Synthesis of amino acid derived imidazolidinium salts as new NHC precatalysts
摘要:
The preparation of new chiral symmetrically and unsymmetrically N,N'-disubstituted imidazolium based NHC salts Ib, IIb, IIIa-c and IVc-h from the amino acids L-proline and L-phenylalanine, is reported. Some preliminary tests have been carried out, demonstrating that the chiral NHCs give chiral induction in organometallic catalysis and can be used as organocatalysts. (C) 2011 Elsevier Ltd. All rights reserved.
One-Pot Synthesis of Unsymmetrical N-Heterocyclic Carbene Ligands from<i>N</i>-(2-Iodoethyl)arylamine Salts
作者:B. A. Bhanu Prasad、Scott R. Gilbertson
DOI:10.1021/ol901189m
日期:2009.8.20
approach that provides symmetrical, unsymmetrical, and asymmetric N-heterocyclic carbene (NHC) ligands is reported. Reaction of iodoethanol with aniline provides N-(2-iodoethyl)arylamine salts that are then converted to the corresponding iodide. Reaction with aliphatic or aromatic amines followed by triethyl orthoformate was used to provide 26 different NHC ligands.
Chiral NHC Ligands for Enantioselective Gold(I) Catalysis Under Aerobic Conditions: the Importance of Conformational Flexibility and Steric Hindrance of NHC Ligand on Reactivity
of chiral NHC−Au−Cl complexes, bearing sterically encumbered NHC ligands, has been accessed by merging anilines with commercially available chiral aminoalcohols and amines. Evaluation of the catalytic activity in enantioselective allenol cyclization has pointed out the importance of the steric hindrance and conformationalflexibility of the NHC core for reactivity. Ion metathesis between NHC−Au−Cl