Convenient modification of the Leimgruber-Batcho indole synthesis: Reduction of 2-nitro-p-pyrrolidinostyrenes by the FeCl3-activated carbon-N2H4H2O system

A new catalytic system containing ferric chloride, activated carbon, and hydrazine has been proposed for the reductive cyclization of β-dialkylamino-2-nitrostyrenes to give the corresponding indoles (Leimgruber-Batcho synthesis). Various substituted indoles may be obtained in high yield under these conditions. © 2011 Springer Science+Business Media, Inc.