New chiral cationic rhodium-aminophosphine complexes for asymmetric transfer hydrogenation of aromatic ketones
- 化学化工－已发表论文 
The new chiral ligands (S,S)-N,N'-bis[o-(diphenylphosphino)benzylidene]1,2-diiminocyclohexane, [(S,S)-1] and (S,S)-N,N'-bis[o-diphenylphosphino]benzyl-1,2-diaminocyclohexane, [(S,S)-2] have been prepared. The interaction of [(S,S)-1] and [(S,S)-2] with [Rh(COD)Cl](2) afforded the corresponding cationic rhodium complexes [(S,S)-3][X] and [(S,S)-4][X] (X = PF6-, BF4- or ClO4-), respectively. [(S,S)-1], [(S,S)-2], [(S,S)-3][X] and [(S,S)-4][X] have been fully characterized by elemental analyses and spectroscopic methods. These chiral cationic rhodium complexes serve as catalytst precursors for the asymmetric transfer hydrogenation of acetophenone derivatives in 2-propanol and [(S,S)-4][PF6] acts as an excellent catalyst in the reduction of m-chloroacetophenone, giving the corresponding optical alcohols in 99% yield and up to 94% ee. (C) 1999 Elsevier Science S.A. All rights reserved.