Nickel-Catalyzed Asymmetric α-Arylation and Heteroarylation of Ketones with Chloroarenes: Effect of Halide on Selectivity, Oxidation State, and Room-Temperature Reactions
摘要:
We report the alpha-arylation of ketones with a range of aryl chlorides with enantioselectivities from 90 to 99% ee catalyzed by the combination of Ni(COD)(2) and (R)-BINAP and the coupling of ketones with a range of heteroaryl chlorides with enantioselectivities up to 99% ee catalyzed by Ni(COD)(2) and (R)-DIFLUORPHOS. The analogous reactions of bromoarenes occur with much lower enantioselectivities. Mechanistic studies showed that the difference in the rates of decomposition of the arylnickel(II) halide intermediates to {[(R)-BINAP]NiX}(2) likely accounts for the difference in the enantioselectivities of the reactions of bromoarenes and chloroarenes. This catalyst decomposition can be overcome by conducting the reactions with [(R)-BINAP]Ni(eta(2)-NC-Ph) (4), which undergoes oxidative addition to haloarenes at room temperature.
Identification of the Active Catalyst for Nickel‐Catalyzed Stereospecific Kumada Coupling Reactions of Ethers
作者:David D. Dawson、Victoria F. Oswald、Andy S. Borovik、Elizabeth R. Jarvo
DOI:10.1002/chem.202000215
日期:2020.3.9
the stereospecific cross-coupling of benzylic ethers. These results demonstrate rapid redox reactions of precatalysts, such that the oxidative state of the precatalyst does not dictate the oxidation state of the active catalyst in solution. These data provide the first experimental evidence for a Ni0 -NiII catalytic cycle for a stereospecific alkyl-alkyl cross-couplingreaction, including spectroscopic
Nickel (0) Complexes as Promising Chemosensors for Detecting the
<i>“Cork Taint”</i>
in Wine
作者:Caterina Damiano、Daniela Intrieri、Paolo Sonzini、Silvia Rizzato、Corrado Di Natale、Roberto Paolesse、Emma Gallo
DOI:10.1002/ejic.202101013
日期:2022.3.29
The oxidative addition of 2,4,6-trichloroanisole (TCA) to Ni(0)(BINAP)(η2-PhCN) (2) represents a valuable procedure for the TCA detection in wine-stoppers due to the formation of the Ni (II) complex (4), showing a distinguishing UV-visible spectrum. Product 4 was characterized by X-ray analysis and allowed the indirect TCA determination in polluted corks as also demonstrated by the principal component
Ligand-enabled stereodivergence in nickel-catalyzed regioselective hydroboration of internal allenes
作者:Xiaoxu Yang、Chunchen Yuan、Shaozhong Ge
DOI:10.1016/j.chempr.2022.10.003
日期:2023.1
extremely rare. Herein, we demonstrate that such stereodivergence can be achieved for nickel-catalyzed hydroboration of internal allenes, which enables convenient synthesis of both stereoisomers of trisubstituted alkenylboronates from the same starting reagents. Mechanistic studies reveal that these nickel-catalyzedallene hydroboration reactions do not follow conventional hydrometallation or borylmetallation
Preparation, Crystal Structure Analysis, and Catalytic Application of [(<i>S</i>)-BINAP]Ni(COD) and [(<i>S</i>)-BINAP]NiBr<sub>2</sub>
作者:Dirk J. Spielvogel、William M. Davis、Stephen L. Buchwald
DOI:10.1021/om020164j
日期:2002.9.1
The efficient preparation of [(S)-BINAP]Ni-(COD) (1) and [(S)-BINAP]NiBr2 (2) is reported. X-ray crystal structure analysis of these potential precatalysts provides the first structural insights into the nickel-BINAP system at both the 0 and +2 oxidation states.