Chiral N-Heterocyclic Carbene Ligands Bearing a Pyridine Moiety for the Copper-Catalyzed Alkylation of<i>N</i>-Sulfonylimines with Dialkylzinc Reagents
Amino acid‐derived chiral imidazolium salts, each bearing a pyridine ring, were developed as N‐heterocyclic carbeneligands. The copper‐catalyzed asymmetric alkylation of various N‐sulfonylimines with dialkylzincreagents in the presence of these chiral imidazolium salts afforded the corresponding alkylated products with high enantioselectivity (up to 99 % ee). The addition of HMPA to the reaction
A novel class of chiral-amine-functionalized ionic liquids (CAFILs) has been synthesized efficiently from natural amino acids, and their structures have been determined by spectroscopic analysis and low temperature X-ray diffraction analysis. The CAFILs have been characterized by physical properties such as melting point, glass transition temperature, thermal degradation and specific rotation. NMR measurements indicate that the CAFILs may be promising alternatives in the field of chiral discrimination. (c) 2006 Elsevier Ltd. All rights reserved.