Divergent reactivity of an indole glucosinolate yields Lossen or Neber rearrangement products: the phytoalexin rapalexin A or a unique β-D-glucopyranose fused heterocycle

Transformation of 1-t-Boc-4-methoxyindole-3-glucosinolate under acidic conditions yielded the potent phytoalexin rapalexin A, providing its first biomimetic synthesis via Lossen type rearrangement, while a novel 1-thioimidocarbonyl-beta-D-glucopyranose heterocyclic system was obtained under basic conditions via Neber type rearrangement.