N-heterocyclic carbene (NHC)-modulated Pd/Cu cocatalyzed three-component synthesis of 2,6-diarylquinolines
作者:Chen Xu、Hong-Mei Li、Xiao-Er Yuan、Zhi-Qiang Xiao、Zhi-Qiang Wang、Wei-Jun Fu、Bao-Ming Ji、Xin-Qi Hao、Mao-Ping Song
DOI:10.1039/c4ob00231h
日期:——
An efficient NHC-modulated Pd/Cu cocatalyzed three-component coupling reaction for the synthesis of 2,6-diarylquinolinesviaoxidation, cyclization and Suzuki reactions.
Stereoelectronic Effects Characterizing Nucleophilic Carbene Ligands Bound to the Cp*RuCl (Cp* = η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>) Moiety: A Structural and Thermochemical Investigation
作者:Jinkun Huang、Hans-Jörg Schanz、Edwin D. Stevens、Steven P. Nolan
DOI:10.1021/om990054l
日期:1999.6.1
The reaction of [Cp*RuCl](4) (1) with carbene ligands affords unsaturated Cp*Ru(L)Cl [Cp* = eta(5)-C5Me5; L = 1,3-R-2-imidazol-2-ylidene [R = cyclohexyl (ICy, 2); 4-methylphenyl (ITol, 3); 4-chlorophenyl (IpCl, 4); adamantyl (IAd, 5)] and 4,5-dichloro-1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMesCl, 6)] complexes 2-6 in high yield. Solution calorimetric investigations of this series provides a measure of the electron donor properties of all ligands, and comparisons are made with IMes [1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene] and the widely used PCy3. Structural information from single X-ray studies for complexes 2, 3, 5, 6, Cp*Ru(IMes)Cl (7), Cp*Ru(PCy3)Cl (8), and Cp*Ru((PPr3)-Pr-i)Cl (9) permits a quantitative treatment of steric parameters associated with these Ligands.
Steric Effects in the Aerobic Oxidation of π-Allylnickel(II) Complexes with <i>N</i>-Heterocyclic Carbenes
作者:Benjamin R. Dible、Matthew S. Sigman
DOI:10.1021/ic0612451
日期:2006.10.1
Pi-allylchloro(NHC)nickel(II) complexes were synthesized and their reactions with O2 were studied. Ligandstericeffects were found to determine the difference between rapid oxidation of the allyl group to produce bis-mu-hydroxonickel complexes and no observable reaction. The ability of the metal-NHC bond to rotate correlates with the ability of the complex to react with O2. In the limiting cases,
作者:Anthony J. Arduengo、H. V. Rasika Dias、Richard L. Harlow、Michael Kline
DOI:10.1021/ja00040a007
日期:1992.7
Four new stable nucleophiliccarbenes have been synthesized and structurally characterized. The remarkable ability of the imidazole nucleus to stabilize a carbene center at the C-2 position is demonstrated by the isolation of 1,3,4,5-tetramethylimidazol-2-ylidene. The isolation of three imidazol-2-ylidenes that bear aryl substituents is counter to speculations based on previous reports