Studies in terpenoid biosynthesis. Part XI. Stereochemistry of some stages in trichothecane biosynthesis
The exo C-4β hydrogen atom of 15-acetoxy-12,13-epoxytrichothec-9-en-3-one (5) has been shown to exchange and this has been used to show that this hydrogen atom in calonectrin is derived from a 2-pro-R mevalonoid hydrogen. Hydroxylation at C-3 in calonectrin biosynthesis and at C-4 in trichothecolone has been shown to proceed with retention of configuration.