- Transition State Differences in Hydrolysis Reactions of Alkyl versus Aryl Phosphate Monoester Monoanions
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Although aryl phosphates have been the subject of numerous experimental studies, far less data bearing on the mechanism and transition states for alkyl phosphate reactions have been presented. Except for esters with very good leaving groups such as 2,4-dinitrophenol, the monoanion of phosphate esters is more reactive than the dianion. Several mechanisms have been proposed for the hydrolysis of the monoanion species. 18O kinetic isotope effects in the nonbridging oxygen atoms and in the P-O(R) ester bond, and solvent deuterium isotope effects, have been measured for the hydrolysis of m-nitrobenzyl phosphate. The results rule out a proposed mechanism in which the phosphoryl group deprotonates water and then undergoes attack by hydroxide. The results are most consistent with a preequilibrium proton transfer from the phosphoryl group to the ester oxygen atom, followed by rate-limiting P-O bond fission, as originally proposed by Kirby and co-workers in 1967. The transition state for m-nitrobenzyl phosphate (leaving group pKa 14.9) exhibits much less P-O bond fission than the reaction of the more labile p-nitrophenyl phosphate (leaving group pKa = 7.14). This seemingly anti-Hammond behavior results from weakening of the P-O(R) ester bond resulting from protonation, an effect which calculations have shown is much more pronounced for aryl phosphates than for alkyl ones.
- Grzyska, Piotr K.,Czyryca, Przemyslaw G.,Purcell, Jamie,Hengge, Alvan C.
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- SYNTHESIS OF THE FIRST TRULY REACTIVE POLYMER-BOUND NADH MODELS
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Improved reduction of benzaldehydes has been obtained with reactive polymer-bound NADH models.
- Mathis, R.,Dupas, G.,Decormeille, A.,Queguiner, G.
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Read Online
- Reactivity of secondary N-alkyl acrylamides in Morita–Baylis–Hillman reactions
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The Morita–Baylis–Hillman (MBH) reaction of secondary N-alkyl acrylamides, discarded up to now from investigations of the scope of activated alkenes, was studied. Optimization of the reaction conditions revealed that a balance must be found between activation of the MBH coupling reaction and that of the undesired competitive aldehyde Cannizzaro reaction. Using 3-Hydroxyquinuclidine (3-HQD) in a 1:1 water-2-MeTHF mixture provides the appropriate conditions that were applicable to a wide range of diversely substituted secondary N-alkyl acrylamides and aromatic aldehydes, giving rise to novel amide-containing MBH adducts under mild and clean conditions.
- Ahmar, Mohammed,Queneau, Yves,Verrier, Charlie,Yue, Xiaoyang
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p. 319 - 330
(2021/10/29)
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- Sodium Aminodiboranate, a New Reagent for Chemoselective Reduction of Aldehydes and Ketones to Alcohols
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Sodium aminodiboranate (NaNH 2(BH 3) 2, NaADBH) is a new member of the old borane family, which exhibits superior performance in chemoselective reduction. Experimental results show that NaADBH can rapidly reduce aldehydes and ketones to the corresponding alcohols in high efficiency and selectivity under mild conditions. There are little steric and electronic effects on this reduction.
- Wang, Jin,Guo, Yu,Li, Shouhu,Chen, Xuenian
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supporting information
p. 1104 - 1108
(2021/05/25)
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- Efficient Solvent-Free Hydrosilylation of Aldehydes and Ketones Catalyzed by Fe2(CO)9/C6H4-o-(NCH2PPh2)2BH
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An efficient solvent-free catalyst system for hydrosilylation of aldehydes and ketones was developed based on iron pre-catalyst Fe2(CO)9/C6H4-o-(NCH2PPh2)2BH. The reactions were tolerant of many functional groups and the corresponding alcohols were isolated in good to excellent yields following basic hydrolysis of the reaction products. The reaction is likely catalyzed by an in situ generated pincer ligated iron hydride complex. Graphic Abstract: [Figure not available: see fulltext.]
- Fang, Fei,Chang, Jiarui,Zhang, Jie,Chen, Xuenian
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p. 3509 - 3515
(2021/03/16)
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- Hydroboration Reaction and Mechanism of Carboxylic Acids using NaNH2(BH3)2, a Hydroboration Reagent with Reducing Capability between NaBH4and LiAlH4
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Hydroboration reactions of carboxylic acids using sodium aminodiboranate (NaNH2[BH3]2, NaADBH) to form primary alcohols were systematically investigated, and the reduction mechanism was elucidated experimentally and computationally. The transfer of hydride ions from B atoms to C atoms, the key step in the mechanism, was theoretically illustrated and supported by experimental results. The intermediates of NH2B2H5, PhCH= CHCOOBH2NH2BH3-, PhCH= CHCH2OBO, and the byproducts of BH4-, NH2BH2, and NH2BH3- were identified and characterized by 11B and 1H NMR. The reducing capacity of NaADBH was found between that of NaBH4 and LiAlH4. We have thus found that NaADBH is a promising reducing agent for hydroboration because of its stability and easy handling. These reactions exhibit excellent yields and good selectivity, therefore providing alternative synthetic approaches for the conversion of carboxylic acids to primary alcohols with a wide range of functional group tolerance.
- Wang, Jin,Ju, Ming-Yue,Wang, Xinghua,Ma, Yan-Na,Wei, Donghui,Chen, Xuenian
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p. 5305 - 5316
(2021/04/12)
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- Scope and limitations of biocatalytic carbonyl reduction with white-rot fungi
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The reductive activity of various basidiomycetous fungi towards carbonyl compounds was screened on an analytical level. Some strains displayed high reductive activities toward aromatic carbonyls and aliphatic ketones. Utilizing growing whole-cell cultures of Dichomitus albidofuscus, the reactions were up-scaled to a preparative level in an aqueous system. The reactions showed excellent selectivities and gave the respective alcohols in high yields. Carboxylic acids were also reduced to aldehydes and alcohols under the same conditions. In particular, benzoic, vanillic, ferulic, and p-coumaric acid were reduced to benzyl alcohol, vanillin, dihydroconiferyl alcohol and 1-hydroxy-3-(4-hydroxyphenyl)propan, respectively.
- Zhuk, Tatyana S.,Skorobohatko, Oleksandra S.,Albuquerque, Wendell,Zorn, Holger
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supporting information
(2021/02/02)
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- KB3H8: An environment-friendly reagent for the selective reduction of aldehydes and ketones to alcohols
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Selective reduction of aldehydes and ketones to their corresponding alcohols with KB3H8, an air- and moisture-stable, nontoxic, and easy-to-handle reagent, in water and THF has been explored under an air atmosphere for the first time. Control experiments illustrated the good selectivity of KB3H8 over NaBH4 for the reduction of 4-acetylbenzaldehyde and aromatic keto esters. This journal is
- Li, Xinying,Mi, Tongge,Guo, Wenjing,Ruan, Zhongrui,Guo, Yu,Ma, Yan-Na,Chen, Xuenian
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supporting information
p. 12776 - 12779
(2021/12/10)
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- Chemoselective reduction of nitroarenes, N-acetylation of arylamines, and one-pot reductive acetylation of nitroarenes using carbon-supported palladium catalytic system in water
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Developing and/or modifying fundamental chemical reactions using chemical industry-favorite heterogeneous recoverable catalytic systems in the water solvent is very important. In this paper, we developed convenient, green, and efficient approaches for the chemoselective reduction of nitroarenes, N-acetylation of arylamines, and one-pot reductive acetylation of nitroarenes in the presence of the recoverable heterogeneous carbon-supported palladium (Pd/C) catalytic system in water. The utilize of the simple, effective, and recoverable catalyst and also using of water as an entirely green solvent along with relatively short reaction times and good-to-excellent yields of the desired products are some of the noticeable features of the presented synthetic protocols. Graphic abstract: [Figure not available: see fulltext.].
- Zeynizadeh, Behzad,Mohammad Aminzadeh, Farkhondeh,Mousavi, Hossein
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p. 3289 - 3312
(2021/05/11)
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- Application of bis(phosphinite) pincer nickel complexes to the catalytic hydrosilylation of aldehydes
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A series of bis(phosphinite) (POCOP) pincer ligated nickel complexes, [2,6-(tBu2PO)2C6H3]NiX (X = SH, 1; SCH2Ph, 2; SPh, 3; NCS, 4; N3, 5), were used to catalyse the hydrosilylation of aldehydes. It was found that both complexes 1 and 2 are active in catalysing the hydrosilylation of aldehydes with phenylsilane and complex 1 is comparatively more active. The expected alcohols were isolated in good to excellent yields after basic hydrolysis of the resultant hydrosilylation products. However, no reaction was observed when complex 3 or 4 or 5 was used as the catalyst. The results are consistent with complexes 1 and 2 serving as catalyst precursors, which generate the corresponding nickel hydride complex [2,6-(tBu2PO)2C6H3]NiH in situ, and the nickel hydride complex is the active species that catalyses this hydrosilylation process. The in situ generation of the nickel hydride species was supported by both experimental results and DFT calculation.
- Chang, Jiarui,Fang, Fei,Tu, Chenhao,Zhang, Jie,Ma, Nana,Chen, Xuenian
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- NaI-mediated oxidative amidation of benzyl alcohols/aromatic aldehydes to benzamides via electrochemical reaction
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In this research, we have developed a mild electrochemical process for oxidative amidation of benzyl alcohols/aromatic aldehydes with cyclic amines into the corresponding benzamides. This electroorganic synthetic method proceeds using NaI as a redox mediator under ambient temperature in undivided cell, providing more than 25 examples of amide products in moderate to good yields. The benefits of this reaction include one-pot synthesis, open air condition, proceed in aqueous media and no requirement of external conducting salt, base and oxidant.
- Rerkrachaneekorn, Tanawat,Tankam, Theeranon,Sukwattanasinitt, Mongkol,Wacharasindhu, Sumrit
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supporting information
(2021/04/15)
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- Whole seeds of Bauhinia variegata L. (Fabaceae) as an efficient biocatalyst for benzyl alcohol preparations from benzaldehydes
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Whole seeds of Bauhinia variegata L. (Fabaceae) were utilized as a biological reducer to transform benzaldehyde into benzyl alcohol. The effects of some variables such as temperature, the load of substrate and co-solvent, were established to optimize the reductive process. Utilizing the optimal reaction conditions, a laboratory-scale reaction (final concentration of the substrate: 21.2 mM) was performed to obtain benzyl alcohol (conversion: 95%; isolated yield: 49%; productivity: 1.11 g L?1 or 0.046 g L?1h?1 of benzyl alcohol). In addition, using these optimal conditions, fourteen substituted benzaldehydes were reduced, with a conversion achieved to their corresponding benzyl alcohols ranging from 62% to >99% (isolated yields from 7% to 70%). Moreover, useful building blocks by the synthesis of the drugs and important commercial products were also obtained. The scope, limitations and advantages of this new biocatalytic synthetic method are also discussed.
- Aimar, Mario L.,Bordón, Daniela L.,Díaz Panero, Mariángeles,Decarlini, María F.,Demmel, Gabriel I.,Rossi, Laura I.,Vázquez, Ana M.
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- Selective hydrogenation of primary amides and cyclic di-peptides under Ru-catalysis
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A ruthenium(II)-catalyzed selective hydrogenation of challenging primary amides and cyclic di-peptides to their corresponding primary alcohols and amino alcohols, respectively, is reported. The hydrogenation reaction operates under mild and eco-benign conditions and can be scaled-up.
- Subaramanian, Murugan,Sivakumar, Ganesan,Babu, Jessin K.,Balaraman, Ekambaram
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supporting information
p. 12411 - 12414
(2020/10/30)
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- Hydrosilylation of Aldehydes and Ketones Catalysed by Bis(phosphinite) Pincer Platinum Hydride Complexes
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Bis(phosphinite) pincer platinum hydride complexes, [2,6-(R2PO)2C6H3]PtH (R=tBu, iPr), were synthesized, characterized and applied to the hydrosilylation of aldehydes and ketones. NMR study and single crystal X-ray diffraction analysis indicated that the hydrides in these two platinum complexes are comparatively less hydridic: down-field 1H NMR resonances (0.71 and 0.98 ppm) and weak Pt?H interactions were observed. Both the platinum complexes were found to be good catalysts for the hydrosilylation of aldehydes and ketones with phenylsilane. The corresponding alcohols were isolated in good to excellent yields following basic hydrolysis of the resultant hydrosilylation products and turnover frequencies (TOFs) up to 3200 h?1 were achieved at 60 °C in toluene, which are much higher than those of the hydrosilylation catalysed by the corresponding nickel pincer hydride complexes. A possible mechanism for the present hydrosilylation process was discussed. (Figure presented.).
- Chang, Jiarui,Fang, Fei,Zhang, Jie,Chen, Xuenian
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p. 2709 - 2715
(2020/06/02)
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- Continuous-Flow Amide and Ester Reductions Using Neat Borane Dimethylsulfide Complex
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Reductions of amides and esters are of critical importance in synthetic chemistry, and there are numerous protocols for executing these transformations employing traditional batch conditions. Notably, strategies based on flow chemistry, especially for amide reductions, are much less explored. Herein, a simple process was developed in which neat borane dimethylsulfide complex (BH3?DMS) was used to reduce various esters and amides under continuous-flow conditions. Taking advantage of the solvent-free nature of the commercially available borane reagent, high substrate concentrations were realized, allowing outstanding productivity and a significant reduction in E-factors. In addition, with carefully optimized short residence times, the corresponding alcohols and amines were obtained in high selectivity and high yields. The synthetic utility of the inexpensive and easily implemented flow protocol was further corroborated by multigram-scale syntheses of pharmaceutically relevant products. Owing to its beneficial features, including low solvent and reducing agent consumption, high selectivity, simplicity, and inherent scalability, the present process demonstrates fewer environmental concerns than most typical batch reductions using metal hydrides as reducing agents.
- ?tv?s, Sándor B.,Kappe, C. Oliver
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p. 1800 - 1807
(2020/02/27)
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- Solid state aldol reactions of solvated and unsolvated lithium pinacolone enolate aggregates
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We reported the first systematic study of the solid-state aldol reactions of solvated and unsolvated lithium pinacolone enolate with a variety of solid aromatic aldehydes utilizing a mortar and pestle condition in comparison with the simple ball milling condition or tetrahydrofuran (THF) solution condition. In solution, the reactions are highly-selective with the aldol condensation product at room temperature. Under the condition of mortar and pestle, the reactions with unsolvated lithium pinacolone enolate showed the mixture of aldol condensation product and aldol addition product at room temperature. With the usage of solvated lithium pinacolone enolate, higher yields for most substrates were obtained. Furthermore, repeating the reactions under a simple ball billing condition with no other precautions at room temperature, we achieved high selectivity and yield of products for all substrates, indicating the powerful ability and the utility of solid-state, mechanochemical aldol reaction conditions.
- Pang, Huan,Williard, Paul G.
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- Bulky N-Heterocyclic-Carbene-Coordinated Palladium Catalysts for 1,2-Addition of Arylboron Compounds to Carbonyl Compounds
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The synthesis of primary, secondary, and tertiary alcohols by the 1,2-addition of arylboronic acids or boronates to carbonyl compounds, including unactivated ketones, using novel bulky yet flexible N-heterocyclic carbene (NHC)-coordinated 2,6-di(pentan-3-yl)aniline (IPent)-based cyclometallated palladium complexes (CYPs) as catalysts is reported. The PhS-IPent-CYP-catalyzed reactions are efficient at low catalyst loadings (0.02–0.3 mol% Pd), and the exceptional catalytic activity for 1,2-addition is attributed to the steric bulk of the NHC ligand. These reactions can yield a wide range of functionalized benzylic alcohols that are difficult to synthesize by classical protocols using highly active organomagnesium or lithium reagents.
- Okuda, Yuta,Nagaoka, Masahiro,Yamamoto, Tetsuya
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p. 6291 - 6300
(2020/11/30)
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- Applicability of aluminum amalgam to the reduction of arylnitro groups
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An array of arylnitro compounds with various functionality were treated with freshly-prepared aluminum amalgam in THF/water solution and resulted in the corresponding arylamines. The Al(Hg)-mediated reductions are relatively rapid with consumption of the amalgam and disappearance of starting material occurring over 20–30 min. The workup of the reductions involves only removal of the insoluble by-products by filtration followed by concentration. Only in some cases is chromatography required to secure the pure product. The desired arylamines are furnished in quantities of 25–100 mg, which in some cases, could be taken on to the next reaction without further purification. Reductions of 4-nitrobenzyl derivatives of carbohydrates or nucleosides were selective in affording the corresponding 4-aminobenzyl products. To show applicability in click chemistry, selected aminobenzyl products are directly azidated to yield products that were then used in click reactions to afford the corresponding 1,2,3-triazoles.
- Luzzio, Frederick A.,Monsen, Paige J.
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supporting information
(2020/11/02)
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- Design, synthesis and antitumor assessment of phenylureas bearing 5-fluoroindolin-2-one moiety
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Background: The development of novel antineoplastic agents remains highly desirable. Objective: This study focuses on the design, synthesis, and antitumor evaluation of phenyl ureas bearing 5-fluoroindolin-2-one moiety. Methods: Three sets of phenylureas were designed and synthesized and their antiproliferative abil-ity was measured against four human carcinoma cell lines (Hela, Eca-109, A549, and MCF-7) via MTT assay. In vivo anticancer activity was further evaluated in xenograft models of human breast cancer (MCF-7). Results: A total of twenty-one new compounds were synthesized and characterized by means of1 H and13 C NMR as well as HR-MS. Three sets of compounds (1a?1c, 2a?2c, and 3a?3c) were ini-tially constructed, and preliminary antiproliferative activities of these molecules were evaluated against Hela, Eca-109, A549 and MCF-7, highlighting the meta-substituted phenylureas (1a?1c) as the most cytotoxic set. A series of meta-substituted phenylureas derivatives (1d?1o) were then designed and synthesized for structure-activity relationship study. Most of the new compounds showed desirable cytotoxicity, among which compound 1g exhibited the most remarkable cyto-toxic effects against the tested human cancer cells with IC50 values ranging from 1.47 to 6.79 μM. Further studies showed that compound 1g suppressed tumor growth in human breast cancer (MCF-7) xenograft models without affecting the body weight of its recipients. Conclusion: In this study, twenty-one new compounds, containing the privileged structures of phenylurea and 5-fluoroindolin-2-one, were designed and synthesized. Subsequent structure-activity studies showed that 1g was the most bioactive antitumor agent among all tested com-pounds, hence a potentially promising lead compound once given further optimization.
- Cai, Yunrui,Chen, Tong,Zhu, Huajian,Zou, Hongbin
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p. 958 - 968
(2020/08/19)
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- Bimetallic Bis-NHC-Ir(III) Complex Bearing 2-Arylbenzo[d]oxazolyl Ligand: Synthesis, Catalysis, and Bimetallic Effects
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Herein, an unprecedented bimetallic bis-NHC Cp*Ir complex 1 bearing 2-arylbenzo[d]oxazolyl and NHC ligands is reported. A significant increase in activity was observed for N-methylation of amines and reduction of aldehydes with MeOH catalyzed by 1 compared to the monometallic analogues (2-11). Under the optimal conditions, it showed to be highly effective in N-methylation of nitroarenes with MeOH as both C1 and H2 source. Substrates, including aromatic amines, ketones, and nitro compounds with various functional groups, can be well-tolerated. Mechanistic studies and DFT calculation highlight the significance of bimetallic centers cooperativity.
- Huang, Shuang,Hong, Xi,Cui, He-Zhen,Zhan, Bing,Li, Zhi-Ming,Hou, Xiu-Feng
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p. 3514 - 3523
(2020/10/09)
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- Reduction over Condensation of Carbonyl Compounds through a Transient Hemiaminal Intermediate Using Hydrazine
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Reduction of carbonyl moieties to the corresponding alcohol using simply hydrazine hydrate has been considerably unfeasible until now due to the well-known condensation reaction. However, herein, we report that using an excess of 20-fold equivalents, the reduction proceeds in excellent yields. 1H NMR study of the reaction and density functional theory (DFT) calculations indicate that the final fate of the hemiaminal intermediate is crucial to obtain the alcohol or the hydrazone.
- Vilches-Herrera, Marcelo,Gallardo-Fuentes, Sebastián,Aravena-Opitz, Mauricio,Yá?ez-Sánchez, Mauricio,Jiao, Haijun,Holz, Jens,B?rner, Armin,Lühr, Susan
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p. 9213 - 9218
(2020/08/14)
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- Method for carrying out reduction on aldehyde and ketone to obtain alcohol
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The invention discloses a method for carrying out reduction on aldehyde and ketone to obtain alcohol. Tri-(pentafluorobenzene-base) borane is used as a catalyst, and hydrogen silane is used as a reducing agent. The method includes adding water into reaction systems and carrying out reduction on the aldehyde or the ketone under the normal-temperature condition to obtain the corresponding alcohol. Compared with the prior art, the method has the advantages that reaction can be quickly carried out under the normal-temperature and normal-pressure conditions, the reaction conditions are mild, the method is high in reaction efficiency, and the yield is 95%-100% as shown by 1H NMR (1H nuclear magnetic resonance) detection; the water can be used as a solvent used in the reaction, and accordingly the method is low in cost and little in pollution; the catalyst and the reducing agent do not contain heavy metal, and accordingly the problem of heavy metal pollution and the like can be solved by theaid of the method.
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Paragraph 0019; 0020; 0036; 0037
(2019/03/30)
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- Enzymatic One-Step Reduction of Carboxylates to Aldehydes with Cell-Free Regeneration of ATP and NADPH
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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
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p. 6119 - 6123
(2019/04/13)
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- Hydrosilylation of carbonyl and carboxyl groups catalysed by Mn(i) complexes bearing triazole ligands
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Manganese(i) complexes bearing triazole ligands are reported as catalysts for the hydrosilylation of carbonyl and carboxyl compounds. The desired reaction proceeds readily at 80 °C within 3 hours at catalyst loadings as low as 0.25 to 1 mol%. Hence, good to excellent yields of alcohols could be obtained for a wide range of substrates including ketones, esters, and carboxylic acids illustrating the versatility of the metal/ligand combination.
- Martínez-Ferraté, Oriol,Chatterjee, Basujit,Werlé, Christophe,Leitner, Walter
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p. 6370 - 6378
(2019/11/20)
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- Green and convenient protocols for the efficient reduction of nitriles and nitro compounds to corresponding amines with NaBH4 in water catalyzed by magnetically retrievable CuFe2O4 nanoparticles
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Abstract: In this study, firstly, CuFe2O4 nanoparticles were prepared by a simple operation. The structure of the mentioned nanoparticles was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, inductively coupled plasma-optical emission spectrometry, vibrating sample magnetometer and also Brunauer–Emmett–Teller and Barrett–Joyner–Halenda analyses. The prepared magnetically copper ferrite nanocomposite was successfully applied as a simple, cost-effective, practicable, and recoverable catalyst on the green, highly efficient, fast, base-free, and ligand-free reduction of nitriles and also on the affordable and eco-friendly reduction of nitro compounds with the broad substrate scope to the corresponding amines with NaBH4 in water at reflux in high to excellent yields. Graphical abstract: [Figure not available: see fulltext.].
- Zeynizadeh, Behzad,Mohammad Aminzadeh, Farkhondeh,Mousavi, Hossein
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- Polypyridyl iridium(III) based catalysts for highly chemoselective hydrogenation of aldehydes
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Iridium-catalyzed transfer hydrogenation (TH) of carbonyl compounds using HCOOR (R = H, Na, NH4) as a hydrogen source is a pivotal process as it provides the clean process and is easy to execute. However, the existing highly efficient iridium catalysts work at a narrow pH; thus, does not apply to a wide variety of substrates. Therefore, the development of a new catalyst which works at a broad pH range is essential as it can gain a broader scope of utilization. Here we report highly efficient polypyridyl iridium(III) catalysts, [Ir(tpy)(L)Cl](PF6)2 {where tpy = 2,2′:6′,2′'-Terpyridine, L = phen (1,10-Phenanthroline), Me2phen (4,7-Dimethyl-1,10-phenanthroline), Me4phen (3,4,7,8-Tetramethyl-1,10-phenanthroline), Me2bpy (4,4′-Dimethyl-2–2′-dipyridyl)} for the chemoselective reduction of aldehydes to alcohols in aqueous ethanol and sodium formate as the hydride source. The reaction can be carried out efficiently in broad pH ranges, from pH 6 to 11. These catalysts are air stable, easy to prepare using commercially available starting materials, and are highly applicable for a wide range of substrates, such as electron-rich or deficient (hetero)arenes, halogens, phenols, alkoxy, ketones, esters, carboxylic acids, cyano, and nitro groups. Particularly, acid and hydroxy groups containing aldehydes were reduced successfully in basic and acidic reaction conditions, demonstrating the efficiency of the catalyst in a broad pH range with high conversion rates under microwave irradiation.
- Pandrala, Mallesh,Resendez, Angel,Malhotra, Sanjay V.
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p. 283 - 288
(2019/09/30)
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- Synthesis of magnetic Fe3O4@SiO2@Cu–Ni–Fe–Cr LDH: an efficient and reusable mesoporous catalyst for reduction and one-pot reductive-acetylation of nitroarenes
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Abstract: Magnetically recoverable Fe3O4@SiO2@Cu–Ni–Fe–Cr LDH was prepared under co-precipitation conditions. Characterization of the mesoporous catalyst was confirmed using Fourier-transformed infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, vibration sample magnetometer, Brunauer–Emmett–Teller, thermogravimetric, differential thermogravimetric analyses and transmission electron microscopy. Reduction of nitroarenes to the corresponding arylamines and one-pot reductive-acetylation of nitroarenes to acetanilides were carried out successfully by nanoparticles of the immobilized Cu–Ni–Fe–Cr layered double hydroxide on silica-coated Fe3O4 in water as a green solvent. All reactions were carried out within 6–22?min affording arylamines and N-arylacetamides in high-to-excellent yields. Reusability of the core–shell nanocatalyst was examined six times without significant loss of its catalytic activity.
- Gilanizadeh, Masumeh,Zeynizadeh, Behzad
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p. 2821 - 2837
(2018/10/31)
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- Sulfonic acid anchored on silica, SiO2@SO3H: A superior solid acid catalyst for quick and solvent-free reductive-deoxygenation of ketones with NaBH3CN
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NaBH3CN as a modified hydroborate agent and due to a strong withdrawing CN group does not show any reducing ability to reduce functional groups in the absence of acidic media (pH ~ 3–4). In this study, the immobilized sulfonic acid on silica, SiO2@SO3H, was prepared and applied as a new solid acid catalyst for extremely enhancing the reducing ability of NaBH3CN. The influence of SiO2@SO3H was highlighted by performing the quick and green reduction of structurally diverse carbonyl compounds involving aldehydes, ketones, α,β-unsaturated enals and enones, α-diketones, and acyloins to the corresponding alcohols or alkanes with NaBH3CN. By the NaBH3CN/SiO2@SO3H system, aldehydes were reduced to the corresponding alcohols and ketonic compounds to alkanes as reductive-deoxygenation products. All reduction reactions were carried out within 3 min at room temperature and under solvent-free conditions to afford the products in high to excellent yields (90–98%).
- Zeynizadeh, Behzad,Kouhkan, Mehri
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p. 1521 - 1528
(2018/11/23)
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- Methanol as hydrogen source: Transfer hydrogenation of aromatic aldehydes with a rhodacycle
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A cyclometalated rhodium complex has been shown to perform highly selective and efficient reduction of aldehydes, deriving the hydrogen from methanol. With methanol as both the solvent and hydrogen donor under mild conditions and an open atmosphere, a wide range of aromatic aldehydes were reduced to the corresponding alcohols, without affecting other functional groups.
- Aboo, Ahmed H.,Bennett, Elliot L.,Deeprose, Mark,Robertson, Craig M.,Iggo, Jonathan A.,Xiao, Jianliang
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supporting information
p. 11805 - 11808
(2018/11/10)
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- COMPOSITIONS AND METHODS FOR REDUCTION OF KETONES, ALDEHYDES AND IMINIUMS, AND PRODUCTS PRODUCED THEREBY
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A method of producing an alcohol, comprises reducing an aldehyde or a ketone with a hydridosilatrane. The reducing is carried out with an activator.
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Paragraph 0076-0077
(2018/01/20)
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- Synthesis of Novel Triazole-incorporated Isatin Derivatives as Antifungal, Antitubercular, and Antioxidant Agents and Molecular Docking Study
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A library of 1,2,3-triazoles efficiently prepared via click chemistry and evaluated for their antifungal, antitubercular, antioxidant, cytotoxicity, molecular docking and ADME prediction.
- Shaikh, Mubarak H.,Subhedar, Dnyaneshwar D.,Khan, Firoz A. Kalam,Sangshetti, Jaiprakash N.,Nawale, Laxman,Arkile, Manisha,Sarkar, Dhiman,Shingate, Bapurao B.
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supporting information
p. 413 - 421
(2017/02/03)
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- Preparation and characterization of a RHA/TiO2 nanocomposite: Introduction of an efficient and reusable catalyst for chemoselective trimethylsilyl protection and deprotection of alcohols and phenols
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In this work, rice husk ash (RHA), as a natural source of amorphous silica, was used as a support for the synthesis of anatase-phase titania nanoparticles leading to the RHA/TiO2 nanocomposite. This nanocomposite was used as an efficient catalyst for the chemoselective trimethylsilylation of various alcohols and phenols and deprotection of the obtained trimethylsilyl ethers. The procedure gave the products in excellent yields in very short reaction times. Also this catalyst can be reused at least six times without loss of its catalytic activity.
- Seddighi, Mohadeseh,Shirini, Farhad,Goli-Jolodar, Omid
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p. 23564 - 23570
(2016/03/12)
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- CSJ acting as a versatile highly efficient greener resource for organic transformations
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Simple, new, greener and efficient alternatives to the existing protocols have been developed for the reduction of aromatic aldehydes to their corresponding alcohols, decarboxylation of substituted benzoic acids (C6-C1) and substituted cinnamic acids (C6-C3) with a hydroxyl group at the para position with respect to the acid group to corresponding phenolic compounds and vinyl phenols respectively by using a natural feedstock, cucumber juice (CSJ), which acts as a greener solvent system, performing a substrate-selective reaction. Additionally, the hydrolysis of the acetyl as well as the benzoyl group of aromatic compounds has been carried out to afford excellent yield by CSJ.
- Maity, Himadri Sekhar,Misra, Kaushik,Mahata, Tanushree,Nag, Ahindra
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p. 24446 - 24450
(2016/03/15)
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- Silatrane as a Practical and Selective Reagent for the Reduction of Aryl Aldehydes to Benzylic Alcohols
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Hydrosilanes are cheap, readily available substrates, yet they do not see as extensive use for simple carbonyl reductions as borohydrides. Hydrosilane reducing agents broadly fall into one of two general categories: either a) they are easy to handle and require expensive and/or hazardous additives, or b) they are difficult and/or dangerous to handle. This work details the discovery of mild and functional group compatible conditions utilizing hydrosilatrane for the selective reduction of aryl aldehydes to benzylic alcohols without unwanted formation of ethers or deoxygenated products. This method offers significant advances in silane reductions as silatrane is an air- and moisture-stable yet relatively reactive reducing agent that can be used in benchtop open air reactions.
- Skrypai, Vladislav,Hurley, Joseph J. M.,Adler, Marc J.
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supporting information
p. 2207 - 2211
(2016/05/09)
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- K-10 and KSF clays as green and recyclable heterogeneous catalysts for the Cannizzaro reaction using DABCO under MWI and solvent-free conditions
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Montmorillonite K-10 and KSF clays as recyclable and heterogeneous catalysts are used to catalyze the Cannizzaro reaction by 1,4-diazabicyclo [2.2.2]octane (DABCO) under microwave irradiation (MWI) and solvent-free conditions in excellent yields within seconds. The solid clays applied in the first cycle are recovered and reused in the subsequent reactions.
- Marvi, Omid,Talakoubi, Maryam
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p. 359 - 365
(2016/05/09)
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- In situ activation of benzyl alcohols with XtalFluor-E: Formation of 1,1-diarylmethanes and 1,1,1-triarylmethanes through Friedel-Crafts benzylation
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The Friedel-Crafts benzylation of arenes using benzyl alcohols activated in situ with XtalFluor-E is described. A wide range of 1,1-diarylmethanes and 1,1,1-triarylmethanes were prepared under experimentally simple and mild conditions, without the need for a transition metal or a strong Lewis acid. Notably, the reactivity observed demonstrates the potential of XtalFluor-E to induce C-OH bond ionization and SN1 reactivity of benzylic alcohols. This journal is
- Desroches, Justine,Champagne, Pier Alexandre,Benhassine, Yasmine,Paquin, Jean-Franois
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supporting information
p. 2243 - 2246
(2015/03/04)
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- Lipophilic M(α,α′-OC5H11)8phthalocyanines (M = H2 and Ni(II)): Synthesis, electronic structure, and their utility for highly efficient carbonyl reductions
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A lipophilic and electron-rich phthalocyanine (α,α′-n-OC5H11)8-H2Pc and its nickel(ii) complex (α,α′-n-OC5H11)8-Ni(ii)Pc have been synthesized and characterized. Detailed analyses of the electronic structure were carried out by spectroscopy, electrochemistry, spectroelectrochemistry, and TD-DFT calculations. A series of experiments demonstrate that the (α,α′-n-OC5H11)8-Ni(ii)Pc complex can be used as a catalyst for highly efficient carbonyl reductions.
- Jiang, Yu,Li, Minzhi,Liang, Xu,Mack, John,Wildervanck, Martijn,Nyokong, Tebello,Qin, Mingfeng,Zhu, Weihua
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p. 18237 - 18246
(2015/10/28)
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- Palladium-catalyzed hydroxymethylation of aryl-and heteroarylboronic acids using aqueous formaldehyde
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Cyclometallated NHC palladium complexes prepared from palladium(II) acetate [Pd(OAc)2] and unsymmetrical 1,3-diarylimidazolinium salts catalyzed the hydroxymethylation of (hetero)arylboronic acids using an excess amount of formalin to afford (hetero)arylm
- Yamamoto, Tetsuya,Zhumagazin, Azamat,Furusawa, Takuma,Tanaka, Ryoji,Yamakawa, Tetsu,Oe, Yohei,Ohtab, Tetsuo
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supporting information
p. 3525 - 3529
(2015/01/09)
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- Palladium-catalyzed arylation of aldehydes with bromo-substituted 1,3-diaryl-imidazoline carbene ligand
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The combination of 0 valent palladium precursor and bromo-substituted 1,3-diaryl-imidazoline carbene ligand precursor such as 1-(2-bromophenyl)-3-(2,6-diisopropylphenyl)-imidazolinium chloride 1a exhibited high catalytic activity for the 1,2-addition of arylboronic acids to aldehydes including aqueous formaldehyde.
- Yamamoto, Tetsuya,Furusawa, Takuma,Zhumagazin, Azamat,Yamakawa, Tetsu,Oe, Yohei,Ohta, Tetsuo
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- Metal-free, visible-light photoredox catalysis: Transformation of arylmethyl bromides to alcohols and aldehydes
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A mild, simple, and controllable metal-free photocatalytic system for the transformation of arylmethyl bromides to corresponding alcohols and aldehydes in high yields with visible-light irradiation has been achieved. Eosin Y was found to be an efficient promoter for this oxidative dehalogenation reaction under photo irradiation conditions.
- Li, Jian,Wang, Hongni,Liu, Li,Sun, Jiangtao
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p. 49974 - 49978
(2014/12/10)
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- Solvent-free reduction of carboxylic acids to alcohols with NaBH4 promoted by 2,4,6-trichloro-1,3,5-triazine and PPh3 in the presence of K2CO3
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A simple, rapid, and eco-friendly method for NaBH4 reduction of carboxylic acids to alcohols under solvent-free conditions was developed using a combination of 2,4,6-trichloro-1,3,5-triazine (TCT) with a catalytic amount of triphenylphosphine as an acid activator. With the 1 : 0.2 : 1.5 : 2 mole ratio of TCT : PPh3 : K2CO3 : NaBH4, carboxylic acids including aromatic acids, aliphatic acids, and N-protected α-amino acids (Fmoc, Z) could readily undergo reduction to give the corresponding alcohols in good to excellent yields within 10 min.
- Jaita, Subin,Kaewkum, Pantitra,Duangkamol, Chuthamat,Phakhodee, Wong,Pattarawarapan, Mookda
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p. 46947 - 46950
(2014/12/10)
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- Lipase catalyzed Cannizzaro-type reaction with substituted benzaldehydes in water
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Lipases were found to catalyze Cannizzaro-type reaction of substituted benzaldehydes in aqueous medium at 30 °C without the addition of any external redox reagent. The ratio of alcohol product to acid product varied with nature of the substituted benzaldehyde, enzyme, and the presence of organic co-solvent.
- Arora, Benu,Pandey, Pramod S.,Gupta, Munishwar N.
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supporting information
p. 3920 - 3922
(2014/07/08)
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- Thermally robust Au99(SPh)42 nanoclusters for chemoselective hydrogenation of nitrobenzaldehyde derivatives in water
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We report the synthesis and catalytic application of thermally robust gold nanoclusters formulated as Au99(SPh)42. The formula was determined by electrospray ionization and matrix-assisted laser desorption ionization mass spectrometry in conjunction with thermogravimetric analysis. The optical spectrum of Au99(SPh)42 nanoclusters shows absorption peaks at ~920 nm (1.35 eV), 730 nm (1.70 eV), 600 nm (2.07 eV), 490 nm (2.53 eV), and 400 nm (3.1 eV) in contrast to conventional gold nanoparticles, which exhibit a plasmon resonance band at 520 nm (for spherical particles). The ceria-supported Au99(SPh)42 nanoclusters were utilized as a catalyst for chemoselective hydrogenation of nitrobenzaldehyde to nitrobenzyl alcohol in water using H2 gas as the hydrogen source. The selective hydrogenation of the aldehyde group catalyzed by nanoclusters is a surprise because conventional nanogold catalysts instead give rise to the product resulting from reduction of the nitro group. The Au 99(SPh)42/CeO2 catalyst gives high catalytic activity for a range of nitrobenzaldehyde derivatives and also shows excellent recyclability due to its thermal robustness. We further tested the size-dependent catalytic performance of Au25(SPh)18 and Au36(SPh)24 nanoclusters, and on the basis of their crystal structures we propose a molecular adsorption site for nitrobenzaldehyde. The nanocluster material is expected to find wide application in catalytic reactions.
- Li, Gao,Zeng, Chenjie,Jin, Rongchao
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p. 3673 - 3679
(2014/03/21)
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- Electrophilicity and nucleophilicity of commonly used aldehydes
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The present approach for determining the electrophilicity (E) and nucleophilicity (N) of aldehydes includes a kinetic study of KMNO4 oxidation and NaBH4 reduction of aldehydes. A transition state analysis of the KMNO4 promoted aldehyde oxidation reaction has been performed, which shows a very good correlation with experimental results. The validity of the experimental method has been tested using the experimental activation parameters of the two reactions. The utility of the present approach is further demonstrated by the theoretical versus experimental relationship, which provides easy access to E and N values for various aldehydes and offers an at-a-glance assessment of the chemical reactivity of aldehydes in various reactions. the Partner Organisations 2014.
- Pratihar, Sanjay
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p. 5781 - 5788
(2014/07/22)
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- Colloid and nanodimensional catalysts in organic synthesis: VI.1 Hydrogenation and hydrogenolysis of carbonyl compounds
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Aldehydes and ketones are found to be hydrogenated to alcohols with hydrogen at atmospheric pressure under the catalysis with nickel nanoparticles. The reaction under study may be used as technologically available and cheap method for hydrogenation of carbonyl groups. It is found that in the case of aromatic ketones hydrogenolysis of C=O bond with partial hydrogenation of aromatic groups takes place.
- Mokhov,Popov,Nebykov
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p. 1656 - 1661
(2015/01/09)
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- Hydrogenation of substituted aromatic nitrobenzenes over 1% 1.0 wt.%Ir/ZrO2 catalyst: Effect of meta position and catalytic performance
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This study is based on 1%Ir/ZrO2 catalyst which was studied in the hydrogenation of aromatic meta-substituted nitrobenzene in liquid phase. The catalyst was prepared by traditional impregnation method using IrCl3 and it has been characterized in terms of temperature-programmed reduction (TPR), ICP-MS, BET area, X-ray diffraction, HR-TEM and XPS measurements. The hydrogenation was evaluated in a batch type reactor at 298 K using ethanol like a solvent. The catalyst showed the formation of zero valent and partially oxidized Iridium (Irδ+) is established post-TPR and XPS characterization. The metal particle size exhibited a wide distribution with mean size 1.8 nm. Ir/ZrO2 was active in all the hydrogenation reactions with elevated conversion and promoted exclusive NO2 group reduction, resulting in the sole formation of the corresponding amino-compound except for CHO and CHCH2 meta-substituted nitrobenzene. We associate this response to a reducible group competition between NO2 and CHO or CHCH2. Reactant activation on the catalyst generates a negatively charged intermediate, consistent with a nucleophilic mechanism. The presence of electron-donating substituents is shown to decrease NO2 reduction rate. This effect is quantified in terms of the Hammett relationship where a linear correlation between the substituent constant (σi) and rate is established and a reaction constant (ρ) 0.639. The data generated provide the first report of the catalytic action of supported Ir in the hydrogenation of meta-substituted nitroarenes and establish the nature of the hydrogenation en liquid phase.
- Campos, Cristian,Torres, Cecilia,Oportus, Marcelo,Pe?a, Miguel A.,Fierro,Reyes, Patricio
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- Synthesis of secondary propargyl alcohols from aromatic and heteroaromatic aldehydes and acetylene in the system KOH-H2O-DMSO
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Ethynylation of aromatic and heteroaromatic aldehydes with acetylene under atmospheric pressure in the catalytic system KOH-H2O-DMSO (aldehyde-KOH molar ratio 1: 2, -5 to -7 C, 3 h) gave secondary propargyl alcohols in 46-67% yield.
- Sobenina,Tomilin,Petrova,Mikhaleva,Trofimov
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p. 356 - 359
(2013/07/26)
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- Synthesis of stilbene, 1,4-distyrylbenzene and 4,4′-distyrylbiphenyl via Horner-Wadsworth-Emmons reaction in phase-transfer catalysis system
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Stilbenes, 1,4-distyrylbenzenes and 4,4′-distyrylbiphenyls were synthesized via Horner-Wadsworth-Emmons (HWE) reaction in liquid-liquid (LL) and solid-liquid (SL) phase transfer catalysis (PTC) systems. The effect of the side reaction, reactants and the third phase on the activity of HWE reaction were investigated. For aldehydes bearing electron-donating substitute, the yields were more than 90% and the products were all (E)-isomers in both PTC systems. The SL-PTC system was milder than LL-PTC system for HWE reaction due to the different mechanisms. The side reaction of aldehyde was similar to Cannizzaro reaction, whereas the molar ratio of benzoic acid to benzyl alcohol as the products was not 1:1. The limited third phase was discovered to exist in LL-PTC system. In SL-PTC system, the third phase could increase substantially the reaction rate. Moreover, the aqueous phase in LL-PTC system could be reused four times without sacrifice of the yield and reaction rate.
- Zhao, Qiangqiang,Sun, Jie,Liu, Baojiang,He, Jinxin
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p. 339 - 347
(2013/10/21)
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- A heteroleptic cyclometalated iridium(iii) fluorophenylpyridine complex from partial defluorohydrogenation reaction: Synthesis, photophysical properties and mechanistic insights
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In this paper, a C-F bond activation reaction of a chloro-bridged iridium(iii) dimer (dfppy)2Ir(μ-Cl)2Ir(dfppy) 2 (1) (dfppy denotes 2-(4,6-difluorophenyl)pyridyl) in the presence of sodium methoxide has been reported, lea
- Li, Liang,Wu, Feng,Zhang, Songlin,Wang, Dawei,Ding, Yuqiang,Zhu, Zhenzhong
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supporting information
p. 4539 - 4543
(2013/04/23)
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- NaBH4/DOWEX(R)50WX4: A convenient reducing system for fast and efficient reduction of carbonyl compounds to their corresponding alcohols
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The reduction of a variety of carbonyl compounds was efficiently carried out with NaBH4/ DOWEX(R)50WX4 system. The reactions were performed to give the corresponding alcohols derivatives in perfect yields in THF at room temperature. Reduction of acyloins and-diketones by this reducing system produced efficiently the corresponding vicinal diols. Also, the reduction of aldehydes over ketones has been accomplished successfully by this system. Regioselectivity of this system was also investigated with exclusive 1,2-reduction of conjugated carbonyl compounds to their corresponding allylic alcohols in high to excellent yields.
- Setamdideh, Davood,Karimi, Zahra,Alipouramjad, Avat
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p. 590 - 596
(2013/10/22)
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- Zn(BH4)2/Al2O3: A new synthetic method for the efficient and convenient reduction of organic carbonyl compounds to their corresponding alcohols
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Zn(BH4)2 (0.5-2 mmol) in the presence of Al 2O3 (1 mmol) reduces a variety of organic carbonyl compounds such as aldehydes, ketones, acyloins, α-diketones and α,β-unsaturated carbonyl compounds to their corresponding alcohols. The reduction reactions were realized in THF at room temperature affording high to excellent yields of the products. The chemoselective reduction of aldehydes over ketones was successfully accomplished with this reducing system. In addition, regioselectivity and exclusive 1,2-reduction of conjugated carbonyl compounds to their corresponding allylic alcohols in high to excellent yields was successfully accomplished.
- Setamdideh, Davood,Khezri, Behrooz,Rahmatollahzadeh, Mehdi
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- Chemoselective Hydrogenation and Transfer Hydrogenation of Olefins and Carbonyls with the Cluster-Derived Ruthenium Nanocatalyst in Water
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Ion pairing of [H3Ru4(CO)12]- with the quaternary ammonium groups of water-soluble poly(diallyldimethylammonium chloride) gives the precursor of a nanocatalyst for hydrogenation and transfer hydrogenation reactions in water. In hydrogenation reactions, "on water" effect is seen for substrates such as cyclohexanones, methyl pyruvate, acetophenone, and safflower oil. With these substrates, higher turnover numbers are obtained in water than in methanol. The cluster-derived catalyst shows unique chemoselectivity, which is not seen either in a catalyst prepared through ion pairing of [RuCl4]- with the quaternary ammonium groups of the same polymer or in commercial (5%) Ru/Al2O3. In contrast to Ru/Al2O3, the [RuCl4]--derived catalyst, or many other ruthenium-based catalytic systems, the cluster-derived catalyst is totally inert toward the hydrogenation of -NO2, -CN, and aromatic ring functionalities. In water, typical ketones and aldehydes could be reduced by using the cluster-derived catalyst and formate as the hydrogen donor. Industrially important cyano- and nitrobenzyl alcohols could thus be made from the corresponding aldehydes. High-resolution TEM data suggest that unique chemoselectivity is a result of highly crystalline ruthenium nanoparticles that consist mainly of Ru(111) crystal planes.
- Indra, Arindam,Maity, Prasenjit,Bhaduri, Sumit,Lahiri, Goutam Kumar
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p. 322 - 330
(2013/03/13)
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