MICROBIAL OXIDATION OF TRICYCLIC SESQUITERPENOIDS CONTAINING A DIMETHYLCYCLOPROPANE RING

Calarene was oxidized by Bacillus megaterium and Diplodia gossypina to give allylic calarenols and calarendiols in which either of the geminal methyl groups of the cyclopropane ring was hydroxylated. Globulol was hydroxylated faster and in higher yields than calarene by both strains. In the case of this compound, vicinal diols were formed and, again, either of the geminal methyl groups was oxidized. Only bacterial strains caused 9-hydroxylation. Mycobacterium smegmatis produced globulol-14-exo-14-oic acid in good yields. Of the geminal methyl groups, the one in the exo-orientation was attacked preferentially by all of the strains tested. Some of the metabolites formed are stereoisomers of known natural products.