A mild, efficient and improved protocol for the synthesis of novel indolyl crown ethers, di(indolyl)pyrazolyl methanes and 3-alkylated indoles using H4[Si(W3O10)3]

Efficient electrophilic substitution reactions of indoles with various aldehydes proceed smoothly in acetonitrile using heteropoly acid (H-4[Si(W3O10)(3)]) to afford the corresponding new indolyl crown ethers and di(indolyl)pyrazolyl methanes. H-4[Si(W3O10)(3)] is also found to catalyze the Michael addition of indoles to alpha,beta-unsaturated compounds for the synthesis of 3-alkylated indoles. (c) 2005 Elsevier Ltd. All rights reserved.