- Highly active rhodium/phosphorus catalytic system for the hydroformylation of α-methylstyrene
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Rhodium catalyzed hydroformylation of α-methylstyrene was investigated in the presence of monodentate phosphine ligands L1-L6. We found that the phosphine with good π-acceptability could efficiently improve the activity of the α-methylstyrene hydroformylation. The big steric hindrance of α-C in α-methylstyrene enhanced the regioselectivity towards the linear aldehyde, which resulted in 3-phenylbutanal as the predominant product (>99.0%). When tris(N-pyrrolyl)phosphine (L1) modified Rh(acac)(CO)2 was employed as the catalyst, the TOF could reach up to 5786 h-1 in the α-methylstyrene hydroformylation at relatively mild conditions (110 °C, 6 MPa).
- Zheng, Xue-Li,Zheng, Cong-Ye,Zhou, Fan-Ding,Fu, Hai-Yan,Yuan, Mao-Lin,Li, Rui-Xiang,Xu, Bin,Chen, Hua
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Read Online
- Pd-Catalyzed Arylation of 1,2-Amino Alcohol Derivatives via β-Carbon Elimination
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Herein, we describe a Pd-catalyzed arylation of 1,2-amino alcohols with aryl halides enabled by a retroallylation manifold. This protocol constitutes a new entry point to β-arylated aldehydes via the intermediacy of in situ generated enamine intermediates. The protocol is characterized by its exquisite regioselectivity profile and broad substrate scope including challenging substrate combinations even in an enantioselective manner.
- Martin, Ruben,Pericàs, Miquel A.,Sau, Miriam
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supporting information
p. 52 - 56
(2021/12/29)
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- Linear Selective Hydroformylation of 2-Arylpropenes Using Water-Soluble Rh-PNP Complex: Straightforward Access to 3-Aryl-Butyraldehydes
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Straightforward access to 3-aryl-butyraldehydes was developed through the aqueous biphasic Rh-catalyzed hydroformylation of 2-arylpropenes using a water-soluble PNP ligand. This protocol accommodates broad substrate scope with high yields (up to 95 %) and excellent linear selectivity (>99 : 1 b/l ratio). The synthesis of rac-ar-turmerone and the gram-scale hydroformylation further demonstrated the practical nature of this method.
- Ru, Tong,Liang, Guanfeng,Zhang, Luyun,Ning, Yingtang,Chen, Fen-Er
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p. 5073 - 5077
(2021/11/09)
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- Optimized iminium-catalysed 1,4-reductions inside the resorcinarene capsule: achieving >90% ee with proline as catalyst
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In previous work, we demonstrated that iminium-catalysed 1,4-reductions inside the supramolecular resorcinarene capsule display increased enantioselectivities as compared to their regular solution counterparts. Utilizing proline as the chiral catalyst, enantioselectivities remained below 80% ee. In this study, the reaction conditions were optimized by determining the optimal capsule loading and HCl content. Additionally, it was found that alcohol additives increase the enantioselectivity of the capsule-catalysed reaction. As a result, we report enantioselectivities of up to 92% ee for iminium-catalysed 1,4-reductions relying on proline as the sole chiral source. This is of high interest, as proline is unable to deliver high enantioselectivities for 1,4-reductions in a regular solution setting. Investigations into the role of the alcohol additive revealed a dual role: it not only slowed down the background reaction but also increased the capsule-catalysed reaction rate.
- Sokolova, Daria,Tiefenbacher, Konrad
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p. 24607 - 24612
(2021/07/29)
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- Method for preparing aldehyde/ketone by breaking C-C key
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The invention discloses a method for preparing aldehyde/ketone by breaking C-C bonds, and the method comprises the following steps of anaerobic condition. In an organic solvent system, an alcohol is used as a reaction raw material, and the C-C bond is selectively broken under the common action of an iron catalyst, an organic base and an additive to obtain aldehyde/ketone. The method is low in cost, easy to obtain, wide in substrate range, simple and product in post-treatment and high in purity, a new synthetic route and a method are developed for an aldehyde ketone compound, and the method has good application potential and research value.
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Paragraph 0095-0098
(2021/11/19)
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- Iron-Catalyzed C-C Single-Bond Cleavage of Alcohols
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An iron-catalyzed deconstruction/hydrogenation reaction of alcohols through C-C bond cleavage is developed through photocatalysis, to produce ketones or aldehydes as the products. Tertiary, secondary, and primary alcohols bearing a wide range of substituents are suitable substrates. Complex natural alcohols can also perform the transformation selectively. A investigation of the mechanism reveals a procedure that involves chlorine radical improved O-H homolysis, with the assistance of 2,4,6-collidine.
- Liu, Wei,Wu, Qiang,Wang, Miao,Huang, Yahao,Hu, Peng
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supporting information
p. 8413 - 8418
(2021/11/01)
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- Highly Selective Hydrogenation of C═C Bonds Catalyzed by a Rhodium Hydride
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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
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supporting information
p. 9657 - 9663
(2021/07/19)
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- Intermetallic Nanocatalyst for Highly Active Heterogeneous Hydroformylation
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Hydroformylation is an imperative chemical process traditionally catalyzed by homogeneous catalysts. Designing a heterogeneous catalyst with high activity and selectivity in hydroformylation is challenging but essential to allow the convenient separation and recycling of precious catalysts. Here, we report the development of an outstanding catalyst for efficient heterogeneous hydroformylation, RhZn intermetallic nanoparticles. In the hydroformylation of styrene, it shows three times higher turnover frequency (3090 h-1) compared to the benchmark homogeneous Wilkinson's catalyst (966 h-1), as well as a high chemoselectivity toward aldehyde products. RhZn is active for a variety of olefin substrates and can be recycled without a significant loss of activity. Density functional theory calculations show that the RhZn surfaces reduce the binding strength of reaction intermediates and have lower hydroformylation activation energy barriers compared to pure Rh(111), leading to more favorable reaction energetics on RhZn. The calculations also predict potential catalyst design strategies to achieve high regioselectivity.
- Chen, Minda,Gupta, Geet,Ordonez, Claudio W.,Lamkins, Andrew R.,Ward, Charles J.,Abolafia, Celia A.,Zhang, Biying,Roling, Luke T.,Huang, Wenyu
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supporting information
p. 20907 - 20915
(2021/12/14)
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- Selective Production of Linear Aldehydes and Alcohols from Alkenes using Formic Acid as Syngas Surrogate
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Performing carbonylation without the use of carbon monoxide for high-value-added products is an attractive yet challenging topic in sustainable chemistry. Herein, effective methods for producing linear aldehydes or alcohols selectively with formic acid as both carbon monoxide and hydrogen source have been described. Linear-selective hydroformylation of alkenes proceeds smoothly with up to 88 % yield and >30 regioselectivity in the presence of single Rh catalyst. Strikingly, introducing Ru into the system, the dual Rh/Ru catalysts accomplish efficient and regioselective hydroxymethylation in one pot. The present processes utilizing formic acid as syngas surrogate operate simply under mild condition, which opens a sustainable way for production of linear aldehydes and alcohols without the need for gas cylinders and autoclaves. As formic acid can be readily produced via CO2 hydrogenation, the protocols represent indirect approaches for chemical valorization of CO2.
- Chen, Junjun,Hua, Kaimin,Liu, Xiaofang,Deng, Yuchao,Wei, Baiyin,Wang, Hui,Sun, Yuhan
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p. 9919 - 9924
(2021/05/31)
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- Organic Ligand-Free Hydroformylation with Rh Particles as Catalyst?
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An efficient and organic ligand-free heterogeneous catalytic system for hydroformylation of olefins is highly desirable for both academy and industry. In this study, simple Rh black was employed as a heterogeneous catalyst for hydroformylation of olefins in the absence of organic ligand. The Rh black catalyst showed good catalytic activity for a broad substrate scope including the aliphatic and aromatic olefins, affording the desired aldehydes in good yields. Taking the hydroformylation of ethylene as an example, 86% yield of propanal and TOF of 200 h–1 were obtained, which was superior to the reported homogeneous catalytic systems. In addition, the catalyst could be reused five times without loss of activity under identical reaction conditions, and the Rh leaching was negligible after each cycle.
- Liu, Shujuan,Dai, Xingchao,Wang, Hongli,Wang, Xinzhi,Shi, Feng
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p. 139 - 143
(2020/01/03)
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- Binuclear Pd(I)-Pd(I) Catalysis Assisted by Iodide Ligands for Selective Hydroformylation of Alkenes and Alkynes
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Since its discovery in 1938, hydroformylation has been thoroughly investigated and broadly applied in industry (>107 metric ton yearly). However, the ability to precisely control its regioselectivity with well-established Rh- or Co-catalysts has thus far proven elusive, thereby limiting access to many synthetically valuable aldehydes. Pd-catalysts represent an appealing alternative, yet their use remains sparse due to undesired side-processes. Here, we report a highly selective and exceptionally active catalyst system that is driven by a novel activation strategy and features a unique Pd(I)-Pd(I) mechanism, involving an iodide-assisted binuclear step to release the product. This method enables β-selective hydroformylation of a large range of alkenes and alkynes, including sensitive starting materials. Its utility is demonstrated in the synthesis of antiobesity drug Rimonabant and anti-HIV agent PNU-32945. In a broader context, the new mechanistic understanding enables the development of other carbonylation reactions of high importance to chemical industry.
- Zhang, Yang,Torker, Sebastian,Sigrist, Michel,Bregovi?, Nikola,Dydio, Pawe?
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supporting information
p. 18251 - 18265
(2020/11/02)
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- Rhodium-Catalyzed Remote C(sp3)?H Borylation of Silyl Enol Ethers
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A rhodium-catalyzed remote C(sp3)?H borylation of silyl enol ethers (SEEs, E/Z mixtures) by alkene isomerization and hydroboration is reported. The reaction exhibits mild reaction conditions and excellent functional-group tolerance. This method is compatible with an array of SEEs, including linear and branched SEEs derived from aldehydes and ketones, and provides direct access to a broad range of structurally diverse 1,n-borylethers in excellent regioselectivities and good yields. These compounds are precursors to various valuable chemicals, such as 1,n-diols and aminoalcohols.
- Li, Jie,Qu, Shuanglin,Zhao, Wanxiang
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supporting information
p. 2360 - 2364
(2020/01/02)
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- Catalyst for catalyzing hydroformylation reaction of gem-disubstituted aromatic olefin and preparation method and application of catalyst
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The invention provides a catalyst for catalyzing a hydroformylation reaction of gem-disubstituted aromatic olefin and a preparation method and application of the catalyst. The catalyst is a complex, aprecursor of the complex comprises rhodium salt, and a ligand comprises a phosphoramidite ligand. When the catalyst is used for catalyzing the hydroformylation reaction of gem-disubstituted aromaticolefin, the efficiency is high, and the reaction conditions are mild.
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Paragraph 0033-0065
(2020/08/06)
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- Iridium-Catalyzed Asymmetric Isomerization of Primary Allylic Alcohols Using MaxPHOX Ligands: Experimental and Theoretical Study
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The asymmetric isomerization of primary allylic alcohols to chiral aldehydes using iridium-catalysts bearing P,N-MaxPHOX ligands has been studied. These catalysts can be fine-tuned as they present three different stereogenic centers to modulate both the reactivity and enantioselectivity of a family of different substrates. The experimental part is supported by a DFT study of the reaction mechanism, which provides new insights into the key steps of this transformation.
- Cabré, Albert,Gar?on, Martí,Gallen, Albert,Grisoni, Lorenzo,Grabulosa, Arnald,Verdaguer, Xavier,Riera, Antoni
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p. 4112 - 4120
(2020/07/04)
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- An umpolung approach to the hydroboration of pyridines: A novel and efficient synthesis of: N -H 1,4-dihydropyridines
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The first inverse hydroboration of pyridine with a diboron(4) compound and a proton source has been realized under simple basic and catalyst-free conditions. This process consists of a formal boryl anion addition to pyridine, which produces an N-boryl pyridyl anion complex, and the subsequent protonation of the anion complex. This process enables a simple and efficient method for the synthesis of multi-substituted N-H 1,4-dihydropyridine (1,4-DHP) derivatives that are difficult to prepare using established methods. Furthermore, this method allows for facile preparation of 4-deuterated 1,4-DHPs from an easily accessible deuterium ion source. This inverse hydroboration reaction represents a new mode for pyridine functionalization.
- Yang, Huan,Zhang, Li,Zhou, Fei-Yu,Jiao, Lei
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p. 742 - 747
(2020/01/31)
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- Styrene Hydroformylation with In Situ Hydrogen: Regioselectivity Control by Coupling with the Low-Temperature Water–Gas Shift Reaction
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The hydroformylation of olefins is one of the most important homogeneously catalyzed industrial reactions for aldehyde synthesis. Various ligands can be used to obtain the desired linear aldehydes in the hydroformylation of aliphatic olefins. However, in the hydroformylation of aromatic substrates, branched aldehydes are formed preferentially with common ligands. In this study, a novel approach to selectively obtain linear aldehydes in the hydroformylation of styrene and its derivatives was developed by coupling with a water–gas shift reaction on a Rh single-atom catalyst without the use of ligands. Detailed studies revealed that the hydrogen generated in situ from the water–gas shift is critical for the highly regioselective formation of linear products. The coupling of a traditional homogeneous catalytic process with a heterogeneous catalytic reaction to tune product selectivity may provide a new avenue for the heterogenization of homogenous catalytic processes.
- Chen, Fang,Lang, Rui,Li, Tianbo,Qiao, Botao,Su, Yang,Wang, Aiqin,Wang, Hua,Zhang, Tao
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supporting information
p. 7430 - 7434
(2020/03/13)
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- Boosting the hydrolytic stability of phosphite ligand in hydroformylation by the construction of superhydrophobic porous framework
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The development of a catalyst that delivers high activities and selectivities with excellent durability is of great importance. Numerous efficient catalysts suffer from the inherent hydrolysis liabilities, plaguing their practical applications. Herein, we show that this challenge can be tackled by constructing them into superhydrophobic porous frameworks, as exemplified by a water-sensitive phosphite ligand, tris(2-tert-butylphenyl) phosphite. The efficiency and long-term stability of the developed system are remarkably high in the hydroformylation of internal olefins after metalation with Rh species, superior to the corresponding homogeneous analogues. The significantly boosted hydrolytic stability allows for catalytic transformations using water as a green solvent, which not only facilitates the isolation of the products, but also furnishes the aldehydes with higher regioselectivities for the desired linear form in comparison with that operated under benchmark conditions using toluene as a reaction medium. Given these promising results, we anticipate the strategy advanced herein will form the basis for constructive perspectives in the enhancement of the water resistance of catalysts and the development of high performance hydroformylation catalysts.
- Tang, Yongquan,Dong, Ke,Wang, Sai,Sun, Qi,Meng, Xiangju,Xiao, Feng-Shou
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- Synthesis of tetra-pincer nickel(ii) and palladium(ii) complexes of resorcin[4]arene-octophosphinite [Res(OPR2)8] and rhodium-catalyzed regioselective hydroformylation reaction
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The condensation reaction of resorcinol with pentanal yielded resorcin[4]arene 1 which on bromination using N-bromosuccinimide at room temperature produced tetra-bromide derivative 2. The reactions of 2 with chlorodiphenylphosphine and o-phenylenephosphoro-chloridite yielded octaphosphinite 3 (hereafter referred to as octaphos) and octaphosphite 4, respectively. The reactions of 3 with Ni(COD)2 or Pd2(dba)3·CHCl3 in appropriate molar ratios yielded tetra-pincer complexes 5 and 6, respectively. The structures of both the complexes were established by single crystal X-ray diffraction studies. The resorcin[4]arene backbone adopts a boat structure in these complexes. Typically, the Rh-catalyzed hydroformylation of styrene prevalently delivers a branched (b) chiral aldehyde. A unique resorcin[4]arene skeleton based octaphos 3 was employed in the Rh-catalyzed hydroformylation of styrene. The hydroformylation of styrene with a metal to ligand ratio of 1:1 (M:L) was found to be regioselective, producing a linear (l) aldehyde as a major product with 100% conversion in 3 h. The l:b ratio surprisingly increased when the ortho positions of styrene were populated by methyl and chloro substituents. The hydroformylation of p-nitro styrene triggered a remarkably high linear:branched aldehyde ratio of 2.4 (71% linear aldehyde) despite its electron withdrawing nature. The highest linear selectivity of 97% (l:b ratio 27.8) was achieved in the case of 2,4,6-trimethylstyrene.
- Ananthnag, Guddekoppa S.,Mondal, Dipanjan,Mague, Joel T.,Balakrishna, Maravanji S.
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p. 14632 - 14641
(2019/10/16)
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- 1, 4-dihydropyridine bifunctional chiral catalyst and preparation method and application thereof
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The invention belongs to the field of organic catalysis, and discloses a novel 1, 4-dihydropyridine bifunctional chiral catalyst and a preparation method and application thereof. The general chemicalstructure formula of the chiral catalyst is shown in formula (I) as shown in specification. According to the invention, a 1, 4-dihydropyridine derivative and a chiral tetrahydropyrrole derivative areused as raw materials, and finally, the novel 1, 4-dihydropyridine bifunctional chiral catalyst is synthesized. The method has mild synthesis reaction conditions and high yield. The operation steps are simple, safe and reliable; the catalyst is environment-friendly, and can be applied to the fields of asymmetric catalytic transfer hydrogenation, chiral fine chemical synthesis, chiral drug or drugintermediate synthesis, chiral new materials, chiral functional molecule synthesis and the like; and the application prospect is wide.
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Paragraph 0085-0088
(2019/06/30)
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- Rhenium-catalyzed α-alkylation of enol acetates with alcohols or ethers
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When benzylic and allylic alcohols were treated with enol acetate in the presence of a catalytic amount of a rhenium complex, ReBr(CO)5, the carbon-carbon bond formation of the alcohols and enol acetate smoothly proceeded to give the corresponding ketones and aldehyde in moderate to good yields. For the reaction of allylic alcohols, γ,δ-unsaturated carbonyl compounds were obtained in good yields. When ethers were used instead of alcohols as the alkylated agent, two alkyl moieties on the ethers were utilized on the reaction.
- Umeda, Rui,Takahashi, Yuuki,Yamamoto, Takaaki,Iseki, Hideki,Osaka, Issey,Nishiyama, Yutaka
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supporting information
p. 92 - 101
(2018/11/01)
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- Supported rhodium liquid metal catalysts for the hydroformylation of olefins
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The hydroformylation of olefins in supported room temperature liquid metals was developed, and the supported Rh liquid metal catalysts (Rh SLMCs) showed unprecedented activity and high selectivity for the hydroformylation of olefins to aldehydes. The turnover frequency is up to 7000?h?1, much higher than that of homogeneous RhCl3?+?3PPh3 catalyst. Moreover, the Rh SLMCs can be recovered conveniently without obvious deactivation, and the total turnover number is up to 250?000. The active Rh(I) catalyst formed in situ can be reduced back to Rh(0) by the free electrons in liquid metal when H2/CO gas is emitted, and thus Rh is not leaked into the organic solvent. Long-chain olefins, cycloolefins and styrenes were applied, and the corresponding aldehydes were obtained in good to excellent yields.
- Sun, Hao,Guo, Wanwan,Liu, Junmei,Feng, Zhipeng,Li, Ruyue,Zhou, Xuyang,Huang, Jun
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- Design and application of hybrid phosphorus ligands for enantioselective Rh-Catalyzed anti-markovnikov hydroformylation of unfunctionalized 1,1-disubstituted Alkenes
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A series of novel hybrid phosphorus ligands were designed and applied to the Rh-catalyzed enantioselective anti-Markovnikov hydroformylation of unfunctionalized 1,1-disubstituted alkenes. By employing the new catalyst, linear aldehydes with β-chirality can be prepared with high yields and enantioselectivities under mild conditions. Furthermore, catalyst loading as low as 0.05 mol % furnished the desired product in good yield and undiminished selectivity, demonstrating the efficiency of this transformation in large-scale synthesis.
- You, Cai,Li, Shuailong,Li, Xiuxiu,Lan, Jialing,Yang, Yuhong,Chung, Lung Wa,Lv, Hui,Zhang, Xumu
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supporting information
p. 4977 - 4981
(2018/04/24)
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- CuH-Catalyzed Asymmetric Reduction of α,β-Unsaturated Carboxylic Acids to β-Chiral Aldehydes
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The copper hydride (CuH)-catalyzed enantioselective reduction of α,β-unsaturated carboxylic acids to saturated aldehydes is reported. This protocol provides a new method to access a variety of β-chiral aldehydes in good yields, with high levels of enantioselectivity and broad functional group tolerance. A reaction pathway involving a ketene intermediate is proposed based on preliminary mechanistic studies and density functional theory calculations.
- Zhou, Yujing,Bandar, Jeffrey S.,Liu, Richard Y.,Buchwald, Stephen L.
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supporting information
p. 606 - 609
(2018/01/26)
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- Iminium Catalysis inside a Self-Assembled Supramolecular Capsule: Scope and Mechanistic Studies
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Although iminium catalysis has become an important tool in organic chemistry, its combination with supramolecular host systems has remained largely unexplored. We report the detailed investigations into the first example of iminium catalysis inside a supramolecular host. In the case of 1,4-reductions of α,β-unsaturated aldehydes, catalytic amounts of host are able to increase the enantiomeric excess of the products formed. Several control experiments were performed and provided strong evidence that the modulation of enantiomeric excess of the reaction product indeed stems from a reaction on the inside of the capsule. The origin of the increased enantioselectivity in the capsule was investigated. Furthermore, the substrate and nucleophile scope were studied. Kinetic investigations as well as the kinetic isotope effect measured confirmed that the hydride delivery to the substrate is the rate-determining step inside the capsule. The exploration of benzothiazolidines as alternative hydride sources revealed an unexpected substitution effect of the hydride source itself. The results presented confirm that the noncovalent combination of supramolecular hosts with iminium catalysis is opening up new exciting possibilities to increase enantioselectivity in challenging reactions.
- Br?uer, Thomas M.,Zhang, Qi,Tiefenbacher, Konrad
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p. 17500 - 17507
(2017/12/15)
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- Catalyst-Controlled Multicomponent Aziridination of Chiral Aldehydes
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A highly diastereoselective and enantioselective method for the multicomponent aziridination of chiral aldehydes has been developed with BOROX catalysts of the VANOL (3,3′-diphenyl-2,2′-bi-1-naphthol) and VAPOL (2,2′-diphenyl-(4-biphenanthrol)) ligands. Very high to perfect catalyst control is observed with most all substrates examined including aldehydes with chiral centers in the α- and β-positions. High catalyst control was also observed for a number of chiral heterocyclic aldehydes allowing for the preparation of epoxy aziridines, bis(aziridines) and ethylene diaziridines. Application of this reaction in the synthesis of β3-homo-d-alloisoleucine and β3-homo-l-isoleucine is reported.
- Mukherjee, Munmun,Zhou, Yubai,Dai, Yijing,Gupta, AniL K.,Pulgam, V. Reddy,Staples, Richard J.,Wulff, William D.
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supporting information
p. 2552 - 2556
(2017/03/06)
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- Rhodium-catalyzed hydroformylation in γ-valerolactone as a biomass-derived solvent
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Rhodium-catalyzed hydroformylation of styrene, α-methylstyrene, dimethyl itaconate, and (R)-limonene was performed in gamma-valerolactone (GVL) as a proposed biomass-based environmentally benign solvent for hydroformylation referring to toluene as a generally used conventional solvent. Both achiral (triphenylphosphine, 1,3-bis(diphenylphoshino)propane) and enantiopure bidentate phosphine ligands ((S,S)-BDPP, (R)-BINAP, (R)-QUINAP, (R,R)-DIOP, (Rc),(Sp)-JOSIPHOS, (S)-SEGPHOS, (S)-(DM)-SEGPHOS) were investigated in in situ generated Rh-diphosphine catalyst systems. In general, the catalysts' activity in GVL was lower than in toluene; however, remarkable chemo- (>99%) and regioselectivities (>95%) were achieved in GVL under identical conditions. The BDPP-modified Rh-catalyst was recycled for three consecutive cycles; however a decrease in its activity was detected.
- Pongrácz, Péter,Bartal, Brigitta,Kollár, László,Mika, László T.
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p. 140 - 145
(2017/09/12)
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- Hydroformylation of Olefins by a Rhodium Single-Atom Catalyst with Activity Comparable to RhCl(PPh3)3
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Homogeneous catalysts generally possess superior catalytic performance compared to heterogeneous catalysts. However, the issue of catalyst separation and recycling severely limits their use in practical applications. Single-atom catalysts have the advantages of both homogeneous catalysts, such as “isolated sites”, and heterogeneous catalysts, such as stability and reusability, and thus would be a promising alternative to traditional homogeneous catalysts. In the hydroformylation of olefins, single-atom Rh catalysts supported on ZnO nanowires demonstrate similar efficiency (TON≈40000) compared to that of homogeneous Wilkinson's catalyst (TON≈19000). HAADF-STEM and infrared CO chemisorption experiments identified isolated Rh atoms on the support. XPS and XANES spectra indicate that the electronic state of Rh is almost metallic. The catalysts are about one or two orders of magnitude more active than most reported heterogeneous catalysts and can be reused four times without an obvious decline in activity.
- Lang, Rui,Li, Tianbo,Matsumura, Daiju,Miao, Shu,Ren, Yujing,Cui, Yi-Tao,Tan, Yuan,Qiao, Botao,Li, Lin,Wang, Aiqin,Wang, Xiaodong,Zhang, Tao
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supporting information
p. 16054 - 16058
(2016/12/26)
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- Copper-Catalyzed Enantioselective Conjugate Addition to α,β-Unsaturated Aldehydes with Various Organometallic Reagents
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β-Substituted aldehydes constitute a very important class of compounds found in nature. Synthesis of this motif can be envisioned by C-C bond formation on enals. For this purpose, we report herein the development of enantioselective copper-catalyzed conjugate addition of various organometallic reagents to α,β-unsaturated aldehydes with (R)-H8BINAP, (R)-TolBINAP, and (R)-SEGPHOS as chiral ligands. Three sets of conditions were successfully developed and several enals were used. Reactivity and regio- and enantioselectivities were strongly dependent on reaction conditions and substrates. Good to excellent regio- and enantioselectivities were obtained with zinc reagents R2Zn and aluminum reagents R3Al. However, the asymmetric conjugate addition of Grignard reagents afforded only moderate to good regio- and enantioselectivities.
- Goncalves-Contal, Sylvie,Gremaud, Ludovic,Palais, La?titia,Babel, Lucille,Alexakis, Alexandre
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p. 3301 - 3308
(2016/09/12)
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- Copper-Catalyzed Asymmetric Conjugate Addition of Dimethylzinc to Acyl-N-methylimidazole Michael Acceptors: Scope, Limitations and Iterative Reactions
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An efficient copper-catalyzed enantioselective conjugate addition of dimethylzinc to unsaturated 2-acyl-N-methylimidazoles has been achieved using a chiral bidentate hydroxyalkyl-NHC ligand. The reactions proceed with excellent regioselectivity (1,4 vs. 1,6 and 1,8) in extended conjugated systems to afford the 1,4-adducts in high enantioselectivities. This regioselectivity could be ascertained by DFT studies highlighting the crucial role of the imidazole ring. Thanks to the development of efficient protocols to regenerate the unsaturated 2-acyl-N-methylimidazole moiety, an iterative process has been developed ultimately leading to 3,5,7 all-syn or anti-anti polydeoxypropionate stereodiads. (Figure presented.).
- Drissi-Amraoui, Sammy,Schmid, Thibault E.,Lauberteaux, Jimmy,Crévisy, Christophe,Baslé, Olivier,de Figueiredo, Renata Marcia,Halbert, Stéphanie,Gérard, Hélène,Mauduit, Marc,Campagne, Jean-Marc
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supporting information
p. 2519 - 2540
(2016/08/16)
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- Iminium Catalysis inside a Self-Assembled Supramolecular Capsule: Modulation of Enantiomeric Excess
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The noncovalent combination of a supramolecular host with iminium organocatalysis is described. Due to cation–π interactions the reactive iminium species is held inside the host and reacts in this confined environment. The products formed differ up to 92 % ee from the control experiments without added host. A model rationalizing the observed difference is presented.
- Br?uer, Thomas M.,Zhang, Qi,Tiefenbacher, Konrad
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p. 7698 - 7701
(2016/07/07)
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- An Effective Pd-Catalyzed Regioselective Hydroformylation of Olefins with Formic Acid
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An effective palladium-catalyzed regioselective hydroformylation of olefins with formic acid is described. The ligand plays a crucial role in directing the reaction pathway. Linear aldehydes can be obtained in up to 93% yield with >20:1 regioselectivity using 1,3-bis(diphenylphosphino)propane (dppp) as the ligand. The reaction process is operationally simple and requires no syngas.
- Ren, Wenlong,Chang, Wenju,Dai, Jie,Shi, Yuan,Li, Jingfu,Shi, Yian
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supporting information
p. 14864 - 14867
(2016/11/29)
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- Exploring the synthetic applicability of a new carboxylic acid reductase from Segniliparus rotundus DSM 44985
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A new carboxylic acid reductase (CAR) gene from Segniliparus rotundus DSM 44985 was overexpressed in Escherichia coli. The recombinant enzyme exhibited high activity toward a variety of aromatic and aliphatic carboxylic acids. Especially, it effectively reduced 4-hydroxybenzoic acid (8a) and 4-nitrobenzoic acid (19a), toward which the known Nocardia CAR exhibited no or little activity. The recombinant E. coli cells co-expressing the Segniliparus CAR and Nocardia PPTase genes catalyzed the reductions of vanillic acid (20a) and 3,4-dihydroxyphenylacetic acid (25a) to give vanillyl alcohol (20c) and 3-hydroxytyrosol (25c) with high yield, respectively. The endogenous aldehyde reductases of E. coli should be responsible for the further reduction of the produced aldehydes. These results demonstrated that Segniliparus CAR was a useful addition to the biocatalyst tool-box for the reduction of carboxylic acids and might find applications in the synthesis of valuable bio-based chemicals from renewable resources.
- Duan, Yitao,Yao, Peiyuan,Chen, Xi,Liu, Xiangtao,Zhang, Rui,Feng, Jinhui,Wu, Qiaqing,Zhu, Dunming
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- Rhenium complex-catalyzed coupling reaction of enol acetates with alcohols
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The reaction of enol acetates with alcohols in the presence of a catalytic amount of a rhenium complex, such as ReBr(CO)5, produced the corresponding ketones and aldehydes in moderate to good yields. It was suggested that the preparation of an ether, an intermolecular dehydrated product, was the first step of the reaction.
- Umeda, Rui,Takahashi, Yuuki,Nishiyama, Yutaka
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supporting information
p. 6113 - 6116
(2015/01/09)
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- Novel C1-symmetric dibenzophosphole ligands: Application in hydroformylation reactions
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A new family of non-symmetrical disubstituted dibenzophospholes possessing different steric and electronic effects have been synthesized and characterized. Their preliminary evaluation in rhodium-catalyzed hydroformylation reactions is presented.
- Oukhrib, Abdelhouad,Bonnafoux, Laurence,Panossian, Armen,Waifang, Sandrine,Nguyen, Duc Hanh,Urrutigoity, Martine,Colobert, Fran?oise,Gouygou, Maryse,Leroux, Frédéric R.
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p. 1431 - 1436
(2014/02/14)
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- IBX works efficiently under solvent free conditions in ball milling
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IBX (2-iodoxybenzoic acid), discovered in 1893, is an oxidant in synthetic chemistry whose extensive use is impeded by its explosiveness at high temperature and poor solubility in common organic solvents except DMSO. Since the discovery of Dess-Martin Periodinane in 1983, several modified IBX systems have been reported. However, under ball milling conditions, IBX works efficiently with various organic functionalities at ambient temperature under solvent free conditions. Also, the waste IBA (2-iodosobenzoic acid) produced from the reactions was in situ oxidized to IBX in the following step using oxone and thus reused for multiple cycles by conserving its efficiency (only ～6% loss after 15 cycles). This work describes an overview of a highly economical synthetic methodology which overcomes the problems of using IBX, efficiently in gram scale and in a non-explosive way. This journal is the Partner Organisations 2014.
- Achar, Tapas Kumar,Maiti, Saikat,Mal, Prasenjit
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p. 12834 - 12839
(2014/04/03)
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- Scope and mechanism in palladium-catalyzed isomerizations of highly substituted allylic, homoallylic, and alkenyl alcohols
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Herein we report the palladium-catalyzed isomerization of highly substituted allylic alcohols and alkenyl alcohols by means of a single catalytic system. The operationally simple reaction protocol is applicable to a broad range of substrates and displays a wide functional group tolerance, and the products are usually isolated in high chemical yield. Experimental and computational mechanistic investigations provide complementary and converging evidence for a chain-walking process consisting of repeated migratory insertion/β-H elimination sequences. Interestingly, the catalyst does not dissociate from the substrate in the isomerization of allylic alcohols, whereas it disengages during the isomerization of alkenyl alcohols when additional substituents are present on the alkyl chain.
- Larionov, Evgeny,Lin, Luqing,Gune, Laure,Mazet, Clment
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supporting information
p. 16882 - 16894
(2015/01/09)
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- A bulky phosphite modified rhodium catalyst for efficient hydroformylation of disubstituted alkenes and macromonomers in supercritical carbon dioxide
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The hydroformylation of disubstituted alkenes and related macromonomers in supercritical CO2 is demonstrated. Higher turnover frequencies were observed for the 1,2-disubstituted alkenes than for the 1,1-disubstituted alkenes. The turnover frequency for poly(styrene) macromonomer hydroformylation compares well with that observed for cyclohexene. The turnover frequency observed for poly(methyl methacrylate) macromonomer hydroformylation is considerably lower than that observed for methyl methacrylate. Unprecedented turnover frequencies are observed in comparison with previous studies where CO2 has been applied as a solvent. This is achieved using rhodium modified with a readily available bulky phosphite ligand without the need of ligand modification to improve solubility in supercritical CO2.
- Koeken, Ard C. J.,Smeets, Niels M. B.
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p. 1036 - 1045
(2013/04/24)
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- Rhodium/bisphosphite catalytic system for hydroformylation of styrene and its derivatives
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Different kinds of mono- and bidentate phosphite ligands were used in Rh-catalyzed hydroformylation of styrene to illustrate the influence of steric and electronic properties of ligands on catalytic performance. High activity (99.9%) and good regioselectivity (85.4%) to the linear aldehyde were achieved under optimum conditions in the presence of Rh/bisphosphite complex (bisphosphite: 2,2′-bis(dipyrrolylphosphinooxy)-1,1′-(±)- binaphthyl). This system makes it possible to prepare functionalized terminal aldehydes from readily available styrene or its derivatives through hydroformylation with high linear selectivity. Copyright
- Zheng, Cong-Ye,Mo, Min,Liang, Hao-Ran,Zheng, Xue-Li,Fu, Hai-Yan,Yuan, Mao-Lin,Li, Rui-Xiang,Chen, Hua
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p. 474 - 478
(2013/08/23)
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- Enantioselective isomerization of primary allylic alcohols into chiral aldehydes with the tol-binap/dbapen/ruthenium(II) catalyst
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Efficient isomerization: The title reaction was catalyzed by the [RuCl 2{(S)-tol-binap}{(R)-dbapen}]/KOH system in ethanol at 25°C (see scheme). A series of E- and Z-configured aromatic and aliphatic allylic alcohols, including a simple primary alkyl-substituted compound (E)-3-methyl-2-hepten-1-ol, were transformed into the chiral aldehydes with at least 99 % ee. dbapen=2-dibutylamino-1-phenylethylamine, tol-binap=2,2′- bis(di-4-tolylphosphanyl)-1,1′-binaphthyl. Copyright
- Arai, Noriyoshi,Sato, Keisuke,Azuma, Keita,Ohkuma, Takeshi
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supporting information
p. 7500 - 7504
(2013/07/26)
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- A novel organocatalytic asymmetric transfer hydrogenation of α,β-unsaturated aldehydes
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α,β-Unsaturated aldehydes reacted with diimide (diazene) in the presence of optically active ammonium salt 1 as a catalyst to give the corresponding saturated aldehydes in excellent yields and up to 98: 2 er. Attractive features of the asymmetric transfer hydrogenation are its high yields, and chemo-, and enantioselectivities.
- Zhang, Bao-Hua,Shi, Lan-Xiang,Guo, Rui-Xia
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p. 2152 - 2154
(2013/12/04)
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- Rhodium/tris-binaphthyl chiral monophosphite complexes: Efficient catalysts for the hydroformylation of disubstituted aryl olefins
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A family of threefold symmetry phosphite ligands, P(O-BIN-OR)3 (BIN = 2,2′-binaphthyl; R = Me, Bn, CHPh2, 1-adamantyl), derived from enantiomerically pure (R)-BINOL, was developed. Cone angles within the range 240-270° were calculated for the phosphite ligands, using the computational PM6 Hamiltonian. Their rhodium complexes formed in situ showed remarkable catalytic activity in the hydroformylation of hindered phenylpropenes, under relatively mild reaction conditions, with full chemoselectivity for aldehydes, high regioselectivity, however with low enantioselectivity. The ether substituents at the ligand affected considerably the catalytic activity on the hydroformylation of 1,1- and 1,2-disubstituted aryl olefins. The kinetics of the hydroformylation of trans-1-phenyl-1-propene, using tris[(R)-2′-benzyloxy-1,1′-binaphthyl-2-yl]phosphite as model ligand, was investigated. A first order dependence in the hydroformylation initial rate with respect to substrate and catalyst concentrations was found, as well as a positive order with respect to the partial pressure of H2, and a slightly negative order with respect to phosphite concentration and CO partial pressure.
- Carrilho, Rui M.B.,Neves,Loureno, Mirtha A.O.,Abreu, Artur R.,Rosado, Mário T.S.,Abreu, Paulo E.,Eusébio, M. Ermelinda S.,Kollár, László,Bayón, J. Carles,Pereira, Mariette M.
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experimental part
p. 28 - 34
(2012/02/04)
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- Copper-catalyzed asymmetric conjugate addition to challenging michael acceptors and synthesis of relevant target molecules
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We report herein the enantioselective Cu-catalyzed conjugate addition of organometallic reagents to sensitive Michael acceptors and their application to the synthesis of relevant target molecules. This is one of the most important methodologies to form a C-C bond in an enantioselective manner. A wide range of α,β-unsaturated aldehydes and β,γ-unsaturated-α- ketoesters has been successfully used. Reactivity, regioand enantioselectivities were strongly dependent on the reaction conditions, therefore moderate to very good results were obtained. Furthermore, γ-substituted-α-ketoesters were used as chiral building blocks for further derivatization with complete retention of the chiral information to obtain key compounds. Schweizerische Chemische Gesellschaft.
- Gremaud, Ludovic,Palais, Laetitia,Alexakis, Alexandre
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scheme or table
p. 196 - 200
(2012/07/28)
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- Preparation of imidazolidin-4-ones and their evaluation as hydrolytically cleavable precursors for the slow release of bioactive volatile carbonyl derivatives
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Imidazolidin-4-ones are suitable in practical applications as hydrolytically cleavable precursors for the controlled release of fragrant aldehydes and ketones. The corresponding profragrances were prepared by treating aliphatic carbonyl compounds with commercially available amino acid amines in the presence of a base to yield mixtures of diastereomers. The two diastereomers isolated from the reaction of glycinamide hydrochloride with (-)-menthone were separated by column chromatography. The absolute stereochemistry of the isomers was determined by NMR spectroscopy and confirmed by X-ray single crystal structure analysis. Under acidic conditions and in protic solvents, the two diastereomers slowly isomerized without releasing the ketone. The hydrolysis of the precursors was investigated by solvent extraction from buffered aqueous solutions and a cationic surfactant emulsion, as well as by dynamic headspace analysis after deposition onto a cotton surface. Generally, ketones were shown to be more readily released than aldehydes. Increasing the size of the substituents at C-5 decreased the rate of hydrolysis in solution and on the cotton surface. Glycinamide-based imidazolidin-4-ones were more efficient than the corresponding oxazolidin-4-ones or oxazolidines. Neither the release rates in solution, nor the hydrophobicity of the precursor structure (which influences deposition), nor the combination of these two parameters allowed easily predicting the performance of the delivery systems in application. Copyright
- Trachsel, Alain,Buchs, Barbara,Godin, Guillaume,Crochet, Aurelien,Fromm, Katharina M.,Herrmann, Andreas
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supporting information; experimental part
p. 2837 - 2854
(2012/07/03)
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- A dual catalyst system provides the shortest pathway for l-menthol synthesis
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We have demonstrated that a combination of enantiopure 2- diarylmethylpyrrolidines and heterogeneous Pd/BaSO4 is an efficient catalytic system for the asymmetric hydrogenation of citral, specifically, a mixture of E-citral and Z-citral in any ratio, and that citronellal is obtained with high enantioselectivity. This dual catalyst system provides a new and more economical route to l-menthol.
- Maeda, Hironori,Yamada, Shinya,Itoh, Hisanori,Hori, Yoji
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experimental part
p. 1772 - 1774
(2012/03/09)
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- Chiral dihydrobenzo[1,4]oxazines as catalysts for the asymmetric transfer-hydrogenation of α,β-unsaturated aldehydes
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A new class of organocatalysts based on the structure of 2,3-dihydrobenzo[1,4]oxazine was prepared and applied in the enantioselective transfer-hydrogenation of α,β-unsaturated aldehydes with Hantzsch ester as hydride donor. These catalysts proved to be particularly effective for the conjugate reduction of β,β-diaryl-substituted acrylaldehydes leading to saturated aldehydes bearing a stereogenic center with two different aryl groups with enantioselectivities of up to 91% ee.
- Ebner, Christian,Pfaltz, Andreas
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supporting information; experimental part
p. 10287 - 10290
(2012/02/01)
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- Highly enantioselective asymmetric isomerization of primary allylic alcohols with an iridium-N,P complex
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Access to chiral aldehydes: The asymmetric isomerization of primary allylic alcohols was studied with a bicyclic phosphine-oxazoline iridium catalyst. This method displays a broad substrate scope and leads to the desired chiral aldehydes with excellent enantioselectivities (see scheme; R1, R 2=Ar or alkyl). Copyright
- Li, Jia-Qi,Peters, Byron,Andersson, Pher G.
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p. 11143 - 11145
(2011/10/31)
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- Copper-catalyzed regio-and enantioselective synthesis of chiral enol acetates and β-substituted aldehydes
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The in situ transformation of α,β-unsaturated aldehydes into α-chloroallylic acetates and subsequent copper-catalyzed regio-and enantioselective (up to 94% ee) allylic alkylation with Grignard reagents provides chiral enol acetates and chiral β-substituted aldehydes in a one-pot protocol.
- Fananas-Mastral, Martin,Feringa, Ben L.
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supporting information; experimental part
p. 13152 - 13153
(2010/12/18)
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- Copper-catalyzed enantioselective 1,4-addition to α,β- unsaturated aldehydes
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Figure presented The first asymmetric Cu-catalyzed conjugate addition of dialkylzinc zinc reagents to a large scope of enals in presence of phosphoramidite, SimplePhos, or (R)-BINAP ligands with enantiomeric excesses up to 90% is reported. Moreover, ACA of Grignard reagents afforded moderate to good 1,4-regioselectivities with enantioselectivities up to 90%.
- Palais, Laetitia,Babel, Lucille,Quintard, Adrien,Belot, Sebastien,Alexakis, Alexandre
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supporting information; experimental part
p. 1988 - 1991
(2010/07/10)
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- CATALYST FOR ASYMMETRIC HYDROGENATION
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This invention aims at providing a catalyst for producing an optically active aldehyde or an optically active ketone, which is an optically active carbonyl compound, by carrying out selective asymmetric hydrogenation of an α,β-unsaturated carbonyl compound, particularly a catalyst which is insoluble in a reaction mixture for obtaining optically active citronellal which is useful as a flavor or fragrance, by carrying out selective asymmetric hydrogenation of citral, geranial or neral; and a method for producing a corresponding optically active carbonyl compound. The invention relates to a catalyst for asymmetric hydrogenation of an α,β-unsaturated carbonyl compound, which comprises a powder of at least one metal selected from metals belonging to Group 8 to Group 10 of the Periodic Table, or a metal-supported substance in which at least one metal selected from metals belonging to Group 8 to Group 10 of the Periodic Table is supported on a support, an optically active cyclic nitrogen-containing compound and an acid.
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Page/Page column 64
(2010/12/31)
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- Improved catalysts for the iridium-catalyzed asymmetric isomerization of primary allylic alcohols based on charton analysis
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An improved generation of chiral cationic iridium catalysts for the asymmetric isomerization of primary allylic alcohols is disclosed. The design of these air-stable complexes relied on the preliminary mechanistic information available, and on Charton analyses using two preceding generations of iridium catalysts developed for this highly challenging transformation. Sterically unbiased chiral aldehydes that were not accessible previously have been obtained with high levels of enantioselectivity, thus validating the initial hypothesis regarding the selected ligand-design elements. A rationale for the high enantioselectivities achieved in most cases is also presented. Achieving enantioselectivity: An improved generation of chiral cationic iridium catalysts for the asymmetric isomerization of primary allylic alcohols is disclosed. The design of these air-stable complexes relies on preliminary mechanistic information and on Charton analyses using two preceding generations of iridium catalysts developed for this highly challenging transformation (see figure).
- Mantilli, Luca,Gerard, David,Torche, Sonya,Besnard, Celine,Mazet, Clement
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supporting information; experimental part
p. 12736 - 12745
(2011/02/21)
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