Shifting the equilibrium of a biocatalytic cascade synthesis to enantiopure epoxides using anion exchangers
作者:Joerg H. Schrittwieser、Iván Lavandera、Birgit Seisser、Barbara Mautner、Jeffrey H. Lutje Spelberg、Wolfgang Kroutil
DOI:10.1016/j.tetasy.2009.02.035
日期:2009.3
successfully employed to shift the equilibrium of a one-pot, two-step, two-enzymecascade reaction affording enantiopureepoxides starting from prochiral α-chloroketones. The α-chloroketones were asymmetrically reduced employing an alcohol dehydrogenase and then transformed further to the corresponding epoxides employing halohydrin dehalogenases. Each epoxide enantiomer could be obtained with up to 93% conversion
Azidolysis of epoxides catalysed by the halohydrin dehalogenase from Arthrobacter sp. AD2 and a mutant with enhanced enantioselectivity: an (S)-selective HHDH
Halohydrin dehalogenase from Arthrobacter sp. AD2 catalysed azidolysis of epoxides with high regioselectivity and low to moderate (S)-enantioselectivity (E = 1-16). Mutation of the asparagine 178 to alanine (N178A) showed increased enantioselectivity towards styrene oxide derivatives and glycidyl ethers. Conversion of aromatic epoxides was catalysed by HheA-N178A with complete enantioselectivity, however the regioselectivity was reduced. As a result of the enzyme-catalysed reaction, enantiomerically pure (S)-beta-azido alcohols and (R)-alpha-azido alcohols (ee >= 99%) were obtained. (C) 2016 Published by Elsevier Ltd.
Resolution of a chiral ester by lipase-catalyzed transesterification with polyethylene glycol in organic media
作者:J. Shield Wallace、Kristin B. Reda、Mark E. Williams、Cary J. Morrow