ZrOCl2•8H2O/silica gel as a new efficient and a highly water-tolerant catalyst system for facile condensation of indoles with carbonyl compounds under solvent-free conditions

ZrOCl(.)8H(2)O/sitica gel as a highly water-tolerant catalyst system has been applied for the preparation of bis(indolyl)methanes via electrophilic substitution reactions of indoles with carbonyl compounds under solvent-free conditions. The yields of the isolated products are from good to excellent. (c) 2006 Published by Elsevier B.V.