- Hydrogenation of α,β-Unsaturated Carbonyl Compounds by Carbon monoxide and Water with Rh6(CO)16 Catalyst under Mild Conditions
-
By controlling such factors as the concentration of water and amine, the carbon-carbon double bond of α,β-unsaturated carbonyl compounds could be selectively hydrogenated under mild water-gas shift reaction (WGSR) conditions using a Rh6(CO)16-Et3N catalys
- Joh, Takashi,Fujiwara, Keisuke,Takahashi, Shigetoshi
-
-
Read Online
- Diastereoselective dl-Hydrocoupling of Benzalacetones by Electroreduction
-
Electroreduction of benzalacetones with an undivided cell in Et 4NOTs/acetonitrile gave cyclized dl-hydrodimers as mixtures of two diastereomers. The hydrodimerization proceeded stereoselectively to afford linear dl-hydrodimers, and the following cyclization led to two thermodynamically stable diasteromers of cyclopentanols.
- Kise, Naoki,Kitagishi, Yasuo,Ueda, Nasuo
-
-
Read Online
- Liquid-Phase Regioselective 1,4-Hydrogenation of Benzylidene Ketones on Rh/AIPO4 Catalysts
-
The liquid-phase catalytic hydrogenation of α,β-unsaturated carbonyl compounds, in the p-XC6H4CH=CHCOR form (E isomers; X = H, Me, MeO, Cl; R = Me, Et, n-Pr, i-Pr, n-Bu, t-Bu, n-Pe, Ph) was carried out by using a rhodium catalyst supported at 1 wt percent
- Cabello, J. A.,Campelo, J. M.,Garcia, A.,Luna, D.,Marinas, J. M.
-
-
Read Online
- Carbonyl regeneration from oximes and semicarbazones by trimethylchlorosilane-dimethylsulphoxide
-
Treatment of oximes and semicarbazones of saturated and α,β-unsaturated ketones and aldehydes with trimethylchlorosilane-dimethyl sulphoxide in dry acetonitrile affords the corresponding carbonyl compounds in excellent yields under mild conditions.
- Ghelfi,Grandi,Pagnoni
-
-
Read Online
- Enzyme-catalysed enantioselective oxidation of alcohols by air exploiting fast electrochemical nicotinamide cycling in electrode nanopores
-
Enantioselective conversion of alcohols to ketones using air as the oxidant is achieved with high rates and efficiency using an indium tin oxide (ITO) electrode in which an alcohol dehydrogenase and a photosynthetic NADPH recycling enzyme are confined within nanopores. The massive catalytic enhancement arising from nanoconfinement is exploited in an air-driven electrochemical cell, which requires no complicating control features yet allows continuous monitoring of the reaction via the current that flows between anode (ITO: Organic chemistry) and cathode (Pt: O2 from air).
- Wan, Lei,Heath, Rachel S.,Siritanaratkul, Bhavin,Megarity, Clare F.,Sills, Adam J.,Thompson, Matthew P.,Turner, Nicholas J.,Armstrong, Fraser A.
-
-
Read Online
- Carbonyl regeneration from p-toluensulfonhylhydrazones by trimethylchlorosilane-dimethylsulfoxide
-
Treatment of p-tosylhydrazones of saturated and α,β-unsaturated ketones and aldehydes with trimethylchlorosilane-dimethyl sulphoxide in dry acetonitrile affords the corresponding carbonyl compounds in excellent yields under mild conditions.
- Ghelfi,Grandi,Pagnoni
-
-
Read Online
- TRANSFER HYDROGENATION BETWEEN ALCOHOLS AND α,β UNSATURATED KETONES WITH RhH(PPh3)3 AS CATALYST. EVIDENCE FOR REGIOSPECIFICITY AND AN UNUSUAL RATE-LIMITING STEP
-
In the hydrogen transfer between an alcohol and an α,β-unsaturated ketone with RhH(PPh3)4 as catalyst under mild conditions the breaking of the O-H bond is, unusually, the rate-determining step, and the hydroxylic hydrogen is selectively transferred to the α-carbon of the ketone.
- Beaupere, D.,Bauer, P.,Nadjo, L.,Uzan, R.
-
-
Read Online
- Syntheses of water-soluble octahedral, truncated octahedral, and cubic Pt-Ni nanocrystals and their structure-activity study in model hydrogenation reactions
-
We developed a facile strategy to synthesize a series of water-soluble Pt, PtxNi1-x (0 xNi1-x nanocrystals were effectively controlled by choice of ratios between the Pt and Ni precursors. In a preliminary study to probe their structure-activity dependence, we found that the shapes, compositions, and capping agents strongly influence the catalyst performances in three model heterogeneous hydrogenation reactions.
- Wu, Yuen,Cai, Shuangfei,Wang, Dingsheng,He, Wei,Li, Yadong
-
-
Read Online
- Homo-coupling reactions of alkenyl- and arylfluorosilanes mediated by a copper(I) salt
-
Homo-coupling reactions of an alkenyl- or arylsilane readily occur with a copper(I) salt in an aprotic polar solvent such as N, N-dimethylformamide or dimethyl sulfoxide under an aerobic condition to give the corresponding conjugated dienes or biaryls, respectively. Optimization of a copper salt and a solvent for the homo-coupling reaction is discussed. The formation of the organocopper intermediates is evidenced by trapping experiments with iodine and by a conjugate addition to methyl vinyl ketone.
- Nishihara, Yasushi,Ikegashira, Kazutaka,Toriyama, Fumihiko,Mori, Atsunori,Hiyama, Tamejiro
-
-
Read Online
- Selective oxidation of alcohols with hydrogen peroxide catalyzed by tungstate ions (WO4=) supported on periodic mesoporous organosilica with imidazolium frameworks (PMO-IL)
-
Tungstate ions supported on the periodic mesoporous organosilica with ionic liquid frameworks (WO4=@PMO-IL) were found to be a recoverable catalyst system for the highly selective oxidation of various primary or secondary alcohols to the corresponding aldehydes or ketones by 30% H2O2as green oxidant under neutral aqueous reaction conditions. The catalyst can be also recovered and efficiently reused in seven subsequent reaction cycles without any remarkable decreasing in the catalyst activity and selectivity. Moreover, N2sorption analysis, transmission electron microscopy (TEM) images, and thermal gravimetric analysis (TGA) showed that the structure regularity and functional groups loaded of the catalyst were not affected during the reaction process.
- Karimi, Babak,Rostami, Fatemeh Bakhshandeh,Khorasani, Mojtaba,Elhamifar, Dawood,Vali, Hojatollah
-
-
Read Online
- RADICAL REACTION OF ACETONYLTRIBUTYLSTANNANE WITH α-(PHENYLSELENO)CARBONYL COMPOUNDS: A NOVEL PROCEDURE FOR PREPARATION OF 1,4-DICARBONYL COMPOUNDS
-
Radical reaction of acetonyltributylstannane 1 with α-(phenylseleno)carbonyl compounds 2 gave 1,4-dicarbonyl compounds in high yield.The SH2' mechanism via the stannyl enolate in equilibrium with acetonylstannane is postulated.
- Watanabe, Yoshihiko,Yoneda, Tetsuo,Ueno, Yoshio,Toru, Takeshi
-
-
Read Online
- Stereo-Divergent Enzyme Cascades to Convert Racemic 4-Phenyl-2-Butanol into either (S)- or (R)-Corresponding Chiral Amine
-
The synthesis of enantiopure chiral amines from racemic alcohols is a key transformation in the chemical industry, e. g., in the production of active pharmaceutical ingredients (APIs). However, this reaction remains challenging. In this work, we propose a one-pot enzymatic cascade for the direct conversion of a racemic alcohol into either (S)- or (R)-enantiomers of the corresponding amine, with in-situ cofactor recycling. This enzymatic cascade consists of two enantio-complementary alcohol dehydrogenases, both NADH and NADPH oxidase for in-situ recycling of NAD(P)+ cofactors, and either (S)- or (R)-enantioselective transaminase. This cell-free biocatalytic system has been successfully applied to the conversion of racemic 4-phenyl-2-butanol into the high value (S)- or (R)-enantiomers of the amine reaching good (73 % (S)) and excellent (>99 % (R)) enantioselectivities.
- Paradisi, Francesca,Romero-Fernandez, Maria
-
-
- Cobalt-catalyzed Divergent Markovnikov and Anti-Markovnikov Hydroamination
-
Catalytic hydroamination of the readily available alkenes is among the most straightforward means to construct diverse alkyl amines. To this end, the facile access to both regioselectivity, i.e., Markovnikov or anti-Markovnikov hydroamination, with minimum reaction-parameter alternation, remains challenging. Herein, we report a cobalt-catalyzed highly selective and divergent Markovnikov and anti-Markovnikov hydroamination of alkenes, in which the switch of regioselectivity is achieved simply by the variation of the addition sequence of 9-BBN.
- Zhang, Xiang-Gui,He, Zi-Xin,Guo, Peng,Chen, Zheng,Ye, Ke-Yin
-
supporting information
p. 22 - 26
(2022/01/04)
-
- On the Origin of Rh-Catalyzed Selective Ring-Opening Amidation of Substituted Cyclopropanols to Access β2-Amino Ketones
-
β2-Amino carbonyls, an α-substituted β-amino scaffold, hold a prominent place in the development of new pharmaceuticals and peptidomimetics. Herein, we report a highly efficient Rh-catalyzed ring-opening amidation of substituted cyclopropanols, which turned out to serve as a linchpin for the selective synthesis of β2-amino ketones to outcompete the formation of β3-isomers. Instead of the generally accepted rationale to consider steric factors for the β2-selectivity, orbital interaction was elucidated to play a more critical role in the amidative ring-opening of cyclopropanols to generate the key Rh-C intermediate. Subsequent inner-sphere acylnitrene transfer was achieved in excellent efficiency (TON > 5000) by using readily accessible dioxazolones as the amino source to afford β2-amino ketones with broad applicability.
- Chang, Sukbok,Heo, Joon,Kim, Dongwook,Lee, Minhan
-
supporting information
p. 3667 - 3675
(2022/03/02)
-
- Heterogeneous Isomerization for Stereoselective Alkyne Hydrogenation to trans-Alkene Mediated by Frustrated Hydrogen Atoms
-
Stereoselective production of alkenes from the alkyne hydrogenation plays a crucial role in the chemical industry. However, for heterogeneous metal catalysts, the olefins in cis-configuration are usually dominant in the products due to the most important and common Horiuti-Polanyi mechanism involved over the metal surface. In this work, through combined theoretical and experimental investigations, we demonstrate a novel isomerization mechanism mediated by the frustrated hydrogen atoms via the H2 dissociation at the defect on solid surface, which can lead to the switch in selectivity from the cis-configuration to trans-configuration without overhydrogenation. The defective Rh2S3 with exposing facet of (110) exhibits outstanding performance as a heterogeneous metal catalyst for stereoselective production of trans-olefins. With the frustrated hydrogen atoms at spatially separated high-valence Rh sites, the isolated hydrogen mediated cis-to-trans isomerization of olefins can be effectively conducted and the overhydrogenation can be completely inhibited. Furthermore, the bifunctional Rh-S/Pd nanosheets have been synthesized through the surface modification of Pd nanosheets with rhodium and sulfide. With the selective semihydrogenation of alkynes into cis-olefins catalyzed by the small surface PdSx ensembles, the bifunctional Rh-S/Pd nanosheets exhibit excellent activity and stereoselectivity in the one-pot alkyne hydrogenation into trans-olefin, which surpasses the most reported homogeneous and heterogeneous catalysts.
- Zhang, Weijie,Qin, Ruixuan,Fu, Gang,Zheng, Nanfeng
-
supporting information
p. 15882 - 15890
(2021/10/02)
-
- Deep eutectic solvents as H2-sources for Ru(II)-catalyzed transfer hydrogenation of carbonyl compounds under mild conditions
-
The employment of easily affordable ruthenium(II)-complexes as pre-catalysts in the transfer hydrogenation of carbonyl compounds in deep eutectic media is described for the first time. The eutectic mixture tetrabutylammonium bromide/formic acid = 1/1 (TBABr/HCOOH = 1/1) acts both as reaction medium and hydrogen source. The addition of a base is required for the process to occur. An extensive optimization of the reaction conditions has been carried out, in terms of catalyst loading, type of complexes, H2-donors, reaction temperature and time. The combination of the dimeric complex [RuCl(p-cymene)-μ-Cl]2 (0.01–0.05 eq.) and the ligand dppf (1,1′-ferrocenediyl-bis(diphenylphosphine)ferrocene) in 1/1 molar ratio has proven to be a suitable catalytic system for the reduction of several and diverse aldehydes and ketones to their corresponding alcohols under mild conditions (40–60 °C) in air, showing from moderate to excellent tolerability towards different functional groups (halogen, cyano, nitro, phenol). The reduction of imine compounds to their corresponding amine derivatives was also studied. In addition, the comparison between the results obtained in TBABr/HCOOH and in organic solvents suggests a non-innocent effect of the DES medium during the process.
- Cavallo, Marzia,Arnodo, Davide,Mannu, Alberto,Blangetti, Marco,Prandi, Cristina,Baratta, Walter,Baldino, Salvatore
-
supporting information
(2021/02/22)
-
- Synthetic ferripyrophyllite: Preparation, characterization and catalytic application
-
Sheet silicates, also known as phyllosilicates, contain parallel sheets of tetrahedral silicate built up by [Si2O5]2- entities connected through intermediate metal-oxygen octahedral layers. The well-known minerals talc and pyrophyllite are belonging to this group based on magnesium and aluminium, respectively. Surprisingly, the ferric analogue rarely occurs in nature and is found in mixtures and conglomerates with other materials only. While partial incorporation of iron into pyrophyllites has been achieved, no synthetic protocol for purely iron-based pyrophyllite has been published yet. Here we report about the first artificial synthesis of ferripyrophyllite under exceptional mild conditions. A similar ultrathin two-dimensional (2D) nanosheet morphology is obtained as in talc or pyrophyllite but with iron(iii) as a central metal. The high surface material exhibits a remarkably high thermostability. It shows some catalytic activity in ammonia synthesis and can serve as catalyst support material for noble metal nanoparticles.
- Qiao, Yunxiang,Theyssen, Nils,Spliethoff, Bernd,Folke, Jan,Weidenthaler, Claudia,Schmidt, Wolfgang,Prieto, Gonzalo,Ochoa-Hernández, Cristina,Bill, Eckhard,Ye, Shengfa,Ruland, Holger,Schüth, Ferdi,Leitner, Walter
-
supporting information
p. 850 - 857
(2021/02/03)
-
- A Titanium-Catalyzed Reductive α-Desulfonylation
-
A titanium(III)-catalyzed desulfonylation gives access to functionalized alkyl nitrile building blocks from α-sulfonyl nitriles, circumventing traditional base-mediated α-alkylation conditions and strong single electron donors. The reaction tolerates numerous functional groups including free alcohols, esters, amides, and it can be applied also to the α-desulfonylation of ketones. In addition, a one-pot desulfonylative alkylation is demonstrated. Preliminary mechanistic studies indicate a catalyst-dependent mechanism involving a homolytic C?S cleavage.
- Kern, Christoph,Selau, Jan,Streuff, Jan
-
supporting information
p. 6178 - 6182
(2021/03/16)
-
- SBA-15 Supported 1-Methyl-2-azaadamanane N-Oxyl (1-Me-AZADO) as Recyclable Catalyst for Oxidation of Alcohol
-
Herein, we designed and synthesized an SBA-15 supported 1-methyl-2-azaadamanane N-oxyl (1-Me-AZADO) and investigated its catalytic performance for selective oxidation of alcohols under Anelli's conditions. The first example of immobilization of 1-Me-AZADO was very important to advance the oxgenation effectively because this supported N-oxyl has excellent catalytic activity for oxidation of alcohols to carbonyl compounds, and more importantly, it can be conveniently recovered and reused at least 6 times without significant effect on its catalytic efficiency.
- Tian, Yangwu,Guo, Xiaqun,Li, Meichao,Li, Chunmei,Hu, Xinquan,Jin, Liqun,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu
-
supporting information
p. 3928 - 3932
(2021/05/26)
-
- Tandem oxidation-dehydrogenation of (hetero)arylated primary alcohols via perruthenate catalysis
-
Tandem oxidative-dehydrogenation of primary alcohols to give a,b-unsaturated aldehydes in one pot are rare transformations in organic synthesis, with only two methods currently available. Reported herein is a novel method using the bench-stable salt methyltriphenylphosphonium perruthenate (MTP3), and a new co-oxidant NEMO&middoPF6 (NEMO = N-ethyl-N-hydroxymorpholinium) which provides unsaturated aldehydes in low to moderate yields. The Ley-Griffith oxidation of (hetero)arylated primary alcohols with N-oxide co-oxidants NMO (NMO = N-methylmorpholine N-oxide)/NEMO, is expanded by addition of the N-oxide salt NEMO&middoPF6 to convert the intermediate saturated aldehyde into its unsaturated counterpart. The discovery, method development, reaction scope, and associated challenges of this method are highlighted. The conceptual value of late-stage dehydrogenation in natural product synthesis is demonstrated via the synthesis of a polyene scaffold related to auxarconjugatin B.
- Bettencourt, Christian J.,Chow, Sharon,Moore, Peter W.,Read, Christopher D.G.,Jiao, Yanxiao,Bakker, Jan Peter,Zhao, Sheng,Bernhardt, Paul V.,Williams, Craig M.
-
p. 652 - 659
(2021/09/08)
-
- Integrated Electro-Biocatalysis for Amine Alkylation with Alcohols
-
The integration of electro and bio-catalysis offers new ways of making molecules under very mild, environmentally benign conditions. We show that TEMPO mediated electro-catalytic oxidation of alcohols can be adapted to work in aqueous buffers, with minimal organic co-solvent, enabling integration with biocatalytic reductive amination using the AdRedAm enzyme. The combined process offers a new approach to amine alkylation with native alcohols, a key bond formation in the chemical economy that is currently achieved via precious metal-catalyzed hydrogen-borrowing technologies. The electrobio transformation is effective for primary and secondary alcohols undergoing coupling with allyl, propargyl, benzyl, and cyclopropyl amines, and has been adapted for use with solid-supported AdRedAm for ease of operation.
- Pe?afiel, Itziar,Dryfe, Robert A. W.,Turner, Nicholas J.,Greaney, Michael F.
-
p. 864 - 867
(2021/01/21)
-
- Bidentate Nitrogen-Ligated I(V) Reagents, Bi(N)-HVIs: Preparation, Stability, Structure, and Reactivity
-
Hypervalent iodine(V) reagents are a powerful class of organic oxidants. While the use of I(V) compounds Dess-Martin periodinane and IBX is widespread, this reagent class has long been plagued by issues of solubility and stability. Extensive effort has been made for derivatizing these scaffolds to modulate reactivity and physical properties but considerable room for innovation still exists. Herein, we describe the preparation, thermal stability, optimized geometries, and synthetic utility of an emerging class of I(V) reagents, Bi(N)-HVIs, possessing datively bound bidentate nitrogen ligands on the iodine center. Bi(N)-HVIs display favorable safety profiles, improved solubility, and comparable to superior oxidative reactivity relative to common I(V) reagents. The highly modular synthesis and in situ generation of Bi(N)-HVIs provides a novel and convenient screening platform for I(V) reagent and reaction development.
- Xiao, Xiao,Roth, Jessica M.,Greenwood, Nathaniel S.,Velopolcek, Maria K.,Aguirre, Jordan,Jalali, Mona,Ariafard, Alireza,Wengryniuk, Sarah E.
-
p. 6566 - 6576
(2021/05/06)
-
- Study on the selective hydrogenation of isophorone
-
3,3,5-Trimethylcyclohexanone (TMCH) is an important pharmaceutical intermediate and organic solvent, which has important industrial significance. The selective hydrogenation of isophorone was studied over noble metal (Pd/C, Pt/C, Ir/C, Ru/C, Pd/SiO2, Pt/SiO2, Ir/SiO2, Ru/SiO2), and non-noble metal (RANEY Ni, RANEY Co, RANEY Cu, RANEY Fe, Ni/SiO2, Co/SiO2, Cu/SiO2, Fe/SiO2) catalysts and using solvent-free and solvent based synthesis. The results show that the solvent has an important effect on the selectivity of TMCH. The selective hydrogenation of isophorone to TMCH can be influenced by the tetrahydrofuran solvent. The conversion of isophorone is 100%, and the yield of 3,3,5-trimethylcyclohexanone is 98.1% under RANEY Ni and THF. The method was applied to the selective hydrogenation of isopropylidene acetone, benzylidene acetone and 6-methyl-5-ene-2-heptanone. The structures of the hydrogenation product target (4-methylpentan-2-one, 4-benzylbutan-2-one and 6-methyl-heptane-2-one) were characterized using 1H-NMR and 13C-NMR. The yields of 4-methylpentan-2-one, 4-benzylbutan-2-one and 6-methyl-heptane-2-one were 97.2%, 98.5% and 98.2%, respectively. The production cost can be reduced by using RANEY metal instead of noble metal palladium. This method has good application prospects. This journal is
- Xu, Lei,Sun, Shaoyin,Zhang, Xing,Gao, Haofei,Wang, Wei
-
p. 4465 - 4471
(2021/02/03)
-
- A stable well-defined copper hydride cluster consolidated with hemilabile phosphines
-
Copper hydrides are very useful in hydrogenation reactions. We report a stable Stryker-type copper hydride reagent protected by hemilabile phosphines: [Cu8H6(dppy)6](OTf)2(Cu8-H, dppy = diphenylphosphino-2-pyridine). The metal core of this cluster has a bicapped octahedral configuration, and the copper-bound hydrides each triply bridges over a triangular face of the octahedron. This cluster is attractive due to its facile preparation and excellent stability under ambient conditions. The comparable activity and selectivity both in the stoichiometric and catalytic reactions makeCu8-Ha promising alternative to Stryker's reagent.
- Yuan, Shang-Fu,Luyang, Heng-Wang,Lei, Zhen,Wan, Xian-Kai,Li, Jiao-Jiao,Wang, Quan-Ming
-
supporting information
p. 4315 - 4318
(2021/05/05)
-
- Highly Selective Hydrogenation of C═C Bonds Catalyzed by a Rhodium Hydride
-
Under mild conditions (room temperature, 80 psi of H2) Cp*Rh(2-(2-pyridyl)phenyl)H catalyzes the selective hydrogenation of the C═C bond in α,β-unsaturated carbonyl compounds, including natural product precursors with bulky substituents in the β position and substrates possessing an array of additional functional groups. It also catalyzes the hydrogenation of many isolated double bonds. Mechanistic studies reveal that no radical intermediates are involved, and the catalyst appears to be homogeneous, thereby affording important complementarity to existing protocols for similar hydrogenation processes.
- Gu, Yiting,Lisnyak, Vladislav G.,Norton, Jack R.,Salahi, Farbod,Snyder, Scott A.,Zhou, Zhiyao
-
supporting information
p. 9657 - 9663
(2021/07/19)
-
- Ambient Hydrogenation and Deuteration of Alkenes Using a Nanostructured Ni-Core–Shell Catalyst
-
A general protocol for the selective hydrogenation and deuteration of a variety of alkenes is presented. Key to success for these reactions is the use of a specific nickel-graphitic shell-based core–shell-structured catalyst, which is conveniently prepared by impregnation and subsequent calcination of nickel nitrate on carbon at 450 °C under argon. Applying this nanostructured catalyst, both terminal and internal alkenes, which are of industrial and commercial importance, were selectively hydrogenated and deuterated at ambient conditions (room temperature, using 1 bar hydrogen or 1 bar deuterium), giving access to the corresponding alkanes and deuterium-labeled alkanes in good to excellent yields. The synthetic utility and practicability of this Ni-based hydrogenation protocol is demonstrated by gram-scale reactions as well as efficient catalyst recycling experiments.
- Beller, Matthias,Feng, Lu,Gao, Jie,Jackstell, Ralf,Jagadeesh, Rajenahally V.,Liu, Yuefeng,Ma, Rui
-
supporting information
p. 18591 - 18598
(2021/06/28)
-
- Chemoselective reduction of ?,¢-unsaturated carbonyl and carboxylic compounds by hydrogen iodide
-
The selective reduction of ?,¢-unsaturated carbonyl compounds was achieved to produce saturated carbonyl compounds with aqueous HI solution. The introduction of an aryl group at an ? or ¢ position efficiently facilitated the reduction with good yield. The reaction was applicable to compounds bearing carboxylic acids and halogen atoms. Through the investigation of the reaction mechanism, it was found that Michael-type addition of iodide occurred to produce ¢-iodo compounds followed by the reduction of C-I bond via anionic and radical paths.
- Matsumoto, Shoji,Marumoto, Hayato,Akazome, Motohiro,Otani, Yasuhiko,Kaiho, Tatsuo
-
p. 590 - 599
(2021/03/29)
-
- Dynamic Kinetic Resolution of Alcohols by Enantioselective Silylation Enabled by Two Orthogonal Transition-Metal Catalysts
-
A nonenzymatic dynamic kinetic resolution of acyclic and cyclic benzylic alcohols is reported. The approach merges rapid transition-metal-catalyzed alcohol racemization and enantioselective Cu-H-catalyzed dehydrogenative Si-O coupling of alcohols and hydrosilanes. The catalytic processes are orthogonal, and the racemization catalyst does not promote any background reactions such as the racemization of the silyl ether and its unselective formation. Often-used ruthenium half-sandwich complexes are not suitable but a bifunctional ruthenium pincer complex perfectly fulfills this purpose. By this, enantioselective silylation of racemic alcohol mixtures is achieved in high yields and with good levels of enantioselection.
- Oestreich, Martin,Seliger, Jan
-
supporting information
p. 247 - 251
(2020/10/29)
-
- Catalytic Aerobic Oxidation of Alkenes with Ferric Boroperoxo Porphyrin Complex; Reduction of Oxygen by Iron Porphyrin
-
We herein describe the development of a mild and selective catalytic aerobic oxidation process of olefins. This catalytic aerobic oxidation reaction was designed based on experimental and spectroscopic evidence assessing the reduction of atmospheric oxygen using a ferric porphyrin complex and pinacolborane to form a ferric boroperoxo porphyrin complex as an oxidizing species. The ferric boroperoxo porphyrin complex can be utilized as an in-situ generated intermediate in the catalytic aerobic oxidation of alkenes under ambient conditions to form oxidation products that differ from those obtained using previously reported ferric porphyrin catalysis. Moreover, the mild reaction conditions allow chemoselective oxidation to be achieved.
- Kimura, Kento,Kurahashi, Takuya,Matsubara, Seijiro,Murano, Shunpei
-
supporting information
p. 2493 - 2497
(2021/12/29)
-
- Ni-Catalyzed Carboxylation of Aziridines en Route to β-Amino Acids
-
A Ni-catalyzed reductive carboxylation of N-substituted aziridines with CO2 at atmospheric pressure is disclosed. The protocol is characterized by its mild conditions, experimental ease, and exquisite chemo- and regioselectivity pattern, thus unlocking a new catalytic blueprint to access β-amino acids, important building blocks with considerable potential as peptidomimetics.
- Davies, Jacob,Janssen-Müller, Daniel,Zimin, Dmitry P.,Day, Craig S.,Yanagi, Tomoyuki,Elfert, Jonas,Martin, Ruben
-
p. 4949 - 4954
(2021/04/07)
-
- Expanding the Biocatalytic Toolbox with a New Type of ene/yne-Reductase from Cyclocybe aegerita
-
This study introduces a new type of ene/yne-reductase from Cyclocybe aegerita with a broad substrate scope including aliphatic and aromatic alkenes/alkynes from which aliphatic C8-alkenones, C8-alkenals and aromatic nitroalkenes were the preferred substrates. By comparing alkenes and alkynes, a ~2-fold lower conversion towards alkynes was observed. Furthermore, it could be shown that the alkyne reduction proceeds via a slow reduction of the alkyne to the alkene followed by a rapid reduction to the corresponding alkane. An accumulation of the alkene was not observed. Moreover, a regioselective reduction of the double bond in α,β-position of α,β,γ,δ-unsaturated alkenals took place. This as well as the first biocatalytic reduction of different aliphatic and aromatic alkynes to alkanes underlines the novelty of this biocatalyst. Thus with this study on the new ene-reductase CaeEnR1, a promising substrate scope is disclosed that describes conceivably a broad occurrence of such reactions within the chemical landscape.
- Karrer, Dominik,Gand, Martin,Rühl, Martin
-
p. 2191 - 2199
(2021/02/26)
-
- Selective upgrading of biomass-derived benzylic ketones by (formic acid)–Pd/HPC–NH2 system with high efficiency under ambient conditions
-
Upgrading biomass-derived phenolic compounds provides a valuable approach for the production of higher-value-added fuels and chemicals. However, most established catalytic systems display low hydrodeoxygenation (HDO) activities even under harsh reaction conditions. Here, we found that Pd supported on –NH2-modified hierarchically porous carbon (Pd/HPC–NH2) with formic acid (FA) as hydrogen source exhibits unprecedented performance for the selective HDO of benzylic ketones from crude lignin-derived oxygenates. Designed experiments and theoretical calculations reveal that the H+/H? species generated from FA decomposition accelerates nucleophilic attack on carbonyl carbon in benzylic ketones and the formate species formed via the esterification of intermediate alcohol with FA expedites the cleavage of C–O bonds, achieving a TOF of 152.5 h?1 at 30°C for vanillin upgrading, 15 times higher than that in traditional HDO processes (~10 h?1, 100°C–300°C). This work provides an intriguing green route to produce transportation fuels or valuable chemicals from only biomass under mild conditions.
- Chen, Yuzhuo,Chen, Zhirong,Gong, Yutong,Mao, Shanjun,Ning, Honghui,Wang, Yong,Wang, Zhenzhen
-
p. 3069 - 3084
(2021/11/16)
-
- Introducing the Dihydro-1,3-azaboroles: Convenient Entry by a Three-Component Reaction, Synthetic and Photophysical Application
-
The (Fmes)BH2·SMe2 reagent (7) reacts sequentially with an acetylene and, e.g., xylylisonitrile in a convenient three-component reaction to give a series of unprecedented dihydro-1,3-azaborole derivatives 16. The tolane-derived example 16a was deprotonated and used as a ligand in organometallic chemistry. Compounds 16 served as the starting materials for the straightforward synthesis of various dihydro-1,3-azaborinine derivatives by treatment with an isonitrile. Several diaryldihydro-1,3-azaboroles showed interesting photophysical properties such as aggregation-induced emission and high fluorescence quantum yields.
- Li, Jun,Daniliuc, Constantin G.,Kartha, Kalathil K.,Fernández, Gustavo,Kehr, Gerald,Erker, Gerhard
-
supporting information
p. 2059 - 2067
(2021/02/06)
-
- Synthesis of (±)-epi-Jungianol by the Gold(I)-Catalyzed Propargyl Claisen Rearrangement/Hydroarylation Cascade Reaction of Propargyl Vinyl Ethers
-
The synthesis of (±)-epi-jungianol was successfully carried out by the gold(I)-catalyzed propargyl Claisen rearrangement/hydroarylation cascade reaction of suitably substituted propargyl vinyl ethers as the key step to form the indane skeleton. Two routes were compared, which involved substrates with a different degree of substitution on the vinyl moiety. The one based on a propargyl vinyl ether bearing an unsubstituted vinyl moiety, despite entailing two additional steps, provided the final compound in a higher overall yield. A method for the preparation of acid sensitive propargyl vinyl ethers with an α-alkyl-substituted vinyl moiety and their reactivity under gold catalysis is also reported.
- Rinaldi, Antonia,Langé, Vittoria,Scarpi, Dina,Occhiato, Ernesto G.
-
p. 1266 - 1273
(2021/02/21)
-
- Iron-catalyzed domino decarboxylation-oxidation of α,β-unsaturated carboxylic acids enabled aldehyde C-H methylation
-
A practical and general iron-catalyzed domino decarboxylation-oxidation of α,β-unsaturated carboxylic acids enabling aldehyde C-H methylation for the synthesis of methyl ketones has been developed. This mild, operationally simple method uses ambient air as the sole oxidant and tolerates sensitive functional groups for the late-stage functionalization of complex natural-product-derived and polyfunctionalized molecules.
- Gong, Pei-Xue,Xu, Fangning,Cheng, Lu,Gong, Xu,Zhang, Jie,Gu, Wei-Jin,Han, Wei
-
supporting information
p. 5905 - 5908
(2021/06/18)
-
- Oxidative Cleavage of Alkenes by O2with a Non-Heme Manganese Catalyst
-
The oxidative cleavage of C═C double bonds with molecular oxygen to produce carbonyl compounds is an important transformation in chemical and pharmaceutical synthesis. In nature, enzymes containing the first-row transition metals, particularly heme and non-heme iron-dependent enzymes, readily activate O2 and oxidatively cleave C═C bonds with exquisite precision under ambient conditions. The reaction remains challenging for synthetic chemists, however. There are only a small number of known synthetic metal catalysts that allow for the oxidative cleavage of alkenes at an atmospheric pressure of O2, with very few known to catalyze the cleavage of nonactivated alkenes. In this work, we describe a light-driven, Mn-catalyzed protocol for the selective oxidation of alkenes to carbonyls under 1 atm of O2. For the first time, aromatic as well as various nonactivated aliphatic alkenes could be oxidized to afford ketones and aldehydes under clean, mild conditions with a first row, biorelevant metal catalyst. Moreover, the protocol shows a very good functional group tolerance. Mechanistic investigation suggests that Mn-oxo species, including an asymmetric, mixed-valent bis(μ-oxo)-Mn(III,IV) complex, are involved in the oxidation, and the solvent methanol participates in O2 activation that leads to the formation of the oxo species.
- Bennett, Elliot L.,Brookfield, Adam,Guan, Renpeng,Huang, Zhiliang,Mcinnes, Eric J. L.,Robertson, Craig M.,Shanmugam, Muralidharan,Xiao, Jianliang
-
supporting information
p. 10005 - 10013
(2021/07/19)
-
- Organometallic Synthesis of Bimetallic Cobalt-Rhodium Nanoparticles in Supported Ionic Liquid Phases (CoxRh100?x@SILP) as Catalysts for the Selective Hydrogenation of Multifunctional Aromatic Substrates
-
The synthesis, characterization, and catalytic properties of bimetallic cobalt-rhodium nanoparticles of defined Co:Rh ratios immobilized in an imidazolium-based supported ionic liquid phase (CoxRh100?x@SILP) are described. Following an organometallic approach, precise control of the Co:Rh ratios is accomplished. Electron microscopy and X-ray absorption spectroscopy confirm the formation of small, well-dispersed, and homogeneously alloyed zero-valent bimetallic nanoparticles in all investigated materials. Benzylideneacetone and various bicyclic heteroaromatics are used as chemical probes to investigate the hydrogenation performances of the CoxRh100?x@SILP materials. The Co:Rh ratio of the nanoparticles is found to have a critical influence on observed activity and selectivity, with clear synergistic effects arising from the combination of the noble metal and its 3d congener. In particular, the ability of CoxRh100?x@SILP catalysts to hydrogenate 6-membered aromatic rings is found to experience a remarkable sharp switch in a narrow composition range between Co25Rh75 (full ring hydrogenation) and Co30Rh70 (no ring hydrogenation).
- Rengshausen, Simon,Van Stappen, Casey,Levin, Natalia,Tricard, Simon,Luska, Kylie L.,DeBeer, Serena,Chaudret, Bruno,Bordet, Alexis,Leitner, Walter
-
-
- Ruthenium-Catalyzed Oxidative Cross-Coupling Reaction of Activated Olefins with Vinyl Boronates for the Synthesis of (E, E)-1,3-Dienes
-
An oxidative cross-coupling reaction between activated olefins and vinyl boronate derivatives has been developed for the highly stereoselective construction of synthetically useful (E,E)-1,3-dienes. The highlight of this reaction is that exclusive stereoselectivity (only E,E-isomer) was achieved from a base-free, ligand-free, and mild catalytic condition with a less expensive [RuCl2(p-cymene)]2 catalyst.
- Dethe, Dattatraya H.,Beeralingappa, Nagabhushana C.,Uike, Amar
-
p. 3444 - 3455
(2021/02/16)
-
- Selective Construction of C?C and C=C Bonds by Manganese Catalyzed Coupling of Alcohols with Phosphorus Ylides
-
Herein, we report the manganese catalyzed coupling of alcohols with phosphorus ylides. The selectivity in the coupling of primary alcohols with phosphorus ylides to form carbon-carbon single (C?C) and carbon-carbon double (C=C) bonds can be controlled by the ligands. In the conversion of more challenging secondary alcohols with phosphorus ylides the selectivity towards the formation of C?C vs. C=C bonds can be controlled by the reaction conditions, namely the amount of base. The scope and limitations of the coupling reactions were thoroughly evaluated by the conversion of 21 alcohols and 15 ylides. Notably, compared to existing methods, which are based on precious metal complexes as catalysts, the present catalytic system is based on earth abundant manganese catalysts. The reaction can also be performed in a sequential one-pot reaction generating the phosphorus ylide in situ followed manganese catalyzed C?C and C=C bond formation. Mechanistic studies suggest that the C?C bond was generated via a borrowing hydrogen pathway and the C=C bond formation followed an acceptorless dehydrogenative coupling pathway. (Figure presented.).
- Liu, Xin,Werner, Thomas
-
supporting information
p. 1096 - 1104
(2020/12/31)
-
- Engineering the large pocket of an (S)-selective transaminase for asymmetric synthesis of (S)-1-amino-1-phenylpropane
-
Amine transaminases offer an environmentally benign chiral amine asymmetric synthesis route. However, their catalytic efficiency towards bulky chiral amine asymmetric synthesis is limited by the natural geometric structure of the small pocket, representing a great challenge for industrial applications. Here, we rationally engineered the large binding pocket of an (S)-selective ?-transaminase BPTA fromParaburkholderia phymatumto relieve the inherent restriction caused by the small pocket and efficiently transform the prochiral aryl alkyl ketone 1-propiophenone with a small substituent larger than the methyl group. Based on combined molecular docking and dynamic simulation analyses, we identified a non-classical substrate conformation, located in the active site with steric hindrance and undesired interactions, to be responsible for the low catalytic efficiency. By relieving the steric barrier with W82A, we improved the specific activity by 14-times compared to WT. A p-p stacking interaction was then introduced by M78F and I284F to strengthen the binding affinity with a large binding pocket to balance the undesired interactions generated by F44. T440Q further enhanced the substrate affinity by providing a more hydrophobic and flexible environment close to the active site entry. Finally, we constructed a quadruple variant M78F/W82A/I284F/T440Q to generate the most productive substrate conformation. The 1-propiophenone catalytic efficiency of the mutant was enhanced by more than 470-times in terms ofkcat/KM, and the conversion increased from 1.3 to 94.4% compared with that of WT, without any stereoselectivity loss (ee > 99.9%). Meanwhile, the obtained mutant also showed significant activity improvements towards various aryl alkyl ketones with a small substituent larger than the methyl group ranging between 104- and 230-fold, demonstrating great potential for the efficient synthesis of enantiopure aryl alkyl amines with steric hindrance in the small binding pocket.
- Liu, He,Wang, Hualei,Wei, Dongzhi,Xie, Youyu,Xu, Feng,Xu, Xiangyang,Yang, Lin
-
p. 2461 - 2470
(2021/04/22)
-
- N-phenyl-N'-(1-methyl-4-phenyl) p-phenylenediamine and preparation method thereof
-
The invention discloses N-phenyl-N'-(1-methyl-4-phenyl) p-phenylenediamine and a preparation method thereof, and relates to the technical field of fine chemical engineering, in particular to N-phenyl-N'-(1-methyl-4-phenyl)p-phenylenediamine and a preparation method thereof. The method comprises the following steps: step 1, dissolving sodium alkoxide and ethyl acetoacetate into an alcohol solvent, heating, dropwise adding benzyl chloride, filtering to remove sodium chloride after the reaction is completed, and then distilling to remove the alcohol solvent; adding liquid caustic soda to carry out reflux reaction, heating and stirring to carry out decarboxylation reaction, and carrying out reduced pressure distillation on an organic phase to obtain 4-phenyl-2-butanone; and step 2, adding 4-phenyl-2-butanone, a catalyst and 4-aminodiphenylamine into a high-pressure reaction kettle, heating, introducing hydrogen while stirring to carry out hydrogenation reduction reaction, filtering to remove the catalyst after the reaction is completed, and decompressing to remove the solvent methanol and water. The invention has the advantages of favorable static or dynamic ozone erosion resistance, simple production process and low cost.
- -
-
Paragraph 0025-0030; 0034-0039; 0043-0046; 0049-0051
(2021/08/14)
-
- Chromium carbides and cyclopropenylidenes
-
Carbon tetrabromide can be reduced with CrBr2in THF to form a dinuclear carbido complex, [CrBr2(thf)2)][CrBr2(thf)3](μ-C), along with formation of [CrBr3(thf)3]. An X-ray diffraction (XRD) study of the pyridine adduct displayed a dinuclear structure bridged by a carbido ligand between 5- and 6-coordinate chromium centers. The carbido complex reacted with two equivalents of aldehydes to form α,β-unsaturated ketones. Treatment of the carbido complex with alkenes resulted in a formal double-cyclopropanation of alkenes by the carbido moiety to afford spiropentanes. Isotope labeling studies using a13C-enriched carbido complex, [CrBr2(thf)2)][CrBr2(thf)3](μ-13C), identified that the quaternary carbon in the spiropentane framework was delivered by carbide transfer from the carbido complex. Terminal and internal alkynes also reacted with the carbido complex to form cyclopropenylidene complexes. A solid-state structure of the diethylcyclopropenylidene complex, prepared from 3-hexyne, showed a mononuclear cyclopropenylidene chromium(iii) structure.
- Irifune, Keiichi,Kurogi, Takashi,Takai, Kazuhiko
-
p. 14281 - 14287
(2021/11/12)
-
- Mechanochemical, Water-Assisted Asymmetric Transfer Hydrogenation of Ketones Using Ruthenium Catalyst
-
Asymmetric catalytic reactions are among the most convenient and environmentally benign methods to obtain optically pure compounds. The aim of this study was to develop a green system for the asymmetric transfer hydrogenation of ketones, applying chiral Ru catalyst in aqueous media and mechanochemical energy transmission. Using a ball mill we have optimized the milling parameters in the transfer hydrogenation of acetophenone followed by reduction of various substituted derivatives. The scope of the method was extended to carbo- and heterocyclic ketones. The scale-up of the developed system was successful, the optically enriched alcohols could be obtained in high yields. The developed mechanochemical system provides TOFs up to 168 h?1. Our present study is the first in which mechanochemically activated enantioselective transfer hydrogenations were carried out, thus, may be a useful guide for the practical synthesis of optically pure chiral secondary alcohols.
- Kolcsár, Vanessza Judit,Sz?ll?si, Gy?rgy
-
-
- Simultaneous Preparation of (S)-2-Aminobutane and d -Alanine or d -Homoalanine via Biocatalytic Transamination at High Substrate Concentration
-
(S)-2-Aminobutane, d-alanine, and d-homoalanine are important intermediates for the production of various active pharmaceutical ingredients and food additives. The preparation of these small chiral amine or amino acids with high water solubility still demands searching for efficient methods. In this work, we identified an ω-transaminase (ω-TA) from Sinirhodobacter hungdaonensis (ShdTA) that catalyzed the kinetic resolution of racemic 2-aminobutane at a concentration of 800 mM using pyruvate as the amino acceptor, leading to the simultaneous isolation of enantiopure (S)-2-aminobutane and d-alanine in 46% and 90% yield, respectively. In addition, (S)-2-aminobutane (98% ee) and d-homoalanine (99% ee) were isolated in 45% and 93% yield, respectively, in the kinetic resolution of racemic 2-aminobutane at a concentration of 400 mM coupled with deamination of l-threonine by threonine deaminase. We thus developed a biocatalytic process for the practical synthesis of these valuable small chiral amine and d-amino acids.
- Li, Jianjiong,Wang, Yingang,Wu, Qiaqing,Yao, Peiyuan,Yu, Shanshan,Zhu, Dunming
-
supporting information
(2022/03/01)
-
- Reduction of α,β-unsaturated carbonyl compounds and 1,3-diketones in aqueous media, using a raney ni-al alloy
-
The treatment of α,β-unsaturated carbonyl compounds and 1,3-diketones with Raney Ni-Al alloy in aqueous media yielded as major reaction products the corresponding saturated alcohols and/or the corresponding hydrocarbons, in a complete transformation of the starting material.
- Simion, Cristian,Mitoma, Yoshiharu,Katayama, Yumi,Simion, Alina Marieta
-
-
- Method for preparing benzalacetone
-
The invention provides a method for preparing benzalacetone. According to the method, acetone and benzaldehyde are used as raw materials, CaO-MgO loaded with potassium carbonate is used as a catalyst,butylated hydroxytoluene is used as a polymerization inhibitor, and aldol condensation is conducted to obtain benzalacetone; product yield and product purity reach 91% or above and 99% or above respectively; and in the preparation process, the molar ratio of benzaldehyde to acetone is 1: (1.7-2.1), the usage amount of CaO-MgO loaded with potassium carbonate accounts for 5%-10% of the mass of acetone, the usage amount of the polymerization inhibitor butylated hydroxytoluene accounts for 0.1%-0.3% of the mass of benzaldehyde, and a molar ratio of magnesium chloride to calcium chloride is (6-8):1. The preparation method is simple, has the characteristics of mild reaction conditions, easy separation and recovery of the catalyst, high product yield, few byproducts and the like, and can easilyrealize industrial production.
- -
-
Paragraph 0011
(2020/03/02)
-
- Ruthenium [NNN] and [NCN]-type pincer complexes with phosphine coligands: synthesis, structures and catalytic applications
-
A series of ruthenium [NNN]- or [NCN]-type complexes (3–7) bearing PPh3 ancillary ligands have been synthesized from pyridine- or phenylene-bridged bis(triazoles) 1 and 2. In the case of [NNN]-pincer complex 3, an unusual and unexpected cis-orientation adopted by two sterically demanding PPh3 ligands was observed, and such configuration proved to be unchanged in solution for a long time. By contrast and as expected, the two phosphines are found to be trans to each other in the case of [NCN]-type pincer complex 4, but an oxidation of RuII center to RuIII occurred. Complex cis-3 underwent ligand exchanges leading to the formations of diphosphine derivatives 5 and 6. As a representative, cis-3 was treated with the base in isopropanol affording a mixture of Ru–hydrido complexes with various phosphine binding modes, one of which (trans-7) bearing two trans-standing phosphines has been successfully isolated and fully characterized. The catalytic performances of all newly synthesized Ru complexes have been examined and compared in transfer hydrogenations of ketones and enones, in which mono-phosphine complexes proved to be significantly superior to their diphosphine counterparts. The catalytic process proved to involve Ru–H key intermediates, but the trans-oriented Ru–H species is unlikely to be the main catalytic contributor. In particular, the best performer cis-3 exhibits high chemoselectivity in certain cases catalyzing α,β-unsaturated ketones, whose behavior is quite different compared to most precedents.
- Zhang, Bo,Wang, Haiying,Yan, Xuechao,Duan, Yu-Ai,Guo, Shuai,Luo, Fei-Xian
-
-
- Catalytic Activity of a Zr MOF Containing POCOP-Pd Pincer Complexes
-
A metal-organic framework assembled from POCOP-Pd pincer complex metallolinkers (1-PdBF4, Zr6O4(OH)4(L-PdMeCN)3(BF4)3, L = (2,6-(OPAr2)2C6H3, Ar = p-C6H4CO2-) has been generated via postsynthetic oxidative I-/BF4- ligand exchange with NOBF4. 1-PdBF4 catalyzes a range of organic transformations, including transfer hydrogenation of unsaturated organic substrates, terminal alkyne hydration, and intramolecular hydroarylation of alkynes. The homogeneous analogue, tBu4POCOP-PdBF4, shows poor catalytic activity for transfer hydrogenation and alkyne hydration and decomposes under the catalytic reaction conditions. Solubility limitations and catalyst deactivation pathways observed for the homogeneous pincer complex propound the advantages of using porous solid supports to immobilize organometallic species.
- Kassie, Abebu A.,Wade, Casey R.
-
p. 2214 - 2221
(2020/07/06)
-
- Glycerol Boosted Rh-Catalyzed Hydroaminomethylation Reaction: A Mechanistic Insight
-
We report a Rh-catalyzed hydroaminomethylation reaction of terminal alkenes in glycerol that proceeds efficiently under mild conditions to produce the corresponding amines in relatively high selectivity towards linear amines, moderate to excellent yields by using a low catalyst loading (1 mol % [Rh], 2 mol % phosphine) and relative low pressure (H2/CO, 1:1, total pressure 10 bar). This work sheds light on the importance of glycerol in enabling enamine reduction via hydrogen transfer. Moreover, evidence for the crucial role of Rh as chemoselective catalyst in the condensation step has been obtained for the first time in the frame of the hydroaminomethylation reaction by precluding deleterious aldol condensation reactions. The hydroaminomethylation proceeds under a molecular regime; the outcome of catalytically active species into metal-based nanoparticles renders the catalytic system inactive.
- Serrano-Maldonado, Alejandro,Dang-Bao, Trung,Favier, Isabelle,Guerrero-Ríos, Itzel,Pla, Daniel,Gómez, Montserrat
-
supporting information
p. 12553 - 12559
(2020/09/09)
-
- Pd-catalyzed oxidative Heck-type arylation of vinyl ketones, alkenes, and acrylates with Sb-aryl-tetrahydrodibenz[c,f][1,5]azastibocines
-
The Pd-catalyzed cross-coupling reactions of Sb-aryl-1,5-azastibocines with alkenes are described. The reactions of azastibocines with alkenes such as vinyl ketones, alkenes, and acrylates in the presence of 10 mol% PdCl2 at 80 °C in DMA under aerobic conditions produced Heck adducts in moderate-to-excellent yields. Single-crystal X-ray and NMR analysis revealed that the aryl donors in this reaction, the Sb-aryl-1,5-azastibocines, are hypervalent compounds that display N–Sb intramolecular non-bonding interaction. These are the first examples of Pd-catalyzed Heck-type arylations using heterocyclic hypervalent organoantimony compounds. Although the reactions proceeded efficiently with the azastibocines, they hardly progressed with trivalent and pentavalent triarylantimony reagents.
- Murata, Yuki,Kakusawa, Naoki,Arakawa, Yukako,Hayashi, Yukako,Morinaga, Shun,Ueda, Masaaki,Hyodo, Tadashi,Matsumura, Mio,Yamaguchi, Kentaro,Kurita, Jyoji,Yasuike, Shuji
-
-
- Protocol for Visible-Light-Promoted Desulfonylation Reactions Utilizing Catalytic Benzimidazolium Aryloxide Betaines and Stoichiometric Hydride Donor Reagents
-
An unprecedented photocatalytic system consisting of benzimidazolium aryloxide betaines (BI+-ArO-) and stoichiometric hydride reducing reagents was developed for carrying out desulfonylation reactions of N-sulfonyl-indoles,-amides, and-amines, and α-sulfonyl ketones. Measurements of absorption spectra and cyclic voltammograms as well as density functional theory (DFT) calculations were carried out to gain mechanistic information. In the catalytic system, visible-light-activated benzimidazoline aryloxides (BIH-ArO-), generated in situ by hydride reduction of the corresponding betaines BI+-ArO-, donate both an electron and a hydrogen atom to the substrates. A modified protocol was also developed so that a catalytic quantity of more easily prepared hydroxyaryl benzimidazolines (BIH-ArOH) is used along with a stoichiometric hydride donor to promote the photochemical desulfonylation reactions.
- Hasegawa, Eietsu,Tanaka, Tsukasa,Izumiya, Norihiro,Kiuchi, Takehiro,Ooe, Yuuki,Iwamoto, Hajime,Takizawa, Shin-Ya,Murata, Shigeru
-
p. 4344 - 4353
(2020/04/09)
-
- Aqueous extract of Shikakai; a green solvent for deoximation reaction: Mechanistic approach from experimental to theoretical
-
This article describes a green method for regeneration of carbonyl compounds from various types of oxime compounds under microwave radiation using I2 and aqueous saponin solution isolated from Shikakai. Effect of saponin concentration on yield percentage of regenerated different types of carbonyl compounds has been discussed. A correlation has been established between saponin concentration and yield percentage of carbonyl compounds. Mechanism of interaction between oxime and saponin is established on the basis of density functional theory. In addition, the quantum chemical parameters for saponin have been determined. Furthermore, electrostatic surface analysis of the saponin is carried out to confirm the mechanism of interaction between saponin and oximes.
- Das, Debadutta,Kudrat-E-Zahan, Md.,Mahal, Ahmed,Mohapatra, Ranjan K.,Parhi, Pankaj K.,Sahu, Raghaba,Sarangi, Ashish K.
-
-
- Ruthenium-Catalyzed Dehydrogenation of Alcohols with Carbodiimide via a Hydrogen Transfer Mechanism
-
Ruthenium-catalyzed oxidative dehydrogenation of alcohols using carbodiimide as an efficient hydrogen acceptor has been developed. The protocol exhibits wide substrate scope with good to excellent yields. The results of the kinetic analysis indicated that the reaction mechanism includes the hydrogen transfer process and that the addition of carbodiimide is essential for the reaction system, and the resulting amidine also could react as a hydrogen acceptor.
- Sueki, Shunsuke,Matsuyama, Mizuki,Watanabe, Azumi,Kanemaki, Arata,Katakawa, Kazuaki,Anada, Masahiro
-
p. 4878 - 4885
(2020/06/02)
-
- Iron(II)-Catalyzed Biomimetic Aerobic Oxidation of Alcohols
-
We report the first FeII-catalyzed biomimetic aerobic oxidation of alcohols. The principle of this oxidation, which involves several electron-transfer steps, is reminiscent of biological oxidation in the respiratory chain. The electron transfer from the alcohol to molecular oxygen occurs with the aid of three coupled catalytic redox systems, leading to a low-energy pathway. An iron transfer-hydrogenation complex was utilized as a substrate-selective dehydrogenation catalyst, along with an electron-rich quinone and an oxygen-activating Co(salen)-type complex as electron-transfer mediators. Various primary and secondary alcohols were oxidized in air to the corresponding aldehydes or ketones with this method in good to excellent yields.
- B?ckvall, Jan-E.,Guemundsson, Arnar,Schlipk?ter, Kim Elisabeth
-
supporting information
p. 5403 - 5406
(2020/02/27)
-
- Metal-Organic Framework Based on Heptanuclear Cu-O Clusters and Its Application as a Recyclable Photocatalyst for Stepwise Selective Catalysis
-
Visible-light driven photoreactions using metal-organic frameworks (MOFs) as catalysts are promising with regard to their environmental friendly features such as the use of renewable and sustainable energy of visible light and potential catalyst recyclability. To develop potential heterogeneous photocatalysts, a family of three copper(II) coordination polymers bearing different Cu-O assemblies have been synthesized with the ligand 4,4-disulfo-[1,1-biphenyl]-2,2-dicarboxylate acid (H4DSDC), namely, {[Cu7(DSDC)2(OH)6(H2O)10]·xH2O}n (1), {[Cu4(DSDC)(4,4-bpy)2(OH)4]·2H2O}n (2), and {Cu2(DSDC)(phen)2(H2O)2}n (3) (4,4-bpy = 4,4-bipyridine and phen = 1,10-phenanthroline). Complex 1 represents a metal-organic framework featuring a NbO type topology constructed from the infinite linkage of heptanuclear [Cu7(μ3-OH)6(H2O)10]8+ clusters by deprotonated DSDC4- ligands, comprising one-dimensional hexagonal channels of a diameter around 11 ? that are filled with water molecules. The infinite waving {[Cu2(OH)2]2+}n ladderlike chains in complex 2 are bridged by DSDC4- and 4,4-bpy ligands into a three-dimensional framework. A two-dimensional layered structure is formed in complex 3 due to the existence of terminal phenanthroline ligands. All of the coordination polymers 1-3 are able to catalyze the visible-light driven oxidation of alcohols at mild conditions using hydrogen peroxide as an oxidant, in which complex 1 demonstrates satisfactory efficiency. Significantly for this photoreaction catalyzed by 1, the extent of oxidation over aryl primary alcohols is fully controllable with time-resolved product selectivity, giving either corresponding aldehydes or carboxylate acids in good yields. It is also remarkable that the photocatalyst could be recovered almost quantitatively on completion of the catalytic cycle without any structure change, and could be recycled for catalytic use for at least five cycles with constant efficiency. This photocatalyst with time-resolved selectivity for different products may provide new insight into the design and development of novel catalytic systems.
- Zhou, Jie,Huang-Fu, Xu,Huang, Yang-Ying,Cao, Chu-Ning,Han, Jie,Zhao, Xiao-Li,Chen, Xu-Dong
-
p. 254 - 263
(2019/12/04)
-
- Efficient aerial oxidation of different types of alcohols using ZnO nanoparticle–MnCO3-graphene oxide composites
-
Graphene–metal nanocomposites have been found to remarkably enhance the catalytic performance of metal nanoparticle-based catalysts. In continuation of our previous report, in which highly reduced graphene oxide (HRG)-based nanocomposites were synthesized and evaluated, we present nanocomposites of graphene oxide (GRO) and ZnO nanoparticle-doped MnCO3 ([ZnO–MnCO3/(1%)GRO]) synthesized via a facile, straightforward co-precipitation technique. Interestingly, it was noticed that the incorporation of GRO in the catalytic system could noticeably improve the catalytic efficiency compared to a catalyst (ZnO–MnCO3) without GRO, for aerial oxidation of benzyl alcohol (BzOH) employing O2 as a nature-friendly oxidant under base-free conditions. The impacts of various reaction factors were thoroughly explored to optimize reaction conditions using oxidation of BzOH to benzaldehyde (BzH) as a model substrate. The catalysts were characterized using X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, Energy dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET), and Raman spectroscopy. The (1%)ZnO–MnCO3/(1%)GRO exhibited significant specific activity (67 mmol.g?1.hr?1) with full convversion of BzOH and >99% BzH selectivity within just 6 min. The catalytic efficiency of the (1%)ZnO–MnCO3/(1%)GRO nanocomposite was significantly better than the (1%)ZnO–MnCO3/(1%)HRG and (1%)ZnO–MnCO3 catalysts, presumably due to the existence of oxygen-possessing groups on the GRO surface and as well as a very high surface area that could have been instrumental in uniformly dispersing the active sites of the catalyst, i.e., ZnO–MnCO3. Under optimum circumstances, various kinds of alcohols were selectively transformed to respective carbonyls with full convertibility over the (1%)ZnO–MnCO3/(1%)GRO catalyst. Furthermore, the highly effective (1%)ZnO–MnCO3/(1%)GRO catalyst could be successfully reused and recycled over five consecutive runs with a marginal reduction in its performance and selectivity.
- Adil, Syed Farooq,Assal, Mohamed E.,Shaik, Mohammed Rafi,Kuniyil, Mufsir,Hashmi, Azhar,Khan, Mujeeb,Khan, Aslam,Tahir, Muhammad Nawaz,Al-Warthan, Abdulrahman,Siddiqui, Mohammed Rafiq H.
-
-
- Aerobic oxidation of alcohols catalyzed by in situ generated gold nanoparticles inside the channels of periodic mesoporous organosilica with ionic liquid framework
-
In situ generated gold nanoparticles inside the nanospaces of periodic mesoporous organosilica with an imidazolium framework (Au?PMO-IL) were found to be highly active, selective, and reusable catalysts for the aerobic oxidation of activated and nonactivated alcohols under mild reaction conditions. The catalyst was characterized by nitrogen adsorption-desorption measurement, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), elemental analysis (EA), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The catalyst exhibited excellent catalytic activity in the presence of either Cs2CO3 (35 °C) or K2CO3 (60 °C) as reaction bases in toluene as a reaction solvent. Under both reaction conditions, various types of alcohols (up to 35 examples) including activated benzylic, primary and secondary aliphatic, heterocyclic, and challenging cyclic aliphatic alcohols converted to the expected carbonyl compounds in good to excellent yields and selectivity. The catalyst was also recovered and reused for at least seven reaction cycles. Data from three independent leaching tests indicated that amounts of leached gold particles were negligible (0.2 ppm). It is believed that the combination of bridged imidazolium groups and confined nanospaces of PMO-IL might be a major reason explaining the remarkable stabilization and homogeneous distribution of in situ generated gold nanoparticles, thus resulting in the highly active and recyclable catalyst system.
- Bigdeli, Akram,Karimi, Babak,Khodadadi Karimvand, Somaiyeh,Khorasani, Mojtaba,Safari, Ali Asghar,Vali, Hojatollah
-
supporting information
p. 70 - 79
(2020/06/08)
-
- Chemoselective Oxidation of p-Methoxybenzyl Ethers by an Electronically Tuned Nitroxyl Radical Catalyst
-
The oxidation of p-methoxy benzyl (PMB) ethers was achieved using nitroxyl radical catalyst 1, which contains electron-withdrawing ester groups adjacent to the nitroxyl group. The oxidative deprotection of the PMB moieties on the hydroxy groups was observed upon treatment of 1 with 1 equiv of the co-oxidant phenyl iodonium bis(trifluoroacetate) (PIFA). The corresponding carbonyl compounds were obtained by treating the PMB-protected alcohols with 1 and an excess of PIFA.
- Hamada, Shohei,Sugimoto, Koichi,Elboray, Elghareeb E.,Kawabata, Takeo,Furuta, Takumi
-
p. 5486 - 5490
(2020/07/24)
-
- Deracemization and Stereoinversion of Alcohols Using Two Mutants of Secondary Alcohol Dehydrogenase from Thermoanaerobacter pseudoethanolicus
-
We developed a one-pot sequential two-step deracemization approach to chiral alcohols using two mutants of Thermoanaerobacter pseudoethanolicus secondary alcohol dehydrogenase (TeSADH). This approach relies on consecutive non-stereospecific oxidation of alcohols and stereoselective reduction of their prochiral ketones using two mutants of TeSADH with poor and good stereoselectivities, respectively. More specifically, W110G TeSADH enables a non-stereospecific oxidation of alcohol racemates to their corresponding prochiral ketones, followed by W110V TeSADH-catalyzed stereoselective reduction of the resultant ketone intermediates to enantiopure (S)-configured alcohols in up to > 99 percent enantiomeric excess. A heat treatment after the oxidation step was required to avoid the interference of the marginally stereoselective W110G TeSADH in the reduction step; this heat treatment was eliminated by using sol-gel encapsulated W110G TeSADH in the oxidation step. Moreover, this bi-enzymatic approach was implemented in the stereoinversion of (R)-configured alcohols, and (S)-configured alcohols with up to > 99 percent enantiomeric excess were obtained by this Mitsunobu-like stereoinversion reaction.
- Hamdan, Samir M.,Musa, Musa M.,Nafiu, Sodiq A.,Takahashi, Etsuko,Takahashi, Masateru
-
-
- A Simple Biosystem for the High-Yielding Cascade Conversion of Racemic Alcohols to Enantiopure Amines
-
The amination of racemic alcohols to produce enantiopure amines is an important green chemistry reaction for pharmaceutical manufacturing, requiring simple and efficient solutions. Herein, we report the development of a cascade biotransformation to aminate racemic alcohols. This cascade utilizes an ambidextrous alcohol dehydrogenase (ADH) to oxidize a racemic alcohol, an enantioselective transaminase (TA) to convert the ketone intermediate to chiral amine, and isopropylamine to recycle PMP and NAD+ cofactors via the reversed cascade reactions. The concept was proven by using an ambidextrous CpSADH-W286A engineered from (S)-enantioselective CpSADH as the first example of evolving ambidextrous ADHs, an enantioselective BmTA, and isopropylamine. A biosystem containing isopropylamine and E. coli (CpSADH-W286A/BmTA) expressing the two enzymes was developed for the amination of racemic alcohols to produce eight useful and high-value (S)-amines in 72–99 % yield and 98–99 % ee, providing with a simple and practical solution to this type of reaction.
- Li, Zhi,Tian, Kaiyuan
-
supporting information
p. 21745 - 21751
(2020/09/21)
-
- Modular O-: Vs. N-coordination of pyridylidene amide ligands to iron determines activity in alcohol oxidation catalysis
-
A family of polydentate pyridine-substituted pyridylidene amide (PYA) complexes bound to iron(ii) was developed. The variation of the coordination set from NN-bidentate PYA to tridentate pincer-type pyPYA2 systems (pyPYA2 = 2,6-bis(PYA)pyridine) had a large influence on the binding mode to iron(ii), including a change from the N- to rare O-coordination of the PYA site and a concomitant shift of the predominant ligand resonance structure. These binding mode variations invoke changes in the reactivity of the complexes, which were probed in the peroxide-mediated oxidation of 1-phenylethanol to acetophenone. A comparison with uncomplexed FeCl2 indicated that bidentate NN coordination is unstable and presumably leads to the dissociation of FeCl2. In contrast, the tridentate ligand binding is robust. Remarkably, the tridentate PYA pincer coordination inhibits catalytic activity in the NNN binding mode, while the ONO coordination greatly enhances catalytic performance. Under optimized conditions, the bis-ligated ONO pincer iron complex [Fe(pyPYA2)2][2PF6] reaches full conversion within one hour (0.5 mol% catalyst loading) and under dilute conditions turnover numbers over 20?000 (0.005 mol% catalyst loading). This journal is
- Verhoeven, Dide G. A.,Albrecht, Martin
-
supporting information
p. 17674 - 17682
(2020/12/30)
-