- Selective hydroboration of alkynes via multisite synergistic catalysis by PCN-222(Cu)
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Zirconium-based porphyrinic MOFs (PMOFs, MOF = metal-organic framework) have gained considerable attention in the field of electric/thermo/photo-catalysis as heterogeneous single-site catalysts; however, the study on multisite synergistic catalysis of PMO
- Ma, L. J.,Tang, Z. Y.,Yuan, J. C.,Zhang, L. J.,Zhang, X. M.
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- Copper-Photocatalyzed Hydroboration of Alkynes and Alkenes
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The photocatalytic hydroboration of alkenes and alkynes is reported. The use of newly-designed copper photocatalysts with B2Pin2 permits the formation a boryl radical, which is used for hydroboration of a large panel of alkenes and a
- Zhong, Mingbing,Gagné, Yohann,Hope, Taylor O.,Pannecoucke, Xavier,Frenette, Mathieu,Jubault, Philippe,Poisson, Thomas
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supporting information
p. 14498 - 14503
(2021/05/21)
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- Solvent- and metal-free hydroboration of alkynes under microwave irradiation
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Boronic esters are versatile building blocks extensively used in organic chemistry and essential to a variety of coupling reactions. In this work, the hydroboration reactions of alkynes were performed without metal catalysts using concomitant microwave ir
- Arnaud, Alexandre,Doléans-Jordheim, Anne,Gioia, Bruna,Radix, Sylvie,Rocheblave, Luc,Walchshofer, Nadia
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- Erratum: Markovnikov-selective hydroboration of olefins catalyzed by a copper N-heterocyclic carbene complex (Organometallics (2019) 38:17 (3322-3326) DOI: 10.1021/acs.organomet.9b00394)
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It has come to our attention that some of the products listed in Table 2 of the article and in eq 1 have the incorrect stereochemistry. The reactions of alkynes with HBpin give the linear E-olefin products, not the branched products as were shown. 1H NMR spectra clearly show two doublets with a large J (18 Hz) for the trans-hydrogens of the alkene product. A DEPT-135 spectrum also confirms that CH and not CH2 is present. Corrected eq 1, Table 2, TOC graphic are shown. Note that the alkene addition products are correctly assigned as branched, displaying a doublet and a quartet for the methyl and methane groups, respectively. NMR spectra for all products are included in the revised Supporting Information. We thank Prof. Jaesook Yun for pointing out this error, as her group has worked on related copper borylations for many years.
- DiBenedetto, Tarah A.,Parsons, Astrid M.,Jones, William D.
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supporting information
p. 3768 - 3769
(2020/11/17)
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- Direct Synthesis of Alkenylboronates from Alkenes and Pinacol Diboron via Copper Catalysis
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We report an efficient approach for the direct synthesis of alkenylboronates using copper catalysis. The Cu/TEMPO catalyst system (where TEMPO = (2,2,6,6-tetramethylpiperidin-1-yl)oxyl) exhibits both excellent reactivity and selectivity for the synthesis of alkenylboronates, starting from inexpensive and abundant alkenes and pinacol diboron. This approach allows for the direct functionalization of both aromatic and aliphatic terminal alkenes. Mechanistic experiments suggest that the alkenylboronates arise from oxyboration intermediates.
- Lu, Wenkui,Shen, Zengming
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supporting information
p. 142 - 146
(2019/01/11)
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- H2-Acceptorless Dehydrogenative Boration and Transfer Boration of Alkenes Enabled by Zirconium Catalyst
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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
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supporting information
p. 16167 - 16171
(2019/11/03)
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- Polyhedral Cu2O Crystals for Diverse Aryl Alkyne Hydroboration Reactions
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Cu2O cubes, octahedra, and rhombic dodecahedra have been used to examine facet-dependent catalytic activity in aryl alkyne hydroboration reactions. Although the reaction can proceed by using ethanol or other alcohols as solvent, the use of 1,4-dioxane gave the best product yield. All particle shapes gave exclusively the E-product, but the rhombic dodecahedra exposing {110} surfaces were consistently far more reactive than the other particle morphologies. A product yield of 99 % was achieved by using Cu2O rhombic dodecahedra to catalyze the hydroboration of phenylacetylene at 60 °C for 5 h. The rhombic dodecahedra have been shown to catalyze a variety of substituted aryl alkynes, which demonstrates their potential as a versatile catalyst.
- Tsai, Hsin-Yi,Madasu, Mahesh,Huang, Michael H.
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p. 1300 - 1303
(2019/01/04)
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- Transition-Metal-Free Deaminative Vinylation of Alkylamines
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The amino group is one of the most fundamental structural motifs in natural products and synthetic chemicals. However, amines potential as effective alkylating agents in organic synthesis is still problematic. A unified strategy has been established for deaminative vinylation of the alkylamines with vinyl boronic acids by C?N bond activation under catalyst-free conditions. The key to the high reactivity is the utilization of pyridinium salt-activated alkylamines, with a base as a promoter. The transformation exhibits good functional group compatibility, and includes inexpensive primary amine feedstocks and amino acids. The proposed method can serve as a powerful synthetic method for late-stage modification of complex compounds. Mechanistic experiments suggest that free radical processes are involved in this system. (Figure presented.).
- Hu, Jiefeng,Cheng, Bo,Yang, Xianyu,Loh, Teck-Peng
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supporting information
p. 4902 - 4908
(2019/09/13)
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- Magnesium-Catalyzed Hydroboration of Terminal and Internal Alkynes
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A magnesium-catalyzed hydroboration of alkynes providing good yields and selectivities for a wide range of terminal and symmetrical and unsymmetrical internal alkynes has been developed. The compatibility with many functional groups makes this magnesium c
- Magre, Marc,Maity, Bholanath,Falconnet, Alban,Cavallo, Luigi,Rueping, Magnus
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supporting information
p. 7025 - 7029
(2019/04/26)
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- Aluminum Hydroxide Secondary Building Units in a Metal-Organic Framework Support Earth-Abundant Metal Catalysts for Broad-Scope Organic Transformations
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The intrinsic heterogeneity of alumina (Al2O3) surface presents a challenge for the development of alumina-supported single-site heterogeneous catalysts and hinders the characterization of catalytic species at the molecular level as well as the elucidation of mechanistic details of the catalytic reactions. Here we report the use of aluminum hydroxide secondary building units (SBUs) in the MIL-53(Al) metal-organic framework (MOF) with the formula Al(μ2-OH)(BDC) (BDC = 1,4-benzenedicarboxylate) as a uniform and structurally defined functional mimic of Al2O3 surface for supporting Earth-abundant metal (EAM) catalysts. The μ2-OH groups in MIL-53(Al) SBUs were readily deprotonated and metalated with CoCl2 and FeCl2 to afford MIL-53(Al)-CoCl and MIL-53(Al)-FeCl precatalysts which were characterized by powder X-ray diffraction, nitrogen sorption, elemental analysis, density functional theory, and extended X-ray fine structure spectroscopy. Activation with NaBEt3H converted MIL-53(Al)-CoCl to MIL-53(Al)-CoH which effectively catalyzed hydroboration of alkynes and nitriles and hydrosilylation of esters. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of AlIII and CoII centers in MIL-53(Al)-CoH while deuterium labeling studies suggested σ-bond metathesis as a key step for the MIL-53(Al)-CoH-catalyzed addition reactions. MIL-53(Al)-FeCl competently catalyzed oxidative Csp3-H amination and Wacker-type alkene oxidation. XANES analysis revealed the oxidation of FeII to FeIII centers in the activated MIL-53(Al)-FeCl catalyst and suggested that oxidative Csp3-H amination occurs via the formation of FeIII-OtBu species by single electron transfer between FeII centers in MIL-53(Al)-FeCl and (tBuO)2 with concomitant generation of 1 equiv of tBuO· radical, C-H activation through hydrogen atom abstraction to generate alkyl radicals, protonation of FeIII-OtBu by aniline to generate MIL-53(Al)-FeIII-anilide, and finally C-N coupling between the FeIII-anilide and alkyl radical to form the Csp3-H amination product and regenerate the FeII catalyst. These highly active single-site MOF-based solid catalysts were readily recovered and reused up to five times without significant decrease in catalytic activity. This work thus demonstrates the great potential of using the aluminum hydroxide SBUs in MOFs to support EAM catalysts for important organic transformations.
- Feng, Xuanyu,Ji, Pengfei,Li, Zhe,Drake, Tasha,Oliveres, Pau,Chen, Emily Y.,Song, Yang,Wang, Cheng,Lin, Wenbin
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p. 3327 - 3337
(2019/03/26)
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- Mild Base Promoted Nucleophilic Substitution of Unactivated sp3-Carbon Electrophiles with Alkenylboronic Acids
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Diverse alkenylboronic acids react smoothly with various sp3-carbon electrophiles such as unactivated alkyl triflates in the presence of mild bases such as K3PO4. The reaction protocol is very mild and thereby enables high functional group tolerance. This transition metal-free condition is orthogonal towards the classic transition metal catalyzed Suzuki coupling. (Figure presented.).
- Liu, Shiwen,Zeng, Xiaojun,Hammond, Gerald B.,Xu, Bo
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supporting information
p. 3667 - 3671
(2018/09/12)
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- Cyclodextrin Cavity-Induced Mechanistic Switch in Copper-Catalyzed Hydroboration
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N-heterocyclic carbene-capped cyclodextrin (ICyD) ligands, α-ICyD and β-ICyD derived from α- and β-cyclodextrin, respectively give opposite regioselectivities in a copper-catalyzed hydroboration. The site-selectivity results from two different mechanisms: the conventional parallel one and a new orthogonal mechanism. The shape of the cavity was shown not only to induce a regioselectivity switch but also a mechanistic switch. The scope of interest of the encapsulation of a reactive center is therefore broadened by this study.
- Zhang, Pinglu,Meijide Suárez, Jorge,Driant, Thomas,Derat, Etienne,Zhang, Yongmin,Ménand, Micka?l,Roland, Sylvain,Sollogoub, Matthieu
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supporting information
p. 10821 - 10825
(2017/08/30)
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- Aqueous-Phase Synthesis of Size-Tunable Copper Nanocubes for Efficient Aryl Alkyne Hydroboration
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Copper nanocubes with average sizes of 82, 95, and 108 nm have been synthesized in an aqueous mixture of cetyltrimethylammonium chloride (CTAC) surfactant, copper acetate, and sodium ascorbate reductant heated at 100 °C for 40 min. Copper nanowires with a
- Thoka, Subashchandrabose,Madasu, Mahesh,Hsia, Chi-Fu,Liu, Shu-Ya,Huang, Michael H.
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p. 2318 - 2322
(2017/09/11)
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- Copper-catalyzed decarboxylative hydroboration of phenylpropiolic acids under ligand-free or both ligand- and base-free conditions
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An efficient copper-catalyzed decarboxylative hydroboration of phenylpropiolic acids with bis(pinacolato)diboron was developed, affording β-vinylboronates as the only products in high yields. Extra hydrogen sources such as methanol are not needed in this
- Zhao, Ying-Wei,Feng, Qiang,Song, Qiu-Ling
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p. 571 - 574
(2016/04/26)
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- Iron-Catalyzed e?Selective dehydrogenative borylation of vinylarenes with pinacolborane
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We report the dehydrogenative borylation of vinylarenes with pinacolborane (HBpin) catalyzed by an iron(0) complex “(PMe3)4Fe”. A variety of monosubstituted and disubstituted vinylarenes underwent this iron-catalyzed transformation, affording E-vinyl boronate esters (VBEs) selectively in hi h ields. In addition we coupled this iron-catal zed dehydrogenative borylation with further transformations of the resulting vinyl boronate esters and developed various one-pot procedures for the functionalization of the vinylic C?H bonds in vinylarenes. Mechanistic studies reveal that this Fe-catalyzed reaction proceeds through syn-insertion of vinylarenes into a Fe-boryl species followed by β-hydrogen elimination from a syn coplanar conformation of the borylalkyl iron intermediate.
- Wang, Chao,Wu, Caizhi,Ge, Shaozhong
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p. 7585 - 7589
(2018/05/23)
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- Straightforward iron-catalyzed synthesis of vinylboronates by the hydroboration of alkynes
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An iron-catalyzed hydroboration of alkynes to produce vinylboronates has been examined. With a straightforward system composed of iron carbonyls and pinacolborane, good to excellent yields and chemoselectivities were achieved for a variety of alkynes. Cop
- Haberberger, Michael,Enthaler, Stephan
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supporting information
p. 50 - 54
(2013/02/23)
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