The totalsynthesis of the spiroindimicin family of natural products with both [5,5] and [5,6] spiro-ring skeletons was achieved via a biomimetic “dimerize-and-divert” strategy. A biocatalytic process for the oxidative dimerization of L-tryptophan was developed for the preparation of a bis-indole intermediate, which was converted to spiroindimicins via regioselective oxidative C3′−C2′′ and C3′−C4′′