- A new palladium-catalyzed phenyl-alkene bond formation
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A new method of palladium-catalyzed phenyl-alkene bond formation is reported. This reaction involves transfer of all three phenyl groups from triphenylantimony onto alkenes containing allylic protons.
- Schmor, Brad,Roy, Rene
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- Ring Contraction of Tropylium Ions into Benzenoid Derivatives
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We report a method to convert substituted tropylium ions into benzenoid derivatives.
- Crocker, Reece D.,Dinh, An H.,Lyons, Demelza J. M.,Mai, Binh Khanh,Nguyen, Thanh Vinh,Ton, Nhan N. H.
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supporting information
p. 2520 - 2525
(2022/04/12)
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- Lewis-Acid-Catalyzed Tandem Cyclization by Ring Expansion of Tertiary Cycloalkanols with Propargyl Alcohols
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A new method for the efficient synthesis of hexahydro-1H-fluorene and octahydrobenzo[a]azulene derivatives through a ring-expansion strategy is reported. With an appropriate combination of thulium(III) trifluoromethanesulfonate and 13X molecular sieves, a range of unsaturated polycyclic compounds were obtained in good yields. Mechanism studies reveal that the reaction is more likely to undergo Meyer–Schuster rearrangement, ring expansion, and Friedel–Crafts-type pathways, which provide a conceptually different strategy for the ring opening of tertiary cycloalkanols.
- Kong, Xiangtao,Li, Xue-Song,Li, Yuke,Liang, Yong-Min,Liu, Hong-Chao,Niu, Zhi-Jie,Wang, Cui-Tian,Wei, Wan-Xu,Zhang, Zhe
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supporting information
p. 9457 - 9462
(2021/12/14)
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- Enantioselective Nickel-Catalyzed Alkyne-Azide Cycloaddition by Dynamic Kinetic Resolution
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The triazole heterocycle has been widely adopted as an isostere for the amide bond. Many native amides are α-chiral, being derived from amino acids. This makes α-N-chiral triazoles attractive building blocks. This report describes the first enantioselective triazole synthesis that proceeds via nickel-catalyzed alkyne-azide cycloaddition (NiAAC). This dynamic kinetic resolution is enabled by a spontaneous [3,3]-sigmatropic rearrangement of the allylic azide. The 1,4,5-trisubstituted triazole products, derived from internal alkynes, are complementary to those commonly obtained by the related CuAAC reaction. Initial mechanistic experiments indicate that the NiAAC reaction proceeds through a monometallic Ni complex, which is distinct from the CuAAC manifold.
- Liu, En-Chih,Topczewski, Joseph J.
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supporting information
p. 5308 - 5313
(2021/05/04)
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- Three-Component Difunctionalization of Cyclohexenyl Triflates: Direct Access to Versatile Cyclohexenes via Cyclohexynes
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Difunctionalization of strained cyclic alkynes presents a powerful strategy to build richly functionalized cyclic alkenes in an expedient fashion. Herein we disclose an efficient and flexible approach to achieve carbohalogenation, dicarbofunctionalization, aminohalogenation and aminocarbonation of readily available cyclohexenyl triflates. We have demonstrated the novel use of zincate base/nucleophile system for effective formation of key cyclohexyne intermediates and selective addition of various carbon and nitrogen nucleophiles. Importantly, leveraging the resulting organozincates enables the incorporation of a broad range of electrophilic partners to deliver structurally diverse cyclohexene motifs. The importance and utility of this method is also exemplified by the modularity of this approach and the ease in which even highly complex polycyclic scaffolds can be accessed in one step.
- Cho, Seoyoung,McLaren, E. J.,Wang, Qiu
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p. 26332 - 26336
(2021/11/10)
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- Electro-mediated PhotoRedox Catalysis for Selective C(sp3)–O Cleavages of Phosphinated Alcohols to Carbanions
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We report a novel example of electro-mediated photoredox catalysis (e-PRC) in the reductive cleavage of C(sp3)?O bonds of phosphinated alcohols to alkyl carbanions. As well as deoxygenations, olefinations are reported which are E-selective and can be made Z-selective in a tandem reduction/photosensitization process where both steps are photoelectrochemically promoted. Spectroscopy, computation, and catalyst structural variations reveal that our new naphthalene monoimide-type catalyst allows for an intimate dispersive precomplexation of its radical anion form with the phosphinate substrate, facilitating a reactivity-determining C(sp3)?O cleavage. Surprisingly and in contrast to previously reported photoexcited radical anion chemistries, our conditions tolerate aryl chlorides/bromides and do not give rise to Birch-type reductions.
- Barham, Joshua P.,K?nig, Burkhard,Karl, Tobias A.,Reiter, Sebastian,Tian, Xianhai,Yakubov, Shahboz,de Vivie-Riedle, Regina
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supporting information
p. 20817 - 20825
(2021/08/18)
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- Iodobenzene-catalyzed oxidative cleavage of olefins to carbonyl compounds
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A metal-free approach for the oxidative cleavage of carbon–carbon double bonds of olefins to carbonyl compounds was established by using oxidant m-CPBA and non-metallic organocatalyst PhI in toluene/H2O. A broad scope of aromatic olefins was used. All the reactions proceeded smoothly at 35 °C in short reaction time to furnish the respective mono- and double carbonyl compounds selectively in moderate to good yields.
- Du, Lele,Wang, Zechao,Wu, Junliang
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supporting information
(2020/07/20)
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- Photochemical Flow Oximation of Alkanes
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The nitrosation of several alkanes using tert-butyl nitrite has been performed in flow showing a remarkable reduction in the reaction time compared with batch processing. Due to the necessity for large excesses of the alkane component a continuous recycling process was devised for the preparation of larger quantities of material.
- Griffiths, Oliver M.,Ruggeri, Michele,Baxendale, Ian R.
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supporting information
p. 1907 - 1912
(2020/10/06)
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- Synthesis of multisubstituted cycloalkenes through carbomagnesiation of strained cycloalkynes
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An efficient synthetic method of seven- and six-membered cycloalkenes through the generation of strained cycloalkynes and following carbomagnesiation is described. Further bond formations of the resulting cycloalkenylmagnesium intermediates with a wide variety of electrophiles enabled us to prepare diverse cycloalkene derivatives including benzoxepine analogs having a fully substituted alkene structure.
- Hosoya, Takamitsu,Karaki, Fumika,Minami, Yasunori,Nishiyama, Yoshitake,Sakata, Yuki,Tamura, Yuya,Yoshida, Suguru
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p. 7147 - 7150
(2020/07/21)
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- Bimolecular vinylation of arenes by vinyl cations
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Styrene derivatives can be easily synthesized from vinyl triflates and arenes under mild reaction conditions, using [Li][Al(OC(CF3)3)4] as a catalyst and LiHMDS as a base. This transformation is likely to involve a vinyl cation intermediate as an electrophile, which is corroborated by DFT calculations, deuterium-labeling and other control experiments. The use of an inert weakly coordinating anion is a decisive factor in this bimolecular vinylation process. This journal is
- Bour, Christophe,Gandon, Vincent,Li, Zhilong
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supporting information
p. 6507 - 6510
(2020/07/02)
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- Grubbs Metathesis Enabled by a Light-Driven gem-Hydrogenation of Internal Alkynes
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[(NHC)(cymene)RuCl2] (NHC=N-heterocyclic carbene) complexes instigate a light-driven gem-hydrogenation of internal alkynes with concomitant formation of discrete Grubbs-type ruthenium carbene species. This unorthodox reactivity mode is harnessed in the form of a “hydrogenative metathesis” reaction, which converts an enyne substrate into a cyclic alkene. The intervention of ruthenium carbenes formed in the actual gem-hydrogenation step was proven by the isolation and crystallographic characterization of a rather unusual representative of this series carrying an unconfined alkyl group on a disubstituted carbene center.
- Biberger, Tobias,Fürstner, Alois,Zachmann, Raphael J.
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supporting information
p. 18423 - 18429
(2020/08/25)
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- Rhodium-Catalyzed Deoxygenation and Borylation of Ketones: A Combined Experimental and Theoretical Investigation
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The rhodium-catalyzed deoxygenation and borylation of ketones with B2pin2 have been developed, leading to efficient formation of alkenes, vinylboronates, and vinyldiboronates. These reactions feature mild reaction conditions, a broad substrate scope, and excellent functional-group compatibility. Mechanistic studies support that the ketones initially undergo a Rh-catalyzed deoxygenation to give alkenes via boron enolate intermediates, and the subsequent Rh-catalyzed dehydrogenative borylation of alkenes leads to the formation of vinylboronates and diboration products, which is also supported by density functional theory calculations.
- Tao, Lei,Guo, Xueying,Li, Jie,Li, Ruoling,Lin, Zhenyang,Zhao, Wanxiang
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supporting information
p. 18118 - 18127
(2020/11/26)
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- Triphosgene and DMAP as Mild Reagents for Chemoselective Dehydration of Tertiary Alcohols
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The utility of triphosgene and DMAP as mild reagents for chemoselective dehydration of tertiary alcohols is reported. Performed in dichloromethane at room temperature, this reaction is readily tolerated by a broad scope of substrates, yielding alkenes preferentially with the (E)-geometry. While formation of the Hofmann products is generally favored, a dramatic change in alkene selectivity toward the Zaitzev products is observed when the reaction is carried out in dichloroethane at reflux.
- Ganiu, Moshood O.,Cleveland, Alexander H.,Paul, Jarrod L.,Kartika, Rendy
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supporting information
p. 5611 - 5615
(2019/08/01)
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- Visible-Light-Induced [4+2] Annulation of Thiophenes and Alkynes to Construct Benzene Rings
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The [4+2] annulation represents an elegant and versatile synthetic protocol for the construction of benzene rings. Herein, a strategy for visible-light induced [4+2] annulation of thiophenes and alkynes, to afford benzene rings, is presented. Under simple and mild reaction conditions, the ready availability and structural diversity of thiophenes and alkynes permit the facile synthesis of several substituted aromatic rings. Valuable drugs and amino acids are also well tolerated. Moreover, DFT calculations explain the high regioselectivity of the reaction.
- Song, Chunlan,Dong, Xin,Wang, Zhongjie,Liu, Kun,Chiang, Chien-Wei,Lei, Aiwen
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supporting information
p. 12206 - 12210
(2019/07/31)
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- Desulfinative palladium-catalyzed cross-coupling of arylsulfonyl hydrazides with aryl bromides under air
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A highly efficient and mild palladium-catalyzed cross-coupling of arylsulfonyl hydrazides and aryl bromides for the selective synthesis of unsymmetrical biaryls has been developed. This methodology has the advantages of easily accessible starting materials, functional group tolerance and a wide range of substrates, which provide rapid access to biaryls derivatives. In this protocol, abundant and stable aryl bromides serve as the aryl sources by coupling reaction of the aryl group generated from arylsulfonyl hydrazides via in situ release of nitrogen and sulfur dioxide. No external oxidants or acids are needed for this kind of transformation.
- Liu, Qingling,Yang, Bo
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- Alkene synthesis by photocatalytic chemoenzymatically compatible dehydrodecarboxylation of carboxylic acids and biomass
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Direct conversion of renewable biomass and bioderived chemicals to valuable synthetic intermediates for organic synthesis and materials science applications by means of mild and chemoselective catalytic methods has largely remained elusive. Development of artificial catalytic systems that are compatible with enzymatic reactions provides a synergistic solution to this enduring challenge by leveraging previously unachievable reactivity and selectivity modes. We report herein a dual catalytic dehydrodecarboxylation reaction that is enabled by a crossover of the photoinduced acridine-catalyzed O-H hydrogen atom transfer (HAT) and cobaloxime-catalyzed C-H-HAT processes. The reaction produces a variety of alkenes from readily available carboxylic acids. The reaction can be embedded in a scalable triple-catalytic cooperative chemoenzymatic lipase-acridine-cobaloxime process that allows for direct conversion of plant oils and biomass to long-chain terminal alkenes, precursors to bioderived polymers.
- Nguyen, Vu T.,Nguyen, Viet D.,Haug, Graham C.,Dang, Hang T.,Jin, Shengfei,Li, Zhiliang,Flores-Hansen, Carsten,Benavides, Brenda S.,Arman, Hadi D.,Larionov, Oleg V.
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p. 9485 - 9498
(2019/10/11)
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- Mechanochemical Oxidative Heck Coupling of Activated and Unactivated Alkenes: A Chemo-, Regio- and Stereo-Controlled Synthesis of Alkenylbenzenes
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In this work, we present an efficient mechanochemical strategy for chemo-, regio- and stereo-selective oxidative Heck coupling of readily accessible arylboron reagents/heteroaromatics with cyclic and acyclic olefins. Mono- and bis-arylation were achieved without the need of ligands, directing groups or prefunctionalized alkenes, and the reaction chemo-selectivity could be controlled by tuning of the oxidative system. This protocol offers the synthesis of alkenylbenzenes in broad substrate scope, satisfactory yields and excellent selectivity even in the gram scale. (Figure presented.).
- Yu, Jingbo,Shou, Haowen,Yu, Wangyang,Chen, Haodong,Su, Weike
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supporting information
p. 5133 - 5139
(2019/11/11)
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- Efficient and selective hydrogenation of C-O bonds with a simple sodium formate catalyzed by nickel
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A Ni-catalyzed hydrogenation of C-O compounds with sodium formate is developed. Various esters, i.e. aryl, alkenyl, benzyl pivalates, and even the aryl ethers, were efficiently reduced with a loading of nickel catalysts down to 0.5 mol%. Reactive functional groups such as C-C double bonds, carbonyl, CN, MeS and halogen groups are tolerable. This reaction can be used for the modification of complex molecules and carried out at a large scale.
- Xi, Xiaoxiang,Chen, Tieqiao,Zhang, Ji-Shu,Han, Li-Biao
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supporting information
p. 1521 - 1524
(2018/02/19)
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- Selective Hydrogenolysis of Dibenzofuran over Highly Efficient Pt/MgO Catalysts to o-Phenylphenol
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Direct selective hydrogenolysis of dibenzofuran (DBF) derived from coal and shale oil to a value-added chemical, ortho-phenylphenol (OPP), with high selectivity (80%) and yield (48%) has been achieved over Pt/MgO at 400 °C and 1.0 MPa by controlling the C-O bond cleavage as well as minimizing the extent of hydrogenation of aromatic rings. Meanwhile, Pt/SiO2, Pt/Al2O3, and Pt/MgO/Al2O3 catalysts were used for the DBF hydrogenolysis and showed lower selectivity for OPP. The influence of reaction parameters has been studied to unveil the optimal reaction conditions. And the phenomenon of OPP dehydrogenation is found over various catalysts for the hydrogenation reaction of OPP. Extensive reactions and catalyst characterizations demonstrated that the OPP selectivity and the dehydrogenation of OPP to DBF follows the order of supports basicity: MgO-900 > MgO > SiO2 > MgO/Al2O3 > Al2O3, which shows that the acid-base properties of supports impact the adsorption and desorption behaviors of DBF and OPP, and results in the disparity of OPP selectivity and the dehydrogenation of OPP. Finally, a plausible reaction pathway and mechanistic understanding are proposed.
- Zhang, Jie,Wang, Lei,Li, Chuang,Jin, Shaohua,Liang, Changhai
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- Regioselective Transfer Hydrodeuteration of Alkenes with a Hydrogen Deuteride Surrogate Using B(C6F5)3 Catalysis
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A regioselective hydrodeuteration of alkenes using monodeuterated cyclohexa-1,4-dienes as surrogates for hydrogen deuteride (HD) gas is reported. The metal-free process proceeds under B(C6F5)3 catalysis presumably by deuteride abstraction to form borodeuteride [DB(C6F5)3]a and highly Br?nsted-acidic Wheland intermediates. Low catalyst loadings (2.5 mol %) are used, and the reaction proceeds at room temperature.
- Walker, Johannes C. L.,Oestreich, Martin
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supporting information
p. 6411 - 6414
(2018/10/20)
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- Silica-coated nano-Fe3O4-supported iminopyridine palladium complex as an active, phosphine-free and magnetically separable catalyst for Heck reactions
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A novel magnetic nanoparticle-supported iminopyridine palladium complex was successfully prepared by attaching palladium acetate to iminopyridine ligand-functionalized silica-coated nano-Fe3O4. The as-prepared catalyst was well characterized and was evaluated in Heck reactions in terms of activity and recyclability. It was found to be highly efficient for the reactions of various aryl iodides and aryl bromides having electron-withdrawing groups with olefins under phosphine-free and inert atmosphere-free conditions. Moreover, the catalyst could be conveniently recovered using an external magnet, and the recyclability was influenced by the base in the Heck reaction. The catalyst could be reused at least six times with no significant loss in activity when triethylamine acted as the base.
- Zhang, Qiang,Zhao, Xin,Wei, Huai-Xin,Li, Ji-Hang,Luo, Jun
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- Efficient Ni-catalyzed conversion of phenols protected with 2,4,6-trichloro-1,3,5-triazine (TCT) to olefins
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An efficient Ni(COD)2/dppf catalyzed olefination of Ar-O-TCT as synthetic equivalents of aryl halides is described. Activation of C-O bonds in phenols as readily available compounds was achieved with 2,4,6-trichloro-1,3,5-triazine (TCT). This method provides practical access to 1,2-disubstituted olefins in high yields and high functional group compatibility.
- Etemadi-Davan,Iranpoor
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supporting information
p. 12794 - 12797
(2017/12/06)
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- Ruthenium(II)-catalyzed olefination: Via carbonyl reductive cross-coupling
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Natural availability of carbonyl groups offers reductive carbonyl coupling tremendous synthetic potential for efficient olefin synthesis, yet the catalytic carbonyl cross-coupling remains largely elusive. We report herein such a reaction, mediated by hydrazine under ruthenium(ii) catalysis. This method enables facile and selective cross-couplings of two unsymmetrical carbonyl compounds in either an intermolecular or intramolecular fashion. Moreover, this chemistry accommodates a variety of substrates, proceeds under mild reaction conditions with good functional group tolerance, and generates stoichiometric benign byproducts. Importantly, the coexistence of KOtBu and bidentate phosphine dmpe is vital to this transformation.
- Wei, Wei,Dai, Xi-Jie,Wang, Haining,Li, Chenchen,Yang, Xiaobo,Li, Chao-Jun
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p. 8193 - 8197
(2017/11/27)
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- Nickel-Catalyzed Direct Synthesis of Aryl Olefins from Ketones and Organoboron Reagents under Neutral Conditions
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Nickel-catalyzed addition of arylboron reagents to ketones results in aryl olefins directly. The neutral condition allows acidic protons of alcohols, phenols, and malonates to be present, and fragile structures are also tolerated.
- Lei, Chuanhu,Yip, Yong Jie,Zhou, Jianrong Steve
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supporting information
p. 6086 - 6089
(2017/05/08)
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- Efficient functionalization of olefins by arylsilanes catalyzed by palladium anionic complexes
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The coupling of organosilanes and different olefins was performed efficiently in the presence of anionic complexes, [CA]2[PdX4] and [CA]2[Pd2X6], where CA?=?imidazolium or pyridinium cation. The reaction proceeds according to a Pd(II)-mediated pathway, and Cu(OAc)2 acts as the re-oxidant of Pd(0) formed during the catalytic process. High product yields were obtained for differently substituted olefins at 80?°C in 4?h. Styrylsilanes reacted in the same conditions giving unsymmetrical 1,3-dienes.
- Silarska,Majchrzak,Marciniec,Trzeciak
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p. 458 - 464
(2016/12/16)
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- Quantitative and Qualitative Analysis of Three Classes of Sulfur Compounds in Crude Oil
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Owing to the environmental hazards arising from sulfur-containing combustion products, strong legal regulations exist to reduce the sulfur content of transportation fuels down to a few ppm. With the ongoing depletion of low-sulfur crude oil reservoirs, increased technological efforts are needed for crude oil refining to meet these requirements. The desulfurization step is a critical part of the refining process but partly suffers from the recalcitrance of certain species to sulfur removal and the inability to quantitatively understand the behavior of individual compound classes during the process. We herein present a new and simple approach for the parallel quantification of three different classes of sulfur species present in crude oils by LC separation and on-line detection and quantification by ICP-MS/MS. This approach will help to estimate the amount of recalcitrant species and thus facilitate the optimization of desulfurization conditions during fuel production.
- Vetere, Alessandro,Pr?frock, Daniel,Schrader, Wolfgang
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p. 10933 - 10937
(2017/08/30)
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- Lewis base-assisted Lewis acid-catalyzed selective alkene formation via alcohol dehydration and synthesis of 2-cinnamyl-1,3-dicarbonyl compounds from 2-aryl-3,4-dihydropyrans
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Acid-catalyzed dehydration of alcohols has been widely employed for the synthesis of alkenes. However, activated alcohols when employed as substrates in dehydration reactions are often plagued by the lack of alkene selectivity. In this work, the reaction system can be significantly improved through enhancing the performance of Lewis acid catalysts in the dehydration of activated alcohols by combining with a Lewis base. Observations of the reaction mechanism revealed that the Lewis base component might have changed the reaction rate order. Although both the principal and side reaction rates decreased, the effect was markedly more observed on the latter reaction. Therefore, the selectivity of the dehydration reaction was improved. On the basis of this observation, a new route to synthesize 2-cinnamyl-1,3-dicarbonyl compounds was developed by using 2-aryl-3,4-dihydropyran as a starting substrate in the presence of a Lewis acid/Lewis base combined catalyst system.
- Liu, Changhui,Pan, Bin,Gu, Yanlong
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p. 979 - 986
(2016/07/06)
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- Simple synthesis method of olefin
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The invention discloses a simple synthesis method of olefin, and relates to the technical field of preparation of an organic compound, i.e., olefin. The olefin is prepared by taking tertiary alcohol as a raw material, sodium bisulfate monohydrate as a catalyst and water as a solvent. Compared with the conventional method, the method provided by the invention has the advantages that the raw materials are simple and readily available, the cost is low, the process time is short, the reaction conditions are mild, and the reaction is easy to operate; the simple synthesis method is a simple method for synthesizing an olefin compound.
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Paragraph 0012; 0019; 0020
(2017/04/28)
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- Effect of direct synthesis Al-SBA-15 supports on the morphology and catalytic activity of the NiMoS phase in HDS of DBT
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A series of Al-SBA-15 (Al-15) materials was prepared by direct synthesis method with a broad range of Si/Al molar ratios (X = 40, 20, 10, 5, and 2.5), and the corresponding NiMoS/Al-15(X) catalysts were used to perform the hydrodesulfurization (HDS) reaction with dibenzothiophene (DBT). The prepared samples were characterized by N2 physisorption, ICP-OES, powder XRD, 27Al MAS NMR, H2-TPR, pyridine-FTIR and HRTEM. Al-SBA-15(10) had the highest number of Br?nsted acid sites and the total acid density of silica-alumina supports increased with Al loading. The enhanced acidity of the Al-15-type materials led to higher catalyst activity compared to those of NiMo/γ-Al2O3 and NiMo/SBA-15. A suitable stacking of the NiMoS slabs favors the hydrogenation reaction of DBT while introduction of Al into the silica supports can help the hydrogenolysis of the C-S bond. The acid density and surface roughness of the support (the surface periodicity of the support in the atomic scale) impact the morphology of the active phase, which, in turn, affects the reaction selectivity of DBT HDS.
- Jiang, Shujiao,Zhou, Yasong,Ding, Sijia,Wei, Qiang,Zhou, Wenwu,Shan, Yacheng
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p. 106680 - 106689
(2016/11/23)
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- Effective hydrodeoxygenation of dibenzofuran by a bimetallic catalyst in water
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Effective hydrodeoxygenation (HDO) of dibenzofuran (DBF) catalyzed by a bimetallic nickel/platinum (Ni/Pt) catalyst in water was demonstrated at 200 °C and 1.2 MPa hydrogen (H2) pressure. The bimetallic catalysts prepared by a wet chemical method exhibit prominent activity that overcomes the limitations of use of a single Ni or Pt metal catalyst. The yield of HDO products can be up to 90%. Reaction results indicate that the conversion of DBF was affected by the reaction temperature and H2 pressure. The deoxygenation selectivity was strongly dependent on reaction temperature. The reaction pathway is also proposed.
- Dong, Peng,Lu, Guo-Ping,Cai, Chun
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p. 1605 - 1609
(2016/02/19)
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- Metal-Free Microwave-Assisted Decarboxylative Elimination for the Synthesis of Olefins
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A metal-free efficient synthesis of olefins via microwave-assisted direct decarboxylative elimination of arylacetic acids is described. This reaction, using commercially available reagent PIFA as oxidant, readily provides a variety of desired products in moderate to good yields.
- Wu, Shu-Wei,Liu, Jia-Li,Liu, Feng
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supporting information
p. 1 - 3
(2016/01/15)
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- The effect of Al2O3 and ionic liquids in palladium catalyzed arylation of cyclohexene. Interaction of Hg(0) with immobilized palladium
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Three-component systems containing Pd(OAc)2, Al2O3, and an IL (IL = ionic liquid) were applied in the Heck arylation of cyclohexene. The highest productivity and selectivity to 4-phenylcyclohexene was noted in reaction catalyzed by Pd/Al2O3 in the presence of a small amount of an IL, dimethyldidodecylammonium lactate (C). The addition of Al2O3 alone to the reaction catalyzed by soluble precursors, PdCl2(PhCN)2 or Pd(OAc)2 and IL, remarkably increased conversion to 4-phenylcyclohexene. Hg(0) inhibited the reaction catalyzed by Pd/Al2O3 by formation of Pd-Hg amalgam immobilized on Al2O3. SEM/EDX studies of Pd/Al2O3 performed after treatment with Hg(0) showed that the IL modified the surface properties of Pd/Al2O3.
- Wirwis,Gil,Pernak,Trzeciak
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p. 188 - 195
(2015/11/23)
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- Copper/Selectfluor-System-Catalyzed Dehydration-Oxidation of Tertiary Cycloalcohols: Access to β-Substituted Cyclohex-2-enones, 4-Arylcoumarins, and Biaryls
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A route to β-substituted cyclohex-2-enones, 4-arylcoumarins, and biaryls has been developed. This approach involves a one-pot Cu0/Selectfluor-catalyzed dehydration-oxidation of tertiary cycloalcohols. Thus, by using 2 equiv. of Selectfluor at 25 C, the dehydration-oxidation of tertiary cyclohexanols and oxabenzocyclohexanols gave β-substituted cyclohex-2-enones and 4-arylcoumarins, respectively; whereas the dehydration-oxidation of tertiary cyclohexanols gave biaryls as the final products by using 2.5 equiv. of Selectfluor at 80 C. A route to β-substituted cyclohex-2-enones, 4-arylcoumarins, and biaryls has been developed. This approach involves a one-pot Cu0/Selectfluor-catalyzed dehydration-oxidation of tertiary cycloalcohols.
- Ren, Shaobo,Zhang, Jian,Zhang, Jiahui,Wang, Heng,Zhang, Wei,Liu, Yunkui,Liu, Miaochang
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p. 5381 - 5388
(2015/08/24)
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- Electron-deficient olefin ligands enable generation of quaternary carbons by Ni-catalyzed cross-coupling
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A Ni-catalyzed Negishi cross-coupling with 1,1-disubstituted styrenyl aziridines has been developed. This method delivers valuable β-substituted phenethylamines via a challenging reductive elimination that affords a quaternary carbon. A novel electron-deficient olefin ligand, Fro-DO, proved crucial for achieving high rates and chemoselectivity for C-C bond formation over β-H elimination. This ligand is easy to access, is stable, and presents a modular framework for reaction discovery and optimization. We expect that these attributes, combined with the fact that the ligands impart distinct electronic properties to a metal, will support the invention of new transformations not previously possible using established ligands.
- Huang, Chung-Yang,Doyle, Abigail G.
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supporting information
p. 5638 - 5641
(2015/05/20)
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- Oxygen-promoted coupling of arylboronic acids with olefins catalyzed by [CA]2[PdX4] complexes without a base
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Abstract An efficient method was developed for the oxidative Heck reaction between arylboronic acids and olefins catalyzed by anionic palladium complexes of the type [CA]x[PdCl4] (x = 1,2) and [CA]2[Pd2Cl6] (CA = imidazolium or pyridinium cation). Molecular oxygen was employed as an environmentally benign oxidant to regenerate Pd(II) species during the reaction. The elaborated protocol could be applied to the coupling of different arylboronic acids with both electron-rich and electron-poor olefins. The catalyst system was further employed for the one-pot oxidative Heck reaction followed by the Heck coupling to build conjugated compounds in good yield. Mass spectrometry (ESI-MS) and UV-vis spectroscopy was used to identify palladium-containing complexes in the reactions. A plausible reaction mechanism of the oxidative Heck reaction was proposed.
- Silarska,Trzeciak
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- Iron-catalyzed olefin hydrogenation at 1 bar H2 with a FeCl3-LiAlH4 catalyst
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The scope and mechanism of a practical protocol for the iron-catalyzed hydrogenation of alkenes and alkynes at 1 bar H2 pressure were studied. The catalyst is formed from cheap chemicals (5 mol% FeCl3-LiAlH4, THF). A homogeneous mechanism operates at early stages of the reaction while active nanoparticles form upon ageing of the catalyst solution. This journal is
- Gieshoff, Tim N.,Villa, Matteo,Welther, Alice,Plois, Markus,Chakraborty, Uttam,Wolf, Robert,Jacobi Von Wangelin, Axel
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supporting information
p. 1408 - 1413
(2015/03/18)
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- Copper-catalyzed allylation of a,a-difluoro-substituted organozinc reagents
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A method for the coupling of organozinc reagents, difluorocarbene, and allylic electrophiles is described. The reaction involves insertion of difluorocarbene into the carbon-zinc bond followed by copper-catalyzed allylic substitution.
- Zemtsov, Artem A.,Kondratyev, Nikolay S.,Levin, Vitalij V.,Struchkova, Marina I.,Dilman, Alexander D.
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p. 818 - 822
(2014/04/03)
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- Palladium-Catalysed Direct Cross-Coupling of Organolithium Reagents with Aryl and Vinyl Triflates
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A palladium-catalysed cross-coupling of organolithium reagents with aryl and vinyl triflates is presented. The reaction proceeds at 50 or 70 C with short reaction times, and the corresponding products are obtained with moderate to high yields, with a variety of alkyl and (hetero)aryl lithium reagents.
- Vila, Carlos,Hornillos, Valentín,Giannerini, Massimo,Fa?anás-Mastral, Martín,Feringa, Ben L.
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supporting information
p. 13078 - 13083
(2016/02/19)
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- Sulfur mediated allylic C-H alkylation of tri- and disubstituted olefins
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A novel transition-metal-free, sulfur mediated allylic C-H alkylation reaction through a one-pot procedure involving an ene-like step between simple olefins and activated sulfoxides to generate allylic sulfonium intermediates, and a subsequent [2,3]-sigmatropic rearrangement step under basic conditions to give allylic C-H alkylation products, has been developed. This method is applicable to tri- and disubstituted olefin substrates in both inter- and intramolecular fashions.
- Hu, Gang,Xu, Jiaxi,Li, Pingfan
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supporting information
p. 6036 - 6039
(2015/01/08)
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- Achieving vinylic selectivity in Mizoroki-heck reaction of cyclic olefins
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In Heck reactions of cyclic olefins, the products usually have aryl groups that end up at the allylic and/or homoallylic position. We herein report new selectivity that adds aryl groups to the vinylic position. Cyclic olefins of various ring size worked well. The desired isomers were produced by palladium-hydride-catalyzed isomerization of the initial products. Thus, a specific catalyst must be used so that it can perform two jobs under one set of reaction conditions. Copyright
- Wu, Xiaojin,Lu, Yunpeng,Hirao, Hajime,Zhou, Jianrong
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p. 6014 - 6020
(2013/06/26)
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- Synthesis and antinociceptive behaviors of new methyl and hydroxyl derivatives of phencyclidine
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Phencyclidine (I) and its derivatives show such pharmacological behaviors as analgesic, anticonsulvant, anti-anxiety and antidepressant, while interacting with central nervous system. In this study, new methyl and hydroxyl derivatives of PCP were synthesized and their antinociceptive behaviors in animals were examined by measuring the number of writhing in a writhing test of visceral pain and the pain scores in Formalin test. Compared to control and PCP groups, findings in experimental groups indicated the new synthesized analogues (compounds II, III and V, 10 mg/kg) of PCP were able to produce more analgesic effects in formalin and writhing tests, especially for compound V. It was concluded that the new synthesized derivatives of PCP could substantially and respectively diminish acute and chronic pains.
- Ahmadi,Kermani,Naderi,Hajikhani,Rezaee,Javadi,Niknafs
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experimental part
p. 763 - 769
(2012/06/30)
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- N-heterocyclic carbene dichotomy in Pd-catalyzed acylation of aryl chlorides via C-H bond functionalization
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The first Pd-catalyzed intramolecular acylation of aryl chlorides via C-H bond functionalization is presented. The method allows for the synthesis of a variety of elusive benzocyclobutenones with a wide range of functional groups and substitution patterns. We demonstrate that a change in the ligand backbone dictates the selectivity pattern.
- Flores-Gaspar, Areli,Gutierrez-Bonet, Alvaro,Martin, Ruben
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p. 5234 - 5237
(2013/01/15)
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- N-heterocyclic carbene dichotomy in Pd-catalyzed acylation of aryl chlorides via C-H bond functionalization
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The first Pd-catalyzed intramolecular acylation of aryl chlorides via C-H bond functionalization is presented. The method allows for the synthesis of a variety of elusive benzocyclobutenones with a wide range of functional groups and substitution patterns. We demonstrate that a change in the ligand backbone dictates the selectivity pattern.
- Flores-Gaspar, Areli,Gutierrez-Bonet, Alvaro,Martin, Ruben
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p. 5234 - 5237,4
(2012/12/12)
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- Heteropolyacid-catalyzed direct deoxygenation of propargyl and allyl alcohols
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The combination of H3[PW12O40] ?nH2O (1 mol %) and Et3SiH led to the direct catalytic deoxygenation of propargyl alcohols, in which proper solvent selection Cl(CH2)2Cl vs CF3CH2OH was the key to obtaining better product yields. Under similar conditions, the deoxygenation of allyl alcohols proceeded to give thermodynamically stable alkenes with migration of the double bonds in good yields.
- Egi, Masahiro,Kawai, Takuya,Umemura, Megumi,Akai, Shuji
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body text
p. 7092 - 7097
(2012/10/07)
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- Preparation of alkylmagnesium reagents from alkenes through hydroboration and boron-magnesium exchange
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Tolerant: Alkylmagnesium reagents can be synthesized from alkenes through a sequence of hydroboration and subsequent boron-magnesium exchange using a method that tolerates different functional groups (see scheme). The resulting alkylmagnesium reagents can be used in carbon-carbon bond forming reactions, such as alkylation reactions or transition-metal-catalyzed cross-coupling reactions. Copyright
- Reichle, Markus A.,Breit, Bernhard
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supporting information; experimental part
p. 5730 - 5734
(2012/08/14)
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- Palladium-catalyzed 1,1-difunctionalization of ethylene
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The 1,1-difunctionalization of ethylene, with aryl/vinyl/heteroaryl transmetalating agents and vinyl electrophiles, is reported. The reaction is high-yielding under a low pressure of ethylene, and regioselectivity is generally high for the 1,1-disubstituted product. The process is highlighted by the use of heteroaromatic cross-coupling reagents, which have not been competent reaction partners in previously reported efforts.
- Saini, Vaneet,Sigman, Matthew S.
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supporting information; experimental part
p. 11372 - 11375
(2012/08/29)
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- Copper-catalyzed alkene arylation with diaryliodonium salts
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Alkenes and arenes represent two classes of feedstock compounds whose union has fundamental importance to synthetic organic chemistry. We report a new approach to alkene arylation using diaryliodonium salts and Cu catalysis. Using a range of simple alkenes, we have shown that the product outcomes differ significantly from those commonly obtained by the Heck reaction. We have used these insights to develop a number of new tandem and cascade reactions that transform readily available alkenes into complex arylated products that may have broad applications in chemical synthesis.
- Phipps, Robert J.,McMurray, Lindsay,Ritter, Stefanie,Duong, Hung A.,Gaunt, Matthew J.
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supporting information; experimental part
p. 10773 - 10776
(2012/08/07)
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- Influence of chiral thiols on the diastereoselective synthesis of γ-lactams from cyclic anhydrides
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The synthesis of γ-lactams from both four-component and imine-anhydride reactions is reported. The synthesis of 2-phenylcyclohexanethiol is described and this compound was evaluated along with an additional seven chiral thiols. A range of selectivity and yields was observed and comparisons to established reactions are made in order to account for the observed reactivity.
- Younai, Ashkaan,Fettinger, James C.,Shaw, Jared T.
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p. 4320 - 4327
(2012/07/28)
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- Heck-Matsuda reactions catalyzed by a hydroxyalkyl-functionalized NHC and palladium acetate
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The functionalized NHC obtained from salt 2 is a good ligand for palladium in the Heck-Matsuda reaction of arenediazonium salts and different alkenes. The reaction is performed with low catalyst loading (0.5-1 mol-% of Pd) and in the absence of a base for acrylates. The protocol is also useful for the preparation of cinnamide derivatives. Compound U-77863 has been prepared successfully in good isolated yield. Cyclohexene was found to be an appropriate substrate for the reaction, giving the corresponding 1-arylcyclohexene as a single regioisomer under the studied reaction conditions. The optimal parameters of the reaction were studied by employing a design of experiments approach. Thus, the use of a small set of reactions allows the trends of the different factors to be studied. This study revealed that the best catalytic system is formed by combination of Pd(OAc)2 and salt 2 in a 1:2 ratio. This catalytic system produces better results without the use of a base. Copyright
- Penafiel, Itziar,Pastor, Isidro M.,Yus, Miguel
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supporting information; experimental part
p. 3151 - 3156
(2012/07/03)
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- Ionic liquids - Advanced reaction media for organic synthesis
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The advantages in the application of ionic liquids as reaction media in organic synthesis, i.e., in the preparation of chromane derivatives, substituted pyrazines, 4-aminofuran-2(5H)-ones, or in bromination of Levulinic acid or dehydration of alcohols, saccharides, and polysaccharides, have been demonstrated on several examples. Ionic liquids with Bronsted acidity have been shown to possess catalytic activity and provide access to convenient technologies for the preparation of various useful compounds. Copyright Merck KGaA.
- Ignat'ev, Nikolai V.,Schulte, Michael,Koppe, Karsten,Barthen, Peter,Zlotin, Sergei G.,Makhova, Nina N.,Sheremetev, Aleksei B.,Valente, Anabela A.
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body text
p. 1205 - 1216
(2011/09/16)
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- An acid-catalyzed formal allylic C-H oxidation of aryl cycloalkenes with N-propylthiosuccinimide
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A mild acid-catalyzed formal allylic C-H oxidation of aryl cycloalkenes with N-propylthiosuccinimide in the presence of various nucleophiles to generate allylic ethers, esters, and sulfonamides is described. A possible reaction mechanism has been proposed.
- Huang, Deshun,Wang, Haining,Guan, Huan,Huang, Hu,Shi, Yian
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supporting information; experimental part
p. 1548 - 1551
(2011/05/03)
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