Racemization of secondary alcohols catalyzed by ruthenium: Application to chemoenzymatic dynamic resolution

• Published in: Tetrahedron: Asymmetry
• Main Authors: Merabet-Khelassi, Mounia, Vriamont, Nicolas, Aribi-Zouioueche, Louisa, Riant, Olivier
• Other Authors: UCL - SST/IMCN/MOST - Molecules, Solids and Reactivity
• Format: Article in Journal/Newspaper
• Language: English
• Published: Pergamon 2011
• Subjects: 1 phenylethanol; Acetic acid ethyl ester; Catalysis; Catalyst; Chemical structure; Enantioselectivity; Priority journal; Racemization; Reaction analysis; Alcohol derivative; Benzyl derivative; Ligand; Ruthenium; Triacylglycerol lipase; Article; Biotransformation; Candida antarctica; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/2078.1/107737; https://doi.org/10.1016/j.tetasy.2011.10.007

In this paper, we have shown that the [RuCl2(p-cymene)] 2 complex associated with simple hemisalen ligands is able to racemize (S)-1-phenylethanol. The influence on the racemization process of the ligand's structure as well as the nature of a co-catalyst have been evaluated and optimized. This [RuCl2(p-cymene)]2/Ligand/TEMPO racemization system was then associated with the Candida Antarctica B lipase in order to carry out dynamic kinetic resolution experiments on rac-phenylethanol. This led us to identify the best conditions for effective DKR, which was then applied to various secondary benzylic and aliphatic alcohols. It was thus possible to obtain (R)-1-cyclohexylethyl acetate from rac-1-cyclohexylethanol in quantitative conversion and with high enantioselectivity (98%). © 2011 Elsevier Ltd. All rights reserved.