- Polyhedral Cu2O Crystals for Diverse Aryl Alkyne Hydroboration Reactions
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Cu2O cubes, octahedra, and rhombic dodecahedra have been used to examine facet-dependent catalytic activity in aryl alkyne hydroboration reactions. Although the reaction can proceed by using ethanol or other alcohols as solvent, the use of 1,4-dioxane gave the best product yield. All particle shapes gave exclusively the E-product, but the rhombic dodecahedra exposing {110} surfaces were consistently far more reactive than the other particle morphologies. A product yield of 99 % was achieved by using Cu2O rhombic dodecahedra to catalyze the hydroboration of phenylacetylene at 60 °C for 5 h. The rhombic dodecahedra have been shown to catalyze a variety of substituted aryl alkynes, which demonstrates their potential as a versatile catalyst.
- Tsai, Hsin-Yi,Madasu, Mahesh,Huang, Michael H.
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Read Online
- Solvent- and metal-free hydroboration of alkynes under microwave irradiation
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Boronic esters are versatile building blocks extensively used in organic chemistry and essential to a variety of coupling reactions. In this work, the hydroboration reactions of alkynes were performed without metal catalysts using concomitant microwave ir
- Arnaud, Alexandre,Doléans-Jordheim, Anne,Gioia, Bruna,Radix, Sylvie,Rocheblave, Luc,Walchshofer, Nadia
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- Aluminum Hydride Catalyzed Hydroboration of Alkynes
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An aluminum-catalyzed hydroboration of alkynes using either the commercially available aluminum hydride DIBAL-H or bench-stable Et3Al?DABCO as the catalyst and H-Bpin as both the boron reagent and stoichiometric hydride source has been developed. Mechanistic studies revealed a unique mode of reactivity in which the reaction is proposed to proceed through hydroalumination and σ-bond metathesis between the resultant alkenyl aluminum species and HBpin, which acts to drive turnover of the catalytic cycle.
- Bismuto, Alessandro,Thomas, Stephen P.,Cowley, Michael J.
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- Heck versus Suzuki palladium catalysed cross-coupling of a vinylboronate ester with aryl halides
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Palladium(O) catalysed cross-coupling of a vinylboronate 1, protected as its' pinacol ester, with aryl halides provides a mixture of the styryl boronates 2 and the styrenes 3 depending upon the reaction conditions.
- Hunt,Stewart,Whiting
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Read Online
- Photoswitchable metal-mediated catalysis: Remotely tuned alkene and alkyne hydroborations
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A photochromic dithienylethene-annulated N-heterocyclic carbene (NHC)-Rh(I) complex was synthesized and found to undergo reversible electrocyclic ring closure upon alternate exposure to UV (λirr 313 nm) and visible (λirr >500 nm) radiation. Under ambient light, the Rh catalyst efficiently promoted the hydroboration of alkenes and alkynes with pinacolborane. However, upon UV irradiation to effect a photocyclization within the NHC ligand, the catalytic activity was reduced by up to an order of magnitude. The disparity in the rates was used to photoswitch the rates of a series of hydroboration reactions, thus demonstrating the first examples of photomodulating a transition-metal catalyst by tuning its electronic properties. The rate attenuation observed under UV irradiation was attributed to inhibition of the rate-determining reductive elimination step arising from a decrease in electron-donating ability of the photocyclized NHC ligated to the Rh center.
- Neilson, Bethany M.,Bielawski, Christopher W.
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- An efficient synthesis of chalcones based on the Suzuki reaction
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A general method for the synthesis of chalcones based on the Suzuki reaction either between cinnamoyl chlorides and phenylboronic acids or between benzoyl chlorides and phenylvinylboronic acids is described.
- Eddarir, Said,Cotelle, Nicole,Bakkour, Youssef,Rolando, Christian
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Read Online
- Zwitterion-Initiated Hydroboration of Alkynes and Styrene
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The hydroboration of alkynes and styrene with HBpin has been developed using tris(pentaflurophenyl)borane (B(C6F5)3) as the initiator of catalysis. The hydroboration is proposed to be initiated by Lewis acid activation of the alkyne by (B(C6F5)3) to form a highly reactive zwitterionic species which subsequently react with HBpin to give the alkenyl boronic ester. This zwitterion has also showed potential to be a competent catalyst for the hydroboration of styrene. The zwitterionic intermediate is analogous to that proposed in the Piers borane-catalysed hydroboration and 1,1-carboboration of alkynes with B(C6F5)3. (Figure presented.).
- Bismuto, Alessandro,Cowley, Michael J.,Thomas, Stephen P.
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Read Online
- Neosilyllithium-Catalyzed Hydroboration of Alkynes and Alkenes in the Presence of Pinacolborane (HBpin)
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We report here a novel protocol for the hydroboration of alkynes and alkenes, which in the presence of neosilyllithium (LiCH2SiMe3) (5 mol %) and pinacolborane efficiently results in the formation of corresponding alkenyl and alkyl b
- Kumar, Gobbilla Sai,Moorthy, Shruti,Karmakar, Himadri,Singh, Saurabh Kumar,Panda, Tarun K.
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supporting information
(2021/11/13)
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- Cobalt-Catalyzed Markovnikov-Type Selective Hydroboration of Terminal Alkynes
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A cobalt-catalyzed Markovnikov-type hydroboration of terminal alkynes with HBpin to access α-alkenyl boronates with good regioselectivity and atom economy is reported. A new ligand has been developed for the cobalt hydride catalyst that has been used for a unique Markovnikov selective insertion of terminal alkynes into metal hydride bond. This operationally simple protocol exhibits excellent functional group tolerance to deliver valuable alkene derivatives.
- Chen, Jieping,Shen, Xuzhong,Lu, Zhan
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supporting information
p. 690 - 694
(2020/11/30)
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- Synthesis method of alkenyl borate
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The invention discloses a synthesis method of alkenyl borate, which comprises the following steps: adding an alkyne substance, pinacolborane and a lithium amide catalyst into a reaction vessel filled with an organic solvent in a nitrogen atmosphere, stirring and mixing, uniformly mixing, reacting at the temperature of 70-110 DEG C for 18-28 hours, filtering and purifying after the reaction is finished to obtain a product, wherein the lithium amide catalyst is lithium bis(trimethylsilyl) amide; the alkyne substance is any one of substances such as phenylacetylene and 4-methyl phenylacetylene. The method is mild in reaction condition, easy to achieve and safe; the target product can be directly synthesized, an intermediate product does not need to be separated, and the highest yield can reach 98%; the catalyst is easy to prepare, and reactant raw materials are easy to obtain; the waste solution in the reaction process is less, other pollution gases and liquids are not discharged, so that the discharge of the waste solution is reduced, and the method has the advantages of protecting the environment and guaranteeing the health of operators.
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Paragraph 0012; 0058-0062
(2021/10/30)
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- Synthesis method of alkenyl boric acid ester
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The invention discloses a synthesis method of alkenyl boric acid ester. The alkenyl boric acid ester compound with a diversified structure is obtained by catalyzing hydroboration of alkyne through rare earth. Particularly, the alkenyl boric acid ester com
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Paragraph 0050-0054
(2021/05/12)
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- Tropylium-Promoted Hydroboration Reactions: Mechanistic Insights Via Experimental and Computational Studies
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Hydroboration reaction of alkynes is one of the most synthetically powerful tools to access organoboron compounds, versatile precursors for cross-coupling chemistry. This type of reaction has traditionally been mediated by transition-metal or main group catalysts. Herein, we report a novel method using tropylium salts, typically known as organic oxidants and Lewis acids, to promote the hydroboration reaction of alkynes. A broad range of vinylboranes can be easily accessed via this metal-free protocol. Similar hydroboration reactions of alkenes and epoxides can also be efficiently catalyzed by the same tropylium catalysts. Experimental studies and DFT calculations suggested that the reaction follows an uncommon mechanistic pathway, which is triggered by the hydride abstraction of pinacolborane with tropylium ion. This is followed by a series ofin situcounterion-activated substituent exchanges to generate boron intermediates that promote the hydroboration reaction.
- Mai, Binh Khanh,Nguyen, Thanh Vinh,Ton, Nhan N. H.
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p. 9117 - 9133
(2021/07/19)
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- Aluminum-Hydride-Catalyzed Hydroboration of Carbon Dioxide
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This study describes the first use of a bis(phosphoranyl)methanido aluminum hydride, [ClC(PPh2NMes)2AlH2] (2, Mes = Me3C6H2), for the catalytic hydroboration of CO2. Complex 2 was synthesized by the reaction of a lithium carbenoid [Li(Cl)C(PPh2NMes)2] with 2 equiv of AlH3·NEtMe2 in toluene at -78 °C. 2 (10 mol %) was able to catalyze the reduction of CO2 with HBpin in C6D6 at 110 °C for 2 days to afford a mixture of methoxyborane [MeOBpin] (3a; yield: 78%, TOF: 0.16 h-1) and bis(boryl)oxide [pinBOBpin] (3b). When more potent [BH3·SMe2] was used instead of HBpin, the catalytic reaction was extremely pure, resulting in the formation of trimethyl borate [B(OMe)3] (3e) [catalytic loading: 1 mol % (10 mol %); reaction time: 60 min (5 min); yield: 97.6% (>99%); TOF: 292.8 h-1 (356.4 h-1)] and B2O3 (3f). Mechanistic studies show that the Al-H bond in complex 2 activated CO2 to form [ClC(PPh2NMes)2Al(H){OC(O)H}] (4), which was subsequently reacted with BH3·SMe2 to form 3e and 3f, along with the regeneration of complex 2. Complex 2 also shows good catalytic activity toward the hydroboration of carbonyl, nitrile, and alkyne derivatives.
- Chia, Cher-Chiek,Teo, Yeow-Chuan,Cham, Ning,Ho, Samuel Ying-Fu,Ng, Zhe-Hua,Toh, Hui-Min,Mézailles, Nicolas,So, Cheuk-Wai
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supporting information
p. 4569 - 4577
(2021/04/09)
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- Transborylation of alkenylboranes with diboranes
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Exchange of boryl moieties between alkenylboranes and diboron reagents has been postulated as a stereospecific cross-metathesis pathway with concomitant formation of mixed diboron reagents. DFT calculations propose a mechanism for the stereocontrolled C(sp2)-B/B′-B′ cross-metathesis with both symmetric and non-symmetric diboron reagents. This journal is
- Bru, Gerard,Carbó, Jorge J.,Dominguez-Molano, Paula,Fernández, Elena,Maza, Ricardo J.,Salvado, Oriol
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supporting information
p. 13361 - 13364
(2021/12/17)
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- Cobalt-Catalyzed Hydroboration of Terminal and Internal Alkynes
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A novel methodology to access synthetically versatile vinylboronic esters through a ligand-controlled cobalt-catalyzed hydroboration of terminal and internal alkynes is reported. The approach relies on the in situ reduction of Co(II) by H-BPin in the presence of bisphosphine ligands generating catalytically active Co(I) hydride complexes. This procedure avoids the use of stoichiometric amounts of base, and no boron-containing byproducts are generated which is translated into high functional group tolerance and atom economy.
- González, María J.,Bauer, Felix,Breit, Bernhard
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supporting information
p. 8199 - 8203
(2021/10/25)
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- Enantioselective Copper-Catalyzed Synthesis of Trifluoromethyl-Cyclopropylboronates
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A copper-catalyzed enantioselective cyclopropanation involving trifluorodiazoethane in the presence of alkenyl boronates has been developed. This transformation enables the preparation of 2-substituted-3-(trifluoromethyl)cyclopropylboronates with high levels of stereocontrol. The products are valuable synthetic intermediates by transformation of the boronate group. This methodology can be applied to the synthesis of novel trifluoromethylated analogues of trans-2-arylcyclopropylamines, which are prevalent motifs in biologically active compounds.
- Altarejos, Julia,Carreras, Javier,Sucunza, David,Vaquero, Juan J.
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supporting information
p. 6174 - 6178
(2021/08/18)
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- Selective hydroboration of alkynes via multisite synergistic catalysis by PCN-222(Cu)
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Zirconium-based porphyrinic MOFs (PMOFs, MOF = metal-organic framework) have gained considerable attention in the field of electric/thermo/photo-catalysis as heterogeneous single-site catalysts; however, the study on multisite synergistic catalysis of PMO
- Ma, L. J.,Tang, Z. Y.,Yuan, J. C.,Zhang, L. J.,Zhang, X. M.
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- Copper-Photocatalyzed Hydroboration of Alkynes and Alkenes
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The photocatalytic hydroboration of alkenes and alkynes is reported. The use of newly-designed copper photocatalysts with B2Pin2 permits the formation a boryl radical, which is used for hydroboration of a large panel of alkenes and a
- Zhong, Mingbing,Gagné, Yohann,Hope, Taylor O.,Pannecoucke, Xavier,Frenette, Mathieu,Jubault, Philippe,Poisson, Thomas
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supporting information
p. 14498 - 14503
(2021/05/21)
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- Creating High Regioselectivity by Electronic Metal-Support Interaction of a Single-Atomic-Site Catalyst
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Ligands are the most commonly used means to control the regioselectivity of organic reactions. It is very important to develop new regioselective control methods for organic synthesis. In this study, we designed and synthesized a single-atomic-site catalyst (SAC), namely, Cu1-TiC, with strong electronic metal-support interaction (EMSI) effects by studying various reaction mechanisms. π cloud back-donation to the alkyne on the metal catalytic intermediate was enhanced during the reaction by using transient electron-rich characteristics. In this way, the reaction achieved highly linear-E-type regioselective conversion of electronically unbiased alkynes and completely avoided the formation of branched isomers (ln:br >100:1, TON up to 612, 3 times higher than previously recorded). The structural elements of the SACs were designed following the requirements of the synthesis mechanism. Every element in the catalyst played an important role in the synthesis mechanism. This demonstrated that the EMSI, which is normally thought to be responsible for the improvement in catalytic efficiency and durability in heterogeneous catalysis, now first shows exciting potential for regulating the regioselectivity in homogeneous catalysis.
- Jing, Hongyu,Li, Jiong,Li, Wen-Hao,Li, Yadong,Wang, Dingsheng,Wang, Yu,Yang, Jiarui,Zhang, Jian,Zhao, Jie
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supporting information
p. 15453 - 15461
(2021/09/30)
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- Highly efficient hydroboration of alkynes catalyzed by porous copper-organic framework under mild conditions
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The hydroboration of alkynes is crucial due to the wide applications in organic synthesis, while such reaction is often completed with low turnover frequency (TOF) value and long reaction time. Therefore, it is very important and necessary that the hydrob
- Gao, Ning,Hu, Tianding,Kang, Xiaomin,Lan, Xingwang,Wang, Zhenguang,Wu, Zhi-Lei,Zhao, Bin
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p. 250 - 257
(2021/10/25)
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- Electrochemical Hydroboration of Alkynes
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Herein we reported the electrochemical hydroboration of alkynes by using B2Pin2 as the boron source. This unprecedented reaction manifold was applied to a broad range of alkynes, giving the hydroboration products in good to excellent yields without the need of a metal catalyst or a hydride source. This transformation relied on the possible electrochemical oxidation of an in situ formed borate. This anodic oxidation performed in an undivided cell allowed the formation of a putative boryl radical, which reacted on the alkyne.
- Aelterman, Maude,Jubault, Philippe,Poisson, Thomas,Sayes, Morgane
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supporting information
p. 8277 - 8282
(2021/05/27)
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- Cs4B4O3F10: First Fluorooxoborate with [BF4] Involving Heteroanionic Units and Extremely Low Melting Point
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Herein, a new congruently melting mixed-anion compound Cs4B4O3F10 has been characterized as the first fluorooxoborate with [BF4] involving heteroanionic units. Compound Cs4B4O3F10 possesses two highly fluorinated anionic clusters and therefore its formula can be expressed as Cs3(B3O3F6) ? Cs(BF4). The influence of [BF4] units on micro-symmetry and structural evolution was discussed based on the parent compound. More importantly, Cs4B4O3F10 shows the lowest melting point among all the available borates and thus sets a new record for such system. This work is of great significance to enrich and tailor the structure of borates using perfluorinated [BF4] units.
- Xia, Ming,Mutailipu, Miriding,Li, Fuming,Yang, Zhihua,Pan, Shilie
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supporting information
p. 9753 - 9757
(2021/05/27)
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- Cyclic (Alkyl)(amino)carbene Ligands Enable Cu-Catalyzed Markovnikov Protoboration and Protosilylation of Terminal Alkynes: A Versatile Portal to Functionalized Alkenes**
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Regioselective hydrofunctionalization of alkynes represents a straightforward route to access alkenyl boronate and silane building blocks. In previously reported catalytic systems, high selectivity is achieved with a limited scope of substrates and/or rea
- Bertrand, Guy,Engle, Keary M.,Gao, Yang,Grotjahn, Douglas B.,Jazzar, Rodolphe,Junor, Glen P.,Kang, Taeho,Kendrick, Aaron,Yazdani, Sima
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supporting information
p. 19871 - 19878
(2021/08/13)
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- Synthesis of Acrylonitriles via Mild Base Promoted Tandem Nucleophilic Substitution-Isomerization of α-Cyanohydrin Methanesulfonates
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Main observation and conclusion: We have developed an efficient synthesis of acrylonitriles via mild base promoted tandem nucleophilic substitution-isomerization of α-cyanohydrin methanesulfonates with alkenylboronic acids. This transition metal-free protocol works under simple and mild conditions and offers good chemical yields for a wide range of substrates and demonstrates good functional group tolerance. (Figure presented.).
- Liu, Shiwen,Meng, Lingling,Zeng, Xiaojun,Hammond, Gerald B.,Xu, Bo
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supporting information
p. 913 - 917
(2021/04/05)
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- Synthesis and Reactivity of Fluorinated Triaryl Aluminum Complexes
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The addition of the Grignard 3,4,5-ArFMgBr to aluminum(III) chloride in ether generates the novel triarylalane Al(3,4,5-ArF)3·OEt2. Attempts to synthesize this alane via transmetalation from the parent borane with trimethylaluminum gave a dimeric structure with bridging methyl groups, a product of partial transmetalation. On the other hand, the novel alane Al(2,3,4-ArF)3 was synthesized from the parent borane and trimethylaluminum. Interestingly, the solid-state structure of Al(2,3,4-ArF)3 shows an extended chain structure resulting from neighboring Al···F contacts. Al(3,4,5-ArF)3·OEt2 was then found to be an effective catalyst for the hydroboration of carbonyls, imines, and alkynes with pinacolborane.
- Ould, Darren M. C.,Carden, Jamie L.,Page, Rowan,Melen, Rebecca L.
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supporting information
p. 14891 - 14898
(2020/10/02)
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- Chemoselective Cross-Coupling of gem-Borazirconocene Alkanes with Aryl Halides
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The direct and chemoselective conversion of the carbon-metal bond of gem-dimetallic reagents enables rapid and sequential formation of multiple carbon-carbon and carbon-heteroatom bonds, thus representing a powerful method for efficiently increasing structural complexity. Herein, we report a visible-light-induced, nickel-catalyzed, chemoselective cross-coupling reaction between gem-borazirconocene alkanes and diverse aryl halides, affording a wide range of alkyl Bpin derivatives in high yields with excellent regioselectivity. This practical method features attractively simple reaction conditions and a broad substrate scope. Additionally, we systematically investigated a Bpin-directed chain walking process underlying the regioselectivity of alkylzirconocenes, thus uncovering the mechanism of the remote functionalization of internal olefins achieved with our method. Finally, DFT calculations indicate that the high regioselectivity of this reaction originates from the directing effect of the Bpin group.
- Bai, Songlin,Gao, Yadong,Jiang, Chao,Qi, Xiangbing,Yang, Chao
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supporting information
p. 11506 - 11513
(2020/07/14)
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- Nickel(II)-Catalyzed Borylation of Alkenyl Methyl Ethers via C-O Bond Cleavage
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A new protocol has been developed for the borylation of conjugated alkenyl methyl ethers using B2Pin2 via C-O bond cleavage catalyzed by Ni(II). In this cross-coupling reaction, both E/Z isomers of alkenyl ethers are converted into (E)-alkenyl boronic esters with good reactivity. This transformation exhibits high chemoselectivity in the presence of competitive C-O bonds such as aryl ether, ester, amide, and thioether groups, thus providing a new method for the construction of various alkenyl boronates.
- Qiu, Xiaodong,Li, Yangyang,Zhou, Li,Chen, Peishan,Li, Fan,Zhang, Yanan,Ling, Yong
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supporting information
p. 6424 - 6428
(2020/08/24)
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- Z-Selective Alkyne Functionalization Catalyzed by a trans-Dihydride N-Heterocyclic Carbene (NHC) Iron Complex
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The Z-selective functionalization of terminal alkynes is a useful transformation in organic chemistry and mainly catalyzed by noble metals. Here, we present the Z-selective hydroboration of terminal alkynes catalyzed by a stable trans-dihydride iron compl
- De Ruiter, Graham,Fridman, Natalia,Garhwal, Subhash
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supporting information
p. 13817 - 13821
(2020/10/09)
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- Reaction Pathways and Redox States in α-Selective Cobalt-Catalyzed Hydroborations of Alkynes
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Cobalt(II) alkyl complexes supported by a monoanionic NNN pincer ligand are pre-catalysts for the regioselective hydroboration of terminal alkynes, yielding the Markovnikov products with α:β-(E) ratios of up to 97:3. A cobalt(II) hydride and a cobalt(II) vinyl complex appear to determine the main reaction pathway. In a background reaction the highly reactive hydrido species specifically converts to a coordinatively unsaturated cobalt(I) complex which was found to re-enter the main catalytic cycle.
- Blasius, Clemens K.,Gade, Lutz H.,Matveeva, Regina,Vasilenko, Vladislav,Wadepohl, Hubert
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supporting information
p. 23010 - 23014
(2020/10/20)
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- Catalyst-free and solvent-free hydroboration of alkynes
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The hydroboration of alkynes with pinacolborane (HBpin) under catalyst- and solvent-free conditions was demonstrated. Various alkynes were smoothly converted into alkenyl boronate esters in good to excellent yields at 110 °C. The gram-scale hydroboration
- Jaladi, Ashok Kumar,Choi, Hyeon Seong,An, Duk Keun
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p. 13626 - 13632
(2020/09/07)
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- Aluminum-Catalyzed Selective Hydroboration of Nitriles and Alkynes: A Multifunctional Catalyst
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The reaction of LH [L = {(ArNH)(ArN)-C=N-C=(NAr)(NHAr)}; Ar =2,6-Et2-C6H3] with a commercially available alane amine adduct (H3Al·NMe2Et) in toluene resulted in the formation of a conjugated bis-guanidinate (CBG)-supported aluminum dihydride complex, i.e., LAlH2 (1), in good yield. The new complex has been thoroughly characterized by multinuclear magnetic resonance, IR, mass, and elemental analyses, including single-crystal structural studies. Further, we have demonstrated the aluminum-catalyzed hydroboration of a variety of nitriles and alkynes. Moreover, aluminum-catalyzed hydroboration is expanded to more challenging substrates such as alkene, pyridine, imine, carbodiimide, and isocyanides. More importantly, we have shown that the aluminum dihydride catalyzed both intra- A nd intermolecular chemoselective hydroboration of nitriles and alkynes over other reducible functionalities for the first time.
- Sarkar, Nabin,Bera, Subhadeep,Nembenna, Sharanappa
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p. 4999 - 5009
(2020/05/01)
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- Practical Solvent-Free Microwave-Assisted Hydroboration of Alkynes
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A simple and rapid protocol for the anti-Markovnikov hydroboration of alkynes assisted by microwave irradiation has been developed. Pinacolborane smoothly reacts with terminal alkynes to obtain (E)-alkenyl boronates in good yields and short reactions times in the absence of solvent. Further transformations on the carbon-boron bond of the adducts can be sequentially achieved without the need of purifying the alkenyl boronates.
- Altarejos, Julia,Sucunza, David,Vaquero, Juan J.,Carreras, Javier
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p. 3024 - 3029
(2020/05/18)
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- Erratum: Markovnikov-selective hydroboration of olefins catalyzed by a copper N-heterocyclic carbene complex (Organometallics (2019) 38:17 (3322-3326) DOI: 10.1021/acs.organomet.9b00394)
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It has come to our attention that some of the products listed in Table 2 of the article and in eq 1 have the incorrect stereochemistry. The reactions of alkynes with HBpin give the linear E-olefin products, not the branched products as were shown. 1H NMR spectra clearly show two doublets with a large J (18 Hz) for the trans-hydrogens of the alkene product. A DEPT-135 spectrum also confirms that CH and not CH2 is present. Corrected eq 1, Table 2, TOC graphic are shown. Note that the alkene addition products are correctly assigned as branched, displaying a doublet and a quartet for the methyl and methane groups, respectively. NMR spectra for all products are included in the revised Supporting Information. We thank Prof. Jaesook Yun for pointing out this error, as her group has worked on related copper borylations for many years.
- DiBenedetto, Tarah A.,Parsons, Astrid M.,Jones, William D.
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supporting information
p. 3768 - 3769
(2020/11/17)
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- Tuning Polarity of Cu-O Bond in Heterogeneous Cu Catalyst to Promote Additive-free Hydroboration of Alkynes
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Precise control of structural parameters to optimize the performance of heterogeneous catalysts remains a challenging issue. A direct route is to adjust the nature of chemical bonds around active centers, but this has not yet been achieved because of the
- Zhang, Jian,Wang, Ziyun,Chen, Wenxing,Xiong, Yu,Cheong, Weng-Chon,Zheng, Lirong,Yan, Wensheng,Gu, Lin,Chen, Chen,Peng, Qing,Hu,Wang, Dingsheng,Li, Yadong
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supporting information
p. 725 - 737
(2020/03/11)
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- Aliphatic α-Boryl-α-bromoketones: Synthesis and Reactivity
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A protocol for the preparation of α-boryl-α-bromoketones from alkenyl MIDA boronates was developed and applied to functionalized aliphatic derivatives. The reaction sequence included regioselective hydroxybromination of olefin moiety, followed by oxidation of alcohol group with Dess–Martin periodinane. The target trifunctional boronate-containing derivatives were obtained in up to 94 % yield over two steps starting from alkenyl MIDA boronates. In some cases, functional groups present in the substrate participated in the bromohydroxylation step via intramolecular nucleophilic attack at the bromonium cation leading to cyclic products. Additionally, the reactivity of aliphatic α-boryl-α-bromoketones was illustrated by nucleophilic substitution at the α-C atom and heterocyclization reactions.
- Ivon, Yevhen M.,Kuchkovska, Yuliya O.,Voitenko, Zoya V.,Grygorenko, Oleksandr O.
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p. 3367 - 3377
(2020/03/13)
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- Selective Dehydrogenative Mono- or Diborylation of Styrenes by Supported Copper Catalysts
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The selective dehydrogenative borylation of alkenes is an attractive method for synthesizing useful borylalkenes. However, very few catalytic systems have been reported that fulfill this objective. All the reported examples are homogeneous catalysts with
- Yoshii, Daichi,Jin, Xiongjie,Mizuno, Noritaka,Yamaguchi, Kazuya
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p. 3011 - 3016
(2019/04/13)
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- Synthesis method of alkenyl boron ester through catalysis of copper
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The invention discloses a synthesis method of alkenyl boron ester. The method comprises the following steps: enabling a substrate to carry out olefin dehydroboration esterification reaction with pinacol diborate in a reaction system comprising the substra
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Paragraph 0060; 0061; 0062
(2019/02/04)
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- The Boron-Wittig Olefination of Aldehydes and Ketones with Bis[(pinacolato)boryl]methane: an Extended Reaction Scope
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Preparation of 2,2-disubstituted and 2-monosubstituted alkenylboronic acid esters from aliphatic and aromatic ketones and aldehydes by the boron-Wittig olefination with bis[(pinacolato)boryl]methane was examined and applied on the multigram scale. The influence of the substrate steric and electronic features on the overall efficiency and stereochemical outcome of the reaction was studied. Additionally, a series of diversely functionalized (hetera)cycloalkylidenemethyl and (hetera)cycloalkyl boronic acid-derived building blocks was synthesized.
- Kovalenko, Maksym,Yarmoliuk, Dmytro V.,Serhiichuk, Dmytro,Chernenko, Daria,Smyrnov, Vladyslav,Breslavskyi, Artur,Hryshchuk, Oleksandr V.,Kleban, Ihor,Rassukana, Yuliya,Tymtsunik, Andriy V.,Tolmachev, Andrey A.,Kuchkovska, Yuliya O.,Grygorenko, Oleksandr O.
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p. 5624 - 5635
(2019/07/31)
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- Stereoselective Synthesis of Vinylboronates by Rh-Catalyzed Borylation of Stereoisomeric Mixtures
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The stereoselective preparation of vinylboronates via rhodium-catalyzed borylation of E/Z mixtures of vinyl actetates is described, and this method was also extended to synthesis of vinyldiboronates. These transformations feature high functional group compatibility and mild reaction conditions. Control experiments support a mechanism that involved a Rh-catalyzed borylation-isomerization sequence. The isomerization of (Z)-vinylboronates to (E)-isomers was also demonstrated.
- Li, Shenhuan,Li, Jie,Xia, Tianlai,Zhao, Wanxiang
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supporting information
p. 462 - 468
(2019/03/28)
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- PEG-mediated recyclable borylative coupling of vinyl boronates with olefins
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This paper reports on the first green and sustainable repetitive batch borylative coupling of vinyl boronates with olefins by the effective immobilization of the [Ru(CO)Cl(H)(PCy3)2] catalyst in poly(ethylene glycols) with different molecular weights (Mw = 600–2000) and ending groups (OH, OMe, OSiMe3) or in biphasic poly(ethylene glycols)/supercritical CO2 (PEGs/scCO2) systems. Within this process, (E)-alkenyl boronates were obtained with high yields and excellent stereo-, regioselectivities. The best strategies permitted to carry out cross-coupling of vinyl boronates with styrene for up to 8–16 repetitive batches respectively, by applying 2 or 4 mol% of Ru-catalyst. The described methods enable the reuse of the TM-catalyst and solvents and the reduction or elimination of the use of volatile organic solvents and metal content in the final products, and obtain high cumulative TON values (up to 440). The biphasic systems also allowed the simplification of the separation procedure by effective product extraction in CO2 stream.
- Szyling,Walkowiak, J?drzej,Sokolnicki, Tomasz,Franczyk, Adrian,Stefanowska,Klarek, Mateusz
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p. 219 - 227
(2019/07/31)
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- Silver-Catalyzed anti-Markovnikov Hydroboration of C-C Multiple Bonds
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A simple silver salt (AgOAc)-catalyzed anti-Markovnikov-selective hydroboration of alkenes, 1,3-dienes, and alkynes with pinacolborane (HBpin) has been described. This strategy provides an efficient and practical method to access various alkyl-, allyl-, a
- Wang, Yan,Guan, Rui,Sivaguru, Paramasivam,Cong, Xuefeng,Bi, Xihe
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supporting information
p. 4035 - 4038
(2019/06/14)
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- Unlocking the catalytic potential of tris(3,4,5-trifluorophenyl)borane with microwave irradiation
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The catalytic activity of tris(3,4,5-trifluorophenyl)borane has been explored in the 1,2-hydroboration reactions of unsaturated substrates. Under conventional conditions, the borane was found to be active only in the hydroboration of aldehyde, ketone and imine substrates, with alkenes and alkynes not being reduced effectively. The use of microwave irradiation on the other hand has permitted alkenes and alkynes to be hydroborated in good yields.
- Carden, Jamie L.,Gierlichs, Lukas J.,Wass, Duncan F.,Browne, Duncan L.,Melen, Rebecca L.
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supporting information
p. 318 - 321
(2019/01/09)
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- NHC-copper-thiophene-2-carboxylate complex for the hydroboration of terminal alkynes
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An air-stable N-heterocyclic carbene-copper thiophene-2-carboxylate (CuTC) complex has been prepared for the stereoselective hydroboration of terminal alkynes using pinacolborane (HBpin) or 1,8-naphthalenediaminatoborane (HBdan). The newly synthesized complex can be directly activated by hydroboranes without a cocatalyst such as a base, and exhibits high reactivity for the hydroboration of alkynes under mild conditions. A gram-scale hydroboration of terminal phenylacetylene demonstrated the applicability of the copper complex for the preparation of alkenyl boronates.
- Jang, Won Jun,Kang, Byung-Nam,Lee, Ji Hun,Choi, Yoon Mi,Kim, Chong-Hyeak,Yun, Jaesook
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supporting information
p. 5249 - 5252
(2019/06/07)
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- AgSbF6-Catalyzed: Anti -Markovnikov hydroboration of terminal alkynes
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AgSbF6-Catalyzed anti-Markovnikov addition of pinacolborane (HBpin) to terminal alkynes to produce the E-vinylboronates is reported. This efficient methodology is scalable, compatible with sterically and electronically diverse alkynes, and works at room temperature under solvent-free condition. The utility of this method is demonstrated in the facile synthesis of the clinically important (E)-2,4,3′,5′-tetramethoxystilbene.
- Mamidala, Ramesh,Pandey, Vipin K.,Rit, Arnab
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supporting information
p. 989 - 992
(2019/01/23)
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- Lithium diisobutyl-: Tert-butoxyaluminum hydride (LDBBA) catalyzed hydroboration of alkynes and imines with pinacolborane
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Lithium diisobutyl-tert-butoxyaluminum hydride (LDBBA)-catalyzed hydroboration of alkynes with pinacolborane (HBpin) was demonstrated. The hydroboration proceeded more efficiently with LDBBA than with other aluminum hydrides and afforded alkenyl boronates in moderate to good yields. In addition, high-yielding LDBBA-catalyzed hydroboration of imines was achieved. The coordination of anionic aluminate with lithium enables effective hydride transfer for hydroboration.
- Jaladi, Ashok Kumar,Kim, Hanbi,Lee, Ji Hye,Shin, Won Kyu,Hwang, Hyonseok,An, Duk Keun
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p. 16524 - 16529
(2019/11/11)
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- Magnesium-Catalyzed Hydroboration of Terminal and Internal Alkynes
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A magnesium-catalyzed hydroboration of alkynes providing good yields and selectivities for a wide range of terminal and symmetrical and unsymmetrical internal alkynes has been developed. The compatibility with many functional groups makes this magnesium c
- Magre, Marc,Maity, Bholanath,Falconnet, Alban,Cavallo, Luigi,Rueping, Magnus
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supporting information
p. 7025 - 7029
(2019/04/26)
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- Zinc-Catalysed Hydroboration of Terminal and Internal Alkynes
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A regioselective hydroboration of alkynes has been developed by using commercially available zinc triflate as a catalyst, in the presence of catalytic amount of NaBHEt3. The reaction tolerates a wide range of terminal alkynes having several synthetically useful functional groups and proceeds regioselectively to furnish hydroborated products in moderate to excellent yields. This system shows moderate chemoselectivity towards terminal C≡C bond over terminal and internal C=C bond and internal C≡C bond.
- Mandal, Souvik,Mandal, Sayantan,Geetharani
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supporting information
p. 4553 - 4556
(2019/08/20)
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- Kinetics and Mechanism of the Arase-Hoshi R2BH-Catalyzed Alkyne Hydroboration: Alkenylboronate Generation via B-H/C-B Metathesis
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The mechanism of R2BH-catalyzed hydroboration of alkynes by 1,3,2-dioxaborolanes has been investigated by in situ 19F NMR spectroscopy, kinetic simulation, isotope entrainment, single-turnover labeling (10B/2H), and density functional theory (DFT) calculations. For the Cy2BH-catalyzed hydroboration 4-fluorophenylacetylene by pinacolborane, the resting state is the anti-Markovnikov addition product ArCH = CHBCy2. Irreversible and turnover-rate limiting reaction with pinacolborane (k ≈ 7 × 10-3 M-1 s-1) regenerates Cy2BH and releases E-Ar-CH═CHBpin. Two irreversible events proceed in concert with turnover. The first is a Markovnikov hydroboration leading to regioisomeric Ar-C(Bpin)═CH2. This is unreactive to pinacolborane at ambient temperature, resulting in catalyst inhibition every ~102 turnovers. The second is hydroboration of the alkenylboronate to give ArCH2CH(BCy2)Bpin, again leading to catalyst inhibition. 9-BBN behaves analogously to Cy2BH, but with higher anti-Markovnikov selectivity, a lower barrier to secondary hydroboration, and overall lower efficiency. The key process for turnover is B-H/C-B metathesis, proceeding by stereospecific transfer of the E-alkenyl group within a transient, μ-B-H-B bridged, 2-electron-3-center bonded B-C-B intermediate.
- Nieto-Sepulveda, Eduardo,Bage, Andrew D.,Evans, Louise A.,Hunt, Thomas A.,Leach, Andrew G.,Thomas, Stephen P.,Lloyd-Jones, Guy C.
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supporting information
p. 18600 - 18611
(2019/11/19)
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- Aluminum Hydroxide Secondary Building Units in a Metal-Organic Framework Support Earth-Abundant Metal Catalysts for Broad-Scope Organic Transformations
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The intrinsic heterogeneity of alumina (Al2O3) surface presents a challenge for the development of alumina-supported single-site heterogeneous catalysts and hinders the characterization of catalytic species at the molecular level as well as the elucidation of mechanistic details of the catalytic reactions. Here we report the use of aluminum hydroxide secondary building units (SBUs) in the MIL-53(Al) metal-organic framework (MOF) with the formula Al(μ2-OH)(BDC) (BDC = 1,4-benzenedicarboxylate) as a uniform and structurally defined functional mimic of Al2O3 surface for supporting Earth-abundant metal (EAM) catalysts. The μ2-OH groups in MIL-53(Al) SBUs were readily deprotonated and metalated with CoCl2 and FeCl2 to afford MIL-53(Al)-CoCl and MIL-53(Al)-FeCl precatalysts which were characterized by powder X-ray diffraction, nitrogen sorption, elemental analysis, density functional theory, and extended X-ray fine structure spectroscopy. Activation with NaBEt3H converted MIL-53(Al)-CoCl to MIL-53(Al)-CoH which effectively catalyzed hydroboration of alkynes and nitriles and hydrosilylation of esters. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of AlIII and CoII centers in MIL-53(Al)-CoH while deuterium labeling studies suggested σ-bond metathesis as a key step for the MIL-53(Al)-CoH-catalyzed addition reactions. MIL-53(Al)-FeCl competently catalyzed oxidative Csp3-H amination and Wacker-type alkene oxidation. XANES analysis revealed the oxidation of FeII to FeIII centers in the activated MIL-53(Al)-FeCl catalyst and suggested that oxidative Csp3-H amination occurs via the formation of FeIII-OtBu species by single electron transfer between FeII centers in MIL-53(Al)-FeCl and (tBuO)2 with concomitant generation of 1 equiv of tBuO· radical, C-H activation through hydrogen atom abstraction to generate alkyl radicals, protonation of FeIII-OtBu by aniline to generate MIL-53(Al)-FeIII-anilide, and finally C-N coupling between the FeIII-anilide and alkyl radical to form the Csp3-H amination product and regenerate the FeII catalyst. These highly active single-site MOF-based solid catalysts were readily recovered and reused up to five times without significant decrease in catalytic activity. This work thus demonstrates the great potential of using the aluminum hydroxide SBUs in MOFs to support EAM catalysts for important organic transformations.
- Feng, Xuanyu,Ji, Pengfei,Li, Zhe,Drake, Tasha,Oliveres, Pau,Chen, Emily Y.,Song, Yang,Wang, Cheng,Lin, Wenbin
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p. 3327 - 3337
(2019/03/26)
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- Aluminium complex-catalysed hydroboration of alkenes and alkynes
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We demonstrate an efficient method for the hydroboration of terminal alkenes or alkynes with pinacolborane (HBpin) using the aluminium catalyst, [κ2-{Ph2P(=Se)NCH2(C5H4N)}Al(CH3)2/sub
- Harinath, Adimulam,Banerjee, Indrani,Bhattacharjee, Jayeeta,Panda, Tarun K.
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supporting information
p. 10531 - 10536
(2019/07/09)
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- Lithium compounds as single site catalysts for hydroboration of alkenes and alkynes
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The hydroboration of alkenes and alkynes using easily accessible lithium compounds [2,6-di-tert-butyl phenolatelithium (1a) and 1,1′ dilithioferrocene (1b)] has been achieved with good yields, high functional group tolerance and excellent chemoselectivity
- Bisai, Milan Kumar,Yadav, Sandeep,Das, Tamal,Vanka, Kumar,Sen, Sakya S.
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supporting information
p. 11711 - 11714
(2019/10/02)
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- Pyridine-amide-oxazoline ligand, synthesizing method, metal complex and application thereof
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The invention discloses a pyridine-amide-oxazoline ligand. The ligand is a compound as shown in a formula (I) or antimer or despinner of the compound as shown in the formula (I), wherein R1 and R2 arerespectively one of hydrocarbyl, benzyl, phenyl or subs
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Paragraph 0139-0144
(2019/04/27)
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- Transition-Metal-Free Deaminative Vinylation of Alkylamines
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The amino group is one of the most fundamental structural motifs in natural products and synthetic chemicals. However, amines potential as effective alkylating agents in organic synthesis is still problematic. A unified strategy has been established for deaminative vinylation of the alkylamines with vinyl boronic acids by C?N bond activation under catalyst-free conditions. The key to the high reactivity is the utilization of pyridinium salt-activated alkylamines, with a base as a promoter. The transformation exhibits good functional group compatibility, and includes inexpensive primary amine feedstocks and amino acids. The proposed method can serve as a powerful synthetic method for late-stage modification of complex compounds. Mechanistic experiments suggest that free radical processes are involved in this system. (Figure presented.).
- Hu, Jiefeng,Cheng, Bo,Yang, Xianyu,Loh, Teck-Peng
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supporting information
p. 4902 - 4908
(2019/09/13)
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- Direct Synthesis of Alkenylboronates from Alkenes and Pinacol Diboron via Copper Catalysis
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We report an efficient approach for the direct synthesis of alkenylboronates using copper catalysis. The Cu/TEMPO catalyst system (where TEMPO = (2,2,6,6-tetramethylpiperidin-1-yl)oxyl) exhibits both excellent reactivity and selectivity for the synthesis of alkenylboronates, starting from inexpensive and abundant alkenes and pinacol diboron. This approach allows for the direct functionalization of both aromatic and aliphatic terminal alkenes. Mechanistic experiments suggest that the alkenylboronates arise from oxyboration intermediates.
- Lu, Wenkui,Shen, Zengming
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supporting information
p. 142 - 146
(2019/01/11)
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