cas 83947-56-2, TRANS-2-(4,4,5,5-TETRAMETHYL-1,3,2-DIOXABOROLAN-2-YL)STYRENE

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Synthesis of tri-substituted vinyl boronates via ruthenium-catalyzed olefin cross-metathesis
Tri-substituted vinyl pinacol boronates are synthesized using cross-metathesis of α-substituted vinyl boronates. The reactions proceed with moderate yields and high Z-selectivity when R1 = methyl. When R1 is larger than a methyl group, yields and Z-selectivity are moderate at best, and the reactions are highly substrate dependent.
Morrill, Christie,Funk, Timothy W.,Grubbs, Robert H.
p. 7733 - 7736
(2004)
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Neosilyllithium-Catalyzed Hydroboration of Alkynes and Alkenes in the Presence of Pinacolborane (HBpin)
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.
supporting information

(2021/11/13)

(Z)-Selective Hydroboration of Terminal Alkynes Catalyzed by a PSP-Pincer Rhodium Complex
A highly (Z)-selective hydroboration of terminal alkynes was achieved using a thioxanthene-based PSP-pincer rhodium catalyst. This hydroboration exhibited good chemoselectivity toward alkynes over carbonyl compounds such as ketones and aldehydes. The mechanistic studies indicated the involvement of rhodium-vinylidene intermediates, and the high (Z)-selectivity could be attributed to the rigid and electron-rich nature of the PSP-rhodium catalyst.
Lyu, Yanzong,Toriumi, Naoyuki,Iwasawa, Nobuharu
supporting information
p. 9262 - 9266
(2021/11/30)

Synthesis method of alkenyl boric acid ester
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 0022-0025

(2021/05/12)

Tropylium-Promoted Hydroboration Reactions: Mechanistic Insights Via Experimental and Computational Studies
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.
supporting information
p. 9117 - 9133
(2021/07/19)

Synthesis method of alkenyl borate
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; 0023-0027

(2021/10/30)

Aluminum-Hydride-Catalyzed Hydroboration of Carbon Dioxide
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
supporting information
p. 4569 - 4577
(2021/04/09)

Zwitterion-Initiated Hydroboration of Alkynes and Styrene
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.
supporting information
p. 2382 - 2385
(2021/01/18)

Photocatalyzed E→Z Contra-thermodynamic Isomerization of Vinyl Boronates with Binaphthol
The photocatalytic contra-thermodynamic E→Z isomerization of vinyl boronates by using a binaphthol catalyst is disclosed. The reaction, based on the transient formation of a suitable chromophore with a BINOL derivative as the catalyst, allowed geometrical isomerization in good-to-excellent Z/E ratio and excellent-to-quantitative yields. The mechanism of this E→Z contra-thermodynamic isomerization was studied, and the formation of a transient chromophore species is suggested.
Brégent, Thibaud,Bouillon, Jean-Philippe,Poisson, Thomas
supporting information
p. 13966 - 13970
(2021/08/25)

Transborylation of alkenylboranes with diboranes
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
supporting information
p. 13361 - 13364
(2021/12/17)

Cobalt-Catalyzed Hydroboration of Terminal and Internal Alkynes
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
supporting information
p. 8199 - 8203
(2021/10/25)

Aluminum Amidinates: Insights into Alkyne Hydroboration
The mechanism of the aluminum-mediated hydroboration of terminal alkynes was investigated using a series of novel aluminum amidinate hydride and alkyl complexes bearing symmetric and asymmetric ligands. The new aluminum complexes were fully characterized and found to facilitate the formation of the (E)-vinylboronate hydroboration product, with rates and orders of reaction linked to complex size and stability. Kinetic analysis and stoichiometric reactions were used to elucidate the mechanism, which we propose to proceed via the initial formation of an Al-borane adduct. Additionally, the most unstable complex was found to promote decomposition of the pinacolborane substrate to borane (BH3), which can then proceed to catalyze the reaction. This mechanism is in contrast to previously reported aluminum hydride-catalyzed hydroboration reactions, which are proposed to proceed via the initial formation of an aluminum acetylide, or by hydroalumination to form a vinylboronate ester as the first step in the catalytic cycle.
Hobson, Katie,Carmalt, Claire J.,Bakewell, Clare
p. 10958 - 10969
(2021/08/03)

Enantioselective Copper-Catalyzed Synthesis of Trifluoromethyl-Cyclopropylboronates
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.
supporting information
p. 6174 - 6178
(2021/08/18)

Hydroboration of Terminal Alkenes and trans-1,2-Diboration of Terminal Alkynes Catalyzed by a Manganese(I) Alkyl Complex
A MnI-catalyzed hydroboration of terminal alkenes and a 1,2-diboration of terminal alkynes with pinacolborane (HBPin) is described. For alkenes, anti-Markovnikov hydroboration takes place; for alkynes the reaction proceeds with excellent trans-1,2-selectivity. The most active pre-catalyst is bench-stable alkyl bisphosphine MnI complex fac-[Mn(dippe)(CO)3(CH2CH2CH3)]. The catalytic process is initiated by migratory insertion of a CO ligand into the Mn–alkyl bond to yield an acyl intermediate, which undergoes B?H bond cleavage of HBPin (for alkenes) and rapid C?H bond cleavage (for alkynes), forming the active MnI boryl and acetylide catalysts [Mn(dippe)(CO)2(BPin)] and [Mn(dippe)(CO)2(C≡CR)], respectively. A broad variety of aromatic and aliphatic alkenes and alkynes was efficiently and selectively borylated. Mechanistic insights are provided based on experimental data and DFT calculations revealing that an acceptorless reaction is operating involving dihydrogen release.
Kirchner, Karl,St?ger, Berthold,Veiros, Luis F.,Weber, Stefan,Zobernig, Daniel
supporting information
p. 24488 - 24492
(2021/10/19)

Selective hydroboration of alkynes via multisite synergistic catalysis by PCN-222(Cu)
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.
p. 63 - 69
(2021/08/03)

Highly efficient hydroboration of alkynes catalyzed by porous copper-organic framework under mild conditions
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
p. 250 - 257
(2021/10/25)

Creating High Regioselectivity by Electronic Metal-Support Interaction of a Single-Atomic-Site Catalyst
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
supporting information
p. 15453 - 15461
(2021/09/30)

Copper-Photocatalyzed Hydroboration of Alkynes and Alkenes
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
supporting information
p. 14498 - 14503
(2021/05/21)

Electrochemical Hydroboration of Alkynes
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
supporting information
p. 8277 - 8282
(2021/05/27)

Cs4B4O3F10: First Fluorooxoborate with [BF4] Involving Heteroanionic Units and Extremely Low Melting Point
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
supporting information
p. 9753 - 9757
(2021/05/27)

Reaction Pathways and Redox States in α-Selective Cobalt-Catalyzed Hydroborations of Alkynes
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
supporting information
p. 23010 - 23014
(2020/10/20)

Catalyst-free and solvent-free hydroboration of alkynes
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
p. 13626 - 13632
(2020/09/07)

Practical Solvent-Free Microwave-Assisted Hydroboration of Alkynes
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
supporting information
p. 3024 - 3029
(2020/05/18)

Aluminum-Catalyzed Selective Hydroboration of Nitriles and Alkynes: A Multifunctional Catalyst
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
supporting information
p. 4999 - 5009
(2020/05/01)

Solvent- and metal-free hydroboration of alkynes under microwave irradiation
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
(2020/01/22)

Magnesium hydrides bearing sterically demanding amidinate ligands: synthesis, reactivity and catalytic application
The synthesis and characterisation of a series of magnesium complexes bearing sterically demanding amidinate ligands is reported; this includes magneisum amides (1a and 1b), hydrides (3a and 3b) and alkyl complexes (2b). The solid and solution state behaviour of the complexes has been investigated using single crystal X-ray diffraction and NMR spectroscopy, revealing the magnesium hydrides to exist as dimers in the solid state, dispite the sterically demanding ligand systems and showing a degree of monomeric character in solution. The stoichiometric and catalytic activity of the amidinate complexes were investigated, with the complexes found to efficiently mediate both the hydroamination of N,N′-diisopropylcarbodiimide and the Tishchenko reaction. The metal hydrides are highly reactive towards coordinating substrates, showing a significant increase in catalytic rate compared with more ubiquitous β-diketiminate magnesium hydrides.
Bakewell, Clare
supporting information
p. 11354 - 11360
(2020/09/02)

Z-Selective Alkyne Functionalization Catalyzed by a trans-Dihydride N-Heterocyclic Carbene (NHC) Iron Complex
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
p. 13817 - 13821
(2020/10/09)

Nickel-Catalyzed Highly Selective Hydroalkenylation of Alkenyl Boronic Esters to Access Allyl Boron
Allyl boron derivatives are valuable building blocks in the synthesis of natural products and bioactive molecules. Herein, a practical strategy of nickel-catalyzed highly selective hydroalkenylation of alkenyl boronic esters was developed. Under the mild
Zhang, Penglin,Zhang, Min,Ji, Yuqi,Xing, Mimi,Zhao, Qian,Zhang, Chun
supporting information
p. 8285 - 8290
(2020/11/12)

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)
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.
supporting information
p. 3768 - 3769
(2020/11/17)

Tuning Polarity of Cu-O Bond in Heterogeneous Cu Catalyst to Promote Additive-free Hydroboration of Alkynes
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
supporting information
p. 725 - 737
(2020/03/11)

Nickel(II)-Catalyzed Borylation of Alkenyl Methyl Ethers via C-O Bond Cleavage
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
supporting information
p. 6424 - 6428
(2020/08/24)

Rhodium-Catalyzed Deoxygenation and Borylation of Ketones: A Combined Experimental and Theoretical Investigation
The rhodium-catalyzed deoxygenation and borylation of ketones with B2pin2 have been developed, leading to efficient formation of alkenes, vinylboronates, and vinyldiboronates. These reactions feature mild reaction conditions, a broad substrate scope, and excellent functional-group compatibility. Mechanistic studies support that the ketones initially undergo a Rh-catalyzed deoxygenation to give alkenes via boron enolate intermediates, and the subsequent Rh-catalyzed dehydrogenative borylation of alkenes leads to the formation of vinylboronates and diboration products, which is also supported by density functional theory calculations.
Tao, Lei,Guo, Xueying,Li, Jie,Li, Ruoling,Lin, Zhenyang,Zhao, Wanxiang
supporting information
p. 18118 - 18127
(2020/11/26)

Zirconium-Catalyzed Synthesis of Alkenylaminoboranes: From a Reliable Preparation of Alkenylboronates to a Direct Stereodivergent Access to Alkenyl Bromides
A simple procedure has been optimized for the preparation of alkenylaminoborane from alkynes using diisopropylaminoborane and HZrCp2Cl. Coupled with a magnesium-catalyzed dehydrogenation, it allowed for the use of air- and moisture-stable diisopropylamine. This synthesis has been extended to a one-pot sequence leading directly to bromoalkenes with controlled stereochemistry. As such, it provides an easy, scalable, cheap process to access alkenylboronates and both (E)- and (Z)-bromoalkenes from commercially available alkynes.
Birepinte, Mélodie,Chabaud, Laurent,Liautard, Virginie,Pucheault, Mathieu
p. 2838 - 2843
(2020/04/16)

Ni-Catalyzed Cyclization of Enynes and Alkynylboronates: Atom-Economical Synthesis of Boryl-1,4-dienes
We report a novel atom-economical Ni-catalyzed cyclization reaction of enynes with alkynylboronates. The reaction employs a non-expensive Ni salt, a phosphine-based ligand and easy-handling alkynylboronates as boron–carbon source. The reaction provides co
Cabrera-Lobera, Natalia,Quirós, M. Teresa,Bu?uel, Elena,Cárdenas, Diego J.
supporting information
p. 14512 - 14516
(2019/11/11)

NHC-copper-thiophene-2-carboxylate complex for the hydroboration of terminal alkynes
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
supporting information
p. 5249 - 5252
(2019/06/07)

Lithium diisobutyl-: Tert-butoxyaluminum hydride (LDBBA) catalyzed hydroboration of alkynes and imines with pinacolborane
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
p. 16524 - 16529
(2019/11/11)

Unlocking the catalytic potential of tris(3,4,5-trifluorophenyl)borane with microwave irradiation
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.
supporting information
p. 318 - 321
(2019/01/09)

AgSbF6-Catalyzed: Anti -Markovnikov hydroboration of terminal alkynes
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
supporting information
p. 989 - 992
(2019/01/23)

La[N(SiMe3)2]3-Catalyzed Hydroboration of Esters and Other Challenging Unsaturated Groups
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
p. 1142 - 1146
(2019/10/22)

Zinc-Catalysed Hydroboration of Terminal and Internal Alkynes
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
supporting information
p. 4553 - 4556
(2019/08/20)

Magnesium-Catalyzed Hydroboration of Terminal and Internal Alkynes
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
supporting information
p. 7025 - 7029
(2019/04/26)

Kinetics and Mechanism of the Arase-Hoshi R2BH-Catalyzed Alkyne Hydroboration: Alkenylboronate Generation via B-H/C-B Metathesis
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.
supporting information
p. 18600 - 18611
(2019/11/19)

Aluminum Hydroxide Secondary Building Units in a Metal-Organic Framework Support Earth-Abundant Metal Catalysts for Broad-Scope Organic Transformations
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
p. 3327 - 3337
(2019/03/26)

Silver-Catalyzed anti-Markovnikov Hydroboration of C-C Multiple Bonds
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
supporting information
p. 4035 - 4038
(2019/06/14)

Aluminium complex-catalysed hydroboration of alkenes and alkynes
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.
supporting information
p. 10531 - 10536
(2019/07/09)

Lithium compounds as single site catalysts for hydroboration of alkenes and alkynes
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.
supporting information
p. 11711 - 11714
(2019/10/02)

Polyhedral Cu2O Crystals for Diverse Aryl Alkyne Hydroboration Reactions
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.
supporting information
p. 1300 - 1303
(2019/01/04)

Transition-Metal-Free Deaminative Vinylation of Alkylamines
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
supporting information
p. 4902 - 4908
(2019/09/13)

Mechanism and Scope of Nickel-Catalyzed Decarbonylative Borylation of Carboxylic Acid Fluorides
This Article describes the development of a base-free, nickel-catalyzed decarbonylative coupling of carboxylic acid fluorides with diboron reagents to selectively afford aryl boronate ester products. Detailed studies were conducted to assess the relative rates of direct transmetalation between aryl boronate esters and diboron reagents and a bisphosphine nickel(aryl)(fluoride) intermediate. These investigations revealed that diboron reagents undergo transmetalation with this Ni(aryl)(fluoride) intermediate at rates significantly faster than their aryl boronate ester congeners. Furthermore, the reactivity of both boron reagents toward transmetalation is enhanced with increasing electrophilicity of the boron center. These mechanistic insights were leveraged to develop a catalytic decarbonylative borylation of acid fluorides that proved applicable to a variety of (hetero)aryl carboxylic acid fluorides as well as diverse diboron reagents. The acid fluorides can be generated in situ directly from carboxylic acids. Furthermore, the mechanistic studies directed the identification of various air-stable Ni pre-catalysts for this transformation.
Malapit, Christian A.,Bour, James R.,Laursen, Simon R.,Sanford, Melanie S.
supporting information
p. 17322 - 17330
(2019/11/03)

H2-Acceptorless Dehydrogenative Boration and Transfer Boration of Alkenes Enabled by Zirconium Catalyst
The first example of an efficient and direct dehydrogenative boration of alkenes for vinyl boronate ester synthesis was achieved using a zirconium catalyst. Our methodology avoids using precious transition metals, additional hydrogen acceptors, high temperatures, and long reaction times, which were required to overcome the reducing ability of borane, to give alkyl boronate esters. Detailed mechanistic studies revealed a reversible reaction pathway and further suggested applying the zirconium complex as a “shuttle catalyst” for transfer boration, which thus sidesteps the use of relatively sensitive borane.
Shi, Xiaonan,Li, Sida,Wu, Lipeng
p. 16167 - 16171
(2019/11/03)

Stereoselective Synthesis of Vinylboronates by Rh-Catalyzed Borylation of Stereoisomeric Mixtures
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
supporting information
p. 462 - 468
(2019/03/28)