Dynamic Kinetic Resolution of a Wide Range of Secondary Alcohols: Cooperation of Dicarbonylchlorido(pentabenzylcyclopentadienyl)ruthenium and CAL‐B

Abstract

The substrate scope in the dynamic kinetic resolution of secondary alcohols was studied by using 31 structurally different alcohols and isopropenyl acetate in the presence of dicarbonylchlorido(pentabenzylcyclopentadienyl)ruthenium and Candida antarctica lipase B (Novozym 435, CAL-B) in toluene. The enzyme and the ruthenium complex were shown to function in a highly compatible manner allowing the conversion of the racemic alcohols into the (R)-acetates

Lipases: Valuable catalysts for dynamic kinetic resolutions

“…Kim et al, 2013;S. Kim et al, 2013;Ko et al, 2007;Koh et al, 1999;Krumlinde et al, 2009;Larsson et al, 1997;Lee et al, 2000;Leijondahl et al, 2009;Lihammar et al, 2011;Mangas-Sánchez et al, 2009;Martín-Matute et al, 2004, 2006Mavrynsky et al, 2009Mavrynsky et al, , 2013Merabet-Khelassi et al, 2011;Norinder et al, 2007;Päiviö et al, 2011;Riermeier et al, 2005;Träff et al, 2008Träff et al, , 2011Warner et al, 2012). These catalysts are homogeneous under the conditions employed in DKR reactions and present differences regarding scope, mode of activation, requirement of additives, compatibility with acyl donors, stability, efficiency and cost.…”

Tuning of the Electronic Properties of a Cyclopentadienylruthenium Catalyst to Match Racemization of Electron‐Rich and Electron‐Deficient Alcohols

“…After chromatography the fractions were pooled, evaporated to dryness and dried in vacuo. 1 H NMR, 13 C NMR, and 19 F NMR spectroscopy were recorded on Bruker Avance 400 MHz instrument. Chemical shifts are reported in ppm, relative to TMS ( 1 H; internal standard, d H = 0.00 ppm) or solvent peaks ( 1 H: CDCl 3 d H = 7.26 ppm and [D 6 ]DMSO d H = 2.50 ppm; 13 C: CDCl 3 d C = 77.0 ppm and [D 6 ]DMSO d C = 39.5 ppm).…”

“…which allow for a highly efficient DKR of alcohols at room temperature. In particular catalysts 4 and 7 give fast racemization reactions at room temperature and these systems have been applied to DKR reactions of various secondary alcohols [12,13] and they allow for scale-up to 100 g-1 kg scales. [14] Recently, Kim and Park reported on substituent effects on the catalytic activity of [{h 5 -Ar 4 C 4 COC(=O)Ar}Ru-(CO) 2 Cl] in racemization of secondary alcohols.…”

Why Leave a Job Half Done? Recent Progress in Enzymatic Deracemizations

“…Other ruthenium catalysts that have recently been employed in dynamic protocols are derivatives 3-6 (Scheme 2b). While 3 has been effectively utilized in the racemization of a series of aromatic and aliphatic secondary alcohols, [33] catalyst 4 has been applied to the DKR of an aliphatic [34] and an allylic [35] sec-alcohol. Additionally, Ru-complex 5 was used to synthesize enantioenriched 1,2-diarylethanols, [36] and 6 has achieved excellent DKR protocols together with a salenol-derived ligand and TEMPO to deracemize 1-phenylethanol, [37] or in combination with 1,4-bis(diphenylphosphino)butane as ligand in order to obtain enantioenriched benzoins ( Figure 1).…”