Total syntheses of (+/-)-spiroindimicins B and C enabled by a late-stage Schollkopf-Magnus-Barton-Zard (SMBZ) reaction

The spiroindimicins are a family of structurally unprecedented alkaloids isolated from the deep-sea-derived marine actinomycete Streptomyces sp. SCSIO 03032. The total syntheses of (+/-)-spiroindimicins B and C are disclosed, the first of any member of this family. Central to the successful strategy was installing the spirocentre using a mild intramolecular Heck reaction, the assembly of a pentacyclic spirobisindole by Fischer indolization and a late-stage Schollkopf-Magnus-Barton-Zard (SMBZ) reaction to construct the trisubstituted pyrrole.