Iron-Palladium Association in the Preparation of Indoles and One-Pot Synthesis of Bis(indolyl)methanes
Résumé
ndoles were prepared by annulation of the parent alkynylanilines with the use of a new FeCl3-PdCl2 catalytic combination. High yields were obtained by using low loadings of the transition-metal complex (FeCl3-PdCl2: 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 FeCl3 acts both as a cooxidant and a Lewis acid are described.