A green and convenient protocol for the synthesis of diarylmethanes via a one-pot, three-component reaction catalyzed by a novel silica tungstic acid (STA) under solvent-free conditions

A cost-effective and eco-friendly synthesis of diarylmethanes derivatives has been developed through the Mannich type Friedel–Crafts addition reaction of tertiary aromatic amine formaldehydes with β-naphthol/indole using silica-supported tungstic acid (STA) as a recyclable heterogeneous acid catalyst in solvent-free condition. Here, we proposed two schemes using the same catalyst. The effects of different solvents have been studied and a comparison of silica-supported tungstic acid with different acid catalysts has also been made.