- Chemo- And regioselective hydroformylation of alkenes with CO2/H2over a bifunctional catalyst
-
As is well known, CO2 is an attractive renewable C1 resource and H2 is a cheap and clean reductant. Combining CO2 and H2 to prepare building blocks for high-value-added products is an attractive yet challenging topic in green chemistry. A general and selective rhodium-catalyzed hydroformylation of alkenes using CO2/H2 as a syngas surrogate is described here. With this protocol, the desired aldehydes can be obtained in up to 97% yield with 93/7 regioselectivity under mild reaction conditions (25 bar and 80 °C). The key to success is the use of a bifunctional Rh/PTA catalyst (PTA: 1,3,5-triaza-7-phosphaadamantane), which facilitates both CO2 hydrogenation and hydroformylation. Notably, monodentate PTA exhibited better activity and regioselectivity than common bidentate ligands, which might be ascribed to its built-in basic site and tris-chelated mode. Mechanistic studies indicate that the transformation proceeds through cascade steps, involving free HCOOH production through CO2 hydrogenation, fast release of CO, and rhodium-catalyzed conventional hydroformylation. Moreover, the unconventional hydroformylation pathway, in which HCOOAc acts as a direct C1 source, has also been proved to be feasible with superior regioselectivity to that of the CO pathway.
- Hua, Kaimin,Liu, Xiaofang,Wei, Baiyin,Shao, Zilong,Deng, Yuchao,Zhong, Liangshu,Wang, Hui,Sun, Yuhan
-
supporting information
p. 8040 - 8046
(2021/11/01)
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- syn-Selective Michael Reaction of α-Branched Aryl Acetaldehydes with Nitroolefins Promoted by Squaric Amino Acid Derived Bifunctional Br?nsted Bases
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Here we describe a direct access to 2,2,3-trisubstituted syn γ-nitroaldehydes by addition of α-branched aryl acetaldehydes to nitroolefins promoted by a cinchona based squaric acid-derived amino acid peptide. Different α-methyl arylacetaldehydes react with β-aromatic and β-alkyl nitroolefins to afford the Michael adducts in high enantioselectivity and syn-selectivity. NMR experiments and DFT calculations predict the reaction to occur through the intermediacy of E-enolate. The interaction between the substrates and the catalyst follows Pápai's model, wherein an intramolecular H-bond interaction in the catalyst between the NH group of one of the tert-leucines and the squaramide oxygen seems to be key for discrimination of the corresponding reaction transition states.
- Campano, Teresa E.,García-Urricelqui, Ane,Mielgo, Antonia,Palomo, Claudio,de Cózar, Abel
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p. 3604 - 3612
(2021/07/26)
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- Insight into decomposition of formic acid to syngas required for Rh-catalyzed hydroformylation of olefins
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Formic acid (FA) is one kind of important bulk chemicals, which is recognized as a sustainable and eco-friendly energy carrier to transport H2 via dehydrogenation or CO via decarbonylation. Expectantly, FA upon decomposition into H2 and CO could be used as the syngas alternative for hydroformylation. In this paper, the behaviors of FA to release H2 as well as CO following the distinct pathways were carefully investigated for the first time, and then established a new hydroformylation protocol free of syngas. It was found that the atmospheric hydroformylation of olefins with formic acid (FA) as syngas alternative was smoothly fulfilled over Xantphos (L1) modified Rh-catalyst under mild conditions (80 °C, Rh concentration 1 mol %, 14 h), resulting in >90% conversion of the olefins along with the high selectivity to the target aldehydes (>93%). By using FA as syngas source, the side-reaction of olefin-hydrogenation was greatly depressed. The in situ FT-IR and the high-pressure 1H NMR spectroscopic analyses were applied to reveal how FA behaves dually as CO surrogate and hydrogen source over L1-Rh(acac)(CO)2 catalytic system, based on which the deeply insight into the catalytic mechanism of hydroformylation of olefins with FA as syngas alternative was offered.
- Liu, Lei,Chen, Xiao-Chao,Yang, Shu-Qing,Yao, Yin-Qing,Lu, Yong,Liu, Ye
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p. 406 - 415
(2020/12/07)
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- Copper-catalyzed hydroformylation and hydroxymethylation of styrenes
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Hydroformylation catalyzed by transition metals is one of the most important homogeneously catalyzed reactions in industrial organic chemistry. Millions of tons of aldehydes and related chemicals are produced by this transformation annually. However, most of the applied procedures use rhodium catalysts. In the procedure described here, a copper-catalyzed hydroformylation of alkenes has been realized. Remarkably, by using a different copper precursor, the aldehydes obtained can be further hydrogenated to give the corresponding alcohols under the same conditions, formally named as hydroxymethylation of alkenes. Under pressure of syngas, various aldehydes and alcohols can be produced from alkenes with copper as the only catalyst, in excellent regioselectivity. Additionally, an all-carbon quaternary center containing ethers and formates can be synthesized as well with the addition of unactivated alkyl halides. A possible reaction pathway is proposed based on our results. This journal is
- Franke, Robert,Geng, Hui-Qing,Meyer, Tim,Wu, Xiao-Feng
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p. 14937 - 14943
(2021/12/02)
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- Cobalt-Catalyzed Aerobic Oxidative Cleavage of Alkyl Aldehydes: Synthesis of Ketones, Esters, Amides, and α-Ketoamides
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A widely applicable approach was developed to synthesize ketones, esters, amides via the oxidative C?C bond cleavage of readily available alkyl aldehydes. Green and abundant molecular oxygen (O2) was used as the oxidant, and base metals (cobalt and copper) were used as the catalysts. This strategy can be extended to the one-pot synthesis of ketones from primary alcohols and α-ketoamides from aldehydes.
- Li, Tingting,Hammond, Gerald B.,Xu, Bo
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p. 9737 - 9741
(2021/05/31)
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- Palladium-Catalyzed Allenamide Carbopalladation/Allylation with Active Methine Compounds
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A palladium-catalyzed allenamide carbopalladation/allylation with active methine compounds has been developed. Various indoles and isoquinolinones bearing a quaternary carbon center were achieved with good efficiency, a broad substrate scope and good functional group tolerance. This reaction underwent cascade oxidative addition, carbopalladation, and allylic alkylation, and two new C-C bonds were formed in one pot.
- Zhu, Xiaoyi,Li, Ruibo,Yao, Hequan,Lin, Aijun
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p. 4630 - 4634
(2021/06/28)
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- Synthesis of rac-ɑ-aryl propionaldehydes via branched-selective hydroformylation of terminal arylalkenes using water-soluble Rh-PNP catalyst
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This work detailed the preparation of a class of water-soluble PNP ligands that differed by the nature of the substitute on phenyl ring of ligands. These ligands were incorporated into water-soluble rhodium-PNP complex catalysts that were used to regioselective hydroformylation of a series of terminal arylalkenes, providing efficient access to rac-α-aryl propionaldehydes in good to excellent yield (up to 97%) and branched-regioselectivity (up to 40:1 b/l ratio). Furthermore, gram-scale and diverse synthetic transformation demonstrated synthetic application of this methodology for non-steroidal antiinflammatory drugs.
- Chen, Fen-Er,Gao, Peng,Ke, Miaolin,Liang, Guanfeng,Ru, Tong
-
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- The first one-pot metathesis-hydroformylation procedure: a straight synthesis of 2-arylpropanals from renewable 1-propenylbenzenes
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Hydroformylation is a consolidated synthetic tool in the chemical industry, both in commodity and in the fine chemicals industry. Olefin metathesis has been largely employed in the petrochemical sector, and, more recently, in the synthesis of specialty chemicals. Although these reactions may be involved in the same synthetic route for various industrial chemicals, to the best of our knowledge, they have never been combined in a one-pot procedure. As a proof of concept, we have demonstrated in the present work that the ruthenium-catalyzed ethenolysis of renewable 1-propenylbenzenes followed by the rhodium-catalyzed hydroformylation of functionalized styrenes formed in the first step could be done in one pot. The integration of these reactions was not straightforward once the catalyst of the first step interfered with the catalyst of the second step. Under optimized conditions, it was possible to synthesize 2-arylpropanals, a class of compounds valuable as synthetic intermediates to access non-steroidal anti-inflammatory drugs, in overall yields of 85-90%, at low catalyst loadings.
- Avenda?o Villarreal, Jesus Alberto,Delolo, Fábio Godoy,Granato, Artur Vicari,Gusevskaya, Elena Vitalievna,dos Santos, Eduardo Nicolau
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p. 8007 - 8013
(2021/12/27)
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- Synergistic Peptide and Gold Catalysis: Enantioselective Addition of Branched Aldehydes to Allenamides
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The combination of a peptide catalyst and a gold catalyst is presented for enantioselective addition reactions between branched aldehydes and allenamides. The two catalysts act in concert to provide γ,δ-enamide aldehydes bearing a fully substituted, benzylic stereogenic center – a structural motif common in many natural products and therapeutically active compounds – with good yields and enantioselectivities. The reaction tolerates a variety of alkyl and alkoxy substituted aldehydes and the products can be elaborated into several chiral building blocks bearing either 1,4- or 1,5- functional group relationships. Mechanistic studies showed that the conformational features of the peptide are important for both the catalytic efficiency and stereochemistry, while a balance of acid/base additives is key for ensuring formation of the desired product over undesired side reactions.
- Nicholls, Leo D. M.,Wennemers, Helma
-
supporting information
p. 17559 - 17564
(2021/10/19)
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- Triphenylphosphine-Based Covalent Organic Frameworks and Heterogeneous Rh-P-COFs Catalysts
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The synthesis of phosphine-based functional covalent organic frameworks (COFs) has attracted great attention recently. Herein, we present two examples of triphenylphosphine-based COFs (termed P-COFs) with well-defined crystalline structures, high specific surface areas, and good thermal stability. Furthermore, rhodium catalysts with these P-COFs as support material show high turnover frequency for the hydroformylation of olefins, as well as excellent recycling performance. This work not only extends the phosphine-based COF family, but also demonstrates their application in immobilizing homogeneous metal-based (e.g., Rh-phosphine) catalysts for application in heterogeneous catalysis.
- Liu, Yubing,Dikhtiarenko, Alla,Xu, Naizhang,Sun, Jiawei,Tang, Jie,Wang, Kaiqiang,Xu, Bolian,Tong, Qing,Heeres, Hero Jan,He, Songbo,Gascon, Jorge,Fan, Yining
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supporting information
p. 12134 - 12139
(2020/09/01)
-
- 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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- MICROCAPSULES AND PROCESSES FOR THEIR PREPARATION
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The present invention provides microcapsules encapsulating hydrophilic or hydrophobic active agents in an inorganic shell, processes for their preparation and compositions comprising them.
- -
-
Page/Page column 28-30
(2019/06/11)
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- Mild Iridium-Catalysed Isomerization of Epoxides. Computational Insights and Application to the Synthesis of β-Alkyl Amines
-
The isomerization of epoxides to aldehydes using the readily available Crabtree's reagent is described. The aldehydes were transformed into synthetically useful amines by a one-pot reductive amination using pyrrolidine as imine-formation catalyst. The reactions worked with low catalyst loadings in very mild conditions. The procedure is operationally simple and tolerates a wide range of functional groups. A DFT study of its mechanism is presented showing that the isomerization takes place via an iridium hydride mechanism with a low energy barrier, in agreement with the mild reaction conditions. (Figure presented.).
- Cabré, Albert,Cabezas-Giménez, Juanjo,Sciortino, Giuseppe,Ujaque, Gregori,Verdaguer, Xavier,Lledós, Agustí,Riera, Antoni
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p. 3624 - 3631
(2019/07/10)
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- Highly Enantioselective Catalytic Kinetic Resolution of α-Branched Aldehydes through Formal Cycloaddition with Homophthalic Anhydrides
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A new catalytic methodology was developed to promote an efficient one-pot kinetic resolution of racemic aldehydes with selectivity (s*) of up to 91 (99:1 d.r., >99 % ee) in a cycloaddition reaction with enolizable anhydrides to afford dihydroisocoumarin products (a core prevalent in natural products and molecules of medicinal interest) containing three contiguous stereocentres.
- Farid, Umar,Aiello, Maria Luisa,Connon, Stephen J.
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p. 10074 - 10079
(2019/07/18)
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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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- FUNCTIONALIZED MAGNETIC NANOPARTICLE, A CATALYST, A METHOD FOR FORMING C-C BONDS
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A functionalized magnetic nanoparticle including an organometallic sandwich compound and a magnetic metal oxide. The functionalized magnetic nanoparticle may be reacted with a metal precursor to form a catalyst for various C—C bond forming reactions. The catalyst may be recovered with ease by attracting the catalyst with a magnet.
- -
-
Paragraph 0210
(2018/04/20)
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- Copper-catalyzed vinylogous aerobic oxidation of unsaturated compounds with air
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A mild and operationally simple copper-catalyzed vinylogous aerobic oxidation of β,γ- and α,β-unsaturated esters is described. This method features good yields, broad substrate scope, excellent chemo- and regioselectivity, and good functional group tolerance. This method is additionally capable of oxidizing β,γ- and α,β-unsaturated aldehydes, ketones, amides, nitriles, and sulfones. Furthermore, the present catalytic system is suitable for bisvinylogous and trisvinylogous oxidation. Tetramethylguanidine (TMG) was found to be crucial in its role as a base, but we also speculate that it serves as a ligand to copper(II) triflate to produce the active copper(II) catalyst. Mechanistic experiments conducted suggest a plausible reaction pathway via an allylcopper(II) species. Finally, the breadth of scope and power of this methodology are demonstrated through its application to complex natural product substrates.
- Zhang, Hai-Jun,Schuppe, Alexander W.,Pan, Shi-Tao,Chen, Jin-Xiang,Wang, Bo-Ran,Newhouse, Timothy R.,Yin, Liang
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p. 5300 - 5310
(2018/04/24)
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- Asymmetric α-Allylation of Aldehydes with Alkynes by Integrating Chiral Hydridopalladium and Enamine Catalysis
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A palladium-catalyzed asymmetric α-allylation of aldehydes with alkynes has been established by integrating the catalysis of enamine and chiral hydridopalladium complex that is reversibly formed from the oxidative addition of Pd(0) to chiral phosphoric acid. The ternary catalyst system, consisting of an achiral palladium complex, a primary amine, and a chiral phosphoric acid allows the reaction to tolerate a wide scope of α,α-disubstituted aldehydes and alkynes, affording the corresponding allylation products in high yields and with excellent levels of enantioselectivity.
- Su, Yong-Liang,Li, Lu-Lu,Zhou, Xiao-Le,Dai, Zhen-Yao,Wang, Pu-Sheng,Gong, Liu-Zhu
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p. 2403 - 2406
(2018/04/27)
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- Rhodium-catalyzed asymmetric hydrogenation of β-branched enamides for the synthesis of β-stereogenic amines
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Using a rhodium complex of a bisphosphine ligand (R)-SDP, β-branched simple enamides with a (Z)-configuration were hydrogenated to β-stereogenic amines in quantitative yields and with excellent enantioselectivities (88-96% ee).
- Zhang, Jian,Liu, Chong,Wang, Xingguang,Chen, Jianzhong,Zhang, Zhenfeng,Zhang, Wanbin
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p. 6024 - 6027
(2018/06/18)
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- Pummerer Cyclization Revisited: Unraveling of Acyl Oxonium Ion and Vinyl Sulfide Pathways
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Two viable pathways (vinyl sulfide and acyl oxonium ion) for the Pummerer cyclization have been unraveled that expand the reaction scope and capabilities. Use of Br?nsted-enhanced Lewis acidity was key to realization of the vinyl sulfide pathway, whereas selective complexation of the sulfur lone pair facilitated the unprecedented acyl oxonium ion pathway. Preliminary mechanistic investigations support these hypotheses. A range of substrates have been explored to understand the reaction parameters.
- Li, Xin,Carter, Rich G.
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p. 5541 - 5545
(2018/09/25)
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- Iron Catalyzed Hydroformylation of Alkenes under Mild Conditions: Evidence of an Fe(II) Catalyzed Process
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Earth abundant, first row transition metals offer a cheap and sustainable alternative to the rare and precious metals. However, utilization of first row metals in catalysis requires harsh reaction conditions, suffers from limited activity, and fails to tolerate functional groups. Reported here is a highly efficient iron catalyzed hydroformylation of alkenes under mild conditions. This protocol operates at 10-30 bar syngas pressure below 100 °C, utilizes readily available ligands, and applies to an array of olefins. Thus, the iron precursor [HFe(CO)4]-[Ph3PNPPh3]+ (1) in the presence of triphenyl phosphine catalyzes the hydroformylation of 1-hexene (S2), 1-octene (S1), 1-decene (S3), 1-dodecene (S4), 1-octadecene (S5), trimethoxy(vinyl)silane (S6), trimethyl(vinyl)silane (S7), cardanol (S8), 2,3-dihydrofuran (S9), allyl malonic acid (S10), styrene (S11), 4-methylstyrene (S12), 4-iBu-styrene (S13), 4-tBu-styrene (S14), 4-methoxy styrene (S15), 4-acetoxy styrene (S16), 4-bromo styrene (S17), 4-chloro styrene (S18), 4-vinylbenzonitrile (S19), 4-vinylbenzoic acid (S20), and allyl benzene (S21) to corresponding aldehydes in good to excellent yields. Both electron donating and electron withdrawing substituents could be tolerated and excellent conversions were obtained for S11-S20. Remarkably, the addition of 1 mol % acetic acid promotes the reaction to completion within 16-24 h. Detailed mechanistic investigations revealed in situ formation of an iron-dihydride complex [H2Fe(CO)2(PPh3)2] (A) as an active catalytic species. This finding was further supported by cyclic voltammetry investigations and intermediacy of an Fe(0)-Fe(II) species was established. Combined experimental and computational investigations support the existence of an iron-dihydride as the catalyst resting state, which then follows a Fe(II) based catalytic cycle to produce aldehyde.
- Pandey, Swechchha,Raj, K. Vipin,Shinde, Dinesh R.,Vanka, Kumar,Kashyap, Varchaswal,Kurungot, Sreekumar,Vinod,Chikkali, Samir H.
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supporting information
p. 4430 - 4439
(2018/04/05)
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- Heck arylation of allyl alcohol catalyzed by Pd(0) nanoparticles
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Pd(0) nanoparticles ca. 2 nm in diameter were obtained by the reduction of PdCl2 and Pd(OAc)2 in water at 80 °C in the presence of a PVP-stabilizing polymer. Pd(0) NPs were successfully used in the Heck coupling of allyl alcohol with iodo- and bromobenzenes. Iodobenzenes reacted under solventless conditions or in DMF solution producing 3-arylpropanals and 2-arylpropanals as the main products. The same products were obtained in the reaction of bromobenzene in TBAB as the reaction medium. The stability of Pd(0) NPs was evidenced in recycling experiments. Similar Heck coupling results were also obtained with the palladium compounds PdCl2(cod) and Pd(OAc)2 under the same conditions.
- Tarnowicz, Stanis?awa,Alsalahi, Waleed,Mieczyńska, Ewa,Trzeciak, Anna M.
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p. 5605 - 5612
(2017/08/26)
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- Stereodivergent coupling of aldehydes and alkynes via synergistic catalysis using Rh and Jacobsen's amine
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We report an enantioselective coupling between α-branched aldehydes and alkynes to generate vicinal quaternary and tertiary carbon stereocenters. The choice of Rh and organocatalyst combination allows for access to all possible stereoisomers with high enantio-, diastereo-, and regioselectivity. Our study highlights the power of catalysis to activate two common functional groups and provide access to divergent stereoisomers and constitutional structures.
- Cruz, Faben A.,Dong, Vy M.
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p. 1029 - 1032
(2017/05/15)
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- Stereodivergent Coupling of Aldehydes and Alkynes via Synergistic Catalysis Using Rh and Jacobsen's Amine
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We report an enantioselective coupling between α-branched aldehydes and alkynes to generate vicinal quaternary and tertiary carbon stereocenters. The choice of Rh and organocatalyst combination allows for access to all possible stereoisomers with high ena
- Cruz, Faben A.,Dong, Vy M.
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p. 1029 - 1032
(2021/09/04)
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- Reaction of azides and enolisable aldehydes under the catalysis of organic bases and: Cinchona based quaternary ammonium salts
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Herein we report a two-step sequence for the preparation of amides starting from azides and enolisable aldehydes. The reaction proceeded via the formation of triazoline intermediates that were converted into amides via Lewis acid catalysis. Preliminary st
- Destro, Dario,Sanchez, Sandra,Cortigiani, Mauro,Adamo, Mauro F. A.
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p. 5227 - 5235
(2017/07/11)
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- Magnetic nanoparticle-supported ferrocenylphosphine: A reusable catalyst for hydroformylation of alkene and Mizoroki-Heck olefination
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We present dopamine (dop) conjugated bis(diphenylphosphino)ferrocenylethylamine (BPPFA) functionalized magnetic nanoparticles (Fe3O4). A ferrocene ({η5-C5H4-PPh2}Fe{η5-C5H3-1-PPh2-2-CH(Me)NH-CH2-CH2-4Ph-1,2-OH}) ligand (dop-BPPF) has been prepared by reaction of (1-[1′,2-bis(diphenylphosphino)-ferrocenyl]ethyl acetate) and dopamine hydrochloride to form dop-BPPF, which was characterized by NMR, IR, FTIR, EA and FAB-MS. This ligand was anchored on ultrasmall (6-8 nm) magnetic nanoparticles (MNP) to yield Fe3O4@dop-BPPF. The resulting ferrocenylphosphine on magnetic nanoparticles was characterized by SEM, EDS, XRD, TEM, TGA, and VSM. The magnetic nature of the materials was investigated. Fe3O4@dop-BPPF exhibits very high catalytic activity for the Pd-catalyzed Mizoroki-Heck reaction and exceptionally high regioselectivity for the Rh-catalyzed hydroformylation reaction with branched aldehydes (up to > 99%). The potential of this Fe3O4@dop-BPPF as a reusable catalyst has been studied for the Mizoroki-Heck reaction, and this catalyst was robustly active even after eleven consecutive cycles.
- Shaikh, M. Nasiruzzaman,Aziz, Md. Abdul,Helal, Aasif,Bououdina, Mohamed,Yamani, Zain H.,Kim, Tae-Jeong
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p. 41687 - 41695
(2016/05/19)
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- Dual Catalysis Using Boronic Acid and Chiral Amine: Acyclic Quaternary Carbons via Enantioselective Alkylation of Branched Aldehydes with Allylic Alcohols
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A ferrocenium boronic acid salt activates allylic alcohols to generate transient carbocations that react with in situ-generated chiral enamines from branched aldehydes. The optimized conditions afford the desired acyclic products embedding a methyl-aryl quaternary carbon center with up to 90% yield and 97:3 enantiomeric ratio, with only water as the byproduct. This noble-metal-free method complements alternative methods that are incompatible with carbon-halogen bonds and other sensitive functional groups.
- Mo, Xiaobin,Hall, Dennis G.
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p. 10762 - 10765
(2016/09/09)
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- Design of Potent and Druglike Nonphenolic Inhibitors for Catechol O-Methyltransferase Derived from a Fragment Screening Approach Targeting the S-Adenosyl- l -methionine Pocket
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A fragment screening approach designed to target specifically the S-adenosyl-l-methionine pocket of catechol O-methyl transferase allowed the identification of structurally related fragments of high ligand efficiency and with activity on the described orthogonal assays. By use of a reliable enzymatic assay together with X-ray crystallography as guidance, a series of fragment modifications revealed an SAR and, after several expansions, potent lead compounds could be obtained. For the first time nonphenolic and small low nanomolar potent, SAM competitive COMT inhibitors are reported. These compounds represent a novel series of potent COMT inhibitors that might be further optimized to new drugs useful for the treatment of Parkinson's disease, as adjuncts in levodopa based therapy, or for the treatment of schizophrenia.
- Lerner, Christian,Jakob-Roetne, Roland,Buettelmann, Bernd,Ehler, Andreas,Rudolph, Markus,Sarmiento, Rosa María Rodríguez
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p. 10163 - 10175
(2016/12/07)
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- Rhodium-complexed hyperbranched poly(ethyleneimine) and polyamidoamine and their non-covalent immobilization on magnetic nanoparticles
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We describe a synthetic strategy for the synthesis and functionalization of hyperbranched poly(ethyleneimine) (H-PEI) and polyamidoamine (H-PAMAM) with phosphine ligands and their non-covalent immobilization on magnetic nanosupports. Treatment of these functionalized hyperbranched polymers with Rh(COD)2BF4 affords polymer-bound Rh(I) complexes that can be utilized in the hydroformylation of alkenes and in one pot hydroformylation-Knoevenagel-hydrogenation reactions. These functionalized hyperbranched polymers are linked to magnetic nanoparticles that are modified with carboxylic acid groups via ionic interactions resulting from the acid-base reactions, and are responsible for facilitating the separation of the polymeric catalysts. These magnetically retrievable polymeric catalysts can be reused for up to four cycles.
- Omar, Suheir,Dutta, Bishnu,Natour, Suzana,Abu-Reziq, Raed
-
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- Surface bonded Rh-bis(diarylphosphine) on magnetic nanoparticles as a recyclable catalyst for hydroformylation of olefins
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A functionalized nanomaterial having an average particles size of less than 10 nm comprising an iron oxide nanoparticle core and a bis(diarylphosphinomethyl) dopamine based ligand layer anchored to the iron oxide nanoparticle core is disclosed. In addition, a catalyst composition for use in a variety of chemical transformations wherein the bisphosphine groups of the functionalized nanomaterial chelate a catalytic metal is disclosed. In addition, a method for producing the functionalized nanomaterial and a method for the hydroformylation of olefins to aldehydes employing the functionalized nanomaterial with high conversion percentage and high selectivity are disclosed.
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Page/Page column 23-24
(2016/11/21)
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- Dual Catalytic Activity of Palladium Doped with a Rhodium Complex in a One-pot, Four Step Process
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The extraction of the two competing reactions from the same catalyst - a composite catalytic-complex@catalytic-metal - is reported. A Wilkinson rhodium based catalyst entrapped within metallic palladium catalyst is shown to perform both hydroformylation and hydrogenation with a ratio that depends on H2 and CO pressures. Here we demonstrate this special reactivity in a one-pot, four step sequence, which include hydroformylations of phenyl acetylenes, reduction of nitrobenzene to aniline, carbonyl-amine condensations forming imines; and imine reductions.
- Shapiro, Leora,Driess, Matthias,Avnir, David
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p. 2033 - 2037
(2015/11/24)
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- Metal and organo-catalysed asymmetric hydroaminomethylation of styrenes
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A new protocol that enables asymmetric hydroaminomethylation of styrenes to afford chiral amines has been developed. Catalysed by an Rh-phosphine species and a chiral phosphoric acid, styrenes are converted into β-chiral amines with good enantioselectivities under syngas in the presence of an amine and Hantzsch ester. The reaction involves two key steps, hydroformylation and reductive amination, with the former catalysed by the Rh species whilst the latter by the phosphoric acid.
- Villa-Marcos, Barbara,Xiao, Jianliang
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p. 106 - 112
(2015/09/28)
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- Dynamic kinetic asymmetric amination of alcohols: From a mixture of four isomers to diastereo- and enantiopure α-branched amines
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The first dynamic kinetic asymmetric amination of alcohols via borrowing hydrogen methodology is presented. Under the cooperative catalysis by an iridium complex and a chiral phosphoric acid, α-branched alcohols that exist as a mixture of four isomers undergo racemization by two orthogonal mechanisms and are converted to diastereo- and enantiopure amines bearing adjacent stereocenters. The preparation of diastereo- and enantiopure 1,2-amino alcohols is also realized using this catalytic system.
- Rong, Zi-Qiang,Zhang, Yao,Chua, Raymond Hong Bing,Pan, Hui-Jie,Zhao, Yu
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p. 4944 - 4947
(2015/05/05)
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- Hydroformylation of olefins and reductive carbonylation of aryl halides with syngas formed ex situ from dehydrogenative decarbonylation of hexane-1,6-diol
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A variety of primary alcohols have been investigated as convenient substrates for the ex situ delivery of carbon monoxide and molecular hydrogen in a two-chamber reactor. The gaseous mixture is liberated in one chamber by an iridium-catalysed dehydrogenative decarbonylation of the alcohol and then consumed in the other chamber in either a rhodium-catalysed hydroformylation of olefins or a palladium-catalysed reductive carbonylation of aryl halides. Hexane-1,6-diol was found to be the optimum alcohol for both reactions where moderate to excellent yields were obtained of the product aldehydes. A relatively low pressure of 1.5-2.4 bar was measured in the closed system during the two transformations.
- Christensen, Stig Holden,Olsen, Esben P. K.,Rosenbaum, Jascha,Madsen, Robert
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p. 938 - 945
(2015/02/19)
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- Promotion effect of water on hydroformylation of styrene and its derivatives with presence of amphiphilic zwitterionic phosphines
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Two kinds of novel zwitterionic phosphines of L1 and L2 have been synthesized in which the sulfonate groups (-SO3-) are incorporated to render them amphiphilic. Both of them are strong π-acceptor ligands in which the positive-charged imidazoliums with intensive electron-withdrawing effect are vicinal to the coordinating phosphorous atoms. The amino-group of piperidyl is additionally incorporated in L2 to make it behave as a hybrid ligand with potential hemilability. The comparison of the ligands of L1 and L2 in Rh-catalyzed hydroformylation of styrene (and its derivatives) and the effect of water on their behaviors were discussed. Without the involvement of water, the catalytic system of Rh(acac)(CO)2-L2 exhibited lower activity than that of Rh(acac)(CO)2-L1 under the same conditions. However, the dramatic promotion effect of water as a suspension was observed especially for Rh(acac)(CO)2-L2 system with TOF spurred up from 195 to 470 h-1. The corresponding in situ high pressure FT-IR spectral information showed that the presence of water in Rh(acac)(CO)2-L2 system greatly facilitated the formation and stability of the active Rh-H species (νRh-H, 2047 cm-1), which was in charge of the efficient hydroformylation of styrene and its derivatives.
- Chen, Sheng-Jie,Li, Yong-Qi,Wang, Peng,Lu, Yong,Zhao, Xiao-Li,Liu, Ye
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p. 212 - 220
(2015/07/28)
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- The rhodium complex of bis(diphenylphosphinomethyl)dopamine-coated magnetic nanoparticles as an efficient and reusable catalyst for hydroformylation of olefins
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A new bis(diphenylphosphinomethyl)dopamine (bpd) ligand has been prepared and anchored on the surface of magnetic nanoparticles (MNPs). The obtained ligand and the surface functionalized nanoparticles of type MNP@bpd have been characterized by various analytical techniques, such as NMR, IR, TEM, XRD, and VSM. TEM shows homogeneous distribution of the particles with the size ranging 5-7 nm. XRD Rietveld analysis confirms the formation of a pure and single Fe3O4 phase with high crystallinity. The ligands anchored on the magnetic nanoparticle surface have been confirmed by the shift of the characteristic Fe-O vibration band in the FT-IR spectrum, and have been supported by the stepwise weight loss in TGA as a function of temperature. The phosphorus content determined by ICP-MS is approximately 0.39 mmol of phosphine per gram of the nanoparticles. Magnetization-field curves recorded at room temperature reveal superparamagnetic behavior. MNP@bpd materials have proven to be excellent catalysts after in situ addition of the rhodium (Rh) metal precursor for the hydroformylation reaction of styrene and its derivatives. The extent of reusability of the catalyst has been tested and was found to be active even after seven consecutive cycles.
- Shaikh, Mohammed Nasiruzzaman,Bououdina, Mohamed,Jimoh, Abiola Azeez,Aziz, Md. Abdul,Helal, Aasif,Hakeem, Abbas Saeed,Yamani, Zain H.,Kim, Tae-Jeong
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p. 7293 - 7299
(2015/09/02)
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- A simple primary amine catalyst for enantioselective α-hydroxylations and α-fluorinations of branched aldehydes
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A new primary amine catalyst for the asymmetric α-hydroxylation and α-fluorination of α-branched aldehydes is described. The products of the title transformations are generated in excellent yields with high enantioselectivities. Both processes can be performed within short reaction times and on gram scale. The similarity in results obtained in both reactions, combined with computational evidence, implies a common basis for stereoinduction and the possibility of a general catalytic mechanism for α-functionalizations. Promising initial results in α-amination and α-chlorination reactions support this hypothesis.
- Witten, Michael R.,Jacobsen, Eric N.
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supporting information
p. 2772 - 2775
(2015/06/16)
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- Dynamic kinetic resolution of 2-phenylpropanal derivatives to yield β-chiral primary amines via bioamination
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The amination of racemic α-chiral aldehydes, 2-phenylpropanal derivatives, was investigated employing ω-transaminases. By medium and substrate engineering the optical purity of the resulting β-chiral chiral amine could be enhanced to reach optical purities up to 99% ee. Using enantiocomplementary ω-transaminases allowed us to access the (R)- as well as the (S)-enantiomer in most cases. It is important to note that the stereopreference of the ω-transaminases found for α-chiral aldehydes did not correlate with the stereopreference previously observed for the amination of methyl ketones. In one case the stereopreference switched even upon exchanging a methyl substituent to a methoxy group.
- Fuchs, Christine S.,Hollauf, Manuel,Meissner, Maximilian,Simon, Robert C.,Besset, Tatiana,Reek, Joost N. H.,Riethorst, Waander,Zepeck, Ferdinand,Kroutil, Wolfgang
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p. 2257 - 2265
(2014/07/21)
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- Synthesis of chiral butenolides using amino-thiocarbamate-catalyzed asymmetric bromolactonization
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The asymmetric cyclization of 4,4-disubstituted 3-butenoic acids is studied. Amino-thiocarbamates are used as the catalysts and N-bromosuccinimide is used as the stoichiometric halogen source. The resulting γ-butanolide products are readily converted into the corresponding γ-butenolides (up to 58% ee) derivatives in one-pot.
- Tan, Chong Kiat,Er, Jun Cheng,Yeung, Ying-Yeung
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p. 1243 - 1246
(2014/02/14)
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- An air-stable cationic iridium hydride as a highly active and general catalyst for the isomerization of terminal epoxides
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We describe the use of an air-stable iridium hydride catalyst for the isomerization of terminal epoxides into aldehydes with perfect regioselectivity. The system operates at low loadings of catalyst (0.5 mol%), is highly practical, scalable, and tolerates functional groups that would not be compatible with Lewis acids typically used in stoichiometric amounts. Evidence for a rare hydride mechanism are provided. This journal is the Partner Organisations 2014.
- Humbert, Nicolas,Vyas, Devendra J.,Besnard, Céline,Mazet, Clément
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supporting information
p. 10592 - 10595
(2014/10/15)
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- Rhodium catalyzed hydroformylation with formaldehyde and an external H 2-source
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The efficiency of the syngas-free rhodium catalyzed hydroformylation of olefins with formaldehyde can be significantly improved by the addition of hydrogen gas or formic acid.
- Uhlemann, Marcus,Doerfelt, Stephan,B?rner, Armin
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p. 2209 - 2211
(2013/05/09)
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- Isomerization of terminal epoxides by a [Pd-H] catalyst: A combined experimental and theoretical mechanistic study
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An unusual palladium hydride complex has been shown to be a competent catalyst in the isomerization of a variety of terminal and internal epoxides. The reaction displayed broad scope and synthetic utility. Experimental and theoretical evidence are provided for an unprecedented hydride mechanism characterized by two distinct enantio-determining steps. These results hold promise for the development of an enantioselective variant of the reaction.
- Vyas, Devendra J.,Larionov, Evgeny,Besnard, Celine,Guenee, Laure,Mazet, Clement
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p. 6177 - 6183
(2013/06/04)
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- β-tert-Butyl aspartate as an organocatalyst for the asymmetric α-amination of α,α-disubstituted aldehydes
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The enantioselective α-amination reaction of α,α- disubstituted aldehydes can lead to a variety of enantioenriched amino aldehydes, amino alcohols, and amino acids. After screening a variety of amino acids and their derivatives, we identified a cheap, simple, commercially available aspartic acid derivative that can catalyze efficiently the reaction between α,α-disubstituted aldehydes and dialkyl azodicarboxylates. The reaction proceeds smoothly leading to the corresponding α-aminated adducts in moderate to quantitative yields and moderate to high enantioselectivities (up to 96% ee). Finally, the conversion of these adducts to α,α-disubstituted quaternary amino acids is also described.
- Theodorou, Alexis,Papadopoulos, Giorgos N.,Kokotos, Christoforos G.
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p. 5438 - 5443
(2013/07/05)
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- Flow Chemistry Syntheses of Styrenes, Unsymmetrical Stilbenes and Branched Aldehydes
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Two tandem flow chemistry processes have been developed. A single palladium-catalysed Heck reaction with ethylene gas provides an efficient synthesis for functionalised styrenes. Through further elaboration the catalyst becomes multi-functional and performs a second Heck reaction providing a single continuous process for the synthesis of unsymmetrical stilbenes. In addition, the continuous, rhodium-catalysed, hydroformylation of styrene derivatives with syngas affords branched aldehydes with good selectivity. Incorporation of an in-line aqueous wash and liquid-liquid separation allowed for the ethylene Heck reaction to be telescoped into the hydroformylation step such that a single flow synthesis of branched aldehydes directly from aryl iodides was achieved. The tube-in-tube semi-permeable membrane-based gas reactor and liquid-liquid separator both play an essential role in enabling these telescoped flow processes.
- Bourne, Samuel L.,O'Brien, Matthew,Kasinathan, Sivarajan,Koos, Peter,Tolstoy, Paeivi,Hu, Dennis X.,Bates, Roderick W.,Martin, Benjamin,Schenkel, Berthold,Ley, Steven V.
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p. 159 - 172
(2013/03/13)
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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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- Ligand-metal cooperating PC(sp3)P pincer complexes as catalysts in olefin hydroformylation
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Ligand-metal cooperation: A new ligand-metal cooperating catalyst for the hydroformylation of olefins is described (see scheme). The mechanism of the H2 activation and C-H bond formation of the catalyst involves an intramolecular cooperation between the structurally remote functionality and the metal center and proceeds without change of the oxidation state of the metal.
- Musa, Sanaa,Filippov, Oleg A.,Belkova, Natalia V.,Shubina, Elena S.,Silantyev, Gleb A.,Ackermann, Lutz,Gelman, Dmitri
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supporting information
p. 16906 - 16909
(2014/01/06)
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- Complementary catalytic strategies to access α-chiral aldehydes
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The present article summarizes the development of two novel and complementary catalytic methods to access α-chiral aldehydes. A C1-symmetric chiral (P,N) ligand with a structure derived from the ubiquitous binepine scaffold has been specifically designed for the Pd-catalyzed α arylation of aldehydes to access indane derivatives with a well-defined quaternary stereocenter in high yields and excellent enantioselectivities. In addition, a dinuclear palladium hydride catalyst has been synthesized for the isomerization of terminal and trisubstituted epoxides into aldehydes and ketones respectively. Combined experimental and theoretical investigations pointed to an unprecedented 'epoxide-opening/hydride-transfer' sequence. The mechanism also features two distinct enantio-determining steps in the kinetic resolution of racemic epoxides. Schweizerische Chemische Gesellschaft.
- Mazet, Clement
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p. 658 - 662
(2013/11/06)
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- Unexpected extension of usage of PPh3/CBr4, a versatile reagent: Isomerization of aromatic allylic alcohols
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The PPh3/CBr4-catalyzed isomerization of 2-aromatic allylic alcohols into the corresponding saturated aldehydes or ketones has been achieved at room temperature in good to excellent yields under mild and metal-free conditions. This new methodology has been applied successfully to the synthesis of ibuprofen in four steps.
- Gong, Wanchun,Liu, Yun,Xue, Jijun,Xie, Zhixiang,Li, Ying
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supporting information
p. 1597 - 1599
(2013/02/23)
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- MICROWAVE INDUCED SINGLE STEP GREEN SYNTHESIS OF SOME NOVEL 2-ARYL ALDEHYDES AND THEIR ANALOGUES
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The present invention provides a process for the preparation of some novel 2-aryl and 2,2-diaryl aldehydes and analogues which are privileged intermediates for commercially important nonsteroidal anti-inflammatory drugs including naproxen, flurbiprofen and potent anticancer drug candidates, including phenstatin through a unique single step synthetic methodology utilizing easily available substrates in the form of aryl alkenes as well as environmentally benign aqueous reaction conditions in the form of solvents such as mixtures of water and DMSO or Dioxane and reagents N-bromosuccinimide, N-iodosuccinimide, N-cholorosuccinimide and phase transfer catalyst such as cetyltrimethyl ammonium bromide, N-hexyl ammonium chloride for a reaction time varying from 1 min-30 min, depending upon microwave or conventional heating, without using expensive transition metal catalysts or lewis acids/bases with yield varying from 35-55%, depending upon the solvent and substrate used. The developed method provides a clean and convenient alternative to access a diverse range of medicinally important 2-aryl and 2,2-diaryl aldehyde based scaffolds in lieu of the conventional multistep protocols employing expensive and hazardous transition metal catalysts and lewis acids/bases.
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Page/Page column 6
(2012/03/08)
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- Oxidative cleavage of α-aryl aldehydes using iodosylbenzene
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We found that α-aryl aldehydes can be cleaved to chain-shortened carbonyl compounds and formaldehyde by various iodosylbenzene complexes. A mechanistic scheme is presented that accounts for the loss of one carbon atom. Formaldehyde is further oxidized to CO and CO2 under the reaction conditions.
- Havare, Nizam,Plattner, Dietmar A.
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supporting information
p. 5078 - 5081,4
(2020/09/15)
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