Domino C-N Bond Formation via a Palladacycle with Diaziridinone. An Approach to Indolo[3,2-b]indoles.

Palladium-catalyzed C-N bond formation is one of the widely used transformations for the synthesis of structurally diverse N-heterocycles. This work describes an efficient palladium-catalyzed multiple-C-N bond formation reaction for the synthesis of highly π-conjugated N-heterocycles, indolo[3,2-b]indoles with di-tert-butyldiaziridinone. The reaction likely proceeds through the initial formation of an indole-fused palladacycle by nucleophilic aminopalladation and subsequent bisamination to give indolo[3,2-b]indoles.