New chiral cationic rhodium–aminophosphine complexes for asymmetric transfer hydrogenation of aromatic ketones

• Published in: Journal of organometallic chemistry Vol. 592; no. 2; pp. 290 - 295
• Main Authors: Gao, Jing-Xing, Yi, Xiao-Dong, Xu, Pian-Pian, Tang, Chun-Liang, Wan, Hui-Lin, Ikariya, Takao
• Format: Journal Article
• Language: English
• Published: LAUSANNE Elsevier B.V 25.12.1999; Elsevier
• Subjects: Asymmetric reduction; Chemistry; Chemistry, Inorganic & Nuclear; Chemistry, Organic; Chiral ligand; Chiral rhodium complexes; Physical Sciences; Prochiral ketone; Science & Technology; Transfer hydrogenation; Asymmetric reduction; Prochiral ketone; Transfer hydrogenation; Chiral rhodium complexes; Chiral ligand; CATALYSIS; chiral ligand; LIGANDS; REDUCTION; IRIDIUM(I); transfer hydrogenation; asymmetric reduction; DIPHOSPHINE COMPLEXES; BINAP-P2N2; chiral rhodium complexes; prochiral ketone; RAY CRYSTAL-STRUCTURE
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/S0022-328X(99)00565-3

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=PF 6 −, BF 4 − or ClO 4 −), 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][PF 6] acts as an excellent catalyst in the reduction of m-chloroacetophenone, giving the corresponding optical alcohols in 99% yield and up to 94% ee.