Practical synthesis of the rebeccamycin aglycone and related analogs by oxidative cyclization of bisindolylmaleimides with a Wacker-type catalytic system

Article abstract of DOI:10.1016/S0040-4039(01)02021-4

Using atmospheric O₂ as the stoichiometric oxidant, Pd²⁺/Cu²⁺-catalyzed oxidative cyclization of the corresponding bisindolylmaleimides provides the rebeccamycin aglycone and related indolo[2,3-a]pyrrolo[3,4-c]carbazoles in 58-88% yield. The method is operationally simple and utilizes readily prepared substrates, making the process amenable to scaleup.