Iron–Palladium Association in the Preparation of Indoles and One‐Pot Synthesis of Bis(indolyl)methanes

Indoles were prepared by annulation of the parent alkynylanilines with the use of a new FeCl 3 –PdCl 2 catalytic combination. High yields were obtained by using low loadings of the transition‐metal complex (FeCl 3 –PdCl 2 : 2 and 1 mol‐%, respectively). One‐pot accesses to bis(indolyl)methanes and trisubstituted indoles through annulation/Friedel–Crafts alkylation and annulation/1,4‐Michael addition sequences, in which FeCl 3 acts both as a cooxidant and a Lewis acid are described.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)