- A relay catalysis strategy for enantioselective nickel-catalyzed migratory hydroarylation forming chiral α-aryl alkylboronates
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Ligand-controlled reactivity plays an important role in transition-metal catalysis, enabling a vast number of efficient transformations to be discovered and developed. However, a single ligand is generally used to promote all steps of the catalytic cycle (e.g., oxidative addition, reductive elimination), a requirement that makes ligand design challenging and limits its generality, especially in relay asymmetric transformations. We hypothesized that multiple ligands with a metal center might be used to sequentially promote multiple catalytic steps, thereby combining complementary catalytic reactivities through a simple combination of simple ligands. With this relay catalysis strategy (L/L?), we report here the first highly regio- and enantioselective remote hydroarylation process. By synergistic combination of a known chain-walking ligand and a simple asymmetric cross-coupling ligand with the nickel catalyst, enantioenriched α-aryl alkylboronates could be rapidly obtained as versatile synthetic intermediates through this formal asymmetric remote C(sp3)-H arylation process.
- Chen, Jian,Liang, Yong,Ma, Jiawei,Meng, Lingpu,Zhang, Yao,Zhu, Shaolin
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supporting information
p. 3171 - 3188
(2021/11/16)
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- Structural contributions to autocatalysis and asymmetric amplification in the soai reaction
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Diisopropylzinc alkylation of pyrimidine aldehydes-the Soai reaction, with its astonishing attribute of amplifying asymmetric autocatalysis-occupies a unique position in organic chemistry and stands as an eminent challenge for mechanistic elucidation. A n
- Athavale, Soumitra V.,Simon, Adam,Houk,Denmark, Scott E.
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supporting information
p. 18387 - 18406
(2020/11/17)
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- A Tunable Route to Prepare α,β-Unsaturated Esters and α,β-Unsaturated-γ-Keto Esters through Copper-Catalyzed Coupling of Alkenyl Boronic Acids with Phosphorus Ylides
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A tunable strategy to prepare α,β-unsaturated esters and α,β-unsaturated-γ-keto esters in good to excellent yields was developed through copper-catalyzed oxidative coupling of phosphorus ylides with alkenyl boronic acids under mild conditions. The reaction without water afforded α,β-unsaturated esters, ketones, and amides while α,β-unsaturated-γ-keto esters, 1,4-α,β-unsaturated diketones and α,β-unsaturated-γ-keto amides were obtained when using 5.0 equiv. of water. H2O18 labeling experiments showed that water played an important role in the formation of α,β-unsaturated-γ-keto esters. A plausible formation mechanism for α,β-unsaturated esters and α,β-unsaturated-γ-keto esters was proposed based on mechanistic studies. Phosphonium salts could also be used directly as coupling partners instead of phosphorus ylides. The reaction exhibited a broad substrate scope, good functional group tolerance, good regioselectivity, and diverse coupling products. (Figure presented.).
- Bi, Hong-Yan,Liu, Feng-Ping,Liang, Cui,Su, Gui-Fa,Mo, Dong-Liang
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supporting information
p. 1510 - 1516
(2018/03/05)
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- Asymmetric Synthesis of α-Aminoboronic Acid Derivatives by Copper-Catalyzed Enantioselective Hydroamination
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A copper-catalyzed regio- and enantioselective hydroamination of alkenyl dan boronates (dan =1,8-diaminonaphthyl) with hydrosilanes and hydroxylamines proceeds to deliver the chiral α-aminoboronic acids in good yields with high enantiomeric ratios. The ke
- Nishikawa, Daiki,Hirano, Koji,Miura, Masahiro
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supporting information
p. 15620 - 15623
(2016/01/09)
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- Rhodium(III)-catalyzed cross-coupling of alkenylboronic acids and N -pivaloyloxylamides
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Rh(III)-catalyzed umpolung amidation of alkenylboronic acids for the synthesis of enamides is reported. This reaction proceeds readily at room temperature and displays an extremely wide spectrum of functional group tolerance. With cooperation of hydrobora
- Feng, Chao,Loh, Teck-Peng
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supporting information
p. 3444 - 3447
(2014/07/21)
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- Preparation of α-imino aldehydes by [1,3]-rearrangements of O-alkenyl oximes
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The synthesis of α-imino aldehydes has been achieved through the thermal [1,3]-rearrangement of O-alkenyl benzophenone oximes. A copper-mediated C-O bond coupling between benzophenone oxime and alkenyl boronic acids provides facile access to the required O-alkenyl oximes and a Horner-Wadsworth-Emmons olefination can be applied to the α-imino aldehyde products to give γ-imino-α,β-unsaturated esters. The scope of the method is described and mechanistic experiments are discussed.
- Kontokosta, Dimitra,Mueller, Daniel S.,Wang, Heng-Yen,Anderson, Laura L.
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supporting information
p. 4830 - 4833
(2013/10/08)
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- Dichloroborane-dioxane: An exceptional reagent for the preparation of alkenyl- and alkylboronic acids
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Terminal alkynes and alkenes were conveniently hydroborated to the corresponding alkenyl- and alkyldichloroboranes using dichloroborane-dioxane in dichloromethane. These dichloroboranes were hydrolyzed by water to the corresponding alkenyl- and alkylboron
- Josyula, Kanth V. B.,Gao, Peng,Hewitt, Chris
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p. 7789 - 7792
(2007/10/03)
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- Kinetic Enzymatic Resolution of Cyclopropane Derivatives
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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
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p. 1273 - 1286
(2007/10/03)
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- Organoboranes. 30. Convenient procedures for the synthesis of alkyl- and alkenylboronic acids and esters
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Alkyl- and alkenyldibromoborane-dimethyl sulfide complexes, readily obtained by the hydroboration of alkenes and alkynes with dibromoborane-dimethyl sulfide (HBBr2-SMe2), react with water, giving the corresponding boronic acids, and with alcohols and glycols to give the corresponding esters. Various procedures have been developed for the preparation of boronic esters with primary and secondary alcohols, glycols, and tertiary alcohols. Boronic acids react with primary and secondary alcohols reversibly to form the corresponding esters. The equilibrium may be conveniently displaced in favor of ester by carrying out the reaction in pentane, from which the water component separates. This procedure does away with the necessity of azeotrope distillation of a ternary mixture, extensively used previously for the esterification of boronic acids.
- Brown, Herbert C.,Bhat,Somayaji, Vishwanatha
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p. 1311 - 1316
(2008/10/08)
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