- Dramatic effect of Lewis acids on the rhodium-catalyzed hydroboration of olefins
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The addition of Lewis acids such as trispentafluoroboron as cocatalysts has been found to have a dramatic effect on the Rh-catalyzed hydroboration of olefins with pinacol borane. For example, aliphatic olefins do not react at all in noncoordinating solvents, but with the addition of 2% of B(C6F5)3, the reaction is complete in minutes. Similarly, the reaction of aromatic olefins with HBPin occurs slowly and nonselectively in the absence of B(C 6F5)3, but is accelerated and occurs more selectively in its presence. Preliminary mechanistic studies suggest that the B(C6F5)3 needs to be present throughout the course of the reaction, not just at the initiation stage, and implicate this species, along with THF, in the heterolytic cleavage of the B-H bond of HBPin.
- Lata, Christopher J.,Crudden, Cathleen M.
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Read Online
- Recyclable Copper Nanoparticles-Catalyzed Hydroboration of Alkenes and β-Borylation of α,β-Unsaturated Carbonyl Compounds with Bis(Pinacolato)Diboron
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Nano-ferrite-supported Cu nanoparticles (Fe-dopamine-Cu NPs) catalyzed anti-Markovnikov-selective hydroboration of alkenes with B2pin2 is reported under mild reaction conditions. This protocol can be applied to a broad range of substrates with high functional group compatibility. In addition, we demonstrated the use of Fe-dopamine-Cu NPs as a catalyst for the β-borylation of α,β-unsaturated ketones and ester, providing alkylboronate esters in up to 98% yield. Reuse of the magnetically recyclable catalyst resulted in no significant loss of activity in up to five reaction runs for both systems. (Figure presented.).
- Shegavi, Mahadev L.,Saini, Suresh,Bhawar, Ramesh,Vishwantha, Meghana Desai,Bose, Shubhankar Kumar
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supporting information
p. 2408 - 2416
(2021/03/16)
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- Site-Fixed Hydroboration of Terminal and Internal Alkenes using BX3/iPr2NEt**
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An unprecedented and general hydroboration of alkenes with BX3 (X=Br, Cl) as the boration reagent in the presence of iPr2NEt is reported. The addition of iPr2NEt not only suppresses alkene polymerizat
- Cui, Xin,Hu, Chenyang,Li, Sida,Liu, Liu Leo,Wu, Lipeng,Zhang, Jiong
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p. 26238 - 26245
(2021/11/09)
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- Iron-Catalyzed Regioselective Alkenylboration of Olefins
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The first examples of an iron-catalyzed three-component synthesis of homoallylic boronates from regioselective union of bis(pinacolato)diboron, an alkenyl halide (bromide, chloride or fluoride), and an olefin are disclosed. Products that bear tertiary or quaternary carbon centers could be generated in up to 87 % yield as single regioisomers with complete retention of the olefin stereochemistry. With cyclopropylidene-containing substrates, ring cleavage leading to trisubstituted E-alkenylboronates were selectively obtained. Mechanistic studies revealed reaction attributes that are distinct from previously reported alkene carboboration pathways.
- Yu, Xiaolong,Zheng, Hongling,Zhao, Haonan,Lee, Boon Chong,Koh, Ming Joo
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supporting information
p. 2104 - 2109
(2020/11/30)
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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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- Metal-free photoinduced C(sp 3)–H borylation of alkanes
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Boronic acids and their derivatives are some of the most useful reagents in the chemical sciences1, with applications spanning pharmaceuticals, agrochemicals and functional materials. Catalytic C–H borylation is a powerful method for introducing these and other boron groups into organic molecules because it can be used to directly functionalize C–H bonds of feedstock chemicals without the need for substrate pre-activation1–3. These reactions have traditionally relied on precious-metal catalysts for C–H bond cleavage and, as a result, display high selectivity for borylation of aromatic C(sp2)–H bonds over aliphatic C(sp3)–H bonds4. Here we report a mechanistically distinct, metal-free borylation using hydrogen atom transfer catalysis5, in which homolytic cleavage of C(sp3)–H bonds produces alkyl radicals that are borylated by direct reaction with a diboron reagent. The reaction proceeds by violet-light photoinduced electron transfer between an N-alkoxyphthalimide-based oxidant and a chloride hydrogen atom transfer catalyst. Unusually, stronger methyl C–H bonds are borylated preferentially over weaker secondary, tertiary and even benzylic C–H bonds. Mechanistic studies indicate that the high methyl selectivity is a result of the formation of a chlorine radical–boron ‘ate?? complex that selectively cleaves sterically unhindered C–H bonds. By using a photoinduced hydrogen atom transfer strategy, this metal-free C(sp3)–H borylation enables unreactive alkanes to be transformed into valuable organoboron reagents under mild conditions and with selectivities that contrast with?those of established metal-catalysed protocols.
- Shu, Chao,Noble, Adam,Aggarwal, Varinder K.
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p. 714 - 719
(2020/11/02)
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- σ-Bond Hydroboration of Cyclopropanes
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Hydroboration of alkenes is a classical reaction in organic synthesis in which alkenes react with boranes to give alkylboranes with subsequent oxidation resulting in alcohols. The double bond (π-bond) of alkenes can be readily reacted with boranes owing to its high reactivity. However, the single bond (σ-bond) of alkanes has never been reacted. To pursue the development of σ-bond cleavage, we selected cyclopropanes as model substrates since they present a relatively weak σ-bond. Herein, we describe an iridium-catalyzed hydroboration of cyclopropanes, resulting in β-methyl alkylboronates. These unusually branched boronates can be derivatized by oxidation or cross-coupling chemistry, accessing "designer"products that are desired by practitioners of natural product synthesis and medicinal chemistry. Furthermore, mechanistic investigations and theoretical studies revealed the enabling role of the catalyst.
- Arifin,Itami, Kenichiro,Kato, Hiroki,Kobayashi, Chisa,Kondo, Hiroki,Matsushita, Kaoru,Miyamura, Shin,Yamaguchi, Junichiro,Yokogawa, Daisuke
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supporting information
p. 11306 - 11313
(2020/07/13)
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- Metal-organic frameworks containing nitrogen-donor ligands for efficient catalytic organic transformations
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Metal-organic framework (MOFs) compositions based on nitrogen donor-based organic bridging ligands, including ligands based on 1,3-diketimine (NacNac), bipyridines and salicylaldimine, were synthesized and then post-synthetically metalated with metal precursors, such as complexes of first row transition metals. Metal complexes of the organic bridging ligands could also be directly incorporated into the MOFs. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
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Page/Page column 49-51
(2020/06/03)
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- Copper-Catalyzed Asymmetric Reduction of β,β-Disubstituted Alkenylboramides
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A highly enantioselective copper-catalyzed reduction of β,β-disubstituted alkenylboron compounds was developed using hydrosilane. The copper hydride catalyst coordinated with chiral Josiphos ligand efficiently discriminated β-geminal substituents to generate corresponding β-chiral alkylboramides with excellent enantioselectivities up to 99% ee. The enantioselective reduction protocol provides a facile approach to β-chiral alkylboron compounds with less sterically discriminating substituents and spans a wide substrate range including aryl-substituted borylalkenes with effective functional group tolerance.
- Park, Yeji,Yun, Jaesook
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supporting information
p. 8779 - 8782
(2019/11/03)
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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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- Earth-Abundant Metal Catalysis Enabled by Counterion Activation
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A precatalyst activation strategy has been developed for earth-abundant metal catalysis enabled by counterion dissociation and demonstrated through alkene hydroboration. Commercially available iron and cobalt tetrafluoroborate salts were found to catalyze
- Agahi, Riaz,Challinor, Amy J.,Carter, Neil B.,Thomas, Stephen P.
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supporting information
p. 993 - 997
(2019/02/14)
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- Alkene hydroboration with pinacolborane catalysed by lithium diisobutyl-: Tert-butoxyaluminum hydride
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Here we developed a highly efficient alkene hydroboration protocol, showing that various alkyl boronates can be smoothly obtained in good yields by reacting alkenes with pinacolborane (HBpin) in the presence of 5 mol% lithium diisobutyl-tert-butoxyaluminum hydride. The coordination of aluminate ions with lithium cations allowed for effective hydride transfer during hydroboration, and the obtained boronate ester was further used for C-C coupling, trifluoroboronate salt formation, and oxidation to alcohol.
- Jaladi, Ashok Kumar,Shin, Won Kyu,An, Duk Keun
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p. 26483 - 26486
(2019/09/12)
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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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- Coupling of Trifluoroacetaldehyde N-Triftosylhydrazone with Organoboronic Acids for the Synthesis of gem-Difluoroalkenes
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The synthesis of alkyl gem-difluoroalkenes remains a difficult task in organic synthesis. Here, we report a general and efficient approach for tackling this problem by gem-difluoroolefination of trifluoroacetaldehyde N-triftosylhydrazone with organoboronic acids. This protocol is operationally simple, free of transition metals, and suitable for a broad range of organoboronic acids. Moreover, the utility of the products was demonstrated by further conversion of the gem-difluorovinyl group.
- Ma, Yu,Reddy, Bhoomireddy Rajendra Prasad,Bi, Xihe
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supporting information
p. 9860 - 9863
(2019/12/24)
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- Ni-catalyzed hydroboration and hydrosilylation of olefins with diboron and silylborane
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Herein we report a Ni-catalyzed formal hydroboration of olefins, which afforded anti-Markovnikov-type alkylboranes with B2pin2 and a stoichiometric amount of water. Formal hydrosilylation using air- and moisture-sensitive silylborane
- Kamei, Toshiyuki,Nishino, Sohshi,Shimada, Toyoshi
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supporting information
p. 2896 - 2899
(2018/06/18)
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- Markovnikov-Selective Hydroboration of Vinylarenes Catalyzed by a Cobalt(II) Coordination Polymer
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Highly efficient and practical hydroboration of alkenes has been catalyzed by an inexpensive and air-stable cobalt(II) coordination polymer (CP) in the presence of KOtBu. Complete conversion of alkenes to alkylboronates were performed within just 5 min with low catalyst loading (0.025 mol%), achieving the record high turnover frequencies of up to 47 520 h-1. For a range of vinylarenes, unusual Markovnikov selectivity was observed.
- Zhang, Guoqi,Wu, Jing,Li, Sihan,Cass, Sean,Zheng, Shengping
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supporting information
p. 7893 - 7897
(2019/01/04)
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- Markovnikov-Selective Co(I)-Catalyzed Hydroboration of Vinylarenes and Carbonyl Compounds
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An NHC-supported Co(I) catalyst has been developed for selective Markovnikov hydroboration of vinylarenes under mild reaction conditions. The hydroboration allows highly selective synthesis of a wide range of secondary and tertiary alkyl boronates in exce
- Verma, Piyush Kumar,Sethulekshmi,Geetharani
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supporting information
p. 7840 - 7845
(2019/01/04)
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- Cobalt-Catalyzed Enantioselective Synthesis of Chiral gem-Bis(boryl)alkanes
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We report an asymmetric synthesis of enantioenriched gem-bis(boryl)alkanes in an enantioselective diborylation of 1,1-disubstituted alkenes catalyzed by Co(acac)2/(R)-DM-segphos. A range of activated and unactivated alkenes underwent this asymmetric diborylation in the presence of cyclooctene as a hydrogen acceptor, affording the corresponding gem-bis(boryl)alkanes with high enantioselectivity. The synthetic utility of these chiral organoboronate compounds was demonstrated through several stereospecific derivatizations and the synthesis of sesquiterpene and sesquiterpenoid natural products.
- Teo, Wei Jie,Ge, Shaozhong
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supporting information
p. 12935 - 12939
(2018/09/20)
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- Enantioselective Copper-Catalyzed Methylboration of Alkenes
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An enantioselective Cu-catalyzed borylative cross-coupling reaction of alkenes, bis(pinacolato)diboron (B2(pin)2), and methyl iodide is reported. Alkenes including styrenes, β-substituted styrenes, and challenging aliphatic olefins were smoothly transferred to the desired methylboration products with excellent diastereoselectivities (dr up to >99:1) and enantioselectivities (er up to 99:1). The utility of this process was demonstrated by the synthesis of naproxen and formal synthesis of two natural products.
- Chen, Bin,Cao, Peng,Liao, Yang,Wang, Min,Liao, Jian
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supporting information
p. 1346 - 1349
(2018/03/09)
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- Cobalt-Catalyzed Diborylation of 1,1-disubstituted Vinylarenes: A Practical Route to Branched gem-Bis(boryl)alkanes
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We report the first catalytic diborylation of 1,1-disubstituted vinylarenes with pinacolborane using a cobalt catalyst generated from bench-stable Co(acac)2 and xantphos. A wide range of 1,1-disubstituted vinylarenes underwent this transformati
- Teo, Wei Jie,Ge, Shaozhong
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supporting information
p. 1654 - 1658
(2018/01/15)
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- Cobalt-Catalyzed Hydroboration of Alkenes, Aldehydes, and Ketones
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An operationally convenient and general method for hydroboration of alkenes, aldehydes, and ketones employing Co(acac)3 as a precatalyst is reported. The hydroboration of alkenes in the presence of HBpin, PPh3, and NaOtBu affords good to excellent yields with high Markovnikov selectivity with up to 97:3 branched/linear selectivity. Moreover, Co(acac)3 could be used effectively to hydroborate aldehydes and ketones in the absence of additives under mild reaction conditions. Inter- and intramolecular chemoselective reduction of the aldehyde group took place over the ketone functional group.
- Tamang, Sem Raj,Bedi, Deepika,Shafiei-Haghighi, Sara,Smith, Cecilia R.,Crawford, Christian,Findlater, Michael
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supporting information
p. 6695 - 6700
(2018/11/21)
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- Manganese-Catalyzed Hydrofunctionalization of Alkenes
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The manganese-catalyzed hydrosilylation and hydroboration of alkenes has been developed using a single manganese(II) precatalyst and reaction protocol. Both reactions proceed with excellent control of regioselectivity and in high yields across a variety of sterically and electronically differentiated substrates (25 examples). Alkoxide activation, using NaOtBu, was key to precatalyst activation and reactivity. Catalysis was achieved across various functional groups and on gram-scale for both the developed methodologies with catalysts loadings as low as 0.5 mol %.
- Carney, Jonathan R.,Dillon, Barry R.,Campbell, Leonie,Thomas, Stephen P.
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supporting information
p. 10620 - 10624
(2018/07/31)
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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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- STABILIZATION OF ACTIVE METAL CATALYSTS AT METAL-ORGANIC FRAMEWORK NODES FOR HIGHLY EFFICIENT ORGANIC TRANSFORMATIONS
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Metal-organic framework (MOFs) compositions based on post?synthetic metalation of secondary building unit (SBU) terminal or bridging OH or OH2 groups with metal precursors or other post-synthetic manipulations are described. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations, including the regioselective boryiation and siiylation of benzyiic C—H bonds, the hydrogenation of aikenes, imines, carbonyls, nitroarenes, and heterocycles, hydroboration, hydrophosphination, and cyclization reactions. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
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Paragraph 0401
(2019/01/07)
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- Base-free nickel-catalyzed hydroboration of simple alkenes with bis(pinacolato)diboron in an alcoholic solvent
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A base-free nickel-catalyzed hydroboration of unreactive simple alkenes with bis(pinacolato)diboron using methanol as the hydride source under mild conditions has been developed. Methanol as the solvent proved to be critical for the base-free conditions and high reactivity. A series of linear alkylboronates were synthesized in moderate to excellent yields with high regioselectivity.
- Li, Jiang-Fei,Wei, Zhen-Zhong,Wang, Yong-Qiu,Ye, Mengchun
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supporting information
p. 4498 - 4502
(2017/10/13)
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- Iron-based catalytic process for the preparation of boric acid ester compound
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The invention relates to a method for preparing an alkyl borate compound based on iron catalysis. The alkyl borate compound has a structural formula I shown in the specification, and is obtained by taking an aromatic olefin compound and bis(pinacolato)dib
- -
-
Paragraph 0046; 0047; 0074; 0075
(2017/08/02)
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- Ruthenium-Catalyzed Anti-Markovnikov Selective Hydroboration of Olefins
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Ruthenium-catalyzed selective hydroboration of styrenes and aliphatic olefins with pinacolborane (HBpin) is reported. This efficient transformation provided products with exclusive anti-Markovnikov selectivity, and this hydroboration protocol is compatible with olefins having electronic and steric divergence as well as diverse functional groups. Hydroboration occurred at room temperature under solvent-free conditions with minimal catalyst load (0.05 mol %) and provided high TON (>1980; >990 per Ru). Mechanistic studies confirmed the involvement of intermediate [{(η6-p-cymene)RuCl}2(μ-H-μ-Cl)] (2). A catalytic cycle including a mononuclear ruthenium intermediate is proposed. The rationale for observed anti-Markovnikov selectivity is provided from reversible 1,3-hydride transfer leading to the regioselective 1,2-insertion on olefins.
- Kisan, Sesha,Krishnakumar, Varadhan,Gunanathan, Chidambaram
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p. 5950 - 5954
(2017/09/15)
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- A Polystyrene-Cross-Linking Bisphosphine: Controlled Metal Monochelation and Ligand-Enabled First-Row Transition Metal Catalysis
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A polystyrene-cross-linking bisphosphine PS-DPPBz was synthesized through radical emulsion copolymerization between 4-t-butylstyrene as a monomer and tetravinylated 1,2-bis(diphenylphosphino)benzene (DPPBz) as a 4-fold cross-linker. The location of the DPPBz bisphosphine moiety at the branching points of the cross-linked network organic polymer allowed controlled bisphosphine monochelation to transition metals under conditions where homogeneous ligands may form bischelated single metal complexes or multinuclear complexes. PS-DPPBz showed high ligand performance in first-row transition metal catalysis, enabling challenging molecular transformations that were not possible through the screening of existing homogeneous ligands. In the Ni-catalyzed amination of aryl chlorides with N-alkyl-substituted primary amines, the substrate scope has been expanded to include 2,6-disubstituted aryl chlorides and N-tertiary-alkyl-substituted primary amines. PS-DPPBz was effective for the Ni-catalyzed C-H/C-O coupling between 1,3-azoles and monocyclic aryl pivalates, which showed poor reactivity in the reported homogeneous catalytic system based on 1,2-bis(dicyclohexylphosphino)ethane (DCYPE). The usefulness of the polymer-cross-linking strategy was also demonstrated in alkene hydroboration reactions catalyzed by Cu or Co.
- Iwai, Tomohiro,Harada, Tomoya,Shimada, Hajime,Asano, Kiichi,Sawamura, Masaya
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p. 1681 - 1692
(2017/08/15)
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- CuII-catalyzed regioselective borylation of alkynes and alkenes
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We developed a regioselective borylation of alkynes and alkenes protocol based on air-stable CuII/multi-dentate ligand system. Our catalytic system gives exclusive β-borylation products for most substrates in excellent chemical yields. We propo
- Liu, Shiwen,Zeng, Xiaojun,Xu, Bo
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supporting information
p. 3706 - 3710
(2016/07/26)
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- Cobalt-Catalyzed Benzylic Borylation: Enabling Polyborylation and Functionalization of Remote, Unactivated C(sp3)-H Bonds
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Cobalt dialkyl and bis(carboxylate) complexes bearing α-diimine ligands have been synthesized and demonstrated as active for the C(sp3)-H borylation of a range of substituted alkyl arenes using B2Pin2 (Pin = pinacolate) as the boron source. At longer reaction times, rare examples of polyborylation were observed, and in the case of toluene, all three benzylic C-H positions were functionalized. Coupling benzylic C-H activation with alkyl isomerization enabled a base-metal-catalyzed method for the borylation of remote, unactivated C(sp3)-H bonds.
- Palmer, W. Neil,Obligacion, Jennifer V.,Pappas, Iraklis,Chirik, Paul J.
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supporting information
p. 766 - 769
(2016/02/05)
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- Iron-Catalyzed Hydroboration: Unlocking Reactivity through Ligand Modulation
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Iron-catalyzed hydroboration (HB) of alkenes and alkynes is reported. A simple change in ligand structure leads to an extensive change in catalyst activity. Reactions proceed efficiently over a wide range of challenging substrates including activated, unactivated and sterically encumbered motifs. Conditions are mild and do not require the use of reducing agents or other additives. Large excesses of borating reagent are not required, allowing control of chemo- and regioselectivity in the presence of multiple double bonds. Mechanistic insight reveals that the reaction is likely to proceed via a highly reactive iron hydride intermediate.
- Espinal-Viguri, Maialen,Woof, Callum R.,Webster, Ruth L.
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supporting information
p. 11605 - 11608
(2016/08/05)
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- Metal-Organic Frameworks Stabilize Solution-Inaccessible Cobalt Catalysts for Highly Efficient Broad-Scope Organic Transformations
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New and active earth-abundant metal catalysts are critically needed to replace precious metal-based catalysts for sustainable production of commodity and fine chemicals. We report here the design of highly robust, active, and reusable cobalt-bipyridine- and cobalt-phenanthroline-based metal-organic framework (MOF) catalysts for alkene hydrogenation and hydroboration, aldehyde/ketone hydroboration, and arene C-H borylation. In alkene hydrogenation, the MOF catalysts tolerated a variety of functional groups and displayed unprecedentedly high turnover numbers of ~2.5 × 106 and turnover frequencies of ~1.1 × 105 h-1. Structural, computational, and spectroscopic studies show that site isolation of the highly reactive (bpy)Co(THF)2 species in the MOFs prevents intermolecular deactivation and stabilizes solution-inaccessible catalysts for broad-scope organic transformations. Computational, spectroscopic, and kinetic evidence further support a hitherto unknown (bpy?-)CoI(THF)2 ground state that coordinates to alkene and dihydrogen and then undergoing σ-complex-assisted metathesis to form (bpy)Co(alkyl)(H). Reductive elimination of alkane followed by alkene binding completes the catalytic cycle. MOFs thus provide a novel platform for discovering new base-metal molecular catalysts and exhibit enormous potential in sustainable chemical catalysis.
- Zhang, Teng,Manna, Kuntal,Lin, Wenbin
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supporting information
p. 3241 - 3249
(2016/03/19)
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- Boron Lewis Acid-Catalyzed Hydroboration of Alkenes with Pinacolborane: BArF3Does What B(C6F5)3Cannot Do!
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The transition-metal-free hydroboration of various alkenes with pinacolborane (HBpin) initiated by tris[3,5-bis(trifluoromethyl)phenyl]borane (BArF3) is reported. The choice of the boron Lewis acid is crucial as the more prominent boron Lewis acid tris(pentafluorophenyl)borane (B(C6F5)3) is reluctant to react. Unlike B(C6F5)3, BArF3is found to engage in substituent redistribution with HBpin, resulting in the formation of ArFBpin and the electron-deficient diboranes [H2BArF]2and [(ArF)(H)B(μ-H)2BArF2]. These in situ-generated hydroboranes undergo regioselective hydroboration of styrene derivatives as well as aliphatic alkenes with cis diastereoselectivity. Another ligand metathesis of these adducts with HBpin subsequently affords the corresponding HBpin-derived anti-Markovnikov adducts. The reactive hydroboranes are regenerated in this step, thereby closing the catalytic cycle.
- Yin, Qin,Kemper, Sebastian,Klare, Hendrik F. T.,Oestreich, Martin
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supporting information
p. 13840 - 13844
(2016/09/21)
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- Cerium-Hydride Secondary Building Units in a Porous Metal-Organic Framework for Catalytic Hydroboration and Hydrophosphination
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We report the stepwise, quantitative transformation of CeIV6(μ3-O)4(μ3-OH)4(OH)6(OH2)6 nodes in a new Ce-BTC (BTC = trimesic acid) metal-organic framework (
- Ji, Pengfei,Sawano, Takahiro,Lin, Zekai,Urban, Ania,Boures, Dean,Lin, Wenbin
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p. 14860 - 14863
(2016/11/29)
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- FeCl2-catalyzed hydroboration of aryl alkenes with bis(pinacolato)diboron
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The first ligand-free ferrous chloride catalyzed anti-Markovnikov hydroboration of un-activated aryl alkenes with bis(pinacolato)diboron (B2pin2) has been reported. The reactions proceeded smoothly with high regioselectivity for a la
- Liu, Yang,Zhou, Yuhan,Wang, Huan,Qu, Jingping
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p. 73705 - 73713
(2015/09/15)
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- Selective synthesis of alkylboronates by copper(I)-catalyzed borylation of allyl or vinyl arenes
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An efficient copper-catalyzed borylation reaction of allyl or vinyl arenes with bis(pinacolato)diboron has been developed, without using ligands. Markovnikov-selectivity is observed in the borylation of allyl arenes with bis(pinacolato)diboron, while the regioselectivity is completely opposite when styrene derivatives are used as substrates. A mechanism involving Cu-B species regioselectively adding olefin double bonds to form the alkylcopper or 3-benzyl copper intermediate, which is followed by protonation to obtain products, is proposed.
- Wen, Yanmei,Xie, Jianying,Deng, Chunmei,Li, Chaode
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p. 4142 - 4147
(2015/05/05)
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- High-activity cobalt catalysts for alkene hydroboration with electronically responsive terpyridine and α-diimine ligands
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Cobalt alkyl complexes bearing readily available and redox-active 2,2′:6′,2″-terpyridine and α-diimine ligands have been synthesized, and their electronic structures have been elucidated. In each case, the supporting chelate is reduced to the monoanionic, radical form that is engaged in antiferromagnetic coupling with the cobalt(II) center. Both classes of cobalt alkyls proved to be effective for the isomerization-hydroboration of sterically hindered alkenes. An α-diimine-substituted cobalt allyl complex proved exceptionally active for the reduction of hindered tri-, tetra-, and geminally substituted alkenes, representing one of the most active homogeneous catalysts known for hydroboration. With limonene, formation of an η3-allyl complex with a C-H agostic interaction was identified and accounts for the sluggish reactivity observed with diene substrates. For the terpyridine derivative, unique Markovnikov selectivity with styrene was also observed with HBPin. (Figure Presented).
- Palmer, W. Neil,Diao, Tianning,Pappas, Iraklis,Chirik, Paul J.
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p. 622 - 626
(2015/03/04)
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- Iminopyridine oxazoline iron catalyst for asymmetric hydroboration of 1,1-disubtituted aryl alkenes
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The highly regio- and enantioselective iron-catalyzed anti-Markovnikov hydroboration of 1,1-disubstituted aryl alkenes is reported by using a novel chiral iminopyridine oxazoline (IPO) ligand, in which the iminopyridine group is proposed to stabilize the iron and chiral oxazoline group to control enantioselectivity. This distinct class of reactive IPO ligands will likely be of high value for a large variety of asymmetric transformations using first-row transition metals.
- Chen, Jianhui,Xi, Tuo,Lu, Zhan
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supporting information
p. 6452 - 6455
(2015/02/05)
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- Chemo-, regio-, and stereoselective iron-catalysed hydroboration of alkenes and alkynes
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The highly chemo-, regio-, and stereoselective synthesis of alkyl- and vinyl boronic esters with good functional group tolerance has been developed using in situ activation of a bench-stable iron(ii) pre-catalyst and pinacolborane (16 examples, 45-95% yield, TOF up to 30000 mol h-1). The first iron-catalysed alkene hydrogermylation is also reported.
- Greenhalgh, Mark D.,Thomas, Stephen P.
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supporting information
p. 11230 - 11232
(2013/11/19)
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- Iron-catalyzed, atom-economical, chemo- and regioselective alkene hydroboration with pinacolborane
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Precious iron: A new PNN iron complex has been developed for use in an iron-catalyzed alkene hydroboration reaction under mild conditions. The environmentally friendly and earth-abundant iron catalyst system is superior to precious-metal systems in terms of efficiency and selectivity for α-olefin hydroborations with pinacolborane. Copyright
- Zhang, Lei,Peng, Dongjie,Leng, Xuebing,Huang, Zheng
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supporting information
p. 3676 - 3680
(2013/04/23)
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- Highly selective bis(imino)pyridine iron-catalyzed alkene hydroboration
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Bis(imino)pyridine iron dinitrogen complexes have been shown to promote the anti-Markovnikov catalytic hydroboration of terminal, internal, and geminal alkenes with high activity and selectivity. The isolated iron dinitrogen compounds offer distinct advan
- Obligacion, Jennifer V.,Chirik, Paul J.
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supporting information
p. 2680 - 2683
(2013/07/19)
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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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- Impregnated copper on magnetite as recyclable catalyst for the addition of alkoxy diboron reagents to C-C double bonds
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A simple protocol for the borylation with use of impregnated copper on magnetite is described. The reactions showed a very broad scope and all type of olefins could be used with similar results. The catalyst could be easily removed by a magnet and it could be reused several times, showing similar activity.
- Cano, Rafael,Ramon, Diego J.,Yus, Miguel
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supporting information; experimental part
p. 3458 - 3460
(2010/08/06)
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- Formation of pinacol boronate esters via pyridine iodoborane hydroboration
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(Chemical Equation Presented) Hydroboration of alkenes with pyridine iodoborane followed by treatment with pinacol/NaOH affords monoalkyl pinacol boronates in moderate to good yield. Dialkylborinic acid derivatives are formed competitively, especially in
- Karatjas, Andrew G.,Vedejs, Edwin
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experimental part
p. 9508 - 9510
(2009/04/06)
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- Rhodium catalysed dehydrogenative borylation of alkenes: Vinylboronates via C-H activation
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We present herein a high yield, highly selective catalytic synthesis of vinylboronate esters (VBEs), including 1,1-disubstituted VBEs, from alkenes without significant hydrogenation or hydroboration, using the simple catalyst precursor, trans-[RhCl(CO)(PPh3)2] (1), and the diboron reagents B2pin2 (2a, pin = pinacolato = OCMe 2CMe2O) or B2neop2 (2b, neop = neopentylglycolato = OCH2CMe2CH2O), or the monoboron reagent HBpin, all of which are commercially available. The reactions were conducted at 80 °C using conventional heating, or in a microwave reactor at 150 °C. The Royal Society of Chemistry.
- Mkhalid, Ibraheem A. I.,Coapes, R. Benjamin,Edes, S. Natasha,Coventry, David N.,Souza, Fabio E. S.,Thomas, Rhodri Ll.,Hall, Jonathan J.,Bi, Si-Wei,Lin, Zhenyang,Marder, Todd B.
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p. 1055 - 1064
(2008/09/20)
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- Catalytic alkene hydroboration mediated by cationic and formally zwitterionic rhodium(I) and iridium(I) derivatives of a P,N-substituted indene
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Cationic (2a,b) and formally zwitterionic (3a,b) Rh(I) and Ir(I) complexes supported by P,N-substituted indene or indenide ligands (respectively) have been employed in the selective hydroboration of substituted vinylarenes with pinacolborane (HBpin, pin = 1,2-O2C2Me4). Notably, 3a,b exhibited remarkably high, but differing, selectivities in the hydroboration of 1-phenylpropene.
- Cipot, Judy,Vogels, Christopher M.,McDonald, Robert,Westcott, Stephen A.,Stradiotto, Mark
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p. 5965 - 5968
(2008/10/09)
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- Alkene-pinacolborane hydroborations catalyzed by lanthanum tris[bis(trimethylsilyl)amide]
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Tris[bis(trimethylsilyl)amide] has been shown to be an effective catalyst for the hydroboration of representative alkenes and styrenes by pinacolborane.
- Horino, Yoshikazu,Livinghouse, Tom,Stan, Magdalena
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p. 2639 - 2641
(2007/10/03)
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- Rhodium catalysed dehydrogenative borylation of vinylarenes and 1,1-disubstituted alkenes without sacrificial hydrogenation - A route to 1,1-disubstituted vinylboronates
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The complex trans-[Rh(Cl)(CO)(PPh3)2] (1) is an efficient catalyst precursor for the dehydrogenative borylation of alkenes without consumption of half the alkene substrate by hydrogenation, giving useful vinylboronate esters including 1,1-disubstituted derviatives that cannot be made by alkyne hydroboration.
- Coapes, R. Benjamin,Souza, Fabio E. S.,Thomas, Rhodri Ll.,Hall, Jonathan J.,Marder, Todd B.
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p. 614 - 615
(2007/10/03)
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- Palladium-catalyzed benzylic C-H borylation of alkylbenzenes with bis(pinacolato)diboron or pinacolborane
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Borylation at the benzylic C-H bond of alkylbenzenes with bis(pinacolato)diboron [(Me4C2O2)B-B(O2C2Me 4)] or pinacolborane [(Me4C2O2)B-H] was carried out at
- Ishiyama, Tatsuo,Ishida, Kousaku,Takagi, Jun,Miyaura, Norio
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p. 1082 - 1083
(2007/10/03)
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