Ru‐(Phosphine‐Oxazoline) Complexes as Effective, Industrially Viable Catalysts for the Enantioselective Hydrogenation of Aryl Ketones

Abstract

Complexes prepared in situ from RuCl 2 (PPh 3 ) 3 and chiral phosphine-oxazoline ligands are effective catalysts for the hydrogenation of various aryl ketones with ees up to 99% and substrate to catalyst ratios of 10,000 -50,000; the reaction tolerates high substrate concentrations and a pilot process has been developed for the hydrogenation of 3,5-bistrifluoromethyl acetophenone.

Ferrocene-derived P,N ligands: synthesis and application in enantioselective catalysis

“…Ligand 27 also proved to be effective in the rutheniumcatalyzed hydrogenation of aryl ketones. High enantioselectivities (up to 99% ee) were obtained with excellent turnover numbers (TON, up to 50,000) [74,75]. In sharp contrast with the catalyst system of Noyori, [76] these complexes contain no N-H group, suggesting a mechanism with a classical C = O coordination-insertion of H 2 .…”

Osmium Pyme Complexes for Fast Hydrogenation and Asymmetric Transfer Hydrogenation of Ketones

“…[5] By employment of 1-substituted Pyme ligands (RPyme; R = Me, tBu, Ph), we have recently isolated the complexes cis-[RuCl 2 A C H T U N G T R E N N U N G (Josiphos)A C H T U N G T R E N N U N G (RPyme)] which are among the most active catalysts for the asymmetric TH of a variety of aryl ketones. [6] It is worth noting that few compounds, namely [RuCl 2 (PP)(NN)] (PP = diphosphane; NN = Pyme, [5d, 7] diamine [3,8] ), [RuCl(NN)A C H T U N G T R E N N U N G (arene)], [4b, 9] [RuCl 2 -A C H T U N G T R E N N U N G (PPh 3 )(oxazoline)], [10] Ru-Binap, [11] and (cyclopentadienone)Ru carbonyl complexes, [12] catalyze both the asymmetric TH and HY of carbonyl compounds. Despite the extensive work on ruthenium-based catalysts, much less attention has been directed towards iron [13] and osmium [13e, 14] congeners, the activity of which appears lower than that of the well-established ruthenium catalysts.…”

Half‐Sandwich η5‐Indenyl‐ and η6‐Areneruthenium(II) Complexes Bearing the Chiral Ligand (4S)‐2‐[(Sp)‐2‐(Diphenylphosphanyl)ferrocenyl]‐4‐(methylethyl)oxazoline (FcPN)

“…Hybrid hemilabile phosphorus-nitrogen ligands are also gaining increasing relevance in coordination and organometallic chemistry since they can reversibly create and/or occupy a vacant coordination site at the metal. [5] In particular, ruthenium complexes containing chiral phosphanylferrocenyloxazoline ligands have proven to be good catalysts in hydrogenation, [6] hydrosilylation, [7] and transfer hydrogenation [8,9] of ketones, imines and ketoximes. However, most of the active species are formed in situ and therefore their coordination chemistry has been scarcely studied.…”

“…However, most of the active species are formed in situ and therefore their coordination chemistry has been scarcely studied. The only isolated ruthenium(II) derivatives with FcPN ligands are either five-coordinate, such as [RuCl 2 {κ 2 (P,N)-FcPN}(PPh 3 )], [9] or octahedral complexes, such as [RuX 2 6 ] [dppm = bis(diphenylphosphanyl)methane]. [10,11] It is interesting to note that no halfsandwich species have been described to date.…”