Exploration of the biomimetic synthesis of indole-diterpene mycotoxins: an unexpected cascade reaction during the attempted synthesis of emindole SB

The key step in an attempted biomimetic synthesis of the indole-diterpene mycotoxin emindole SB delivers the pentacyclic compound resulting from 6-endo cyclisation instead of the product arising by the 5-exo reaction required in the putative biosynthetic pathway.