Efficient kinetic resolution of ( R,S)‐1‐trimethylsilylethanol via lipase‐mediated enantioselective acylation in ionic liquids

• Published in: Chirality
• Main Authors: Lou, Wen‐Yong, Zong, Min‐Hua
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2006
• Subjects: Antarc*; Antarctica
• Online Access: http://dx.doi.org/10.1002/chir.20307; http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fchir.20307; https://onlinelibrary.wiley.com/doi/pdf/10.1002/chir.20307

Abstract Efficient enantioselective acylation of ( R , S )‐1‐trimethylsilylethanol {( R , S )‐1‐TMSE} with vinyl acetate catalyzed by immobilized lipase from Candida antarctica B (i.e., Novozym 435) was successfully conducted in ionic liquids (ILs). A remarkable enhancement in the initial rate and the enantioselectivity of the acylation was observed by using ILs as the reaction media when compared to the organic solvents tested. Also, the activity, enantioselectivity, and thermostability of Novozym 435 increased with increasing hydrophobicity of ILs. Of the six ILs examined, the IL C 4 MIm·PF 6 gave the fastest initial rate and the highest enantioselectivity, and was consequently chosen as the favorable medium for the reaction. The optimal molar ratio of vinyl acetate to ( R , S )‐1‐TMSE, water activity, and reaction temperature range were 4:1, 0.75, and 40 –50°C, respectively, under which the initial rate and the enantioselectivity ( E value) were 27.6 mM/h and 149, respectively. After a reaction time of 6 h, the ee of the remaining ( S )‐1‐TMSE reached 97.1% at the substrate conversion of 50.7%. Additionally, Novozym 435 was effectively recycled and reused in C 4 MIm·PF 6 for five consecutive runs without substantial lose in activity and enantioselectivity. The preparative scale kinetic resolution of ( R , S )‐1‐TMSE in C 4 MIm·PF 6 is shown to be very promising and useful for the industrial production of enantiopure ( S )‐1‐TMSE. Chirality 2006. © 2006 Wiley‐Liss, Inc.