Asymmetric Hydrogenation of α-Chloro Aromatic Ketones Catalyzed by η⁶-Arene/TsDPEN−Ruthenium(II) Complexes

Abstract

Asymmetric hydrogenation of various alpha-chloro aromatic ketones with Ru(OTf)(TsDPEN)(eta6-arene) (TsDPEN = N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine) produces the chiral chlorohydrins in up to 98% ee. This reaction can be conducted even on a 206-g scale. The hydrogenation of an alpha-chloro ketone with a phenol moiety has been utilized for the synthesis of (R)-norphenylephrine without protection-deprotection operations. [reaction: see text].

Activation and Deactivation of Cp*Ir(TsDPEN) Hydrogenation Catalysts in Water

“…[2,4] Recently it was discovered that these amido complexes can be easily converted into catalysts for direct hydrogenation. [5][6][7][8][9] The key insight is that protonation of 16e diamido complexes generates cationic derivatives that are sufficiently electrophilic to activate H 2 directly. [10,11] Upon exposure to H 2 , these cationic complexes convert to amino hydrides that in turn reduce ketones and imines following the pathway for traditional TH catalysis (Scheme 1).…”

Hydrogenation of Quinolines Using a Recyclable Phosphine‐Free Chiral Cationic Ruthenium Catalyst: Enhancement of Catalyst Stability and Selectivity in an Ionic Liquid

“…Considering that methanol has been successfully used in the asymmetric hydrogenation of ketones by Noyori and coworkers, [9] we first examined the asymmetric hydrogenation Scheme 1. Asymmetric hydrogenation of quinoline 2 a catalyzed by Ru/ Ts-dpen catalysts.…”

“…[8] Recently, Noyori and co-workers reported that chiral h 6 -arene/Ntosylethylenediamine-Ru II complexes (which are known as excellent catalysts for asymmetric transfer hydrogenation, for example Ru/Ts-dpen) can be used for the asymmetric hydrogenation of prochiral ketones under slightly acidic conditions. [9] Inspired by this important breakthrough and following our continued pursuit of developing effective and environmentally benign catalyst systems for asymmetric hydrogenations, [10] herein we report a practical and efficient catalyst system of Ru/Ts-dpen in [BMIM]PF 6 (BMIM = 1-nbutyl-3-methylimidazolium) for the enantioselective hydrogenation of quinolines (Scheme 1).…”

Synthesis of polyethylene glycol supported chiral monosulfonamide and its application in asymmetric transfer hydrogenation of prochiral ketones

“…The conversions were determined by GC analysis. Enantiomeric excesses were determined by optical rotation measurements [22,23]. As shown in Table 1, for various ketones, including 2-substituted, electron-rich, and electron-deficient variants, the catalyst afforded good to excellent conversions and enantioselectivities.…”