Asymmetric Hydrogenation Catalyzed by Bis(dimethylglyoximato)cobalt(II)-Chiral Cocatalyst (Amino Alcohol) System
-
The catalytic asymmetric hydrogenations of α-diketones, α-keto carboxylates, α-(acylamino)acrylates, α-phenylacrylophenone, and α-phenylacrylate were examined with bis(dimethylglyoximato)cobalt(II)-chiral cocatalyst (amino alcohol) and with simple achiral
- Ohgo, Yoshiaki,Takeuchi, Seiji,Natori, Yukikazu,Yoshimura, Juji
-
-
Read Online
- Efficient and Selective Carboligation with Whole-Cell Biocatalysts in Pickering Emulsion
-
Pickering emulsions (PEs) are particle-stabilized multiphase systems with promising features for synthetic applications. Described here is a novel, simplified set-up employing catalytically active whole cells for simultaneous emulsion stabilization and sy
- R?llig, Robert,Plikat, Christoph,Ansorge-Schumacher, Marion B.
-
-
Read Online
- Enantioselective oxidation of vic-diols to optically active α-hydroxy ketones by a fructose-derived dioxirane
-
Optically active α-hydroxy ketones 3 have been prepared in moderate to good enantioselectivities through asymmetrization of meso-, and kinetic resolution of, racemic vic-diols 2 by enantioselective oxidation with the in situ generated dioxirane from the fructose-derived ketone 1; the opposite sense in-the-enantioselectivity of the two processes is explained in terms of the hydrogen-bonded transition-state structures for the concerted C-H oxygen insertion.
- Adam, Waldemar,Saha-Moeller, Chantu R.,Zhao, Cong-Gui
-
-
Read Online
- Purification and covalent immobilization of benzaldehyde lyase with heterofunctional chelate-epoxy modified magnetic nanoparticles and its carboligation reactivity
-
In this work, histidine-tagged recombinant benzaldehyde lyase from Pseudomonas fluorescens Biovar I (BAL, EC 4.1.2.38) was immobilized on the magnetically responsive epoxy-chelate magnetic support following a two-step mechanism; that is, the protein is ph
- Tural, Bilsen,Tural, Servet,Ertas, Erdal,Yalinkilic, Ibrahim,Demir, Ayhan S.
-
-
Read Online
- Generation and reactivity of phenylhydroxycarbenes in solution
-
We provide evidence for the first successful generation of phenylhydroxycarbene and 4-trifluoromethylphenylhydroxycarbene in solution. The carbene tautomers of the corresponding benzaldehyde derivatives had been prepared under cryogenic matrix-isolation conditions before but their reactivity, apart from a prototypical quantum mechanical tunneling [1,2]-H-shift reaction, had not been studied. Here our strategy is to employ suitable carbene precursors for the McFadyen–Stevens reaction, to generate the parent and the para-CF3-substituted phenylhydroxycarbenes, and to react them with benzaldehyde or acetone in a highly facile, allowed six-electron carbonyl-ene reaction toward the corresponding α-hydroxy ketones. Our findings are supported by computations at the DLPNO-CCSD(T)/cc-pVQZ//B3LYP/def2-TZVP level of theory.
- Keul, Felix,Mardyukov, Artur,Schreiner, Peter R.
-
supporting information
(2022/01/19)
-
- Direct Synthesis of Vinylene Carbonates from Aromatic Aldehydes**
-
Substituted vinylene carbonates were directly prepared from aromatic aldehydes following a one-pot Benzoin condensation/transcarbonation sequence under solvent-free conditions. The combination of a N-phenyl substituted triazolium salt NHC precursor and 4-dimethylaminopyridine (DMAP) was found essential to reach high yield and selectivity. The reaction scope was investigated with a range of aromatic aldehydes and the corresponding vinylene carbonates were obtained with 32–86 % isolated yields (14 examples).
- Duguet, Nicolas,Ibrahimli, Leyli,Onida, Killian
-
supporting information
(2022/04/03)
-
- Visible Light Enabled Formal Cross Silyl Benzoin Reaction as an Access to α-Hydroxyketones
-
In this work, a visible-light enabled coupling of acylsilanes with aldehydes to give a range of cross-benzoin type products α-hydroxyketones is described. The reaction could proceed at ambient temperature, with the irradiation of low energy visible light, and without addition of photosensitizer or any other additives. (Figure presented.).
- Ma, Liyao,Yu, Yinghua,Xin, Luoting,Zhu, Lei,Xia, Jiajin,Ou, Pengcheng,Huang, Xueliang
-
supporting information
p. 2573 - 2577
(2021/04/05)
-
- Zinc salt-catalyzed reduction of α-aryl imino esters, diketones and phenylacetylenes with water as hydrogen source
-
The zinc salt-catalyzed reduction of α-aryl imino esters, diketones and phenylacetylenes with water as hydrogen source and zinc as reductant was successfully conducted. The presented method provides a low-cost, environmentally friendly and practical preparation of α-aryl amino esters, α-hydroxyketones and phenylethylenes. By using D2O as deuterium source, the corresponding products were obtained in high efficiency with excellent deuterium incorporation rate, which gives a cheap and safe tool for access to valuable deuterium-labelled compounds. This journal is
- Shen, Guoli,Liu, Haojie,Chen, Jingchao,He, Zhenxiu,Zhou, Yongyun,Wang, Lin,Luo, Yang,Su, Zhimin,Fan, Baomin
-
supporting information
p. 3601 - 3610
(2021/05/04)
-
- Organocatalytic Synthesis of Substituted Vinylene Carbonates
-
The organocatalytic synthesis of substituted vinylene carbonates from benzoins and acyloins was studied using diphenyl carbonate as a carbonyl source. A range of N-Heterocyclic Carbene (NHC) precursors were screened and it was found that imidazolium salts were the most active for this transformation. The reaction occurs at 90 °C under solvent-free conditions. A wide range of substituted vinylene carbonates (symmetrical and unsymmetrical, aromatic or aliphatic), including some derived from natural products, were prepared with 20–99% isolated yields (24 examples). The reaction was also developed using thermomorphic polyethylene-supported organocatalysts as recoverable and recyclable species. The use of such species facilitates the workup and allows the synthesis of vinylene carbonates on the preparative scale (>30 g after 5 runs). (Figure presented.).
- Onida, Killian,Haddleton, Alice J.,Norsic, Sébastien,Boisson, Christophe,D'Agosto, Franck,Duguet, Nicolas
-
supporting information
p. 5129 - 5137
(2021/09/18)
-
- N-PEGylated Thiazolium Salt: A Green and Reusable Homogenous Organocatalyst for the Synthesis of Benzoins and Acyloins
-
N-PEGylated-thiazolium salt is used as efficient catalyst for the benzoin condensation. The catalyst was synthesized by reaction of activated polyethylene glycol 10,000 (PEG-10000) with 4-methyl-5-thiazoleethanol (sulfurol). Reaction mixture undergoes temperature-assisted phase transition and catalyst separated by simple filtration. After reaction course, catalyst can be recycled and reused without any apparent loss of activity which makes this process cost effective and hence ecofriendly. Synthesized benzoins and acyloins by this method have been characterized on the basis of melting point and 1H-NMR spectral studies. Graphic Abstract: [Figure not available: see fulltext.]
- Haghighi, Ali Javaheri,Mokhtari, Javad,Karimian, Khashayar
-
p. 1646 - 1652
(2020/10/19)
-
- Rapid, chemoselective and mild oxidation protocol for alcohols and ethers with recyclable N-chloro-N-(phenylsulfonyl)benzenesulfonamide
-
Chlorine is the 20th most abundant element on the earth compared to bromine, iodine, and fluorine, a sulfonimide reagent, N-chloro-N-(phenylsulfonyl)benzenesulfonamide (NCBSI) was identified as a mild and selective oxidant. Without activation, the reagent was proved to oxidize primary and secondary alcohols as well as their symmetrical and mixed ethers to corresponding aldehydes and ketones. With recoverable PS-TEMPO catalyst, selective oxidation over chlorination of primary and secondary alcohols and their ethers with electron-donating substituents was achieved. The reagent precursor of NCBSI was recovered quantitatively and can be reused for synthesizing NCBSI.
- Badani, Purav,Chaturbhuj, Ganesh,Ganwir, Prerna,Misal, Balu,Palav, Amey
-
supporting information
(2021/06/03)
-
- Selective Aerobic Oxidation of Benzyl Alcohols with Palladium(0) Nanoparticles Suspension in Water
-
Abstract: This study concerns one of the rare applications of a suspension of palladium nanoparticles in water for oxidation reactions. The aqueous suspension containing well dispersed nanoparticles of 3.85?nm was obtained following a straightforward procedure involving the reduction of Na2PdCl4 with NaBH4 in the presence of PVP as stabilizing agent. In the way of oxidative catalytic valorisation of lignin, the aqueous suspension was directly applied as catalytic medium for the selective oxidation of vanillic alcohol into vanillin (80?°C, O2, 1?h) with more than 90% yield. Reusability of the catalytic medium has been demonstrated, acting as “quasi-homogeneous catalyst”. More sophisticated lignin-derived substrates like veratryl alcohol and hydrobenzoin gave yields of 50–80% to the respective aldehyde and ketone. In parallel, this as-synthesized suspension was directly used to prepare a Pd/TiO2 catalyst, the latter showing less efficiency for the catalytic transformations. Graphic Abstract: [Figure not available: see fulltext.]
- Bourbiaux, Dolorès,Mangematin, Stéphane,Djakovitch, Laurent,Rataboul, Franck
-
p. 3239 - 3249
(2021/03/16)
-
- Ruthenium(II)-Catalyzed Cross-Coupling of Benzoyl Formic Acids with Toluenes: Synthesis of 2-Phenylacetophenones
-
Herein, we report a direct method to synthesize 2-phenylacetophenone through a ruthenium(II)-catalyzed cross-coupling reaction between acyl and benzyl radical. The various derivatives of 2-phenylacetophenone were prepared easily in moderate to good yields. These reactions provide a straightforward pathway to synthesize a variety of ketones bearing various functional groups.
- Chen, Yujie,Dai, Chenyang,Huang, Zhibin,Jiang, Yaqiqi,Shu, Sai,Yang, Shan,Zhao, Yingsheng
-
p. 2955 - 2961
(2021/07/22)
-
- Palladium-catalyzed synthesis of α-aryl acetophenones from styryl ethers and aryl diazonium saltsviaregioselective Heck arylation at room temperature
-
Preparation of α-aryl acetophenones from styryl ethers and aryldiazonium salts is described. The reaction is catalyzed by palladium acetate at room temperature in the absence of ligand and base. The developed method is highly attractive in terms of reaction conditions, substrate scope, functional group tolerance and yields. Synthetic applications of the present method are demonstrated by preparing α-aryl indoles and 3-aryl isocoumarin from styryl ethers.
- Kandasamy, Jeyakumar,Lee, Yong Rok,Singh, Adesh Kumar,Venkatesh, Rapelly
-
supporting information
p. 7832 - 7837
(2021/09/28)
-
- Synthesis of hydroxy benzoin/benzil analogs and investigation of their antioxidant, antimicrobial, enzyme inhibition, and cytotoxic activities
-
In this study, hydroxy benzoin (1-7), benzil (8-14), and benzoin/benzil-O-β-D-glucosides (15-25) were synthesized to investigate their biological activities. An efficient method for synthesizing hydroxy benzoin compounds (1-7) was prepared from four diffe
- Yayli, Nurettin,Kili?, G?zde,Celik, Gonca,Kahriman, Nuran,Kanbolat, Seyda,Bozdeveci, Arif,Karaoglu, Sengül Alpay,Aliyazicioglu, Rezzan,Sellitepe, Hasan Erdin?,Dogan, Inci Selin,Aydin, Ali
-
p. 788 - 804
(2021/07/26)
-
- Ultrasound-assisted aqueous phase synthesis of benzoin and derivatives thereof
-
The invention relates to a rapid and simple preparation method of benzoin and derivatives thereof. Benzoin and derivatives thereof can be synthesized under the assistance of ultrasonic waves at room temperature under a water phase condition. Taking benzoin as an example, in the operation, benzaldehyde, alkali and a catalyst are subjected to a room-temperature water phase reaction for about 15 minutes, and the product benzoin is separated out; and after filtering is conducted, a raw material benzaldehyde is added, and circular reaction is conducted. The alkali and the catalyst can be recycled. The synthesis route of the benzoin and the derivative is green and environment-friendly, and has a good application prospect in the fields of chemical engineering and medicines.
- -
-
Paragraph 0017-0019
(2021/10/27)
-
- Enantioselective N-heterocyclic carbene-catalysed intermolecular crossed benzoin condensations: Improved catalyst design and the role of in situ racemisation
-
The enantioselective intermolecular crossed-benzoin condensation mediated by novel chiral N-heterocyclic carbenes derived from pyroglutamic acid has been investigated. A small library of chiral triazolium ions were synthesised. Each possessed a tertiary alcohol H-bond donor and a variable N-aryl substituent. It was found that increasing both the steric requirement and the electron-withdrawing characteristics of the N-aryl ring led to more chemoselective, efficient and enantioselective chemistry, however both quenching the reaction at different times and deuterium incorporation experiments involving the product revealed that this is complicated by product racemisation in situ (except in the case of benzoin itself), which explains the dependence of enantioselectivity on the electrophilicity of the reacting aldehydes common in the literature. Subsequent protocol optimisation, where one reacting partner was an o-substituted benzaldehyde, allowed a range of crossed-benzoins to be synthesised in moderate-good yields with moderate to excellent enantioselectivity.
- Delany, Eoghan G.,Connon, Stephen J.
-
supporting information
p. 248 - 258
(2021/01/14)
-
- Preparation of a novel bridged bis(β-cyclodextrin) chiral stationary phase by thiol-ene click chemistry for enhanced enantioseparation in HPLC
-
A bridged bis(β-cyclodextrin) ligand was firstly synthesized via a thiol-ene click chemistry reaction between allyl-ureido-β-cyclodextrin and 4-4′-thiobisthiophenol, which was then bonded onto a 5 μm spherical silica gel to obtain a novel bridged bis(β-cyclodextrin) chiral stationary phase (HTCDP). The structures of HTCDP and the bridged bis(β-cyclodextrin) ligand were characterized by the 1H nuclear magnetic resonance (1H NMR), solid state 13C nuclear magnetic resonance (13C NMR) spectra spectrum, scanning electron microscope, elemental analysis, mass spectrometry, infrared spectrometry and thermogravimetric analysis. The performance of HTCDP in enantioseparation was systematically examined by separating 21 chiral compounds, including 8 flavanones, 8 triazole pesticides and 5 other common chiral drugs (benzoin, praziquantel, 1-1′-bi-2-naphthol, Tr?ger's base and bicalutamide) in the reversed-phase chromatographic mode. By optimizing the chromatographic conditions such as formic acid content, mobile phase composition, pH values and column temperature, 19 analytes were completely separated with high resolution (1.50-4.48), in which the enantiomeric resolution of silymarin, 4-hydroxyflavanone, 2-hydroxyflavanone and flavanone were up to 4.34, 4.48, 3.89 and 3.06 within 35 min, respectively. Compared to the native β-CD chiral stationary phase (CDCSP), HTCDP had superior enantiomer separation and chiral recognition abilities. For example, HTCDP completely separated 5 other common chiral drugs, 2 flavanones and 3 triazole pesticides that CDCSP failed to separate. Unlike CDCSP, which has a small cavity (0.65 nm), the two cavities in HTCDP joined by the aryl connector could synergistically accommodate relatively bulky chiral analytes. Thus, HTCDP may have a broader prospect in enantiomeric separation, analysis and detection. This journal is
- Gong, Bolin,Guo, Siyu,Zhang, Ning
-
p. 35754 - 35764
(2021/12/02)
-
- C3 The symmetry contains a chiral ligand H3L of an amide bond. Preparation method and application
-
The invention discloses C. 3 Chiral ligand H with symmetric amide bond3 L Relates to the technical field of material chemistry and chiral chemistry. The invention further provides the chiral ligand H. 3 L Preparation method and application thereof. The present invention has the advantage that the chiral ligand H of the present invention is a chiral ligand. 3 The L has a higher C. 3 The symmetric and flexible amide group enables coordination of the lanthanide metal ions with high coordination number and high oxygen affinity to be assembled into a novel structure-structure lanthanide metal chiral porous coordination cage. Moreover, the abundant chiral amide groups and amino acid residues on the ligand framework can be directly introduced into the synthesized lanthanide metal chiral porous coordination cage, thereby being beneficial to generating multiple chiral recognition sites and unique chiral microenvironments which mimic the biological enzyme binding pocket and further realize the purpose of high enantioselectivity separation of a series of chiral small molecule compounds.
- -
-
Paragraph 0092-0100
(2021/09/08)
-
- Microbial synthesis of (S)- And (R)-benzoin in enantioselective desymmetrization and deracemization catalyzed by aureobasidium pullulans included in the blossom protect agent
-
In this study, we examined the Aureobasidium pullulans strains DSM 14940 and DSM 14941 included in the Blossom Protect agent to be used in the bioreduction reaction of a symmetrical dicarbonyl compound. Both chiral 2-hydroxy-1,2-diphenylethanone antipodes were obtained with a high enantiomeric purity. Mild conditions (phosphate buffer [pH 7.0, 7.2], 30 ?C) were successfully employed in the synthesis of (S)-benzoin using two different methodologies: benzyl desymmetrization and rac-benzoin deracemization. Bioreduction carried out with higher reagent concentrations, lower pH values and prolonged reaction time, and in the presence of additives, enabled enrichment of the reaction mixture with (R)-benzoin. The described procedure is a potentially useful tool in the synthesis of chiral building blocks with a defined configuration in a simple and economical process with a lower environmental impact, enabling one-pot biotransformation.
- Ko?odziejska, Renata,Studzinska, Renata,Tafelska-Kaczmarek, Agnieszka,Pawluk, Hanna,Mlicka, Dominika,Wozniak, Alina
-
-
- Structural insights into the desymmetrization of bulky 1,2-dicarbonyls through enzymatic monoreduction
-
Benzil reductases are dehydrogenases preferentially active on aromatic 1,2-diketones, but the reasons for this peculiar substrate recognition have not yet been clarified. The benzil reductase (KRED1-Pglu) from the non-conventional yeast Pichia glucozyma showed excellent activity and stereoselectivity in the monoreduction of space-demanding aromatic 1,2-dicarbonyls, making this enzyme attractive as biocatalyst in organic chemistry. Structural insights into the stereoselective monoreduction of 1,2-diketones catalyzed by KRED1-Pglu were investigated starting from its 1.77 ? resolution crystal structure, followed by QM and classical calculations; this study allowed for the identification and characterization of the KRED1-Pglu reactive site. Once identified the recognition elements involved in the stereoselective desymmetrization of bulky 1,2-dicarbonyls mediated by KRED1-Pglu, a mechanism was proposed together with an in silico prediction of substrates reactivity.
- Rabuffetti, Marco,Cannazza, Pietro,Contente, Martina Letizia,Pinto, Andrea,Romano, Diego,Hoyos, Pilar,Alcantara, Andres R.,Eberini, Ivano,Laurenzi, Tommaso,Gourlay, Louise,Di Pisa, Flavio,Molinari, Francesco
-
supporting information
(2021/01/25)
-
- Sol-gel synthesis of ceria-zirconia-based high-entropy oxides as high-promotion catalysts for the synthesis of 1,2-diketones from aldehyde
-
Efficient Lewis-acid-catalyzed direct conversion of aldehydes to 1,2-diketones in the liquid phase was enabled by using newly designed and developed ceria–zirconia-based high-entropy oxides (HEOs) as the actual catalysts. The synergistic effect of various cations incorporated in the same oxide structure (framework) was partially responsible for the efficiency of multicationic materials compared to the corresponding single-cation oxide forms. Furthermore, a clear, linear relationship between the Lewis acidity and the catalytic activity of the HEOs was observed. Due to the developed strategy, exclusively diketone-selective, recyclable, versatile heterogeneous catalytic transformation of aldehydes can be realized under mild reaction conditions.
- Dinjar, Kristijan,Djerdj, Igor,Koj?inovi?, Jelena,Kukovecz, ákos,Markovi?, Berislav,Mileti?, Aleksandar,Nagy, Sándor Balázs,Sapi, Andras,Stenzel, David,Széchenyi, Aleksandar,Szenti, Imre,Tang, Yushu,Tatar, Dalibor,Varga, Gábor,Ziegenheim, Szilveszter
-
supporting information
(2021/10/20)
-
- Responsive Emulsions for Sequential Multienzyme Cascades
-
Multienzyme cascade biocatalysis is an efficient synthetic process, avoiding the isolation/purification of intermediates and shifting the reaction equilibrium to the product side. However, multienzyme systems are often limited by their incompatibility and cross-reactivity. Herein, we report a multi-responsive emulsion to proceed multienzyme reactions sequentially for high reactivity. The emulsion is achieved using a CO2, pH, and thermo-responsive block copolymer as a stabilizer, allowing the on-demand control of emulsion morphology and phase composition. Applying this system to a three-step cascade reaction enables the individual optimal condition for each enzyme, and a high overall conversion (ca. 97 % of the calculated limit) is thereby obtained. Moreover, the multi-responsiveness of the emulsion allows the facile and separate yielding/recycling of products, polymers and active enzymes. Besides, the system could be scaled up with a good yield.
- Sun, Zhiyong,Zhao, Qingcai,Haag, Rainer,Wu, Changzhu
-
p. 8410 - 8414
(2021/03/09)
-
- Metal-free porous phosphorus-doped g-C3N4photocatalyst achieving efficient synthesis of benzoin
-
Photocatalytic organic synthesis is mostly limited by the shortcomings of insufficient light absorption, high photogenerated electron-hole recombination rate and inadequate reactive sites of photocatalysts. To solve these problems, phosphorus-doped g-C3N4with a porous structure was constructed. Benefiting from enhanced light absorption and electron-hole separation efficiency, PCNT has intensive oxygen activation ability to generate superoxide radicals, and is highly active in organic synthesis. In addition, PCNT has enhanced surface nucleophilicity, which is conducive to the carbon-carbon coupling process of the intermediate product benzaldehyde molecules and benzyl alcohol molecules in the benzoin condensation reaction. Metal-free PCNT is expected to replace the previously used highly toxic cyanide catalysts and provide a new way for the low-cost and efficient photocatalytic synthesis of benzoin.
- Li, Yuanjin,Wang, Shuhui,Wu, Jin,Wang, Qiuyan,Ma, Changqiu,Jiang, Daheng,Hu, Wanglai,Zhu, Lixin,Xu, Xiaoliang
-
p. 12682 - 12686
(2021/04/14)
-
- Oxidative carbon-carbon bond cleavage of 1,2-diols to carboxylic acids/ketones by an inorganic-ligand supported iron catalyst
-
The carbon-carbon bond cleavage of 1,2-diols is an important chemical transformation. Although traditional stoichiometric and catalytic oxidation methods have been widely used for this transformation, an efficient and valuable method should be further explored from the views of reusable catalysts, less waste, and convenient procedures. Herein an inorganic-ligand supported iron catalyst (NH4)3[FeMo6O18(OH)6]·7H2O was described as a heterogeneous molecular catalyst in acetic acid for this transformation in which hydrogen peroxide was used as the terminal oxidant. Under the optimized reaction conditions, carbon-carbon bond cleavage of 1,2-diols could be achieved in almost all cases and carboxylic acids or ketones could be afforded with a high conversion rate and high selectivity. Furthermore, the catalytic system was used efficiently to degrade renewable biomass oleic acid. Mechanistic insights based on the observation of the possible intermediates and control experiments are presented.
- Chen, Weiming,Xie, Xin,Zhang, Jian,Qu, Jian,Luo, Can,Lai, Yaozhu,Jiang, Feng,Yu, Han,Wei, Yongge
-
supporting information
p. 9140 - 9146
(2021/11/23)
-
- Iron-catalysed regioselective thienyl C–H/C–H coupling
-
Regioselective thienyl–thienyl coupling is arguably one of the most important transformations for organic electronic materials. A prototype of ideal organic synthesis to couple two thienyl groups by cutting two C–H bonds requires formal removal of two hydrogen atoms with an oxidant, which often limits the synthetic efficiency and versatility for oxidation-sensitive substrates (for example, donor and hole-transporting materials). Here, we found that diethyl oxalate, used together with AlMe3, acts as a two-electron acceptor in an iron-catalysed C–H activation. We describe the regioselective thienyl C–H/C–H coupling with an iron(III) catalyst, a trisphosphine ligand, AlMe3 and diethyl oxalate under mild conditions. The efficient catalytic system accelerated by ligand optimization polymerizes thiophene-containing monomers into homo- and copolymers bearing a variety of electron-donative π motifs. The findings suggest the versatility of iron catalysis for the synthesis of functional polymers, for which the potential of this ubiquitous metal has so far not been fully appreciated. [Figure not available: see fulltext.].
- Doba, Takahiro,Ilies, Laurean,Nakamura, Eiichi,Sato, Wataru,Shang, Rui
-
p. 631 - 638
(2021/07/25)
-
- Spectroscopic evidence of chirality in tetranuclear Cu(II)-Schiff base complexes, catalytic potential for oxidative kinetic resolution of racemic benzoin
-
Two chiral Schiff base ligands 2-((1-hydroxy-3-phenylpropan-2-ylimino)methyl)-6-methoxyphenol (L1H2) and 2-(4-hydroxy-3-isopropylbut-1-enyl)-6-methoxyphenol (L2H2) have been synthesized by the condensation of l-phenylalaninol/l-valinol and o-vanillin (2-hydroxy-3-methoxy benzaldehyde). A tetranuclear homometallic Cu(II) complex [Cu4(L1H)2(L1)2] (ClO4)2 (C1) and a hexanuclear heterometallic complex [Cu4(L2)4Na2(DMF)2(H2O)] (ClO4)2 (C2) have been synthesized with the ligands. Both the complexes possess cubane like Cu4O4 core with interesting structural variations and inherit the chirality of their corresponding ligands. The catalytic potential of the complexes has been explored for the oxidative kinetic resolution of racemic benzoin. The electronic, optical and chiroptical properties of the ligands and the complexes have been studied by DFT and TD-DFT calculations.
- Sadhukhan, Dipali,Ghosh, Prithwi,Ghanta, Susanta
-
p. 1714 - 1724
(2020/12/17)
-
- Homochiral Dodecanuclear Lanthanide "cage in Cage" for Enantioselective Separation
-
It is extremely difficult to anticipate the structure and the stereochemistry of a complex, particularly when the ligand is flexible and the metal node adopts diverse coordination numbers. When trivalent lanthanides (LnIII) and enantiopure amino acid ligands are utilized as building blocks, self-assembly sometimes yields rare chiral polynuclear structures. In this study, an enantiopure carboxyl-functionalized amino acid-based ligand with C3 symmetry reacts with lanthanum cations to give a homochiral porous coordination cage, (Δ/λ)12-PCC-57. The dodecanuclear lanthanide cage has an unprecedented octahedral "cage-in-cage"framework. During the self-assembly, the chirality is transferred from the enantiopure ligand and fixed by the binuclear lanthanide cluster to give 12 metal centers that have either Δor λ homochiral stereochemistry. The cage exhibits excellent enantioselective separation of racemic alcohols, 2,3-dihydroquinazolinones, and multiple commercially available drugs. This finding exhibits a rare example of a multinuclear lanthanide complex with a dual-walled topology and homochirality. The highly ordered self-assembly and self-sorting of flexible amino acids and lanthanides shed light on the chiral transformation between different complicated artificial systems that mimic natural enzymes.
- Zhu, Chengfeng,Tang, Haitong,Yang, Keke,Fang, Yu,Wang, Kun-Yu,Xiao, Zhifeng,Wu, Xiang,Li, Yougui,Powell, Joshua A.,Zhou, Hong-Cai
-
supporting information
p. 12560 - 12566
(2021/08/23)
-
- Enantioselective Acyloin Rearrangement of Acyclic Aldehydes Catalyzed by Chiral Oxazaborolidinium Ion
-
A catalytic enantioselective acyloin rearrangement of acyclic aldehydes to synthesize highly optically active acyloin derivatives is described. In the presence of a chiral oxazaborolidinium ion catalyst, the reaction provided chiral α-hydroxy aryl ketones in high yield (up to 95%) and enantioselectivity (up to 98% ee). In addition, the enantioselective acyloin rearrangement of α,α-dialkyl-α-siloxy aldehydes produced chiral α-siloxy alkyl ketones in high yield (up to 92%) with good enantioselectivity (up to 89% ee).
- Cho, Soo Min,Lee, Si Yeon,Ryu, Do Hyun
-
supporting information
p. 1516 - 1520
(2021/03/03)
-
- Pd-Catalyzed Decarboxylative Cycloaddition for the Synthesis of Highly Substituted δ-Lactones and Lactams
-
An efficient palladium-catalyzed decarboxylative cycloaddition process of vinyl cyclic carbonates and vinyloxazolidinones for the synthesis of highly substituted δ-lactone and δ-lactam derivatives was developed. This protocol exhibits several unique characteristics, including broad substrate scope, good functional group tolerance, and operational convenience, which enables a regioselective access to a variety of lactone and lactam scaffolds in moderate to good yield. The redox-neutral catalytic system promotes formation of substituted scaffolds with in situ generation of a cyclic tetra-substituted double bond functionality.
- Shi, Linlin,He, Yingdong,Gong, Jianxian,Yang, Zhen
-
p. 324 - 332
(2020/11/17)
-
- Method for preparing benzoin in micro-reaction device
-
The invention relates to a method for preparing benzoin in a microreactor. According to the invention, benzaldehyde and sodium cyanide are used as raw materials, and benzoin is prepared through benzoin condensation. According to the preparation method for
- -
-
Paragraph 0018-0035
(2020/05/01)
-
- Synthesis of pentafluorobenzene-based NHC adducts and their catalytic activity in the microwave-assisted reactions of aldehydes
-
N-Heterocyclic carbenes (NHCs) have been widely used in organometallic chemistry as ligands, as well as standalone organocatalysts in various reactions, mostly using aromatic aldehydes as substrates. We have previously demonstrated the efficiency of azolium-2-carboxylate zwitterions in the hydroxymethylation of aldehydes, especially aliphatic aldehydes, under microwave irradiation. In the present work, we report a series of pentafluorobenzene-based NHC adducts and their efficiency in the hydroxymethylation and self-condensation of aliphatic and aromatic aldehydes using microwave irradiation. The free carbenes are released under the reaction conditions and 1,3-dimesityl-2-(perfluorophenyl)imidazolidine and 1,3-bis(2,6-dimethylphenyl)-2-(perfluorophenyl)imidazolidine proved to be the most potent precatalysts.
- Papadaki, Evanthia,Magrioti, Victoria
-
supporting information
(2019/12/24)
-
- N-Heterocyclic Carbene Acyl Anion Organocatalysis by Ball-Milling
-
The ability to conduct N-heterocyclic carbene-catalysed acyl anion chemistry under ball-milling conditions is reported for the first time. This process has been exemplified through applications to intermolecular-benzoin, intramolecular-benzoin, intermolecular-Stetter and intramolecular-Stetter reactions including asymmetric examples and demonstrates that this mode of mechanistically complex organocatalytic reaction can operate under solvent-minimised conditions.
- Nicholson, William I.,Seastram, Alex C.,Iqbal, Saqib A.,Reed-Berendt, Benjamin G.,Morrill, Louis C.,Browne, Duncan L.
-
p. 131 - 135
(2019/12/11)
-
- Bio-inspired NHC-organocatalyzed Stetter reaction in aqueous conditions
-
The first bio-inspired N-Heterocyclic Carbene (NHC)-catalyzed Stetter reaction in aqueous medium is reported with benzaldehyde and chalcone as model substrates. A screening of azolium salts as precatalysts revealed the remarkable efficiency of synthetic thiazolium salt 8 (up to 90% conversion in pure water at 75 °C). The reaction was successfully extended to various simple aldehyde substrates. The effect of temperature was also investigated in order to extend the reaction to lower temperature allowing a potential application to sensitive biomolecules. This study highlighted the influence of both solvent and temperature on the 1,4-diketone 3/benzoin 4 ratio. New precatalysts 26 and 27 were designed and synthesized to explore a possible compartmentalization of the reaction in aqueous conditions. Owing to the use of inexpensive metal-free N-Heterocyclic Carbene (NHC) as a bioinspired catalyst, we anticipate that this green strategy in aqueous conditions will be attractive for bioconjugation of many biomolecule-type aldehydes and enone derivatives. This journal is
- Barthélémy, Philippe,Debiais, Mégane,Desvergnes, Valérie,Drain, Reihana,Hamoud, Aladin
-
p. 40709 - 40718
(2020/11/23)
-
- Scalable Aerobic Oxidation of Alcohols Using Catalytic DDQ/HNO3
-
A selective, practical, and scalable aerobic oxidation of alcohols is described that uses catalytic amounts of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and HNO3, with molecular oxygen serving as the terminal oxidant. The method was successfully applied to the oxidation of a wide range of benzylic, propargylic, and allylic alcohols, including two natural products, namely, carveol and podophyllotoxin. The conditions are also applicable to the selective oxidative deprotection of p-methoxybenzyl ethers.
- Arseniyadis, Stellios,Clavier, Louis,Copin, Chloé,Fournier, Jean,Giffard, Jean-Fran?ois,Jean, Alexandre,Katsina, Tania,Macedo Portela Da Silva, Nayane,Tamion, Rodolphe
-
supporting information
p. 856 - 860
(2020/07/14)
-
- Green preparation method α - hydroxyketone
-
The invention relates to a green preparation method of alpha-hydroxyketone. The method comprises the following steps: adding ketone, iodine, 1,4-diazabicyclo[2.2.2]octane and methanol into a glass reaction bottle in sequence; then stirring and reacting for 14 to 30h at room temperature in an air atmosphere under the irradiation of a 23W compact type fluorescent lamp, so as to obtain a reaction mixture; carrying out silica gel column chromatographic separation to obtain the pure alpha-hydroxyketone. The green preparation method provided by the invention has the characteristics of greenness, high efficiency, simplicity in operation, moderate conditions, wide applicability and easiness for industrialization.
- -
-
Paragraph 0087-0090
(2020/08/27)
-
- Novel chiral stationary phases based on 3,5-dimethyl phenylcarbamoylated β-cyclodextrin combining cinchona alkaloid moiety
-
Novel chiral selectors based on 3,5-dimethyl phenylcarbamoylated β-cyclodextrin connecting quinine (QN) or quinidine (QD) moiety were synthesized and immobilized on silica gel. Their chromatographic performances were investigated by comparing to the 3,5-dimethyl phenylcarbamoylated β-cyclodextrin (β-CD) chiral stationary phase (CSP) and 9-O-(tert-butylcarbamoyl)-QN-based CSP (QN-AX). Fmoc-protected amino acids, chiral drug cloprostenol (which has been successfully employed in veterinary medicine), and neutral chiral analytes were evaluated on CSPs, and the results showed that the novel CSPs characterized as both enantioseparation capabilities of CD-based CSP and QN/QD-based CSPs have broader application range than β-CD-based CSP or QN/QD-based CSPs. It was found that QN/QD moieties play a dominant role in the overall enantioseparation process of Fmoc-amino acids accompanied by the synergistic effect of β-CD moiety, which lead to the different enantioseparation of β-CD-QN-based CSP and β-CD-QD-based CSP. Furthermore, new CSPs retain extraordinary enantioseparation of cyclodextrin-based CSP for some neutral analytes on normal phase and even exhibit better enantioseparation than the corresponding β-CD-based CSP for certain samples.
- Zhu, Lunan,Zhu, Junchen,Sun, Xiaotong,Wu, Yaling,Wang, Huiying,Cheng, Lingping,Shen, Jiawei,Ke, Yanxiong
-
p. 1080 - 1090
(2020/05/25)
-
- Catalytic Asymmetric Acyloin Rearrangements of α-Ketols, α-Hydroxy Aldehydes, and α-Iminols by N, N′-Dioxide-Metal Complexes
-
A highly enantioselective acyloin rearrangement of cyclic α-ketols has been developed with a chiral Al(III)-N,N′-dioxide complex as catalyst. This strategy provided an array of optically active 2-acyl-2-hydroxy cyclohexanones in moderate to good yields with high enantioselectivities. The asymmetric isomerizations of acyclic α-hydroxy aldehydes and α-iminols were achieved as well under modified conditions, affording the corresponding chiral α-hydroxy ketones and α-amino ketones in moderate results. Moreover, further transformations of product to enantioenriched diols were carried out.
- Dai, Li,Li, Xiangqiang,Zeng, Zi,Dong, Shunxi,Zhou, Yuqiao,Liu, Xiaohua,Feng, Xiaoming
-
supporting information
p. 5041 - 5045
(2020/07/03)
-
- Photocatalytic Coproduction of Deoxybenzoin and H2 through Tandem Redox Reactions
-
Photocatalytic H2 evolution from organic feedstocks with simultaneous utilization of photogenerated holes achieves solar energy storage and coproduces value-Added chemicals. Here we show visible-light H2 production from benzyl alcohol (BAL) with controllable generation of deoxybenzoin (DOB) or benzoin (BZ) through tandem redox reactions. Particularly, DOB synthesis circumvents the use of expensive feedstocks and environmentally unfriendly catalysts that are required previously. Under the irradiation of blue LEDs, the key of steering the major product to DOB rather than BZ is to decrease the conduction band bottom potentials of the ZnIn sulfide catalysts by increasing the Zn/In ratio, which results in the dehydration of intermediate hydrobenzoin (HB) to DOB proceeding in a redox-neutral mechanism and consuming an electron-hole pair. As a proof of concept, this method is used to synthesize DOB derivatives in gram scale.
- Luo, Nengchao,Hou, Tingting,Liu, Shiyang,Zeng, Bin,Lu, Jianmin,Zhang, Jian,Li, Hongji,Wang, Feng
-
p. 762 - 769
(2020/01/02)
-
- 1-butyl-3-methylimidazolium bromide as a solvent and precatalyst for stetter reaction
-
Stetter reaction between aromatic aldehydes and acrylonitrile/ethyl acrylate performing in [Bmim]Br in the presence of NaOH is described. N-Heterocyclic carbene (NHC) generates in situ is shown to be an efficient catalyst. Benzoin condensation also occured as side reaction.
- Phungpis, Baramee,Hahnvajanawong, Viwat
-
p. 2028 - 2032
(2020/09/02)
-
- A Bifunctional Iron Nanocomposite Catalyst for Efficient Oxidation of Alkenes to Ketones and 1,2-Diketones
-
We herein report the fabrication of a bifunctional iron nanocomposite catalyst, in which two catalytically active sites of Fe-Nx and Fe phosphate, as oxidation and Lewis acid sites, were simultaneously integrated into a hierarchical N,P-dual doped porous carbon. As a bifunctional catalyst, it exhibited high efficiency for direct oxidative cleavage of alkenes into ketones or their oxidation into 1,2-diketones with a broad substrate scope and high functional group tolerance using TBHP as the oxidant in water under mild reaction conditions. Furthermore, it could be easily recovered for successive recycling without appreciable loss of activity. Mechanistic studies disclose that the direct oxidation of alkenes proceeds via the formation of an epoxide as intermediate followed by either acid-catalyzed Meinwald rearrangement to give ketones with one carbon shorter or nucleophilic ring-opening to generate 1,2-diketones in a cascade manner. This study not only opens up a fancy pathway in the rational design of Fe-N-C catalysts but also offers a simple and efficient method for accessing industrially important ketones and 1,2-diketones from alkenes in a cost-effective and environmentally benign fashion.
- Ma, Zhiming,Ren, Peng,Song, Tao,Xiao, Jianliang,Yang, Yong,Yuan, Youzhu
-
p. 4617 - 4629
(2020/05/19)
-
- AIR OXIDATION METHOD OF BENZYLIC POSITION OF ORGANIC COMPOUND AND AIR OXIDATION CATALYST
-
PROBLEM TO BE SOLVED: To provide an air oxidation method by which a hydroxy group or oxo group can be introduced by efficient air oxidation of a benzylic position under relatively mild reaction conditions by using a metal complex as a catalyst without a joint use of an additive agent. SOLUTION: An air oxidation method is a method for carrying out air oxidation of a benzylic position of an organic compound having the benzylic position includes bringing the organic compound into contact with molecular oxygen in the presence of a catalyst that is a polynuclear metal complex including two or more kinds of metals. SELECTED DRAWING: None COPYRIGHT: (C)2020,JPO&INPIT
- -
-
Paragraph 0066-0072
(2020/12/01)
-
- Electron Donor-Acceptor Complex-Initiated Photochemical Cyanation for the Preparation of α-Amino Nitriles
-
An electron donor-acceptor complex-initiated α-cyanation of tertiary amines has been described. The reaction protocol provides a novel method to synthesize various α-amino nitriles under mild conditions. The reaction can proceed smoothly without the presence of photocatalysts and transition metal catalysts, and either oxidants are unnecessary or O2 is the only oxidant. The practicality of this method is showcased not only by the late-stage functionalization of natural alkaloid derivatives and pharmaceutical intermediate, but also by the applicability of a stop-flow microtubing reactor.
- Xia, Qing,Li, Yufei,Cheng, Lan,Liang, Xin,Cao, Chenlin,Dai, Peng,Deng, Hongping,Zhang, Weihua,Wang, Qingmin
-
supporting information
p. 9638 - 9643
(2020/12/21)
-
- Chiral Benzoins via Asymmetric Transfer Hemihydrogenation of Benzils: The Detail that Matters
-
The synthesis of enantiomerically pure benzoins by hydrogenation of readily available benzils has been long thwarted by their base-sensitivity. We show here that an iron(II) hydride complex catalyzes the asymmetric transfer hydrogenation of benzils from 2-propanol. When strictly base-free conditions are granted, excellent enantioselectivity is achieved even with o-substituted substrates, which are particularly challenging to prepare with other methods. Hence, under optimized reaction conditions, chiral benzoins were prepared in good yields (up to 83%) and excellent enantioselectivity (up to 98% ee) in short reaction times (30-75 min). Also, this work confirms that both enantiomers of the benzoin products can be accessed when a metal catalyst is used, which is a clear advantage over enzymatic methods.
- Luca, Lorena De,Mezzetti, Antonio
-
supporting information
p. 5807 - 5814
(2020/05/22)
-
- Fast-Synthesis of α-Phosphonyloxy Ketones as Drug Scaffolds in a Capillary Microreactor
-
A simple, room temperature approach for the fast single-step synthesis of α-phosphonyloxy ketone, a drug scaffold, has been developed which involves highly reactive species i.e., 1,2-dicarbonyls that readily react with trialkyl phosphites and formic acids in batch as well as in continuous-flow with the flow rate of 3 ml/min (tR = ～4 s). The present approach reduced the synthesis time from hours to minutes in batch, which was further lowered to a few seconds precisely controlled by single capillary microfluidics. A wide range of 1,2-dicarbonyl derivatives were smoothly transformed to their corresponding α-phosphonyloxy ketones in moderate to good yields (50–82 %) under optimized flow-reaction conditions. Further, the α-phosphonyloxy ketones produced can be utilized in batch process to form benzoin, oxazole core, and α,α′-diarylated carbonyl compounds in 82 %, 50 %, and 54 % yields, respectively, which are alternative key precursors/scaffolds of natural products and active pharmaceutical ingredients (APIs).
- Ramanjaneyulu, Bandaru T.,Vidyacharan, Shinde,Yim, Se Jun,Kim, Dong-Pyo
-
p. 7730 - 7734
(2019/12/24)
-
- A novel bi-functional surfactant-based paramagnetic deep-eutectic catalyst for improved benzoin condensation and multi-component synthesis of pyrrole derivatives
-
A new professional magnetic surfactant-based deep-eutectic (DE) and viscose liquefy catalyst (GS2+·2FeCl4, MGSFe) was synthesized by an optimized reaction of the as-prepared cationic gemini-surfactant (GS) with two moles of FeCl3·6H2O. The structure of the GS and MGSFe were characterized by NMR, FT-IR, UV–visible, CHN, pH, surface tension (?), and vibrating sample magnetometry (VSM) analyses. The MGSFe, that is a high viscose brownish liquid at >50 °C, was successfully tested as a highly active paramagnetic catalyst for improved benzoin condensation and three-component synthesis of substituted pyrroles with the highest turnover number (TON) and turnover frequency (TOF) that ever reported for this purpose. The superior activity of MGSFe is due to its amphiphile properties, the synergistic effects between GS2+ and 2FeCl4 ? as hydrogen-bond-donor and magnetic hydrogen-bond-acceptor components of this novel magneto-responsive DE, and reusability without loss of activity even in four consequence cycles run for synthesis of pyrroles. This magnetic GS-based DE can be used as oil miscible additive, pollutant adsorbent, and carrier of biomaterials to targeted poisons.
- Tamaddon, Fatemeh,Tadayonfar, SeydEhsan
-
-
- Halogenated 1,2,3-triazole carbene, and preparation method and application thereof
-
The invention provides a halogenated 1,2,3-triazole carbene, and a preparation method and an application thereof. The halogenated 1,2,3-triazole carbene has a structure represented by formula [1]; andin the formula [1], R1 and R2 are independently selecte
- -
-
Paragraph 0162-0166
(2019/10/01)
-
- Benzoin compound preparing method
-
The invention provides a benzoin compound preparing method. Specifically, the benzoin compound preparing method takes mesoporous material immobilized imidazolium salt ion liquid as catalysts to catalyze aromatic aldehydes into various benzoin compounds. T
- -
-
Paragraph 0060; 0061
(2019/05/02)
-
- Redetermination of the Structure of a Water-Soluble Hypervalent Iodine(V) Reagent AIBX and Its Synthetic Utility in the Oxidation of Alcohols and Synthesis of Isoxazoline N-Oxides
-
The structure of a water-soluble hypervalent iodine(V) reagent AIBX is re-examined through its single-crystal X-ray analysis and theoretical calculations including Mayer bond order and localized orbital locator (LOL) and AIBX is believed to be a pseudocyclic iodylarene because of the strong electron-withdrawing nature of the trimethylammonium cation on its phenyl ring, which would decrease the electron density of carboxylic anion and make the ortho-carboxyl oxygen anion incapable to form hypervalent bond with iodine atom. However, the cyclic benziodoxole structure of AIBX could be obtained by adding a Br?nsted acid, which was supported by the calculation result including the increase of Mayer bond order and the shortening of the I-O bond length. Moreover, the fact that the system of AIBX and TFA could oxidize various alcohols to their corresponding carbonyl compounds would indicate that AIBX constitutes a cyclic benziodoxole structure under acidic conditions. In addition, an efficient method has been developed for the synthesis of isoxazoline N-oxides via AIBX-induced dehydrogenative cyclization using β-keto esters as substrates and methyl nitroacetate as a nucleophile.
- Shen, Hui-Jie,Duan, Ya-Nan,Zheng, Ke,Zhang, Chi
-
p. 14381 - 14393
(2019/11/13)
-
- Efficient Oxidation of Benzylic and Aliphatic Alcohols Using a Bioinspired Cross-Bridged Cyclam Manganese Complex with H2O2
-
The cross-bridged cyclam manganese complex Mn(Me2EBC)Cl2 efficiently catalyzes the oxidation of benzylic and aliphatic alcohols at pH 3 in a mixture of acetonitrile and water at room temperature. The environmentally benign and high oxygen content oxidant H2O2 was adopted. Conversions of the alcohols to the corresponding carbonyl compounds reached 98 % with good to excellent selectivity. In addition, several lignin model compounds were also catalytically oxidized under these conditions, with excellent conversion (up to 96 %) and selectivity (up to 99 %).
- Zhang, Zhan,Khrouz, Lhoussain,Yin, Guochuan,Andrioletti, Bruno
-
supporting information
p. 323 - 327
(2018/11/27)
-
- N-Heterocyclic Carbene-Catalyzed Decarboxylative Alkylation of Aldehydes
-
We found that N-heterocyclic carbene catalysis promoted the unprecedented decarboxylative coupling of aryl aldehydes and tertiary or secondary alkyl carboxylic acid-derived redox-active esters to produce aryl alkyl ketones. The mild and transition-metal-free reaction conditions are attractive features of this method. The power of this protocol was demonstrated by the functionalization of pharmaceutical drugs and natural product. A reaction pathway involving single electron transfer from an enolate form of Breslow intermediate to a redox ester followed by recombination of the resultant radical pair to form a carbon-carbon bond is proposed.
- Ishii, Takuya,Kakeno, Yuki,Nagao, Kazunori,Ohmiya, Hirohisa
-
supporting information
p. 3854 - 3858
(2019/04/25)
-
- Asymmetric aerobic oxidation of secondary alcohols catalyzed by poly(: N-vinyl-2-pyrrolidone)-stabilized gold clusters modified with cyclodextrin derivatives
-
Surface modification of poly(N-vinyl-2-pyrrolidone)-stabilized gold clusters (1.8 ± 0.6 nm) with aminated cyclodextrins induced aerobic oxidative kinetic resolution of racemic secondary alcohols (krel = 1.2).
- Hirano, Koto,Takano, Shinjiro,Tsukuda, Tatsuya
-
supporting information
p. 15033 - 15036
(2020/01/03)
-
- HPLC with cellulose Tris (3,5-DimethylPhenylcarbamate) chiral stationary phase: Influence of coating times and coating amount on chiral discrimination
-
Coating cellulose tris (3,5-dimethylphenylcarbamate) (CDMPC) on silica gels with large pores have been demonstrated as an efficient way for the preparation of chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC). During the process, a number of parameters, including the type of coating solvent, amount of coating, and the method for subsequent solvent removing, have been proved to affect the performance of the resultant CSPs. Coating times and the concentration of coating solution, however, also makes a difference to CSPs' performance by changing the arrangement of cellulose derivatives while remaining the coating amount constant, have much less been studied before, and thereby, were systematically investigated in this work. Results showed that CSPs with more coating times exhibited higher chiral recognition and column efficiency, suggesting that resolution was determined by column efficiency herein. Afterwards, we also investigated the effect of coating amount on the performance of CSPs, and it was shown that the ability of enantio-recognition did not increase all the time as the coating amount; and four of seven racemates achieved best resolution when the coating amount reached to 18.37%. At the end, the reproducibility of CDMPC-coated CSPs were further confirmed by two methods, ie, reprepared the CSP-0.15-3 and reevaluated the effect of coating times.
- Wei, Qiuhong,Su, Hongjiu,Gao, Diannan,Wang, Shudong
-
p. 164 - 173
(2019/01/18)
-
- Three-State Switchable Chiral Stationary Phase Based on Helicity Control of an Optically Active Poly(phenylacetylene) Derivative by Using Metal Cations in the Solid State
-
An unprecedented three-state switchable chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC) was developed using a helical poly(phenylacetylene) bearing a chiral (R)-α-methoxyphenylacetic acid residue as the pendant (poly-1). The left- and right-handed helical conformations were induced in poly-1-based CSP upon coordination with a catalytic amount of soluble sodium and cesium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate salts (MBArF), respectively, which are soluble in the HPLC conditions [hexane-2-propanol (95:5, v/v)]. The switch between the two different helical states of poly-1 can be easily achieved by rinsing the poly-1-based CSP with MeOH and the subsequent addition of the proper MBArF salt. Using this dynamic helical CSP, we demonstrate how changes on the orientation of the secondary structure of a chiral polymer (right-handed, left-handed, and racemic helices) can alter and even invert the elution order of the enantiomers. This study was done without adding chiral additives or changing the mobile phase, which could produce changes on the retention times and make it more difficult to determine the role of the secondary structure during the chiral recognition process.
- Hirose, Daisuke,Isobe, Asahi,Qui?oá, Emilio,Freire, Félix,Maeda, Katsuhiro
-
supporting information
(2019/06/10)
-
