Chemical-Microbiological Synthesis of Cryptomeridiol Derivatives by Gliocladium roseum:  Semisynthesis of 11-Hydroxyeudesmanolides

Biotransformations of 4α- and 4β-hydroxyeudesmane derivatives by the filamentous fungus Gliocladium roseum were achieved. Hydroxylation at C-11 was the main action of this microorganism, producing new cryptomeridiol (12 and 14) and 4-epi-cryptomeridiol derivatives (6 and 7), respectively, in good yields. The biotransformation activity of G. roseum toward 4β-hydroxyeudesmane was focused on the isopropyl moiety, but more scattered on the 4α-hydroxylated derivative, acting in both the “A” and “B” rings and the isopropyl group of the molecule. Semisyntheses of 11-hydroxyeudesmanolides from the isolated 11,12-dihydroxylated metabolites were also accomplished and used in assigning the stereochemistry of hydroxylation.