Triarylaminium salt facilitated Friedel-Crafts reaction of indoles with enamides and vinyl ethers

Commercially available stable radical cation triarylaminium salt can be used as an efficient initiator for Friedel-Crafts reaction of indoles with enamides to regioselectively construct complex indole derivatives and for double Friedel-Crafts reaction of indoles with vinyl ethers to offer 3,3'-Bis(indolyl)alkane derivatives. The ready availability of the starting materials and the usefulness of the products make this strategy attractive. (C) 2013 Elsevier Ltd. All rights reserved.