DIASTEREOSELECTIVE SYNTHESIS OF CHIRAL (TRIAZOLINYLIDENE)RHODIUM COMPLEXES CONTAINING AN AXIS OF CHIRALITY

Deprotonation of chiral triazolium salts 1 and reaction of the resulti ng nucleophilic carbenes with [(COD)RhCl](2) or [(NBD)RhCl](2) afforde d square-planar complexes 2-6 in yields of 65-95%. The complexes conta in an axis of chirality and a diastereomeric excess of up to 97% was a chieved. The relative and absolute configurations of these complexes w ere determined by NMR spectroscopic investigations and X-ray structure analysis. The application of the rhodium(COD) complexes as catalysts in an asymmetric hydrosilylation reaction has been examined, resulting in enantiomeric excesses of up to 44%. Similar results were achieved for aromatic and aliphatic ketones and a nonlinear temperature effect (principle of isoinversion) was observed.