Studies in terpenoid biosynthesis. Part 35. Biosynthetic sequences leading to the diterpenoid aphidicolin in Cephalosporium aphidicola
[17-14C]-Labelled samples of 18-hydroxyaphidicol-16-ene,3α, 18-dihydroxyaphidicol-l6-ene, 16β,17 and 16β,18-dihydroxyaphidicolane, and 3α, 16β, 18- and 16β,17,18-trihydroxyaphidicolane have been prepared from aphidicolin and shown to be incorporated into aphidicolin by Cephalosporium aphidicola to the extent of 0.86, 16.4, 3.5, 20.5, 52.6, and 16.9%, respectively. These results suggest that although the major pathway of aphidicolin biosynthesis involves the 16β-alcohols, the 16-enes may also be utilized whilst a metabolic grid relationship may exist between the variously hydroxylated 16β-alcohols.