Racemization of secondary alcohols catalyzed by ruthenium: application to chemoenzymatic dynamic resolution
作者:Mounia Merabet-Khelassi、Nicolas Vriamont、Louisa Aribi-Zouioueche、Olivier Riant
DOI:10.1016/j.tetasy.2011.10.007
日期:2011.10
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%). (C) 2011 Elsevier Ltd. All rights reserved.