- Configurational Stability of a Cyclopropyl Grignard Reagent Containing a Metalated 2-Hydroxymethyl Group
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Mixtures of cis- and trans-2-bromo-3-(hydroxymethyl)-1,1-dimethylcyclopropane were treated with methylmagnesium bromide to metalate the hydroxyl groups and then with magnesium to form metalated Grignard reagents.The compositions of products obtained upon hydrolysis with D2O indicated that the metalated Grignard reagents in refluxing diethyl ether did not undergo significant cis-trans isomerization.This work provides an example of the configurational stability of a cyclopropyl Grignard reagent with a secondary rather than a tertiary α-carbon.Because of these resultswith cyclopropyl Grignard reagents containing a metalated hydroxyl group, prior observations on additions of allylic Grignard reagents to 3-(hydroxymethyl)cyclopropenes only of products resulting from a cis relationship of magnesium and hydroxymethyl must be due to the stereochemistry of the addition process rather than to a subsequent isomerization.
- Richey, Herman G.,Moses, L. Meredith
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Read Online
- Reaction of Methylbutenol with Hydroxyl Radical: Mechanism and Atmospheric Implications
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The tropospheric fate of 2-methyl-3-buten-2-ol (methylbutenol, MBO), a recently identified emission by vegetation, was investigated by measuring its UV absorption cross sections (210-300 nm) and the rate coefficient for its reaction with hydroxyl free radicals.UV absorption cross sections were found to be too small for photolysis to be an important removal pathway for MBO in the troposphere.The rate constant applicable under tropospheric conditions for the reaction of OH with MBO was determined to be k=(8.2 +/- 1.2) * 10-12 e((610 +/- 50)/T) cm3 molecule-1 s-1.The OH reaction proceeds mainly via addition of the OH to the double bond in MBO.In the absence of O2, about 15-20percent of the adducts eliminate the alcohol-OH group.However, O2 can scavenge the adduct before it decomposes at T 300 K.This mechanism was confirmed by measuring the rate coefficients for the reactions of OD and 18OH and determining the rate coefficient for the OH reaction in the presence of 7-13 Torr of O2 and in SF6 buffer gas.The elimination of alcohol-OH group was substantiated by observing OH production in the reactions of 18OH and OD.The obtained OH reaction rate coefficient suggests that the primary daytime loss of MBO in the troposphere is via its reaction with OH.
- Rudich, Yinon,Talukdar, Ranajit,Burkholder, James B.,Ravishankara, A. R.
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Read Online
- Cationic Ru complexes anchored on POM via non-covalent interaction towards efficient transfer hydrogenation catalysis
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The ionic materials consisting of cationic Ru complexes and Wells-Dawson polyoxometalate anion (POM, K6P2W18O62) have been constructed via a non-covalent interaction. The as-synthesized catalysts have been characterized thoroughly by NMR, XRD, FESEM, and FT-IR, etc. The characterization suggested that a hydrogen bond interaction occurred between the proton of the amine ligand in the cationic Ru complexes and the oxygen atom of the POM anion. The hydrogen bond played an important role in enhancing catalytic activity for the transfer hydrogenation of methyl levulinate (ML) to γ-valerolactone (GVL) under very mild conditions. Especially, the transfer hydrogenation reaction proceeded via a heterogeneous catalysis approach and the heterogenized catalysts even afforded much better catalytic performance than homogeneous analogs. Notably, the catalysts can be recycled without an obvious loss of activity, and further extended to highly selective transfer hydrogenation of α,β-unsaturated ketones and aldehydes, etc. into the corresponding α,β-unsaturated alcohols without any base external additives. The high catalytic performance of these anchored catalysts was highly related to the hydrogen bond interaction and the basicity of the polyanion. The obtained knowledge from this work could lead us to a new catalysis concept of tethering active homogeneous complexes for constructing highly active anchored Ru complex catalysts for hydrogenation reaction.
- Chen, Manyu,Cui, Kai,Hou, Zhenshan,Peng, Qingpo,Wang, Jiajia,Wei, Xinjia,Zhao, Xiuge
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- Metal oxide coated ceramic corrugated plate catalyst, preparation and application in preparation of key intermediates of citral
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The present disclosure belongs to the technical field of catalysis, and particularly relates to a metal oxide coated ceramic corrugated plate catalyst, its preparation method and application thereof in preparation of key intermediates of citral. The catalyst consists of a ceramic corrugated plate carrier and a metal oxide active layer coated on a surface of the carrier, wherein the metal oxide active layer is a metal oxide formed by active ingredient titanium and at least four other metal elements selected from vanadium, chromium, manganese, iron, zirconium, niobium and molybdenum.
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(2021/04/14)
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- Ir nanoclusters confined within hollow MIL-101(Fe) for selective hydrogenation of α,β-unsaturated aldehyde
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Although the selective hydrogenation of α,β-unsaturated aldehyde to unsaturated alcohol (UOL) is an extremely important transformation, it is still a great challenge to achieve high selectivity to UOL due to thermodynamic favoring of the C[dbnd]C hydrogenation over the C[dbnd]O hydrogenation. Herein, we report that iridium nanoclusters (Ir NCs) confined within hollow MIL-101(Fe) expresses satisfied reaction activity (93.9%) and high selectivity (96.2%) for the hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL) under 1 bar H2 atmosphere and room temperature. The unique hollow structure of MIL-101(Fe) benefits for the fast transport of reactant, ensuring the comparable reaction activity and better recyclability of Ir@MIL-101(Fe) than the counterparts which Ir NCs were on the surface of MIL-101(Fe). Furthermore, The X-ray photoelectron spectroscopy data indicates the electropositive Ir NCs, owing to the electron transfer from Ir to MIL-101(Fe), can interact with oxygen lone pairs, and Fourier transform infrared spectrum shows the Lewis acid sites in MIL-101(Fe) can strongly interact with C[dbnd]O bond, which contributes to a high selectivity for COL. This work suggests the considerable potential of synergetic effect between hollow MOFs and metal nanoclusters for selective hydrogenation reactions.
- Chen, Yurong,Li, Guangqin,Li, Yinle,Liu, Qian,Liu, Qinghua,Liu, Qinglin,Su, Hui
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supporting information
(2021/08/13)
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- Preparation method of 3-methyl-2-butenol
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The invention provides a preparation method of 3-methyl-2-butenol. The preparation method comprises the following steps: carrying out an isomerization reaction on 2-methyl-3-butene-2-ol in a tubular reactor under the catalysis of a ruthenium catalyst to obtain the 3-methyl-2-butenol. No solvent is added in a reaction process, 2-methyl-3-butene-2-ol is subjected to the isomerization reaction in thetubular reactor to obtain a mixture of the 3-methyl-2-butene-2-ol and the 2-methyl-3-butene-2-ol, the mixture is rectified and separated to obtain the pure 3-methyl-2-butene-2-ol, and the 3-methyl-2-butene-2-ol obtained through recovery is returned to a reaction process, and continues to participate in the reaction. The method has the advantages of simple process flow, few side reactions, high reaction selectivity and high conversion rate.
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Paragraph 0026-0027; 0028-0029; 0030-0031; 0032-0049
(2020/12/08)
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- Method for preparing 3-methyl-2-butenol through photocatalysis
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The invention discloses a method for preparing 3-methyl-2-butenol through photocatalysis. The 3-methyl-3-butenol is efficiently subjected to isomerization reaction through photocatalysis reaction to obtain the 3-methyl-2-butenol. The method solves the problem of generation of isoamyl alcohol in the traditional preparation process of 3-methyl-2-butenol, and has the advantages of mild reaction conditions, simple operation, high product yield and easy separation.
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Paragraph 0037-0053
(2021/01/04)
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- Preparation method of allylic alcohol
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The invention belongs to the technical field of fine chemical industry. A heterogeneous catalyst technology is adopted, a complex catalyst is of a chelate structure and is formed by diphosphine ligandand transition metal compounds, the complex catalyst is used for catalyzing heterogeneous rearrangement of 3-methyl-3-butene-1-alcohol, production of by-products such as isoamyl alcohol and isopreneare inhibited at the same time, the conversion rate of raw materials is increased, and the product selectivity is improved. The invention provides a preparation method of the catalyst. The invention relates to a preparation method of allylic alcohol. Preparation is carried out by adopting a 3-methyl-3-butene-1-alcohol heterogeneous rearrangement technology. The preparation method is characterizedin that heterogeneous rearrangement is completed with the 1,3-bi(diphenylphosphine)propane-palladium-acetate chelate complex as the catalyst and on the conditions that hydrogen exists, the temperatureranges from 50 DEG C to 80 DEG C, and the time ranges from 20 minutes to 2 hours. According to the preparation method, the raw materials are easy to get, the cost is low, the repeated usage time number of catalysts is large, no three wastes are produced, and the energy consumption is low; and because of energy saving, consumption reduction and environmental protection, and the high conversion rate of the raw materials and the high product selectivity, the preparation method is suitable for preparing allylic alcohol and is especially suitable for preparing high-quality allylic alcohol.
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Paragraph 0023-0036
(2020/02/20)
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- Scalable synthesis of the aroma compounds d6-β-ionone and d6-β-cyclocitral for use as internal standards in stable isotope dilution assays
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C13 Norisoprenoids are important aroma compounds in wine, giving positive attributes to the overall wine aroma even when found at very low levels. β-Ionone is considered one of the most important aroma compounds giving violet, woody and raspberry aromas to wine, fruits and vegetables in which it is found. Due to its potent aroma at low levels, precise analytical methods are desired for its quantification. Stable isotope dilution assay (SIDA) is one of the most important of these methods but requires the use of isotopically labelled standards. Herein, we describe the scalable synthesis of d6-β-ionone and d6-β-cyclocitral, another aroma compound with smokey and fruity notes, starting from the relatively inexpensive deuterated starting material d6-acetone.
- Mosaferi, Shabnam,Jelley, Rebecca E.,Fedrizzi, Bruno,Barker, David
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supporting information
(2020/12/02)
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- Visible-Light-Promoted Intramolecular α-Allylation of Aldehydes in the Absence of Sacrificial Hydrogen Acceptors
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We report herein an unprecedented protocol for radical cyclization of aldehydes with pendant alkenes via synergistic photoredox, cobaloxime, and amine catalysis. The transformation was achieved in the absence of external oxidants, providing a variety of 5-, 6-, and 7-membered ring products with alkene transposition in satisfactory yields. The reaction exhibits wide functional group compatibility and occurs under mild conditions with extrusion of H2.
- Liu, Feng,Liu, Jia-Li,tu, Jia-Lin
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supporting information
p. 7369 - 7372
(2020/10/05)
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- Engineering Catalysts for Selective Ester Hydrogenation
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The development of efficient catalysts and processes for synthesizing functionalized (olefinic and/or chiral) primary alcohols and fluoral hemiacetals is currently needed. These are valuable building blocks for pharmaceuticals, agrochemicals, perfumes, and so forth. From an economic standpoint, bench-stable Takasago Int. Corp.'s Ru-PNP, more commonly known as Ru-MACHO, and Gusev's Ru-SNS complexes are arguably the most appealing molecular catalysts to access primary alcohols from esters and H2 (Waser, M. et al. Org. Proc. Res. Dev. 2018, 22, 862). This work introduces economically competitive Ru-SNP(O)z complexes (z = 0, 1), which combine key structural elements of both of these catalysts. In particular, the incorporation of SNP heteroatoms into the ligand skeleton was found to be crucial for the design of a more product-selective catalyst in the synthesis of fluoral hemiacetals under kinetically controlled conditions. Based on experimental observations and computational analysis, this paper further extends the current state-of-the-art understanding of the accelerative role of KO-t-C4H9 in ester hydrogenation. It attempts to explain why a maximum turnover is seen to occur starting at 25 mol % base, in contrast to only 10 mol % with ketones as substrates.
- Dub, Pavel A.,Batrice, Rami J.,Gordon, John C.,Scott, Brian L.,Minko, Yury,Schmidt, Jurgen G.,Williams, Robert F.
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p. 415 - 442
(2020/03/04)
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- Nickel-Catalyzed Asymmetric Reductive 1,2-Carboamination of Unactivated Alkenes
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Starting from diverse alkene-tethered aryl iodides and O-benzoyl-hydroxylamines, the enantioselective reductive cross-electrophilic 1,2-carboamination of unactivated alkenes was achieved using a chiral pyrox/nickel complex as the catalyst. This mild, modular, and practical protocol provides rapid access to a variety of β-chiral amines with an enantioenriched aryl-substituted quaternary carbon center in good yields and with excellent enantioselectivities. This process reveals a complementary regioselectivity when compared to Pd and Cu catalysis.
- He, Jun,Xue, Yuhang,Han, Bo,Zhang, Chunzhu,Wang, You,Zhu, Shaolin
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supporting information
p. 2328 - 2332
(2020/01/08)
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- PROCESS FOR PRODUCING PRENOL AND PRENAL FROM ISOPRENOL
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The present invention relates to a process for preparing 3-methyl-2-butenol (prenol) and 3-methyl-2-butenal (prenal) from 3-methyl-3-butenol (isoprenol), in which 3-methyl-3-butenol is subjected to a catalytic isomerization over a carbon-supported Pd catalyst in the presence of a gas mixture comprising 1% to 15% by volume of oxygen to obtain a first product mixture, and the first product mixture is subjected to an oxidative dehydrogenation over a Pd catalyst comprising SiO2 and/or Al2O3 as support material, or over a carbon-supported Pd/Au catalyst in the presence of a gas mixture comprising 5% to 25% by volume of oxygen.
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Paragraph 0119-0129
(2019/03/30)
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- Boron-Templated Dimerization of Allylic Alcohols to Form Protected 1,3-Diols via Acid Catalysis
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We report an unprecedented boron-templated dimerization of allylic alcohols that generates a 1,3-diol product with two stereogenic centers in high yield and diastereoselectivity. This acid-catalyzed reaction is achieved via in situ formation of a boronic ester intermediate that facilitates selective cyclization and formation of a cyclic boronic ester product. High yields are observed with a variety of allylic alcohols, and mechanistic studies confirm the role of boron as a template for the reaction.
- Nazari, S. Hadi,Forson, Kelton G.,Martinez, Erin E.,Hansen, Nicholas J.,Gassaway, Kyle J.,Lyons, Nathan M.,Kenney, Karissa C.,Valdivia-Berroeta, Gabriel A.,Smith, Stacey J.,Michaelis, David J.
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supporting information
p. 9589 - 9593
(2019/12/02)
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- An On-Demand, Selective Hydrogenation Catalysis over Pt?Fe Nanocatalysts under Ambient Condition
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The selective hydrogenation of organic compounds with multiple unsaturated bonds is of significant for fine chemicals, while simultaneously achieving high selectivities of different potential products is still great challenge. Herein, we have successfully designed a nanocatalysis system, which can serve as a control switch of selective α, β-unsaturated aldehydes hydrogenation towards potential products in a highly on-demand fashion. We demonstrate that the PtFe nanospheres (NSs) represent excellent selectivity (>92.8 %) to unsaturated alcohols with high conversion (>99.7 %), due to the higher electron density of the active Pt atoms. When introducing AlCl3, the selectivity of saturated aldehydes enhances to 97.1 % at 95.8 % conversion, owing to synergy between PtFe NSs and AlCl3. Finally, the PtFe?A NSs generated by etching away the Fe can promote the selectivity saturated alcohols (>99.7 %) with the highest activity, on account of more exposed active sites after the chemical etching. Significantly, the developed nanocatalysis system can also exhibit high activity/selectivity for other typical α, β-unsaturated aldehydes as well as excellent stability after consecutive reactions. This work provides a guideline for the rational design highly active and selective Pt-based nanocatalyst.
- Yang, Chengyong,Bai, Shuxing,Feng, Yonggang,Huang, Xiaoqing
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p. 2265 - 2269
(2019/04/13)
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- The Low Dimensional Co-Based Nanorods as a Novel Platform for Selective Hydrogenation of Cinnamaldehyde
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Abstract: Since hydrogenation of C=C bond in the cinnamaldehyde is thermodynamically favored, the selective hydrogenation of C=O group is challenging. Developing effective catalysts for this transformation has been hindered by the intrinsic disadvantages of traditional materials for decades. Hereby, we report the synthesis of the low dimensional Co based nanorods (NRs) as the effective platform for C=O groups hydrogenation in the conjugated compounds. The Pt/Co-NRs catalyst is simply fabricated by loading the Pt nano-particles (NPs) on the Co-NRs and the stability of the Co-NRs support is improved by coordination between the Pt NPs and the pyridinic N ring. Resorting to XRD, FT-IR, XPS, HRTEM, DTG-TG characterization methods, the catalytic mechanism for C=O bond hydrogenation has been proposed. The synergistic effects of K+ and OH? enhance the polarization of C=O group, leading to more adsorption of C=O groups on the Co-NRs so as to promote its hydrogenation performance. In the absence of spatial micropores in low dimensional Co based nanorods, the Pt/Co-NRs catalyst is more advantageous for mass transfer. Under optimal conditions, the conversion of cinnamaldehyde is 97.9% with 92.7% selectivity of cinnamyl alcohol within 3 h. In addition, the selectivity of cinnamyl alcohol changes slightly (only 2.4% fluctuations) after five recycle tests. Graphical Abstract: [Figure not available: see fulltext.].
- Yuan, Tao,Liu, Derong,Gu, Jianshan,Xia, Yongde,Pan, Yue,Xiong, Wei
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p. 2906 - 2915
(2019/04/30)
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- Silver-promoted cascade radical cyclization of γ,δ-unsaturated oxime esters with P(O)H compounds: synthesis of phosphorylated pyrrolines
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A cascade radical cyclization was realized for the first silver-promoted imino-phosphorylation of γ,δ-unsaturated oxime esters, which provided a step-economical and redox-neutral route to access a variety of phosphorylated pyrrolines in good to excellent yields. Moreover, a new bulky trivalent phosphine ligand with a pyrroline motif was obtained through a deoxidation process.
- Chen, Chen,Bao, Yinwei,Zhao, Jinghui,Zhu, Bolin
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supporting information
p. 14697 - 14700
(2019/12/11)
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- PROCESS FOR THE PREPARATION OF 3-METHYL-2-BUTEN-1-AL
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Process for the preparation of 3-methyl-2-buten-1-al, wherein2-methyl-3-buten-2-ol is reacted to 3-methyl-2-buten-1-al in the presence of a catalyst, wherein the catalyst comprises a catalytically active metal and wherein the reaction is conducted at a pH of ≤ 7.
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Page/Page column 40
(2019/07/13)
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- Magnetic Anchored CoPt Bimetallic Nanoparticles as Selective Hydrogenation Catalyst for Cinnamaldehyde
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Selective hydrogenation reaction of cinnamaldehyde is crucial for its appliction in fine chemical industries. The traditional noble metal catalyst for this reaction is expensive and often involving tedious steps. In this work, the magnetic anchored CoPt/Fe3O4 catalyst is prepared by a simple wet-impregnation method and evaluted as catalyst for selective hydrogenation of cinnamaldehyde. Electrons transfer directly from Co to Pt NPs can enhance H2 dissociation capability in the Co NPs interface, thereby strengthen the overall catalytic performance. Under optimum conditions, the conversion of cinnamaldehyde is 95% with 84% selectivity of cinnamyl alcohol. Furthermore, the magnetic interaction between the outer Co NPs and the Fe3O4 support maintains the stability of cinnamyl alcohol selectivity after repeated tests.
- Yuan, Tao,Liu, Derong,Pan, Yue,Pu, Xiaoqin,Xia, Yongde,Wang, Jinbo,Xiong, Wei
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p. 851 - 859
(2018/11/30)
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- NH2-MIL-125(Ti)-derived porous cages of titanium oxides to support Pt-Co alloys for chemoselective hydrogenation reactions
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The change of atom density induced structural collapse in the transformation process from metal-organic frameworks (MOFs) to their inorganic counterparts is a major challenge to the achievement of porous hollow structures. Herein, we develop an amino acid-mediated strategy for transformation of NH2-MIL-125(Ti) to successfully synthesize well-defined porous cages of titanium oxides (PCT) due to sheets serving as structural scaffolds. On this basis, PCT supported Pt-based nanoparticles are generated via a similar synthetic route, and are utilized to study the selective hydrogenation of carbonyl groups in α,β-unsaturated aldehydes, benefiting from the specific structures of PCT and tunable electronic structures of Pt mainly affected by doping with metal species such as Co. In this case, Pt-Co/PCT composites give 96% selectivity for cinnamyl alcohol at 100% conversion of cinnamaldehyde under 0.2 MPa H2 and 80 °C for 3 h. This research would offer a promising strategy for important organic transformations in academic and industrial research to selectively synthesize high-value-added products.
- Gu, Zhizhi,Chen, Liyong,Li, Xuezhao,Chen, Lin,Zhang, Yingyue,Duan, Chunying
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p. 2111 - 2117
(2019/02/20)
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- Multicomponent Pt-Based Zigzag Nanowires as Selectivity Controllers for Selective Hydrogenation Reactions
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The selective hydrogenation of α, β-unsaturated aldehyde is an extremely important transformation, while developing efficient catalysts with desirable selectivity to highly value-added products is challenging, mainly due to the coexistence of two conjugated unsaturated functional groups. Herein, we report that a series of Pt-based zigzag nanowires (ZNWs) can be adopted as selectivity controllers for α, β-unsaturated aldehyde hydrogenation, where the excellent unsaturated alcohol (UOL) selectivity (>95%) and high saturated aldehyde (SA) selectivity (>94%) are achieved on PtFe ZNWs and PtFeNi ZNWs+AlCl3, respectively. The excellent UOL selectivity of PtFe ZNWs is attributed to the lower electron density of the surface Pt atoms, while the high SA selectivity of PtFeNi ZNWs+AlCl3 is due to synergy between PtFeNi ZNWs and AlCl3, highlighting the importance of Pt-based NWs with precisely controlled surface and composition for catalysis and beyond.
- Bai, Shuxing,Bu, Lingzheng,Shao, Qi,Zhu, Xing,Huang, Xiaoqing
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supporting information
p. 8384 - 8387
(2018/06/29)
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- An iridium-SPO complex as bifunctional catalyst for the highly selective hydrogenation of aldehydes
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A secondary phosphine oxide (SPO) ligand (tert-butyl(phenyl)phosphine oxide) was employed to generate an Ir-SPO complex which shows a particular ability to activate dihydrogen under mild conditions without the help of an external base or additive. Such an iridium(i) complex serves as a precursor for homogeneous catalysis since under H2 it is converted to a mixture of several iridium(iii) hydride species that are the active catalysts. This system was found to be a highly active catalyst for the hydrogenation of substituted aldehydes, giving very high conversions and chemoselectivities for a wide range of substrates. The SPO ligand presumably plays a key role in the catalytic process through heterolytic cleavage of H2 by metal-ligand cooperation. In addition, an exhaustive characterization of the different iridium hydride species was performed by 1D and 2D NMR spectroscopy. The oxidative addition of H2 to the Ir(i)-SPO complex is highly stereoselective, as all generated Ir(iii) hydrides are homochiral. Finally, the crystal structure, as determined by X-ray diffraction, of a dinuclear iridium(iii) hydride complex is described.
- Cano, Israel,Martínez-Prieto, Luis M.,Vendier, Laure,Van Leeuwen, Piet W. N. M.
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p. 221 - 228
(2018/01/17)
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- Pt/Ferric Hydroxyphosphate: An Effective Catalyst for the Selective Hydrogenation of Α,Β-Unsaturated Aldehydes (Ketones) into Α,Β-Unsaturated Alcohols
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Abstract: Four micro (nano)-sized mesoporous ferric hydroxyphosphates (FHP) are synthesized by a reverse microemulsion-solvothermal method, and then are used as supports to prepare supported Pt catalysts. The mean particle diameter of Pt nanoparticles (NPs) was 4.5–4.6?nm. When the four different Pt/FHP catalysts were used into the hydrogenation of α,β-unsaturated aldehydes (ketones) to their corresponding unsaturated alcohols, Pt/FHP (c) catalyst showed better catalytic performance than the other three partners. Under the optimal experimental conditions, several tested α,β-unsaturated aldehydes could be effectively transformed into corresponding unsaturated alcohols over Pt/FHP (c) catalyst. The catalyst could be recycled and reused several times without activity loss. We propose the stronger interaction between the Pt NPs and ferric ions of the FHP (c) are responsible for its good catalytic performance, and this stronger interaction should be rooted in its enhanced Lewis acid strength.
- Liu, Cheng,Luo, Wei,Liu, Junhua,Sun, Lei,Yang, Yue,Liu, Gui,Wang, Fang,Zhong, Wei,Guild, Curtis,Suib, Steven L.
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p. 555 - 563
(2018/01/11)
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- Selective hydrogenation of unsaturated aldehydes over Pt nanoparticles promoted by the cooperation of steric and electronic effects
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The selective hydrogenation of α,β-unsaturated aldehydes to unsaturated alcohols can reach high selectivity and activity at room temperature using Pt nanoparticles immobilized on a non-porous Al2O3 support stabilized by aspartic acid. Aspartic acid molecules had a significant steric effect on CC hydrogenation and could modify the electronic state of metal particles.
- Liu, Hangyu,Mei, Qingqing,Li, Shaopeng,Yang, Youdi,Wang, Yanyan,Liu, Huizhen,Zheng, Lirong,An, Pengfei,Zhang, Jing,Han, Buxing
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supporting information
p. 908 - 911
(2018/02/07)
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- Highly Networked Platinum–Tin Nanowires as Highly Active and Selective Catalysts towards the Semihydrogenation of Unsaturated Aldehydes
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The selective hydrogenation of α,β-unsaturated aldehydes to unsaturated alcohols is an important process for many industrial applications, whereas the realization of excellent conversion efficiency and selectivity remains a significant challenge. Herein, we report the preparation of a class of networked Pt–Sn nanowires (Pt–Sn NWs) for the selective hydrogenation of unsaturated aldehydes to the desired unsaturated alcohols. The optimized Pt1.5Sn NWs delivered a high conversion efficiency (98.1 %) for the hydrogenation of cinnamaldehyde (CAL) and excellent selectivity to cinnamyl alcohol (COL) (90.6 %); thus, they outperformed Pt1.5Sn nanoparticles (NPs) as well as Pt NPs. The high performance of the Pt1.5Sn NWs was expanded to the hydrogenation of other α,β-unsaturated aldehydes. X-ray photoelectron spectroscopy revealed that a high ratio of metallic Pt in the Pt1.5Sn NWs boosted the conversion of CAL and that a high Sn content favored the hydrogenation of the C=O bond, both of which lead to excellent activity and selectivity.
- Zhu, Meiwu,Huang, Bin,Shao, Qi,Pi, Yecan,Qian, Yong,Huang, Xiaoqing
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p. 3214 - 3218
(2018/08/24)
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- Rhodium-Catalyzed Synthesis of α,β-Unsaturated Ketones through Sequential C-C Coupling and Redox Isomerization
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A novel Rh(I)-catalyzed sequential C-C coupling and redox isomerization between allylic alcohols and 1,3-dienes has been accomplished. This versatile protocol provides expeditious access to a broad range of polysubstituted α,β-unsaturated ketones with excellent atom economy and regioselectivity.
- Li, Hong-Shuang,Guo, Guili,Zhang, Rui-Ze,Li, Fei
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supporting information
p. 5040 - 5043
(2018/08/24)
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- Method for preparing 3-methyl-2-butenol
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The invention provides a method for preparing 3-methyl-2-butenol (isoprenol) through isomerization of 3-methyl-3-butenol. A catalyst reaction system contains 1) a carbonyl iron compound, 2) an organic base, and 3) an epoxy group ligand. A solvent with an ether structure is added into an isomerization reaction, so that the activity of a catalyst can be improved, and the product selectivity is improved. During catalysis and separation, a mixed gas of carbon monoxide (CO) and nitrogen (N2) is introduced, wherein the volume content of the CO is 100-100000ppm. The catalyst and a raw material namely the 3-methyl-3-butenol are separated from a product namely isoprenol through rectification, and the catalyst does not need to be additionally separated. The catalyst keeps high activity and long life operation.
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Paragraph 0044; 0045; 0046; 0047; 0048; 0049; 0050-0053
(2017/10/26)
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- Copper-Catalyzed Enantio-, Diastereo-, and Regioselective [2,3]-Rearrangements of Iodonium Ylides
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The first highly enantioselective, diastereoselective, and regioselective [2,3]-rearrangement of iodonium ylides has been developed as a general solution to catalytic onium ylide rearrangements. In the presence of a chiral copper catalyst, substituted allylic iodides couple with α-diazoesters to generate metal-coordinated iodonium ylides, which undergo [2,3]-rearrangements with high selectivities (up to >95:5 r.r., up to >95:5 d.r., and up to 97 % ee). The enantioenriched iodoester products can be converted stereospecifically into a variety of onium ylide rearrangement products, as well as compounds that are not accessible by classical onium ylide rearrangements.
- Xu, Bin,Tambar, Uttam K.
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supporting information
p. 9868 - 9871
(2017/08/08)
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- New In(OiPr)3-MCM-41 heterogeneous catalyst in MPV reductions of unsaturated carbonyl compounds: effect of mesoporous SBA-15 and MCM-41 as supporting surfaces on catalytic activity of In(OiPr)3
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Indium tri-isopropoxide, In(OiPr)3, was immobilized on mesoporous material, MCM-41, and denoted as “In(OiPr)3-MCM-41”. This new heterogeneous catalyst was characterized by XRD, 29Si NMR-, N2 adsorption–desorption isotherms and ICP-OES techniques. The new heterogeneous catalyst, In(OiPr)3-MCM-41, was tested for the capable of catalyzed Meerwein–Ponndorf–Verley (MPV) reduction of unsaturated aldehydes and ketones with low catalyst loadings under mild conditions and showed good to excellent catalytic activities. Also, effect of supporting surfaces, both of SBA-15 and MCM-41, on catalytic activity of In(OiPr)3 were examined. In(OiPr)3-SBA-15 heterogeneous catalyst in comparison with the In(OiPr)3-MCM-41 catalyst, display comparatively higher catalytic activity in the MPV reduction of unsaturated aldehydes and ketones. Also, similiar reaction times and selectivities for the unsaturated alcohols were obtained with the In(OiPr)3-SBA-15 catalyst compared with the In(OiPr)3-MCM-41 catalyst. The reason for the lower activity observed for MCM-41 sample may be due to smaller pore size of the In(OiPr)3-MCM-41 catalyst as compared with In(OiPr)3-SBA-15 catalyst can creat restrict site accessibility for the carbonyl compounds. Eventually, effect of supporting surfaces, SBA-15 and MCM-41, on catalytic activity of In(OiPr)3 insignificant for MPV reduction of unsaturated carbonyl compounds.
- Karatas, Burcu Uysal,Oksal, Birsen S.,Karatas, Erhan
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- Highly selective transfer hydrogenation of α,β-unsaturated carbonyl compounds using Cu-based nanocatalysts
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Simultaneous dehydrogenation of cyclohexanol to cyclohexanone and hydrogenation of α,β-unsaturated carbonyl compounds to corresponding α,β-unsaturated alcohols was carried out in a single pot reaction without addition of any external hydrogen donor. Cu nanoclusters supported on nanocrystalline MgO were found to be the active catalyst for the chemoselective transfer hydrogenation of unsaturated carbonyl compounds to produce the corresponding alcohols with very high yields. Transfer hydrogenation of cyclohexanol and cinnamaldehyde produced cyclohexanone and cinnamyl alcohol with 100% selectivity. This Cu/MgO catalyst can be easily recovered and recycled up to more than five times without any significant loss of activity, which confirmed the true heterogeneous nature of this catalyst. Several α,β-unsaturated compounds were also tested for this reaction and it was found that for all the cases the yield is >95%. The ease of handling without requiring high pressure H2 or a hazardous hydrogen source makes this transfer hydrogenation more practical and useful.
- Siddqui, Nazia,Sarkar, Bipul,Pendem, Chandrashekar,Khatun, Rubina,Sivakumar Konthala,Sasaki, Takehiko,Bordoloi, Ankur,Bal, Rajaram
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p. 2828 - 2837
(2017/07/15)
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- Visible-Light Promoted Distereodivergent Intramolecular Oxyamidation of Alkenes
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The visible-light-promoted diastereodivergent intramolecular oxyamination of alkenes is described to construct oxazolindinones, pyrrolidinones and imidazolidones via mild generation of primary amidyl radicals from functionalized hydroxylamines. A unique phenomenon of highly diastereoselective ring-opening of aziridines controlled by electron sacrifices was observed. Highly diastereoselective amino alcohols derivatives were obtained efficiently through this protocol in gram scales. The mechanistic studies suggested the isolatable anti-aziridine intermediates were generated quickly from primary amidyl radicals and the diastereoselectivities were controlled by pKavalues of the electron sacrifices.
- Ren, Xiang,Guo, Qihang,Chen, Jianhui,Xie, Hujun,Xu, Qing,Lu, Zhan
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supporting information
p. 18695 - 18699
(2016/12/26)
-
- Recyclable, green and efficient epoxidation of olefins in water with hydrogen peroxide catalyzed by polyoxometalate nanocapsule
-
A practical method for the selective epoxidation of alkenes was discovered using HxPMo12O40 H4Mo72Fe30(CH3COO)15O254 as a catalyst in the presence of H2O2 as a green oxidant. However, the simple catalyst system involving polyoxometalates and H2O2 exercised the most successful system in obtaining high to excellent yields of epoxide products for different alkenes, including aromatic and aliphatic alkenes at room temperature in water. The effectiveness of this catalyst is evidenced by 99% selectivity to epoxide and 97-99% efficiency of H2O2 utilization. The stability of PMo > Mo72Fe30 under a catalytic reaction has been confirmed by XRD, FT-IR and Raman spectroscopies.
- Fareghi-Alamdari, Reza,Hafshejani, Shahrbanou Moradpour,Taghiyar, Hamid,Yadollahi, Bahram,Farsani, Mostafa Riahi
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-
- A process for the preparation of unsaturated alcohols
-
The invention provides a preparation method of unsaturated alcohol. The preparation method comprises the following steps: uniformly mixing unsaturated halogenated hydrocarbon, water, a catalyst and a non-polar organic solvent, adding an alkaline solution, adjusting the pH value to be 5-8, reacting at 20-150 DEG C, and purifying to obtain unsaturated alcohol. The method provided by the invention is simple in process, mild in condition, relatively less in three-waste emission, high in yield, and convenient in purification and separation of products.
- -
-
Paragraph 0038-0040
(2017/05/12)
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- Enhancing Metal-Support Interactions by Molybdenum Carbide: An Efficient Strategy toward the Chemoselective Hydrogenation of α,β-Unsaturated Aldehydes
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Metal-support interactions are desired to optimize the catalytic turnover on metals. Herein, the enhanced interactions by using a Mo2C nanowires support were utilized to modify the charge density of an Ir surface, accomplishing the selective hydrogenation of α,β-unsaturated aldehydes on negatively charged Irδ- species. The combined experimental and theoretical investigations showed that the Irδ- species derive from the higher work function of Ir (vs. Mo2C) and the consequently electron transfer. In crotonaldehyde hydrogenation, Ir/Mo2C delivered a crotyl alcohol selectivity as high as 80 %, outperforming those of counterparts (2C was highlighted by its higher selectivity as well as the better activity. Additionally, the efficacy for various substrates further verified our Ir/Mo2C system to be competitive for chemoselective hydrogenation.
- He, Sina,Shao, Zheng-Jiang,Shu, Yijin,Shi, Zhangping,Cao, Xiao-Ming,Gao, Qingsheng,Hu, Peijun,Tang, Yi
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p. 5698 - 5704
(2016/04/20)
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- Electronic interactions between a stable electride and a nano-alloy control the chemoselective reduction reaction
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Controlling the electronic structure of heterogeneous metal catalysts is considered an efficient method to optimize catalytic activity. Here, we introduce a new electronic effect induced by the synergy of a stable electride and bimetallic nanoparticles for a chemoselective reduction reaction. The electride [Ca24Al28O64]4+·(e-)4, with extremely low work function, promotes the superior activity and selectivity of a Ru-Fe nano-alloy for the conversion of α,β-unsaturated aldehydes to unsaturated alcohols in a solvent-free system. The catalyst is easily separable from the product solution and reusable without notable deactivation. Mechanistic studies demonstrate that electron injection from the electride to the Ru-Fe bimetallic nanoparticles promotes H2 dissociation on the highly charged active metal and preferential adsorption of CO bonds over CCs bond of the unsaturated aldehydes, to obtain the thermodynamically unfavorable but industrially important product.
- Ye, Tian-Nan,Li, Jiang,Kitano, Masaaki,Sasase, Masato,Hosono, Hideo
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p. 5969 - 5975
(2016/08/31)
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- Chemoselective transfer hydrogenation of α,β-unsaturated carbonyl compounds using potassium formate over amine-grafted Ru/AlO(OH) catalysts
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Grafting of 3-(2-aminoethylamino)propyltrimethoxysilane onto Ru/AlO(OH) resulted in an active and highly chemoselective heterogeneous catalyst for the transfer hydrogenation of α,β-unsaturated carbonyl compounds to the corresponding allylic alcohols. Potassium formate was used as a sustainable hydrogen donor. A range of substrates including cinnamaldehyde, α-amylcinnamaldehyde, citral, 3-methyl-2-butenal, trans-2-pentenal, and trans-hexenal were selectively hydrogenated at the CO moiety with >96% selectivity. In comparison, the unmodified 1 wt% Ru/AlO(OH) catalyzed hydrogenation of cinnamaldehyde at the CC bond, yielding 3-phenylpropanal as the product. Higher loaded samples with 2-10 wt% Ru exhibited 20-25% selectivity to cinnamyl alcohol. The results show that low coordination sites were more selective to hydrogenation of the internal CC than the terminal CO bond. Immobilization of the amine via chemical bonding with hydroxyl groups of the AlO(OH) support blocks adjacent exposed metal sites, increasing the chemoselective reduction of CO. Optimum results were achieved at an amine/Ru ratio of 6. The catalyst maintained high activity and chemoselectivity even after five cycles.
- Gao, Yanxiu,Wang, Jie,Han, Aijuan,Jaenicke, Stephan,Chuah, Gaik Khuan
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p. 3806 - 3813
(2016/06/13)
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- Conformational Analysis, Thermal Rearrangement, and EI-MS Fragmentation Mechanism of (1(10)E,4E,6S,7R)-Germacradien-6-ol by 13C-Labeling Experiments
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An uncharacterized terpene cyclase from Streptomyces pratensis was identified as (+)-(1(10)E,4E,6S,7R)-germacradien-6-ol synthase. The enzyme product exists as two interconvertible conformers, resulting in complex NMR spectra. For the complete assignment of NMR data, all fifteen (13C1)FPP isotopomers (FPP=farnesyl diphosphate) and (13C15)FPP were synthesized and enzymatically converted. The products were analyzed using various NMR techniques, including 13C, 13C COSY experiments. The (13C)FPP isotopomers were also used to investigate the thermal rearrangement and EI fragmentation of the enzyme product. All 15 isotopomers of (13C1)- and fully labeled (13C15)farnesyl diphosphate were synthesized and converted to the title compound by a newly characterized bacterial terpene cyclase from Streptomyces pratensis. The enzyme products were used for structure elucidation of the sesquiterpene alcohol, full assignment of NMR data and a conformational analysis, and investigation of its Cope rearrangement and of its EI-MS fragmentation mechanism.
- Rabe, Patrick,Barra, Lena,Rinkel, Jan,Riclea, Ramona,Citron, Christian A.,Klapschinski, Tim A.,Janusko, Aron,Dickschat, Jeroen S.
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supporting information
p. 13448 - 13451
(2015/11/09)
-
- Nickel-Catalyzed Regioselective Reductive Cross-Coupling of Aryl Halides with Polysubstituted Allyl Halides in the Presence of Imidazolium Salts
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The nickel-catalyzed direct reductive cross-coupling of aryl halides with readily accessible polysubstituted allyl halides provides an efficient method for preparing diverse allylated arenes under mild conditions. Both allyl bromides and allyl chlorides are compatible with the transformation.
- Zhang, Zhan,Xu, Lijun,Chen, Zhengkai,Liu, Zhubo,Miao, Maozhong,Song, Jinyu,Ren, Hongjun
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supporting information
p. 2784 - 2788
(2015/12/18)
-
- A Highly Active and Easily Accessible Cobalt Catalyst for Selective Hydrogenation of C=O Bonds
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The substitution of high-price noble metals such as Ir, Ru, Rh, Pd, and Pt by earth-abundant, inexpensive metals like Co is an attractive goal in (homogeneous) catalysis. Only two examples of Co catalysts, showing efficient C=O bond hydrogenation rates, are described. Here, we report on a novel, easy-to-synthesize Co catalyst family. Catalyst activation takes place via addition of 2 equiv of a metal base to the cobalt dichlorido precatalysts. Aldehydes and ketones of different types (dialkyl, aryl-alkyl, diaryl) are hydrogenated quantitatively under mild conditions partially with catalyst loadings as low as 0.25 mol%. A comparison of the most active Co catalyst with an Ir catalyst stabilized by the same ligand indicates the superiority of Co. Unique selectivity toward C=O bonds in the presence of C=C bonds has been observed. This selectivity is opposite to that of existing Co catalysts and surprising because of the directing influence of a hydroxyl group in C=C bond hydrogenation.
- R?sler, Sina,Obenauf, Johannes,Kempe, Rhett
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supporting information
p. 7998 - 8001
(2015/07/08)
-
- Air-stable gold nanoparticles ligated by secondary phosphine oxides for the chemoselective hydrogenation of aldehydes: Crucial role of the ligand
-
The synthesis of air-stable and homogeneous gold nanoparticles (AuNPs) employing tert-butyl(naphthalen-1-yl)phosphine oxide as supporting ligand is described via NaBH4 reduction of a Au(I) precursor, [(tert-butyl(naphthalen-1-yl)phosphine oxide)AuCl]2. This highly reproducible and simple procedure furnishes small (1.24 ± 0.16 nm), highly soluble nanoparticles that are found to be highly active catalysts for the hydrogenation of substituted aldehydes, giving high conversions and chemoselectivities for a wide variety of substrates. In addition to catalytic studies the role of the novel stabilizer in the remarkable activity and selectivity exhibited by this system was interrogated thoroughly using a wide range of techniques, including ATR FT-IR, HRMAS NMR, XPS, and EDX spectroscopy. In particular, isotopic labeling experiments enabled us to probe the coordination mode adopted by the SPO ligand bound to the nanoparticle surface by ATR FT-IR spectroscopy. In combination with a series of control experiments we speculate that the SPO ligand demonstrates ligand-metal cooperative effects and plays a seminal role in the heterolytic hydrogenation mechanism.
- Cano, Israel,Chapman, Andrew M.,Urakawa, Atsushi,Van Leeuwen, Piet W. N. M.
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supporting information
p. 2520 - 2528
(2014/03/21)
-
- Substrate specificity and subcellular localization of the aldehyde-Alcohol redox-Coupling reaction in carp cones
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Our previous study suggested the presence of a novel conespecific redox reaction that generates 11-cis-retinal from 11-cisretinol in the carp retina. This reaction is unique in that 1) both 11-cis-retinol and all-trans-retinal were required to produce 11-cis-retinal; 2) together with 11-cis-retinal, all-trans-retinol was produced at a 1:1 ratio; and 3) the addition of enzyme cofactors such as NADP(H) was not necessary. This reaction is probably part of the reactions in a cone-specific retinoid cycle required for cone visual pigment regeneration with the use of 11-cis-retinol supplied from Mueller cells. In this study, using purified carp cone membrane preparations, we first confirmed that the reaction is a redox-coupling reaction between retinals and retinols. We further examined the substrate specificity, reaction mechanism, and subcellular localization of this reaction. Oxidation was specific for 11-cis-retinol and 9-cis-retinol. In contrast, reduction showed low specificity: many aldehydes, including all-trans-, 9-cis-, 11-cis-, and 13-cis-retinals and even benzaldehyde, supported the reaction. On the basis of kinetic studies of this reaction (aldehyde-alcohol redox-coupling reaction), we found that formation of a ternary complex of a retinol, an aldehyde, and a postulated enzyme seemed to be necessary, which suggested the presence of both the retinol- and aldehydebinding sites in this enzyme. A subcellular fractionation study showed that the activity is present almost exclusively in the cone inner segment. These results suggest the presence of an effective production mechanism of 11-cis-retinal in the cone inner segment to regenerate visual pigment.
- Sato, Shinya,Fukagawa, Takashi,Tachibanaki, Shuji,Yamano, Yumiko,Wada, Akimori,Kawamura, Satoru
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p. 36589 - 36597
(2014/01/17)
-
- Self-assembled benzophenone bis-urea macrocycles facilitate selective oxidations by singlet oxygen
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This manuscript investigates how incorporation of benzophenone, a well-known triplet sensitizer, within a bis-urea macrocycle, which self-assembles into a columnar host, influences its photophysical properties and affects the reactivity of bound guest molecules. We further report the generation of a remarkably stable organic radical. As expected, UV irradiation of the host suspended in oxygenated solvents efficiently generates singlet oxygen similar to the parent benzophenone. In addition, this host can bind guests such as 2-methyl-2-butene and cumene to form stable solid host-guest complexes. Subsequent UV irradiation of these complexes facilitated the selective oxidation of 2-methyl-2-butene into the allylic alcohol, 3-methyl-2-buten-1-ol, at 90% selectivity as well as the selective reaction of cumene to the tertiary alcohol, α,α′-dimethyl benzyl alcohol, at 63% selectivity. However, these products usually arise through radical pathways and are not observed in the presence of benzophenone in solution. In contrast, typical reactions with benzophenone result in the formation of the reactive singlet oxygen that reacts with alkenes to form endoperoxides, diooxetanes, or hydroperoxides, which are not observed in our system. Our results suggest that the confinement, the formation of a stable radical species, and the singlet oxygen photoproduction are responsible for the selective oxidation processes. A greater understanding of the mechanism of this selective oxidation could lead to development of greener oxidants.
- Geer, Michael F.,Walla, Michael D.,Solntsev, Kyril M.,Strassert, Cristian A.,Shimizu, Linda S.
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p. 5568 - 5578
(2013/07/26)
-
- Process for preparing 3-substituted 2-alkenals, in particular prenal
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The present invention to a process for preparing 2-alkenals of the formula I in which R1 is selected from hydrogen and C1-C4-alkyl; and R2 is selected from hydrogen, C1-C12-alkyl, C2-C12-alkenyl, C4-C8-cycloalkyl and C6-C10-aryl, wherein C1-C12-alkyl and C1-C12-alkenyl may be substituted with C5-C7-cycloalkyl or C5-C7-cylcoalkenyl ; comprising dehydrogenating an alkenol of the formula II, an alkenol of the formula III or a mixture thereof, wherein R1 and R2 are each as defined above, wherein the alkenol II, the alkenol II or a mixture thereof is brought into contact with a catalytic system comprising at least one ligand and a metal compound selected from ruthenium(II) compounds and iridium(I) compounds, and wherein the hydrogen formed during the dehydrogenation is removed from the reaction mixture by: i) reaction with a reoxidant selected from C3-C12-alkanones, C4-C9-cycoalkanones, benzaldehyde and mixtures thereof; and/or ii) purely physical means.
- -
-
Paragraph 0124
(2013/06/06)
-
- PROCESS FOR PREPARING 3-SUBSTITUTED 2-ALKENALS, IN PARTICULAR PRENAL
-
The present invention to a process for preparing 2-alkenals of the formula (I) in which R1 is selected from hydrogen and C1-C4-alkyl; and R2 is selected from hydrogen, C1-C12-alkyl, C2-C12-alkenyl, C4-C8-cycloalkyl and C6-C-10 aryl, wherein C1-C12-alkyl and C1-C12-alkenyl may be substituted with C5-C7-cycloalkyl or C5-C7-cylcoalkenyl; comprising dehydrogenating an alkenol of the formula (II), an alkenol of the formula (III) or a mixture thereof, wherein R1 and R2 are each as defined above, wherein the alkenol II, the alkenol III or a mixture thereof is brought into contact with a catalytic system comprising at least one ligand and a metal compound selected from ruthenium(II) compounds and iridium(I) compounds, and wherein the hydrogen formed during the dehydrogenation is removed from the reaction mixture by: i) reaction with a reoxidant selected from C3-C12-alkanones, C4-C9-cycoalkanones, benzaldehyde and mixtures thereof; and/or ii) purely physical means.
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Page/Page column 27
(2013/06/06)
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- New heterogeneous B(OEt)3-MCM-41 catalyst for preparation of α,β-unsaturated alcohols
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Grafting of boron tri-ethoxide on mesoporous MCM-41 resulted in a highly active catalyst for the Meerwein-Ponndorf-Verley (MPV) reduction and the catalyst denoted as B(OEt)3-MCM-41. Chemoselective reduction of α,β-unsaturated aldehydes and ketones to the corresponding α,β-unsaturated alcohols was achieved by MPV reduction reaction using a new B(OEt)3-MCM-41 catalyst. The prepared new heterogeneous catalyst, B(OEt)3-MCM-41, was characterized in detail by using XRD, 29Si NMR-, 11B NMR-, 13C NMR-, and TEM, N2 adsorption, and ICP-OES. The results demonstrated the successful homogenous distribution of the B(OEt)3 on the MCM-41 support. The heterogeneous B(OEt)3-MCM-41 catalyst, in comparison with the homogeneous B(O i Pr)3 and B(OEt)3 catalysts, displayed similiar catalytic activity in the MPV reduction of α,β-unsaturated aldehydes and ketones with alcohols as reductants. Reduced reaction times and very high selectivities for the unsaturated alcohols were obtained with the heterogenous catalyst compared with the homogeneous catalysts. The B(OEt)3-MCM-41 catalyst was found to be encouraging, as is is recyclable up to six cycles without any significant loss in its catalytic activity.
- Uysal, Burcu,Oksal, Birsen S.
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p. 3893 - 3911
(2015/06/08)
-
- Core-shell AgNP@CeO2 nanocomposite catalyst for highly chemoselective reductions of unsaturated aldehydes
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Selective silver: A core-shell AgNP-CeO2 nanocomposite (AgNP@CeO2) acted as an effective catalyst for the chemoselective reductions of unsaturated aldehydes to unsaturated alcohols with H2 (see figure). Maximizing the AgNP-CeO2 interaction successfully induced the heterolytic cleavage of H2, resulting in highly chemoselective reductions. Furthermore, a highly dispersed AgNP@CeO2 system was also developed that exhibited a higher activity than the original AgNP@CeO2. Copyright
- Mitsudome, Takato,Matoba, Motoshi,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information
p. 5255 - 5258
(2013/05/22)
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- Remarkable effect of bases on core-shell AgNP@CeO2 nanocomposite-catalyzed highly chemoselective reduction of unsaturated aldehydes
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A highly dispersed coreshell silver nanoparticleceria nanocomposite catalyst (AgNP@CeO2-D) was prepared. The addition of bases was found to enhance the catalytic efficiency of AgNP@CeO2-D significantly in the chemoselective reduction of diverse unsaturated aldehydes to the corresponding unsaturated alcohols.
- Mitsudome, Takato,Matoba, Motoshi,Yamamoto, Masaaki,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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p. 660 - 662
(2013/07/05)
-
- Coupling reaction of magnesium alkylidene carbenoids with α-sulfonylallyllithiums: An efficient route to multi-substituted vinylallenes
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A variety of vinylallenes were successfully synthesized from 1-chlorovinyl p-tolyl sulfoxides and allyl or vinyl sulfones. Allyl and vinyl sulfones served as α-sulfonylallyllithium sources were prepared from carbonyl compounds in three or four steps in good overall yields. The coupling reaction of α-sulfonylallyllithiums with magnesium alkylidene carbenoids, which were generated from 1-chlorovinyl p-tolyl sulfoxides and isopropylmagnesium chloride, afforded multi-substituted vinylallenes in up to 88% yield. Georg Thieme Verlag KG Stuttgart · New York.
- Kimura, Tsutomu,Kobayashi, Gen,Ishigaki, Masashi,Inumaru, Mio,Sakurada, Jo,Satoh, Tsuyoshi
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p. 3623 - 3632
(2013/02/23)
-
- Synthesis of alcohols from m-fluorophenylsulfones and dialkylboranes: Application to the C14-C35 building block of E7389
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The reaction of m-fluorophenylsulfone anions with dialkylboranes, followed by alkaline hydroperoxide oxidation, yields alcohols in high yields. Optimization of the process, scope and limitation, and application to the synthesis of one of the C14-C35 building blocks of E7389, a right half analogue of halichondrin B, are reported.
- Liu, Lei,Henderson, James A.,Yamamoto, Akihiko,Bremond, Paul,Kishi, Yoshito
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p. 2262 - 2265
(2012/06/30)
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- Comparison of heterogeneous B(OiPr)3-MCM-41 and homogeneous B(OiPr)3, B(OEt)3 catalysts for chemoselective MPV reductions of unsaturated aldehydes and ketones
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Boron tri-isopropoxide, B(OiPr)3, was immobilized on mesoporous material, MCM-41, and denoted as "B(OiPr) 3-MCM-41". The prepared new heterogeneous catalyst, B(O iPr)3-MCM-41, was characterized in details by using PXRD, FT-IR-, 11B NMR-, 29Si NMR-, 13C NMR-, TEM, EDX, N2 adsorption and ICP-OES. The results demonstrated the successful homogenous distribution of the B(OiPr)3 on the MCM-41 support. Heterogeneous B(OiPr)3-MCM-41 catalyst in comparison with the homogeneous B(OiPr)3 and B(OEt) 3 catalysts, display similiar catalytic activity in the Meerwein-Ponndorf-Verley (MPV) reduction of unsaturated aldehydes and ketones with alcohols as reductants. Reduced reaction times, higher rate constants and very high selectivities for the unsaturated alcohols were obtained with the heterogenous catalyst than the homogeneous catalysts. In most cases, there were no side products other than the desired alcohol. The B(OiPr) 3-MCM-41 catalyst was found to be encouraging as the catalyst is recyclable up to six cycles without any significant loss in its catalytic activity. This work enriches the family of heterogeneous MPV catalysts for chemoselective reductions of unsaturated aldehydes and ketones.
- Uysal, Burcu,Oksal, Birsen S.
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experimental part
p. 204 - 216
(2012/10/18)
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- A new method for the chemoselective reduction of aldehydes and ketones using boron tri-isopropoxide, B(OiPr)3: Comparison with boron tri-ethoxide, B(OEt)3
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A chemoselective Meerwein-Ponndorf-Verley reduction process of various aliphatic and allylic α,β-unsaturated aldehydes and ketones is described. This chemoselective reduction is catalysed by boron triisopropoxide B(Oi Pr)3. Kinetics of reduction of aldehydes and ketones to corresponding alcohols were also examined and rate constant of each carbonyl compounds were measured. Rate constant and reduction yield of each carbonyl compounds in the presence of B(Oi Pr)3 were compared with those in the presence of B(OEt)3. The alcohols that are the reduction product were analysed by GC-MS. The rate constants and alcohol yields were found to be higher with B(OEt)3 than with B(Oi Pr) 3. The mechanism proposed involves a six-membered transition state in which both the alcohol and the carbonyl are coordinated to the same boron centre of a boron alkoxide catalyst. Indian Academy of Sciences.
- Uysal, Burcu,Oksal, Birsen S.
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supporting information; experimental part
p. 681 - 685
(2012/06/18)
-
- Synthesis, Properties, and applications of diazotrifluropropanoyl- containing photoactive analogs of farnesyl diphosphate containing modified linkages for enhanced stability
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Photoactive analogs of farnesyl diphosphate (FPP) are useful probes in studies of enzymes that employ this molecule as a substrate. Here, we describe the preparation and properties of two new FPP analogs that contain diazotrifluoropropanoyl photophores linked to geranyl diphosphate via amide or ester linkages. The amide-linked analog (3) was synthesized in 32P-labeled form from geraniol in seven steps. Experiments with Saccharomyces cerevisiae protein farnesyltransferase (ScPFTase) showed that 3 is an alternative substrate for the enzyme. Photolysis experiments with [ 32P]3 demonstrate that this compound labels the β-subunits of both farnesyltransferase and geranylgeranyltransferase (types 1 and 2). However, the amide-linked probe 3 undergoes a rearrangement to a photochemically unreactive isomeric triazolone upon long term storage making it inconvenient to use. To address this stability issue, the ester-linked analog 4 was prepared in six steps from geraniol. Computational analysis and X-ray crystallographic studies suggest that 4 binds to protein farnesyl transferase (PFTase) in a similar fashion as FPP. Compound 4 is also an alternative substrate for PFTase, and a 32P-labeled form selectively photocrosslinks the β-subunit of ScPFTase as well as E. coli farnesyldiphosphate synthase and a germacrene-producing sesquiterpene synthase from Nostoc sp. strain PCC7120 (a cyanobacterial source). Finally, nearly exclusive labeling of ScPFTase in crude E. coli extract was observed, suggesting that [32P]4 manifests significant selectivity and should hence be useful for identifying novel FPP-utilizing enzymes in crude protein preparations.
- Hovlid, Marisa L.,Edelstein, Rebecca L.,Henry, Olivier,Ochocki, Joshua,Degraw, Amanda,Lenevich, Stepan,Talbot, Trista,Young, Victor G.,Hruza, Alan W.,Lopez-Gallego, Fernando,Labello, Nicholas P.,Strickland, Corey L.,Schmidt-Dannert, Claudia,Distefano, Mark D.
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experimental part
p. 51 - 67
(2010/10/21)
-