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 the 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 condition 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.