Biocatalytic Cascade for the Synthesis of Enantiopure β-Azidoalcohols and β-Hydroxynitriles
作者:Joerg H. Schrittwieser、Iván Lavandera、Birgit Seisser、Barbara Mautner、Wolfgang Kroutil
DOI:10.1002/ejoc.200900091
日期:2009.5
one-pot reaction sequence starting from prochiral α-chloroketones leading to enantiopure β-azidoalcohols and β-hydroxynitriles is described. Asymmetric bioreduction of α-chloroketones by hydrogen transfer catalysed by an alcohol dehydrogenase (ADH) established the stereogenic centre in the first step to furnish enantiopure chlorohydrin intermediates. Subsequent biocatalysed ring closure to the epoxide
Three building blocks 2, 3 and 4 for the total synthesis of microsclerodermins (1) have been efficiently constructed from carboxylic acid 6, 14, and 20, respectively.
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.