Amino Alcohol Coordination in Ruthenium(II)-Catalysed Asymmetric Transfer Hydrogenation of Ketones

Abstract

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A Facile Synthesis of a Wide Variety of Cationic Ruthenium Hydrido-Arene Complexes of binap (=1,1′-Binaphthalene-2,2′-diylbis(diphenylphosphane)) and MeObiphep (=6,6′-Dimethoxybiphenyl-2,2′-diylbis(diphenylphosphane))

“…In many cases the Ru-catalyst precursor contains an h 6 -arene ligand [4] [7] [11] [14 ± 16], together with nitrogen or phosphorus ligands. These complexes can be prepared by allowing commercially available Cl-bridged h 6 -arene (e.g., p-cymene) Ruthenium complexes to react with monodentate or bidentate N-or P-donors to afford catalyst precursors in good yield [17a] (see Scheme 1).…”

Bulky Monodentate Phosphoramidites in Palladium‐Catalyzed Allylic Alkylation Reactions: Aspects of Regioselectivity and Enantioselectivity

“…[66,67] (R)-3,3'-Trimethylsilyl-1,1'-binaphtyl-2,2'-diol was synthesised as reported by Buisman et al [68] N-Benzyl-(1R,2S)-norephedrine was synthesised by a literature procedure. [69] [{Pd(…”

Catalytic Asymmetric Transfer Hydrogenation of Ketones Using [Ru(p-cymene)Cl2]2 with Chiral Amino Alcohol Ligands

“…Wills et al [26][27][28][29] have investigated transfer hydrogenation of various ketones using (1R,2S)-cis-1-aminoindan-2-ol as a ligand (Scheme 1, B) with high asymmetric induction (70-98%). Van Leeuwen et al [30,31] have investigated various substituted amino ethanol and norephedrine based ligands and tetradentate ligands for transfer hydrogenation of ketones. Best results (88% conversion of acetophenone with 95% ee) were obtained using (1R,2S)-N-benzyl-norephedrine as a ligand (Scheme 1, C).…”

“…Scheme 4 Proposed 18-electron catalyst precursor formed by reaction of Ru(arene) complex and amino alcohol ligand [17,30] Catalytic Asymmetric Transfer Hydrogenation of Ketones 235 alcohol ligand and also the effect of additional chiral center outside the coordination sphere on the conversion and chiral selectivity. As a first step transfer hydrogenation of acetophenone was investigated using Ru, Rh and Ir metal complexes as catalyst precursors with 1R,2S-ephedrine (Ep) and amino alcohols prepared as ligands and the results are presented in Table 1.…”

“…From the literature, it can be clearly seen that amino alcohol structure and substituents significantly affect conversion as well as selectivity, though the exact reasons for the observed effects (steric and electronic) are still not understood completely [9,30,31,35]. From the literature, it was observed that most of the amino alcohol derivatives investigated have chiral centers on adjacent carbon atoms and are mostly derived from ephedrine or norephedrine.…”