Synthesis and characterization of asymmetric NHC complexes
作者:Sandra C. Zinner、Wolfgang A. Herrmann、Fritz E. Kühn
DOI:10.1016/j.jorganchem.2007.10.047
日期:2008.4
New chiral and non-chiral rhodium(I) - NHC complexes were synthesized. The first attempt by deprotonation of an imidazolinium salt with KOtBu and reaction with [Rh(COD)Cl](2) leads to the corresponding rhodium(I) complex. Due to the basic conditions during the reaction a loss of chirality occurs. An alternative transmetallation reaction with a silver(I) - NHC complex yields the desired rhodium (I) - NHC complex under retention of chirality. Both Rh complexes were fully characterized by analytical methods. (C) 2007 Elsevier B.V. All rights reserved.
Synthesis of chiral silver(I) diaminocarbene complexes from (R,R)-4,5-di-tert-butylimidazoline
A preparation of chiral silver(I) diaminocarbene complexes was developed by treatment of imidazolinium salts derived from (R,R)-4,5-di-tert-butylimidazoline with silver(I) oxide. Complexes having the chirality on the heterocycle and methyl, benzyl or picolyl groups on the nitrogen atoms have been prepared. We also performed the synthesis of diaminocarbenes having in addition the chiral (S)-1-phenylethyl moiety on the nitrogen atoms. X-ray structures of two of these carbenes (N,N ' -dimethyl and N,N ' -dibenzyl) are presented. Several methods for the preparation of imidazolinium salts are described. (C) 2001 Elsevier Science B.V. All rights reserved.