Chiral pyridine-containing ligands in asymmetric catalysis

Use of tridentate TsDPEN/pyridine ligands in ruthenium-catalysed asymmetric reduction of ketones

“…Pyridine-containing ligands have also been used extensively in non-asymmetric hydrogen-transfer processes, and for hydrogen-generation from organic molecules. 13 Other applications of pyridine-containing ligands have been reported, 14 as have their applications in highly active non-asymmetric hydrogenations of ketones.…”

“…1,[6][7][8][9][10][11][12][13][14][15][16][17] Early examples include Schiff base 3 (the Ir complex of which reduced acetophenone in up to 84% ee), 8 the BINOL-derived 4 (the complex with Ru(PPh3)3Cl2 gave up to 97% ee in ATH in iPrOH), 10 as well as 2-(2'-pyridyl)pyridines, 6 phenanthrolines 7 and pyridines combined with phosphines in tridentate donor ligands. 9 More recent examples include a series of Ru(II) complexes of pyridine/phosphine tridentate ligands together with phosphines, for example 5 (gave an alcohol of 93% ee from acetophenone reduction in iPrOH), 11a reported by Yu and co-workers.…”

“…16 was likewise achieved via the corresponding imine 20 from (1R,2R)-(−)-N-p-tosyl-1,2-cyclohexanediamine (10) (Scheme 2). The synthesis of (R,R)-{2-[(pyridin-2-ylmethyl)-amino]-cyclohexyl}-carbamic acid tert-butyl ester (14) was completed by treatment of mono-Boc diamine 15 22 with 2-pyridinecaboxaldehyde (12) in CH2Cl2 to give the intermediate imine, which was reduced by NaBH4 (Scheme 3).…”

Enantioselective addition of phenylacetylene to N‐aryl arylimines catalyzed by Cu(II)‐pyridine containing N‐tosylatedaminoimine ligand complex

“…1,2 Pyridine-containing molecules, with a lone pair of electrons at the nitrogen atom, are important ligands in coordination chemistry. 3 Their special coordination chemistry and high stability toward moisture and oxygen in the atmosphere attracted a great deal of interest in chemistry. The first application of chiral pyridine-containing ligands was Ir-catalyzed transfer hydrogenation reaction reported by Zassinovich et al in 1981.…”

Synthesis and characterization of four new unsymmetrical potentially pentadentate Schiff base ligands and related Zn(II) and Cd(II) complexes

“…The synthesis of transition metal complexes of unsymmetrical Schiff bases ligands with nitrogen, oxygen and sulfur atoms is an important area of study with implications in bioinorganic chemistry [4,5,16], catalysis [17] and medical chemistry [18].…”