- 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)
-
- 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)
-
- 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)
-
- 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
-
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
-
-
- 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)
-
- 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)
-
- 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)
-
- 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)
-
- A recyclable Ru(CO)Cl(H)(PPh3)3/PEG catalytic system for regio- and stereoselective hydroboration of terminal and internal alkynes
-
This paper reports on the first repetitive batch selective hydroboration of terminal and internal alkynes in a series of poly(ethylene glycols) (PEGs), used as solvents and media for the immobilization of a Ru(CO)Cl(H)(PPh3)3 catalyst. The system based on 2 mol% of Ru?H complex and poly(ethylene glycol) with α-methyl/ω-trimethylsilyl ending groups (Mw=2000) was found to be the most efficient, and was able to carry out over 19 complete runs with the Z-addition of pinacolborane to the phenylacetylene. With the use of one portion of the developed catalytic system, the hydroboration of five different alkynes was performed consecutively, and led to five different products being obtained with high yields and purities. The developed strategy was characterized by high TON values and it was found to be the best recyclable protocol, leading to alkenyl boronates in all reported cases. (Figure presented.).
- Szyling, Jakub,Franczyk, Adrian,Stefanowska, Kinga,Walkowiak, J?drzej
-
p. 2966 - 2974
(2018/08/17)
-
- An Effective Catalytic Hydroboration of Alkynes in Supercritical CO2 under Repetitive Batch Mode
-
A facile method for the synthesis of unsaturated organoboron compounds by hydroboration of terminal and internal alkynes in supercritical (sc) CO2 has been presented for the first time. The reactions performed in scCO2 in the presence of Ru catalysts (selectivity, productivity) are compared with those in a traditionally used solvent or without it. Moreover, the catalytic systems based on the application of scCO2 have been successfully tested for the processes under repetitive batch conditions. This strategy permitted us to obtain boryl-substituted olefins with high yields and selectivities up to the 16th catalytic cycle if using Ru(CO)Cl(H)(PPh3)3 as a catalyst. The process applied the self-dosing catalyst, which is gradually released to the reaction mixture under supercritical conditions in the individual batch. Such an approach has a positive impact on process sustainability and economy.
- Szyling, Jakub,Franczyk, Adrian,Stefanowska, Kinga,Klarek, Mateusz,Maciejewski, Hieronim,Walkowiak, J?drzej
-
p. 531 - 539
(2018/02/14)
-
- Efficient heterogeneous hydroboration of alkynes: enhancing the catalytic activity by Cu(0) incorporated CuFe2O4 nanoparticles
-
CuFe2O4 magnetic nanoparticles (NPs) are typically further calcined at high temperature to eliminate the reduced state of the Cu(0) source. Here we report the discovery of Cu(0) incorporated in CuFe2O4 that enables the catalytic activity for hydroboration of alkynes to be enhanced. This catalyst system has a low working temperature and short reacting time, and wide tolerance of substituted alkynes such as ynoate, ynamide and ynone. The Cu-CuFe2O4 catalyst was prepared by a simple hydrothermal method and well characterized by SEM, TEM, PXRD, XPS and EDS. Recycling of the catalyst was also achieved without obvious loss of activity after six runs. Furthermore, the mechanism of this reaction was also investigated.
- Zeng, Xianghua,Gong, Chunhua,Guo, Haiyang,Xu, Hao,Zhang, Junyong,Xie, Jingli
-
supporting information
p. 17346 - 17350
(2018/11/01)
-
- Synthesis, characterization, and catalytic performance of Aluminum and Tin Compounds with β-diketiminato ligand
-
Two new tin (II) and tin (IV) compounds [LSnCl] (1) and [LSnCl3] (2), bearing the β-diketiminato ligand LH (L = HC(CMeNAr)2, Ar = 2,6-Et2C6H3) were synthesized by the reactions of LH with n-BuLi, then
- Ding, Yi,Liu, Xin,Ma, Xiaoli,Liu, Yashuai,Zhong, Mingdong,Li, Wenling,Yang, Zhi,Yang, Ying
-
-
- Pd-catalyzed hydroborylation of alkynes: A ligand controlled regioselectivity switch for the synthesis of α- Or β-vinylboronates
-
A ligand controlled selective hydroborylation of alkynes to α- or β-vinylboronates has been developed using a Pd catalyst. The high α-selectivity displayed by this reaction can be switched to furnish β-vinylboronates by altering the ligand from a trialkylphosphine to N-heterocyclic carbene. A variety of terminal alkynes are shown to furnish the corresponding α- or β-vinylboronates in good to excellent selectivity and yield. The mechanistic studies suggest that the solvent is the proton source and bromobenzene functions as an important additive in driving this reaction forward.
- Ojha, Devi Prasan,Prabhu, Kandikere Ramaiah
-
supporting information
p. 432 - 435
(2016/02/18)
-
- An Aluminum Dihydride Working as a Catalyst in Hydroboration and Dehydrocoupling
-
The well-defined aluminum dihydride LAlH2 (L = HC(CMeNAr)2, Ar = 2,6-Et2C6H3) (1) operates in catalysis like a transition metal complex. The catalytic activity of 1 for hydroboration of terminal alkynes was investigated. Furthermore, catalyst 1 effectively initiated the dehydrocoupling of boranes with amines, thiols, and phenols, respectively, to form compounds with B-E bonds (E = N, S, O) under elimination of H2. Quantum mechanical calculations indicate that hydroboration and dehydrocoupling reactions occur via three consecutive cycloaddition reactions involving the activation of the X-H (X = Al, B, C, and O) σ-bonds.
- Yang, Zhi,Zhong, Mingdong,Ma, Xiaoli,Nijesh, Karikkeeriyil,De, Susmita,Parameswaran, Pattiyil,Roesky, Herbert W.
-
supporting information
p. 2548 - 2551
(2016/03/12)
-
- Synthesis of vinyl boronates from aldehydes by a practical boron-Wittig reaction
-
A highly stereoselective boron-Wittig reaction between stable and readily accessible 1,1-bis(pinacolboronates) and aldehydes furnishes a variety of synthetically useful di- and trisubstituted vinyl boronate esters.
- Coombs, John R.,Zhang, Liang,Morken, James P.
-
supporting information
p. 1708 - 1711
(2015/04/14)
-
- Catalytic non-conventional trans-hydroboration: A theoretical and experimental perspective
-
We have studied the nonconventional trans-hydroboration reaction of alkynes both experimentally and theoretically. A catalytic system based on the in situ mixture of [{Rh- (cod)Cl}2]/PCy3 (cod=1,5-cyclooctadiene, Cy=cyclohexyl) has been able to activate pinacolborane and catecholborane and transfer boryl and hydride groups onto the same unhindered carbon atom of the terminal alkynes. The presence of a base (Et3N) favored the non-conventional trans-hydroboration over the traditional cis-hydroboration. Varying the substrate had a significant influence on the reaction, with up to 99% conversion and 94% regioselectivity observed for para-methyl- phenylacetylene. Both DFT and quantum mechanical/molecular mechanical ONIOM calculations were carried out on the [RhCl(PR3)2] system. To explain the selectivity towards the (Z)-alkenylboronate we explored several alternative mechanisms to the traditional cishydroboration, using propyne as a model alkyne. The proposed mechanism can be divided into four stages: 1) isomerization of the alkyne into the vinylidene, 2) oxidative addition of the borane reagent, 3) vinylidene insertion into the Rh-H bond, and finally 4) reductive elimination of the C-B bond to yield the 1-alkenylboronate. Calculations indicated that the vinylidene insertion is the selectivity- determining step. This result was consistent with the observed Z selectivity when the sterically demanding phosphine groups, such as PCy3 and PiPr3, were introduced. Finally, we theoretically analyzed the effect of the substrate on the selectivity; we identified several factors that contribute to the preference for aryl alkynes over aliphatic alkynes for the Z isomer. The intrinsic electronic properties of aryl substituents favored the Z-pathway over the E-pathway, and the aryl groups containing electron donating substituents favored the occurrence of the vinylidene reaction channel.
- Cid, Jessica,Carbo, Jorge J.,Fernandez, Elena
-
supporting information; experimental part
p. 1512 - 1521
(2012/03/27)
-
- PURINES AS PKC-THETA INHIBITORS
-
A chemical genus of purines, which are useful as PKCθ inhibitors, is disclosed. The genus is represented by the formula (I); A representative example is: (II)
- -
-
Page/Page column 62; 63
(2008/12/05)
-
- Palladium-Catalyzed Cross-Coupling of Stereospecific Potassium Cyclopropyl Trifluoroborates with Aryl Bromides
-
(Matrix presented) Stereospecific cyclopropanation of alkenylboronic esters of pinacol followed by in situ treatment with excess KHF2 afforded the corresponding potassium cyclopropyl trifluoroborates in high yields, which then underwent Suzuki-
- Fang, Guo-Hua,Yan, Zheng-Jun,Deng, Min-Zhi
-
p. 357 - 360
(2007/10/03)
-
- Kinetic Enzymatic Resolution of Cyclopropane Derivatives
-
The kinetic enzymatic resolution of various cyclopropane derivatives was systematically investigated. The study focused on synthetically useful cyclopropylmethanols (e.g., 18a/j or 19a/j) as well as some rarely investigated cyclopropanols (e.g., 24/25 or 27). The combination of enantioselective catalytic or diastereoselective synthesis of enantiomerically enriched compounds with enzymatic approaches ultimately led to the most convenient route to enantiomerically pure starting materials. Again, this was especially proven for the synthesis of cyclopropanols 18a/j and 19a/j. Key to the successful investigation was to rigorously establish an analytical tool for the analysis of enantiomeric composition of reaction mixtures.
- Pietruszka, Joerg,Rieche, Anja C. M.,Wilhelm, Thorsten,Witt, Andreas
-
p. 1273 - 1286
(2007/10/03)
-