Room-Temperature Synthesis of Diindolylmethanes Using Silica-Supported Sulfuric Acid as a Reusable Catalyst Under Solvent-Free Conditions

Abstract

Efficient electrophilic substitution reactions of indoles with various aromatic and aliphatic aldehydes were carried out using a catalytic amount of H₂SO₄ · SiO₂ under solvent-free conditions to afford the corresponding bis(indolyl)methanes in excellent yields.

Keywords:

• Aldehydes
• H₂SO₄ · SiO₂
• indole
• solvent-free

Notes

^a Isolated yields after column chromatography.

^a Reactions performed with 1.0 mmol of 4-nitrobenzaldehyde, 2 mmol of indole, and 50 mg of H₂SO₄ · SiO₂ mixed for 8 min under solvent-free conditions at room temperature.

^b Isolated yields after purification.