A straightforward access to specific bisindole systems related to caulersin

Abstract

Two sets of starting materials were tested to trigger domino processes involving C3 insertion of indole fragments and C–C migration, thereby enabling the synthesis of a specific bisindole framework with a central troponoid core related to caulersin. The reaction between bis(indolyl)methane and methyl bromopyruvate oxime under BF₃·Et₂O-mediated conditions successfully delivered the desired product, whereas methyl 2-(hydroxyimino)-3-(1H-indol-3-yl)propanoate reacted with indole-3-carbinol to produce an unexpected cyclohept[1,2-b:5,4-b′]bisindole derivative.