Palladium-catalyzed oxidative cyclization of aniline-tethered alkylidenecyclopropanes with O: a facile protocol to selectively synthesize 2- and 3-vinylindoles.

A novel palladium-catalyzed oxidative cyclization of aniline-tethered alkylidenecyclopropanes using molecular oxygen as the terminal oxidant through β-carbon elimination of aminopalladation intermediates is disclosed. The reaction opens up an effective way to obtain a series of 2- and 3-vinylindoles which are important synthetic intermediates in many natural indole derivatives.