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Updated: Apr 27, 2026

Free Radicals in Chemical Biology: from Chemical Behavior to Biomarker Development
Published on: April 15, 2013
cis-trans Isomerization of silybins A and B
Michaela Novotná1, Radek Gažák1,2, David Biedermann1
1Institute of Microbiology, v.v.i. AS CR, Vídeňská 1083, Prague 4, CZ-14220, Czech Republic.
Abstract:
Methods were developed and optimized for the preparation of the 2,3-cis- and the 10,11-cis-isomers of silybin by the Lewis acid catalyzed (BF3∙OEt2) isomerization of silybins A (1a) and B (1b) (trans-isomers). The absolute configuration of all optically pure compounds was determined by using NMR and comparing their electronic circular dichroism data with model compounds of known absolute configurations. Mechanisms for cis-trans-isomerization of silybin are proposed and supported by quantum mechanical calculations.
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