Asymmetrische katalysen: XXVII. Rh-komplexe mit von tropolon abgeleiteten optisch aktiven liganden

In tropolone, the oxygen atoms were replaced stepwise by NC★ HMePh groups. The resulting compounds were introduced as anionic ligands into Rh(COD) complexes. The new ligands and complexes were analytically and spectroscopically characterized. The conformation of the NCH(Me)(Ph) substituent in the Rh(COD) complex of the troponiminate anion was determined by NOE ¹H NMR difference spectroscopy. Only small optical inductions were obtained in the asymmetric hydrosilylation of acetophenone with diphenylsilane using the in situ catalysts from Rh(COD)Cl]₂ and the new ligands as well as the new complexes. The enantiomeric excess rose to 5 and 33%, respectively, when ( + )-norphos and (?) -diop were used as cocatalysts and the new complexes as procatalysts.