Issue 91, 2016

Aqueous biphasic iron-catalyzed asymmetric transfer hydrogenation of aromatic ketones

Abstract

For the first time, an iron(II) catalyst is used in the biphasic asymmetric transfer hydrogenation (ATH) of ketones to enantioenriched alcohols employing water and potassium formate as the proton and hydride source, respectively. The precatalyst [FeCl(CO)(P–NH–N–P)]BF4 (P–NH–N–P = (S,S)-PPh2CH2CH2NHCHPhCHPhNCHCH2PPh2) in the organic phase with the substrate is activated by base to produce a system that rivals the best ruthenium biphasic ATH catalysts in activity but not enantioselectivity. Biorenewable 2-methyltetrahydrofuran as a cosolvent and biodegradable TWEEN80 as a surfactant were added to the reaction mixture to greatly decrease the mass-transfer limitations caused by the biphasic reaction mixture. The enantioselectivity of the reduction was as high as 76% depending on the substitution pattern of the arylketone employed. NMR studies verified the formation of an iron hydride [FeH(CO)(PPh2CH2CH2NHCHPhCHPhNCHCHPPh2)] intermediate as was observed in our 2-propanol-based ATH studies.

Graphical abstract: Aqueous biphasic iron-catalyzed asymmetric transfer hydrogenation of aromatic ketones

Supplementary files

Article information

Article type
Paper
Submitted
08 Sep 2016
Accepted
09 Sep 2016
First published
09 Sep 2016
This article is Open Access
Creative Commons BY license

RSC Adv., 2016,6, 88580-88587

Aqueous biphasic iron-catalyzed asymmetric transfer hydrogenation of aromatic ketones

K. Z. Demmans, O. W. K. Ko and R. H. Morris, RSC Adv., 2016, 6, 88580 DOI: 10.1039/C6RA22538A

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