Why p‐Cymene? Conformational Effect in Asymmetric Hydrogenation of Aromatic Ketones with a η⁶‐Arene/Ruthenium(II) Catalyst

Abstract

The global reaction route mapping (GRRM) methods conveniently define transition states in asymmetric hydrogenation and transfer hydrogenation of aromatic ketones via the [RuH{(S,S)-TsNCH(C6 H5 )CH(C6 H5 )NH2 }(η(6) -p-cymene)] intermediate. Multiple electrostatic CH/π interactions are the common motif in the preferred diastereometric structures.

The Development of Phosphine‐Free "Tethered" Ruthenium(II) Catalysts for the Asymmetric Reduction of Ketones and Imines

“…The η 6 ‐arene ring is typically benzene, p ‐cymene, 1,3,5‐trimethylbenzene or hexamethylbenzene. However, it is catalyst 2 , derived from N ‐tosyl‐1,2‐diphenylethylene‐1,2‐diamine (TsDPEN) and where the arene is p ‐cymene,8 that is the most widely applied example 9. These complexes are commonly referred to as Noyori catalysts in the context of ATH.…”

“…This complex then abstracts two hydrogen atoms from the donor, typically isopropanol, formic acid/triethylamine (FA/TEA) mixture or sodium formate, to form hydride 4 (Figure ). The isolation and characterisation of the 16‐electron complex 3 and the hydride derivative 4 ,7 coupled to mechanistic studies10–12 and several computational investigations,8,13 have now provided an insight into the process of asymmetric induction. Importantly, complex 4 is formed predominantly as one diastereoisomer, rendering the Ru atom chiral and of one configuration.…”

Stereoarrayed CF3‐Substituted 1,3‐Diols by Dynamic Kinetic Resolution: Ruthenium(II)‐Catalyzed Asymmetric Transfer Hydrogenation

“…As suggested by Noyori et al [9] and by us [5a] for aryl ketones and trifluoromethyl ketones,respectively,the stereochemical control is enforced by either as tabilizing CH-p or CH-F attractive electrostatic interaction. In the present case, the CH-F interaction overrides the CH-p interaction in the first step,thus leading to the intermediate formation of (S)-2a on the way to anti-3a ( Figure 3).…”

Study of Potential Energy Surfaces towards Global Reaction Route Mapping

“…The story of GRRM will be continued. Applications to excited states and photochemical processes,35,53,170 and also to various aspects of chemical reactions have been in progress 171–179. Developments in computational technologies extend the area of GRRM.…”