Base-catalyzed oxidation of silybin and isosilybin into 2,3-dehydro derivatives

R. Gazak (1) , Patrick Trouillas (2) , D. Biedermann (1) , K. Fuksova (1) , P. Marhol (1) , Marek Kuzma (3) , Vladimír Křen (4)

1 MBU / CAS - Institute of Microbiology of the Czech Academy of Sciences [Prague, Czech Republic]
2 LCSN - Laboratoire de Chimie des Substances Naturelles
3 Institute of Microbiology
4 Centre of Biocatalysis and Biotransformation, Institute of Microbiology

The base-catalyzed oxidation of the flavonolignans, silybin, and isosilybin into the corresponding 2,3-dehydro derivatives has been studied and optimized. Various bases, solvents, and reaction conditions were tested to achieve the best yields. The influence of water on the course of the reaction was also observed. It was found that this oxidation reaction was probably based on the disproportionation of the (iso)silybin (or some intermediate) molecule, as the reaction also proceeds in the absence of oxygen. We report here for the first time the preparation of optically pure 2,3-dehydroisosilybins A and B.

Domaines: Chimie; Chimie organique

R. Gazak, Patrick Trouillas, D. Biedermann, K. Fuksova, P. Marhol, et al.. Base-catalyzed oxidation of silybin and isosilybin into 2,3-dehydro derivatives. Tetrahedron Letters, 2013, 54 (4), pp.315-317. ⟨10.1016/j.tetlet.2012.11.049⟩. ⟨hal-00937874⟩