Ru(II) pyridyl-based NNN complex catalysts for (asymmetric) transfer hydrogenation of ketones at room temperature

Asymmetric Transfer Hydrogenation of Arylketones Catalyzed by Enantiopure Ruthenium(II)/Pybox Complexes Containing Achiral Phosphonite and Phosphinite Ligands

“…Thus, the groups of Zhang [14] and Beller [15] described the use of in situ-generated ruthenium complexes, containing bis(oxazolinylmethyl)amine (ambox ligand) ( Figure 1A) [14] and pyridine(bis)imidazolines (pybim ligand) ( Figure 1B) [15], respectively. On the other hand, it has also been reported that isolated ruthenium complexes with C 1 -symmetry N,N,N donor ligands ( Figure 1C-E) [16][17][18] efficiently catalyze the asymmetric transfer hydrogenation of aryl ketones. In all of these examples, the presence of the NH functionality in the enantiopure ligand is a requisite for achieving high reactivity and enantioselectivity.…”

Ruthenium(II) complexes bearing (NNN) ligand: catalytic evaluation of different solvent-mediated coordination modes

“…[37][38][39][40] Taking into consideration the differences in both structural coordination mode, our complexes resulted less active and straightly less stereoselective in comparison with other similar catalytic systems reported in literature. 16,35,[41][42] In those systems better results might depend on the presence of an additive in formation of bimetallic 6-membered transition state or in alternative on the presence of an additional phosphine ligand known for reducing the acidity of metal center that favors the hydride transfer. Furthermore, the results obtained with our complexes, indicated that the steric hindrance around the Ru center in the transition state, deriving both from the ligand and the substrate, could affect the reactivity and the enantioselectivity of the reactions.…”

“…[8][9][10] On the other hand, there is a great interest in transition metal complexes with tridentate amine ligands, especially those containing a pyridine due to its unique electronic and steric properties. 8,[11][12][13][14][15][16][17] Some of them have good efficiency in the catalytic epoxidation reaction [18][19] and in transfer hydrogenation of aryl ketones. 20 Starting from this consideration here is reported the synthesis of a new tridentate ligand 1 (Figure 1) and the study of its different coordination modes to a ruthenium metal center.…”

Synthesis of Single‐enantiomer Bioactive Molecules: A Brief Overview

“…Organometallics are largely used in asymmetric synthesis in organic chemistry. Recently, DU et al synthesized the Ru(II) complexes and efficiently used them in transfer hydrogenation. The Ru(II) complexes bearing pyridyl‐based benzimidazolyl‐imidazolinyl tridentate NNN ligands were used in the transfer hydrogenation of ketones, giving chiral hydroxyls up to 99% yields and 97% ee values (Scheme ).…”