- La[N(SiMe3)2]3-Catalyzed Hydroboration of Esters and Other Challenging Unsaturated Groups
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The commercially available homoleptic lanthanum amide La[N(SiMe3)2]3 (LaNTMS) is reported to enable the hydroboration of esters using pinacolborane (HBpin) as the reducing agent. A wide range of substrates inclu
- Kang, Zihan,Xu, Xiaojuan,Xue, Mingqiang,Yan, Dandan
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- Magnesium-catalyzed hydroboration of esters: Evidence for a new zwitterionic mechanism
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A magnesium-catalyzed ester hydroboration reaction rapidly and efficiently (a pathway involving a zwitterionic alkoxyborate is proposed. The Royal Society of Chemistry 2014.
- Mukherjee, Debabrata,Ellern, Arkady,Sadow, Aaron D.
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- Palladium on carbon as an efficient, durable and economical catalyst for the alcoholysis of B2pin2
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Hydrogen has attracted much attention as one of the most promising chemical fuel candidates because of its zero emission during consumption. In order to solve the freezing problem of water based hydrolysis process, herein, the Pd/C as an efficient and stable catalyst for the methanolysis, ethanolysis, propanolysis and butanolysis of B2pin2 for the generation of hydrogen has been first developed. The large kinetic isotope effect (KIE) of kH/kD = 5.0, D2 formation from CD3OD and in situ tandem reaction have confirmed that alcohol is the only hydrogen source. Interestingly, the order of Ea of these alcohols in H2 evolution is MeOH (methanol, 29.57 kJ/mol) nBuOH (n-butanol, 41.98 kJ/mol), which is consistent with the known order of acidities of these alcohols (MeOH > EtOH > PrOH > nBuOH).
- Li, Ning,Liu, Xiang,Meng, Xu,Shen, Jialu,Zhou, Junjie
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- Green hydroboration of carboxylic acids and mechanism investigation
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A catalyst-free and solvent-free method for the hydroboration of a variety of carboxylic acids with pinacolborane was developed. The hydroboration of various aromatic and aliphatic carboxylic acids as well as dicarboxylic acids with HBpin could be completed within 6 h at room temperature or within 1 h at 60 °C to give the products in quantitative yields under neat conditions without the need for any solvent or metal catalyst. The possible reaction mechanism was investigated in detail based on the corresponding DFT calculations and the stoichiometric reaction of acetic acid with different equivalents of HBpin (at room temperature and 0 °C) and it revealed the stepwise nature of the protocol.
- Wang, Weifan,Luo, Man,Zhu, Da,Yao, Weiwei,Xu, Li,Ma, Mengtao
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- Super hydride catalyzed ester and isocyanate hydroboration
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Commercially available, eco-friendly lithium triethylborohydride (LiHBEt3, Super hydride) was shown to be an excellent catalyst for the solvent-free hydroboration of esters using pinacolborane at ambient reaction conditions. This was achieved w
- Behera, Bedabyas,Ding, Yi,Du, Zonggang,Kumar, Arun
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- Hydroboration of nitriles, esters, and amides catalyzed by simple neosilyllithium
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We present here an efficient method for the hydroboration of organic nitriles, carboxylic esters, and carboxamides with pinacolborane (HBpin) using an alkali metal catalyst, neosilyllithium (LiCH2SiMe3), in neat reaction conditions. The reactions were accomplished with efficient catalytic reactivity and demonstrated by neosilyllithium at room temperature, in solvent-free condition, to afford a high yield of the corresponding N-boryl amines, boryl ethers, and amine hydrochlorides. The protocol for the catalytic reaction presented in this paper is simple and efficient, with diverse substrate scope for nitriles, carboxylic esters, and carboxamides showing excellent functional group tolerance. DLPNO-CCSD(T) calculations were also performed, showing that the hydroboration of nitriles catalyzed by neosilyllithium occurs through the pre-coordination of the nitrile at Lewis acid lithium followed by hydride migration from the B–H entity.
- Bandyopadhyay, Ayan,Bhattacharjee, Jayeeta,Kumar Singh, Saurabh,Kumari, Kusum,Moorthy, Shruti,Panda, Tarun K.,Sai Kumar, Gobbilla
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supporting information
(2022/03/31)
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- N-Heterocyclic Carbene-Phosphinidenide Complexes as Hydroboration Catalysts
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The reactions of the N-heterocyclic carbene-phosphinidene adducts (NHC)PSiMe3 and (NHC)PH with the dinuclear ruthenium and osmium complexes [(η6-p-cymene)MCl2]2 (M = Ru, Os) afforded the half-sandwich complexes
- Bhattacharjee, Jayeeta,Bockfeld, Dirk,Tamm, Matthias
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supporting information
p. 1098 - 1109
(2022/01/27)
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- Catalytic Hydroboration of Esters by Versatile Thorium and Uranium Amide Complexes
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The challenging hydroboration of esters is achieved using simple uranium and thorium amides, U[N(SiMe3)2]3 and [(Me3Si)2N]2An[κ2-(N,C)-CH2Si(CH3)2N(SiMe3)] (An = Th or U) acting as precatalysts in the reaction with pinacolborane (HBpin). All three complexes showed impressive catalytic activities, reaching excellent yields. A large scope of esters was investigated including aliphatic, aromatic, and heterocyclic esters that were transformed cleanly to the corresponding hydroborated alcohols, which readily hydrolyzed to the free alcohols. Moreover, the actinide catalysts demonstrated unexpected high functional tolerance toward nitro, halide, cyano, and heteroaromatic functional groups. The reaction exhibited excellent selectivity toward the ester when additional double and triple unsaturated C-C bonds were present. Lactones and poly caprolactone have been successfully cleaved to the monomeric units, showing a great promise toward polymer degradation and recycling. Detailed kinetic studies are provided in order to determine the rate dependence on the concentration of catalyst, HBpin, and ester. A plausible mechanism is proposed based on stoichiometric reactions, DFT calculations, thermodynamic measurements, and deuterium-labeling studies.
- Makarov, Konstantin,Kaushansky, Alexander,Eisen, Moris S.
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p. 273 - 284
(2022/01/03)
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- Hydroborative reduction of amides to amines mediated by La(CH2C6H4NMe2-: O)3
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The deoxygenative reduction of amides to amines is a great challenge for resonance-stabilized carboxamide moieties, although this synthetic strategy is an attractive approach to access the corresponding amines. La(CH2C6H4NMe2-o)3, a simple and easily accessible lanthanide complex, was found to be highly efficient not only for secondary and tertiary amide reduction, but also for the most challenging primary reduction with pinacolborane. This protocol exhibited good tolerance for many functional groups and heteroatoms, and could be applied to gram-scale synthesis. The active species in this catalytic cycle was likely a lanthanide hydride.
- Gong, Mingliang,Guo, Chenjun,Luo, Yunjie,Xie, Hongzhen,Zhang, Fangcao
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p. 779 - 791
(2022/01/22)
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- Synthesis and characterization of rare-earth metallate amido complexes bearing the 2-amidate-functionalized indolyl ligand and their application in the hydroboration of esters with pinacolborane
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The reactions of 2-amidate-functionalized indolyl proligand 2-(2,6-iPr2C6H3NHCO)C8H5NH (H2L) with [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 were studied leading to the synthesis and characterization of a series of novel discrete trinuclear rare-earth metallate amido complexes containing the anion [{η1:(μ2-η1:η1):η1-LREN(SiMe3)2}3(μ3-Cl)]? and cation Li+(THF)4 (RE = Y(1a), Nd (1b), Sm (1c), Gd (1d), Dy (1e), Er (1f), and Yb (1g)) in good yields by silylamine elimination. All of the complexes were characterized by spectroscopic methods, elemental analyses and single-crystal X-ray diffraction, and complexes 1a and 1c were additionally characterized by NMR spectroscopy. As proof of principle of their activity, these complexes were used as precatalysts for the hydroboration of esters using HBpin as the hydride source displaying high activity under neat and room temperature conditions. As a result, the ligand, ionic and multinuclear cooperative effects on catalytic activity were observed.
- Bao, Qin,Gao, Jianjian,Hong, Dongjing,Mu, Xiaolong,Song, Lulu,Wang, Shaowu,Wei, Yun,Zhou, Shuangliu,Zhu, Xiancui
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p. 2953 - 2961
(2022/02/21)
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- Boric acid as a precatalyst for BH3-catalyzed hydroboration
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We report that boric acid, BO3H3, is a good precatalyst for the BH3-catalyzed hydroboration of esters using pinacolborane as a borylation agent. Using microwave irradiation as an energy source, we demonstrated that a dozen esters were converted into the c
- Fontaine, Frédéric-Georges,Légaré Lavergne, Julien,To, Hoang-Minh
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p. 31941 - 31949
(2021/12/01)
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- La(CH2C6H4NMe2-o)3-catalyzed reduction of esters to alcohols with pinacolborane
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Catalytic reduction of esters is a favourable synthetic strategy to obtain the corresponding alcohols. La(CH2C6H4NMe2-o)3, a simple and facilely accessible lanthanide complex, can serve as a highly efficient catalyst for the reduction of esters with pinacolborane (HBpin), selectively affording alcohols in good yields under mild conditions. This protocol exhibits good tolerance for many functional groups such as C-C double bond, nitro, halogen, furyl, and thienyl groups. A lanthanum hydride species like [La]-H·HBpin is supposed to play a crucial role in promoting the interaction of esters with HBpin.
- Zhang, Fangcao,Gong, Mingliang,Xie, Hongzhen,Luo, Yunjie
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supporting information
p. 17654 - 17659
(2021/10/04)
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- Readily available lithium compounds as catalysts for the hydroboration of carbodiimides and esters
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Selective and efficient hydroboration of esters and carbodiimides to alcohols and amines by two well-defined and readily accessible lithium complexes, 2,6-di-tert-butyl phenolate lithium (1a) and 1,1’-dilithioferrocene (1b) are described. A range of aliphatic, aromatic, and cyclic esters with various functional groups were selectively converted into the corresponding boronate esters. Similarly, the single hydroboration of carbodiimides with aliphatic and aromatic substituents on the nitrogen atoms was studied. A possible mechanistic pathway of the hydroboration of carbodiimides with HBpin has been proposed using NMR studies and DFT calculations. These reactions are convenient alternatives to stoichiometric hydride reduction or hydrogenation. The employing of lithium complexes is also significant, because of the need to find cheap and green alternatives to noble metal complexes.
- Bisai, Milan Kumar,Das, Tamal,Gour, Kritika,Sen, Sakya S.,Vanka, Kumar
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supporting information
(2021/06/26)
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- Progressing the Frustrated Lewis Pair Abilities of N-Heterocyclic Carbene/GaR3Combinations for Catalytic Hydroboration of Aldehydes and Ketones
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Exploiting the steric incompatibility of the tris(alkyl)gallium GaR3 (R = CH2SiMe3) and the bulky N-heterocyclic carbene (NHC) 1,3-bis(tert-butyl)imidazol-2-ylidene (ItBu), here we report the B-H bond activation of pinacolborane (HBPin), which has led to
- Bole, Leonie J.,Uzelac, Marina,Hernán-Gómez, Alberto,Kennedy, Alan R.,O'Hara, Charles T.,Hevia, Eva
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supporting information
p. 13784 - 13796
(2021/07/26)
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- Hydroboration of Nitriles, Esters, and Carbonates Catalyzed by Simple Earth-Abundant Metal Triflate Salts
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During the past decade earth-abundant metals have become increasingly important in homogeneous catalysis. One of the reactions in which earth-abundant metals have found important applications is the hydroboration of unsaturated C?C and C?X bonds (X=O or N). Within these set of transformations, the hydroboration of challenging substrates such as nitriles, carbonates and esters still remain difficult and often relies on elaborate ligand designs and highly reactive catalysts (e. g., metal alkyls/hydrides). Here we report an effective methodology for the hydroboration of challenging C≡N and C=O bonds that is simple and applicable to a wide set of substrates. The methodology is based on using a manganese(II) triflate salt that, in combination with commercially available potassium tert-butoxide and pinacolborane, catalyzes the hydroboration of nitriles, carbonates, and esters at room temperature and with near quantitative yields in less than three hours. Additional studies demonstrated that other earth-abundant metal triflate salts can facilitate this reaction as well, which is further discussed in this report.
- Thenarukandiyil, Ranjeesh,Satheesh, Vanaparthi,Shimon, Linda J. W.,de Ruiter, Graham
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p. 999 - 1006
(2021/03/30)
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- Manganese-Catalyzed Hydroborations with Broad Scope
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Reductive transformations of easily available oxidized matter are at the heart of synthetic manipulation and chemical valorization. The applications of catalytic hydrofunctionalization benefit from the use of liquid reducing agents and operationally facile setups. Metal-catalyzed hydroborations provide a highly prolific platform for reductive valorizations of stable C=X electrophiles. Here, we report an especially facile, broad-scope reduction of various functions including carbonyls, carboxylates, pyridines, carbodiimides, and carbonates under very mild conditions with the inexpensive pre-catalyst Mn(hmds)2. The reaction could be successfully applied to depolymerizations.
- Ghosh, Pradip,Jacobi von Wangelin, Axel
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supporting information
p. 16035 - 16043
(2021/06/16)
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- Mild catalytic deoxygenation of amides promoted by thorium metallocene
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The organoactinide-catalyzed (Cp*2ThMe2) hydroborated reduction of a wide range of tertiary, secondary, and primary amides to the corresponding amines/amine-borane adductsviadeoxygenation of the amides is reported herein. The catalytic reactions proceed under mild conditions with low catalyst loading and pinacolborane (HBpin) concentration in a selective fashion. Cp*2ThMe2is capable of efficiently catalysing the gram-scale reaction without a drop in efficiency. The amine-borane adducts are successfully converted into free amine products in high conversions, which increases the usefulness of this catalytic system. A plausible mechanism is proposed based on detailed kinetics, stoichiometric, and deuterium labeling studies.
- Eisen, Moris S.,Saha, Sayantani
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supporting information
p. 12835 - 12841
(2020/10/05)
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- Magnesium-catalyzed hydroboration of organic carbonates, carbon dioxide and esters
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A low-valent magnesium(i) complex [(XylNacnac)Mg]2 was employed as a highly efficient precatalyst for the hydroboration of a variety of cyclic and linear organic carbonates, polycarbonates, CO2 and esters with HBpin under mild conditions. The resultant boronates can be used for the preparation of the corresponding value-added diols, triols or alcohols through hydrolysis.
- Cao, Xu,Lu, Kai,Ma, Mengtao,Wang, Weifan,Xue, Fei,Yao, Weiwei
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supporting information
p. 2776 - 2780
(2020/03/13)
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- Application of deprotonated phenyl bridged beta-ketimine lithium compound in preparation of alcohol from ester
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The invention discloses application of a deprotonated phenyl bridged beta-ketimine lithium compound in the preparation of alcohol from ester. Ester and borane are used as raw materials, a hydroboration reaction is carried out; and after the hydroboration reaction is finished, silica gel and methanol are added, and a hydrolysis reaction is carried out to obtain alcohol. According to the applicationof the invention, the deprotonated phenyl bridged beta-ketimine lithium compound disclosed for the first time is used for catalyzing the hydroboration reaction of the ester and pinacol borane, so that a kind of efficient catalytic borohydride method is developed; the compound is simple in structure, easy to synthesize and capable of catalyzing the hydroboration reaction of the ester and borane with high activity. Compared with an existing catalytic system, the compound is easy to store, and particularly, exerts far smaller harm in use than an existing organic lithium reagent.
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Paragraph 0017
(2020/10/21)
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- Hydroboration method for organic carbonate
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The invention discloses a hydroboration method for organic carbonate, and belongs to the technical field of organic matter synthesis. The method comprises the following steps: adding a beta-diimine monovalent magnesium compound into a mixture of pinacolborane and organic carbonate; stirring and reacting at room temperature. According to the hydroboration method for the organic carbonate disclosedby the invention, the activity of the beta-diimine monovalent magnesium compound serving as a catalyst for catalyzing the organic carbonate and the pinacolborane is high; the substrate universality iswide; the reaction catalytic efficiency is high; the product yield is high; the hydroboration method for the organic carbonate has very high practicability.
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Paragraph 0076-0081
(2019/08/20)
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- Reduction of Cyclic and Linear Organic Carbonates Using a Readily Available Magnesium Catalyst
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Efficient reduction of cyclic and linear organic carbonates catalyzed by a readily available earth alkaline catalyst has been achieved. The described homogenous reaction based on a ligand-free magnesium catalyst provides an indirect route for the conversion of CO2 into valuable alcohols. The reaction proceeds with high yields under mild reaction conditions, with low catalyst loading and short reaction times, and shows a broad applicability toward various linear and cyclic carbonates. Additionally, it can be applied for the depolymerization of polycarbonates.
- Szewczyk, Marcin,Magre, Marc,Zubar, Viktoriia,Rueping, Magnus
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p. 11634 - 11639
(2019/12/02)
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- La[N(SiMe3)2]3-Catalyzed Ester Reductions with Pinacolborane: Scope and Mechanism of Ester Cleavage
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Tris[N,N-bis(trimethylsilyl)amido]lanthanum (LaNTMS) is an efficient, highly active, and selective homogeneous catalyst for ester reduction with pinacolborane (HBpin). Alkyl and aryl esters are cleaved to the corresponding alkoxy- and aryloxy-boronic esters which can then be straightforwardly hydrolyzed to alcohols. Ester reduction is achieved with 1 mol % catalyst loading at 25-60 °C, and most substrates are quantitatively reduced in 1 h. Nitro, halide, and amino functional groups are well tolerated, and ester reduction is completely chemoselective over potentially competing intra- or intermolecular alkene or alkyne hydroboration. Kinetic studies, isotopic labeling, and density functional theory calculations with energetic span analysis argue that ester reduction proceeds through a rate-determining hydride-transfer step that is ligand-centered (hydride is transferred directly from bound HBpin to bound ester) and not through a metal hydride-based intermediate that is often observed in organolanthanide catalysis. The active catalyst is proposed to be a La-hemiacetal, [(Me3Si)2N]2La-OCHR(OR)[HBpin], generated in situ from LaNTMS via hydroboronolysis of a single La-N(SiMe3)2 bond. These results add to the growing compendium of selective oxygenate transformations that LaNTMS is competent to catalyze, further underscoring the value and versatility of homoleptic lanthanide complexes in homogeneous catalytic organic synthesis.
- Barger, Christopher J.,Motta, Alessandro,Weidner, Victoria L.,Lohr, Tracy L.,Marks, Tobin J.
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p. 9015 - 9024
(2019/10/02)
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- POCN Ni(ii) pincer complexes: Synthesis, characterization and evaluation of catalytic hydrosilylation and hydroboration activities
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A series of iminophosphinite POCN pincer Ni(ii) complexes, (POCN)NiMe and (POCN)NiLn(BX4) (L = CH3CN, n = 0, 1; X = F, Ph, C6F5), have been developed and subjected to catalytic hydrosilylation of alkenes, aldehydes and ketones and hydroboration of carbonyl compounds. The stoichiometric reactivity of (POCN)NiMe and (POCN)Ni(BF4) with PhSiH3 and HBPin suggests that catalytic reactions proceed via the hydride intermediate (POCN)NiH. With regard to reactions with HBPin, efficient and mild hydroboration of a variety of carbonyl compounds, including highly chemoselective hydroboration of benzaldehyde in the presence of other common potent reductive functional groups, such as alkenes, alkynes, esters, amides, nitriles, nitro compounds and even ketones, and the first example of base metal catalyzed hydroboration of amides, including mild direct hydroborative reduction of primary and secondary amides to borylated amines were demonstrated for (POCN)NiMe.
- Gudun, Kristina A.,Segizbayev, Medet,Adamov, Assyl,Balanay, Mannix P.,Khalimon, Andrey Y.,Plessow, Philipp N.,Lyssenko, Konstantin A.
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supporting information
p. 1732 - 1746
(2019/03/07)
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- Interconverting Lanthanum Hydride and Borohydride Catalysts for C=O Reduction and C?O Bond Cleavage
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The high catalytic reactivity of homoleptic tris(alkyl) lanthanum La{C(SiHMe2)3}3 is highlighted by C?O bond cleavage in the hydroboration of esters and epoxides at room temperature. The catalytic hydroboration tolerates functionality typically susceptible to insertion, reduction, or cleavage reactions. Turnover numbers (TON) up to 10 000 are observed for aliphatic esters. Lanthanum hydrides, generated by reactions with pinacolborane, are competent for reduction of ketones but are inert toward esters. Instead, catalytic reduction of esters requires activation of the lanthanum hydride by pinacolborane.
- Patnaik, Smita,Sadow, Aaron D.
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supporting information
p. 2505 - 2509
(2019/02/01)
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- Method for preparing alcoholic compound from aliphatic carboxylic acid without catalytic reaction
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The invention discloses a method for preparing an alcoholic compound from an aliphatic carboxylic acid without the catalytic reaction. In an inert gas atmosphere, 4,4,5,5-tetramethyl-1,3,2-dioxa-borolane and the carboxylic acid are evenly stirred and mixed in a dehydration and deoxidization reaction flask, and react for 8-10 hours to obtain a boric acid ester; and the carboxylic acid is acetic acid, caproic acid, valeric acid, heptylic acid, trimethylacetic acid, adipic acid and the like. The aliphatic carboxylic acid efficiently is used to react with borane to implement hydroboration withouta catalyst for the first time, and a novel scheme is provided for the preparation of the boric acid ester through hydroboration of a carbonyl compound and the borane and the further hydrolysis of theboric acid ester into an alcohol.
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Paragraph 0016; 0020-0021
(2019/04/04)
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- Facile reduction of carboxylic acids to primary alcohols under catalyst-free and solvent-free conditions
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We report the development of a facile protocol for the deoxygenative hydroboration of aliphatic and aryl carboxylic acids to afford corresponding primary alcohols under solvent-free and catalyst-free conditions. The reaction proceeds under ambient temperature exhibits good tolerance towards various functional groups and generates quantitative yields. The plausible mechanism involves the formation of Lewis acid-base adducts as well as the liberation of hydrogen gas.
- Harinath, Adimulam,Bhattacharjee, Jayeeta,Panda, Tarun K.
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supporting information
p. 1386 - 1389
(2019/02/05)
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- Selective Hydroboration of Carboxylic Acids with a Homogeneous Manganese Catalyst
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Catalytic reduction of carboxylic acid to the corresponding alcohol is a challenging task of great importance for the production of a variety of value-added chemicals. Herein, a manganese-catalyzed chemoselective hydroboration of carboxylic acids has been developed with a high turnover number (>99?000) and turnover frequency (>2000 h-1) at 25 °C. This method displayed tolerance of electronically and sterically differentiated substrates with high chemoselectivity. Importantly, aliphatic long-chain fatty acids, including biomass-derived compounds, can efficiently be reduced. Mechanistic studies revealed that the reaction occurs through the formation of active manganese-hydride species via an insertion and bond metathesis type mechanism.
- Barman, Milan K.,Das, Kuhali,Maji, Biplab
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p. 1570 - 1579
(2019/01/30)
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- Method for preparing boric acid esters on basis of hydroboration of aliphatic carboxylic acids
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The invention relates to the application of N-butyllithium, in particular to a method for preparing boric acid esters on the basis of hydroboration of aliphatic carboxylic acids. The method comprisesthe following steps: uniformly stirring and mixing a catalyst, borane and carboxylic acids sequentially, reacting for 10-20 minutes, exposing in air to terminate the reaction and removing a solvent from reaction liquid under reduced pressure to obtain boric acid esters with different substituent groups. The N-butyllithium disclosed by the invention can catalyze the hydroboration of carboxylic acids and boranes at a room temperature with high activity; the consumption of the catalyst is only 0.2 mol percent of the molar amount of carboxylic acids; compared with an existing catalytic system, thecommercial reagent n-butyllithium is utilized, reaction conditions are mild, and the yield of the boric acid esters with the different substituent groups is up to 99 percent under limited conditions.
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Paragraph 0016; 0017; 002
(2019/03/06)
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- N-butyl lithium based fatty alcohol preparation method
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The invention relates to an n-butyl lithium based fatty alcohol preparation method. In an inert gas atmosphere, borane and aliphatic carboxylic acid are mixed, then n-butyl lithium taken as the catalyst is added to carry out hydroboration reactions; and after the hydroboration reactions, silica gel and methanol are added to carry out hydrolysis reactions to obtain the fatty alcohols. N-butyl lithium can efficiently catalyze the hydroboration reactions between carboxylic acids and borane at a room temperature, the used catalyst only accounts for 0.2 mol% of the carboxylic acids, compared with aconventional catalyst system, a commercial catalyst namely n-butyl lithium is adopted, the reaction conditions are mild, and the yield of fatty alcohols with different substitutes under restricted conditions is high.
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Paragraph 0018
(2019/05/08)
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- Room-temperature preparation method for boric acid ester
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The invention relates to a room-temperature preparation method for boric acid ester. The method comprises the steps of sequentially uniformly stirring and mixing a catalyst, borane and carboxylic acid, reacting for 50-60 minutes, exposing the reaction product in air to terminate the reaction, carrying out decompression on reaction liquid, and removing the solvent, so as obtain boric acid ester with different substituents. An aniline lithium compound disclosed by the invention is capable of catalyzing hydroboration reaction between carboxylic acid and borane at the room temperature in a high-activity manner, and the use amount of the catalyst is only 0.6mol% of the molar weight of carboxylic acid; and compared with an existing catalytic system, the method has the advantages that by utilizing commercial reagent, namely the aniline lithium compound, the reaction conditions are mild, and the yield of boric acid ester with different substituents under a limited condition can reach 99%.
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Paragraph 0017; 0026; 0027
(2019/04/06)
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- Ruthenium-Catalyzed Deoxygenative Hydroboration of Carboxylic Acids
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An efficient deoxygenative hydroboration of carboxylic acids to alkyl boronate esters under mild reaction condition is reported. Both aromatic and aliphatic carboxylic acids exhibited excellent reactivities with minimal catalyst load of 0.1 mol% and reactions occurred under neat conditions. This catalytic transformation selectively provides alkyl boronate esters, which can be conveniently hydrolyzed to obtain the corresponding alcohols. Remarkably, this reduction reaction proceeds with the liberation of molecular hydrogen.
- Kisan, Sesha,Krishnakumar, Varadhan,Gunanathan, Chidambaram
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p. 4772 - 4776
(2018/06/08)
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- B (β - diimines) rare earth [...] and in the application of the borane boron in hydrogenation reaction
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The invention discloses application of bis(beta-diketiminato) rare-earth amides to aldehyde and borane hydroboration catalyzing. The molecular formula is [2-Me-C6H4-NC(Me)CHC(Me)N-C6H4-2-Me]2Ln-N(SiMe3)2, wherein Ln refers to rare earth metal selected fro
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Paragraph 0056-0057
(2018/07/07)
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- Aluminum-Catalyzed Hydroboration of Alkenes
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The aluminum-catalyzed hydroboration of alkenes with HBpin is reported using simple commercially available aluminum hydride precatalysts [LiAlH4 or sodium bis(2-methoxyethoxy)aluminum hydride (Red-Al)]. Good substrate scope and functional group
- Bismuto, Alessandro,Cowley, Michael J.,Thomas, Stephen P.
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p. 2001 - 2005
(2018/03/13)
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- Tris(2,4,6-trifluorophenyl)borane: An Efficient Hydroboration Catalyst
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The metal-free catalyst tris(2,4,6-trifluorophenyl)borane has demonstrated its extensive applications in the 1,2-hydroboration of numerous unsaturated reagents, namely alkynes, aldehydes and imines, consisting of a wide array of electron-withdrawing and donating functionalities. A range of over 50 borylated products are reported, with many reactions proceeding with low catalyst loading under ambient conditions. These pinacol boronate esters, in the case of aldehydes and imines, can be readily hydrolyzed to leave the respective alcohol and amine, whereas alkynyl substrates result in vinyl boranes. This is of great synthetic use to the organic chemist.
- Lawson, James R.,Wilkins, Lewis C.,Melen, Rebecca L.
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supporting information
p. 10997 - 11000
(2017/08/22)
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- Method for preparing borate on basis of tricyclopentadienyl rare earth metal complex
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The invention discloses a method for preparing borate on the basis of a tricyclopentadienyl rare earth metal complex. The method comprises the following steps: uniformly stirring and mixing a catalyst, borane and aldehyde, and performing reaction to prepa
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Paragraph 0025
(2017/07/19)
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- Magnesium amide catalyzed selective hydroboration of esters
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Magnesium amide complexes such as Mg{N(SiMe3)2}2 (1) xylLMgN(SiMe3)2·THF (2) [xylL = ArNC(NiPr2)NAr; (Ar = 2,6-Me2-C6H3)] and dippLMgN(SiMe3)2·THF (3) [dippL = ArNC(NiPr2)NAr; (Ar = 2,6-iPr2-C6H3)] are reported as highly efficient pre-catalysts for the hydroboration of a wide range of esters using pinacolborane (HBpin) under mild reaction conditions. Moreover, we have shown compound 1 catalyzed chemoselective reduction of esters in the presence of other reducible functional groups such as alkene, alkyne and nitro.
- Barman, Milan Kr.,Baishya, Ashim,Nembenna, Sharanappa
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p. 4152 - 4156
(2017/04/03)
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- Zinc hydridotriphenylborates supported by a neutral macrocyclic polyamine
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The zinc hydridotriphenylborates [(L)Zn(TMDS)][HBPh3] and [(L)ZnX][HBPh3] (L = Me4TACD, Me4[12]aneN4; TMDS = N(SiHMe2)2; X = Cl, Br, I) were synthesized by BPh3-mediated β-SiH abstraction and salt metathesis with KHBPh3, respectively. CO2 is rapidly inserted into the B-H bonds. [(L)Zn(TMDS)][HBPh3] catalyzes the hydroboration of polar substrates including CO2.
- Mukherjee, Debabrata,Wiegand, Ann-Kristin,Spaniol, Thomas P.,Okuda, Jun
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supporting information
p. 6183 - 6186
(2017/07/11)
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- Magnesium hydridotriphenylborate [Mg(thf)6][HBPh3]2: A versatile hydroboration catalyst
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Magnesium bis(hydridotriphenylborate), isolated as a solvent-separated ion pair [Mg(thf)6][HBPh3]2, effectively catalyzed the hydroboration of several unsaturated substrates including CO2.
- Mukherjee, Debabrata,Shirase, Satoru,Spaniol, Thomas P.,Mashima, Kazushi,Okuda, Jun
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supporting information
p. 13155 - 13158
(2016/11/09)
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- Multiple regioselective functionalizations of quinolines via magnesiations
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A wide range of polyfunctionalized quinolines was prepared via chemo- and regioselective magnesiation reactions using appropriate Mg reagents, such as i-PrMgCl-LiCl, MesMgBr·LiCl, Mes2Mg·2LiBr, TMPMgCl·LiCl, and TMP2Mg·2LiCl. An application to the total synthesis of the biologically active compound talnetant was performed (six steps, 28%).
- Boudet, Nadege,Lachs, Jennifer R.,Knochel, Paul
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p. 5525 - 5528
(2008/09/17)
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- Novel isomerically pure tetrasubstituted allylboronates: Stereocontrolled synthesis of α-exomethylene γ-lactones as aldol-like adducts with a stereogenic quaternary carbon center
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In spite of their inherent isomerization tendency and low reactivity, 1-alkoxycarbonyl vinylcopper(I) intermediates from the conjugate addition of organocuprates onto acetylenic esters were trapped with very high cis-addition selectivity with iodomethylboronic esters in the presence of HMPA. The resulting isomerically pure 3,3-disubstituted allylboronates react with aldehydes in a highly diastereo- and enantioselective manner, providing α-exomethylene γ-lactones with a stereogenic quaternary β-carbon center. Copyright
- Kennedy, Jason W. J.,Hall, Dennis G.
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p. 898 - 899
(2007/10/03)
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- Mixed Esters of Boric Acid with Amino Alcohols and Diols
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B(OC2H5)3 reacts with diols to give 2-ethoxy-1,3-dioxa-2-boracycloalkanes (1-4) which, on azeotropic distillation in toluene with amino alcohols, give mixed boric acid esters of the type (5-8, a-g).The structures of these compounds are discussed on the basis of IR and Raman spectra and MS, 1H, and 11B NMR data, and with reference to an X-ray investigation published previously. .The presence of a boron -- nitrogen coordination is proposed in all cases. - Keywords: Mixed Boric Esters, 2-Aminoorganyloxy-1,3-dioxa-2-boracyclopentanes, 2- Aminoorganyloxy-5,5-dimethyl-1,3-dioxa-2-boracyclohexanes, Boron-Nitrogen Coordination
- Heller, Gert,Seeger, Karlheinz
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p. 547 - 556
(2007/10/02)
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