A variety of chiral and achiral imidazoliumsalts is synthesized. Methylene-, ethylene-, propylene- and pyridinyl-bridged bis(imidazolium) halides are used to generate the respective free chelating carbenes. The synthesis of palladium complexes of general formula [cis-CH 2 NC(H)=C(H)N(R)C} 2 PdX 2 ] with these chelating N-heterocyclic carbene ligands is reported. Structural proofs of complexes 28
Synthesis of unsymmetrical imidazolium salts by direct quaternization of N-substituted imidazoles using arylboronic acids
作者:Shiqing Li、Fan Yang、Taiyong Lv、Jingbo Lan、Ge Gao、Jingsong You
DOI:10.1039/c4cc00474d
日期:——
Imidazolium salts were conveniently prepared by direct aryl quaternization using arylboronic acids. This process features the tolerance of a broad range of functional groups and excellent chemoselectivity, and is especially effective for the synthesis of unsymmetrical imidazolium salts.
Isoprene-Mediated Lithiation of 1-Alkylimidazoles: Chiral Induction of the Alkyl Substituent
作者:Isidro M. Pastor、Rosario Torregrosa、Miguel Yus
DOI:10.2174/157017810791514850
日期:2010.7.1
The isoprene-mediated lithiation of imidazoles bearing a secondary alkyl substituent at the nitrogen (7, 8 and 13) and the subsequent nucleophilic addition to different electrophiles allows the preparation of the corresponding 2- functionalized imidazoles 10, 11 and 14. The presence of a stereogenic center in the alkyl substituent induces diastereoselection during the nucleophilic addition step with a prochiral electrophile (i.e. pivalaldehyde), producing the expected imidazole derivative with excellent overall yield, but low de (up to 26%).
Chiral, bridged bis(imidazolin-2-ylidene) complexes of palladium
作者:Sabine K. Schneider、Jürgen Schwarz、Guido D. Frey、Eberhardt Herdtweck、Wolfgang A. Herrmann
DOI:10.1016/j.jorganchem.2007.04.049
日期:2007.10
Varieties of chiral, bridged bisimidazolium salts as well as the synthesis of palladium complexes of general formula [bridgeNC(H)C(H)N(R∗)C¯}2PdBr2] with the corresponding chelating N-heterocyclic carbene ligands is reported. This is the first systematic study of chiral bis(imidazolin-2-ylidene)palladium(II) complexes bearing chiral groups on the endocyclic nitrogens. Structural proof of such a chiral palladium(II)
Supported Au Nanoparticles with <i>N</i>-Heterocyclic Carbene Ligands as Active and Stable Heterogeneous Catalysts for Lactonization
作者:Rong Ye、Aleksandr V. Zhukhovitskiy、Roman V. Kazantsev、Sirine C. Fakra、Brent B. Wickemeyer、F. Dean Toste、Gabor A. Somorjai
DOI:10.1021/jacs.8b01017
日期:2018.3.21
aggregation-inhibitors during the NP synthesis, and NHCs, well-known for their strong attachment to the gold surface, provide a handle to modify the stereochemistry, stereoelectronics, and chemical functionality of the NP surface. Indeed, compared to "ligandless" Au NPs which are virtually inactive below 80 °C, the NHC-ligated Au NP catalysts enable a model lactonization reaction to proceed at 20 °C on the same