Efficient synthesis of biologically interesting 3,4-diaryl-substituted succinimides and maleimides: application of iron-catalyzed carbonylations.

A straightforward two-step synthesis of trans-3,4-disubstituted succinimides through a palladium-catalyzed Sonogashira reaction and an iron-catalyzed double carbonylation is described. In situ oxidative dehydrogenation gave the corresponding 3,4-diarylmaleimides. By starting from readily available aryl and heteroaryl halides, a variety of new analogues and derivatives of bioactive 3,4-bisindolylmaleimides are obtained in good yield and selectivity.