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Published on: November 21, 2017
Biocatalytic racemization of aliphatic, arylaliphatic, and aromatic alpha-hydroxycarboxylic acids
Silvia M Glueck1, Monika Pirker, Bettina M Nestl
1Department of Chemistry, Organic and Bioorganic Chemistry, University of Graz, Heinrichstrasse 28, A-8010 Graz, Austria.
Abstract:
[reaction: see text] Biocatalytic racemization of a range of aliphatic, (aryl)aliphatic, and aromatic alpha-hydroxycarboxylic acids was accomplished by using whole resting cells of a range of Lactobacillus spp. The mild (physiological) reaction conditions ensured an essentially "clean" isomerization in the absence of side reactions, such as elimination or decomposition. Whereas straight-chain aliphatic 2-hydroxycarboxylic acids were racemized with excellent rates (up to 85% relative to lactate), steric hindrance was observed for branched-chain analogues. Good rates were observed for aryl-alkyl derivatives, such as 3-phenyllactic acid (up to 59%) and 4-phenyl-2-hydroxybutanoic acid (up to 47%). In addition, also mandelate and its o-chloro analogue were accepted at a fair rate (45%). This biocatalytic racemization represents an important tool for the deracemization of a number of pharmaceutically important building blocks.
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