GREEN SYNTHESIS OF BIS (INDOLYL) METHANES IN AQUEOUS MEDIUM CATALYZED BY PLANT EXTRACT

Application of aqueous extract of Sapindus trifoliatus fruit has been explored to catalyze the reaction of indole with differently substituted aromatic aldehydes to afford bis(indolyl)methanes. Bis(indolyl)methanes are very useful scaffolds in the synthesis of pharmacologically active molecules. Literature abounds with various strategies to synthesize bis(indolyl)methanes. Many of them suffer from certain disadvantages. Hence there is scope and need to search for better alternatives to metamorphose bis(indolyl)methanes. We devised a protocol for the synthesis of bis(indolyl)methanes that offered many advantages over reported ones. The reaction was carried out in aqueous medium at room temperature and the catalyst was used almost in its natural form. This is the most economical and entirely green synthetic route to bis(indolyl)methanes as the catalyst material costs only $2 per kg; occurs naturally in plenty in many parts of the world; is in harmony with environment as it is of natural origin and does not harm humans even if consumed (in small quantity). The product formed using this approach was separated by filtration, without use of any organic solvent. The catalytic efficiency of the extract was partly due to its acidic nature (pH = 3.86) and partly due to its behavior as natural surfactant. Aqueous extracts of some other plants were used as catalyst but extract of Sapindus trifoliatus fruit showed the best efficiency in terms of yield and reaction time.