An exceedingly sterically demanding, rigid, and chiral NHC ligand, IBiox[(-)-menthyl] (1), was prepared and structurally characterized. With a buried volume of approximately 50%, this ligand arguably represents one of the most sterically demanding monodentate ligands. The ability to use aryl chloride substrates in intramolecular palladium-catalyzed alpha-arylations reveals its unique reactivity. Moreover, C(2)-symmetric 1 allows the highly enantioselective formation of oxindoles with up to 99% ee.
“Elusion, Confusion” could well be the title of the story of the discovery and re‐discovery of the sandwich complexes, best represented by the accidentally found prototype ferrocene. The two most important competitors in this fiercely contested field, E. O. Fischer und G. Wilkinson, were reconciled (even in terms of dancing) only after they were jointly awarded the Nobel Prize. This keen competition in the 1950s contributed decisively to what R. S. Nyholm called the “Renaissance of Inorganic Chemistry”.
A short synthesis of thiazole-annelated imidazolium salts is presented. Deprotonation of these salts allowed the formation of new N-heterocyclic carbenes (NHCs) and the investigation of their respective electronic properties, which were determined by X-ray crystal structure analysis and IR spectroscopy of the corresponding iridium carbonyl complexes. Finally, the ability of these NHCs to form the corresponding palladium complexes was demonstrated.
Indole derivatives R 0140IBiox[(-)-menthyl]: A Sterically Demanding Chiral NHC Ligand. -An exceedingly sterically demanding, rigid chiral ligand, is prepared and applied in the asymmetric α-arylation of amides. The ability to use aryl chloride substrates reveals its unique reactivity. -(WUERTZ, S.; LOHRE, C.; FROEHLICH, R.; BERGANDER, K.; GLORIUS*, F.; J. Am. Chem. Soc. 131 (2009) 24, 8344-8345; Org.-Chem. Inst.,
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