Rhodium-Catalyzed Oxidative Annulation of Hydrazines with Alkynes Using a Nitrobenzene Oxidant

Rhodium-catalyzed oxidative annulation of hydrazines with alkynes has been accomplished using 1,3-dinitrobenzene as an oxidant. A variety of hydrazines with alkynes were converted to 1-aminoindole derivatives in good to high yields. Mechanistic investigations support the idea that 1,3-dinitrobenzene serves as the oxidant during C–H activation. This is, to our knowledge, the first report of a nitrobenzene compound used as the oxidant in transition-metal-catalyzed C–H activation.