Chemical-Microbiological Synthesis of 6β-Eudesmanolides from 11-Hydroxyl Derivatives obtained by Rhizopus nigricans cultures: Synthesis of 6β-Dendroserins.

Article abstract of DOI:10.1016/S0040-4020(01)86290-6

The relationship between the structure of the substrates and the action of the fungus Rhizopus nigricans has been studied in order to obtain, in the highest possible yield, 11-hydroxyl derivatives which were dehydrates to the "exo" position, hydroborated with 9-BBN and oxidized with RuH2(PPh3)4 to give 11-R and 11-S-6-epi-dendroserin.In course of the biotransformation processes, 8α-hydroxyl and 7α-hydroxyl derivatives were also obtained, as well as the oxidation of the hydroxyl groups at C-1, an unusual process with Rhizopus nigricans.We have proved that the eudesmanones are more easily hydroxylated at C-11 than the hydroxyeudesmane compounds.Key Words: Biotransformation; 6β-eudesmanolides; 11-hydroxyeudesmanes; Rhizopus nigricans