Diammonium Hydrogen Phosphate as an Efficient and Inexpensive Catalyst for the Synthesis of Bis(indolyl)methanes under Solvent-Free Conditions

Bis(indolyl)methanes were synthesized by the reaction of indole derivatives and aromatic andaliphatic aldehydes in the presence of diammonium hydrogen phosphate as a solid catalystunder solvent-free conditions. This methodologyoffers significant improvements for the synthesis of bis(indolyl) methanes with regard to the yield of products, simplicity in operation, and green aspects by avoiding toxic catalysts and solvents