Pauson–Khand reaction of 2-ethynyl aniline: Synthesis of fused ring indoles by organocuprate conjugate addition followed by spontaneous dehydration

The Pauson–Khand reaction of 2-ethynyl aniline gives the expected cyclopentenone product, with the aniline alpha to the ketone. Treatment with organocuprates gives not the simple conjugate addition product, but the indole derived from an addition–cyclisation–nucleophilic attack sequence.