An efficient synthesis of benzoxazoles using silica-supported tin exchanged silicotungstic acid catalyst

An efficient method for the preparation of benzoxazoles by reacting aminophenols with orthoesters in the presence of silica-supported tin exchanged silicotungstic acid catalyst under mild conditions with high yield and selectivity is demonstrated. The catalysts were characterized by FT-IR and pyridine adsorbed FT-IR. The catalyst exhibited consistent activity upon recycling and is highly active compared to other catalysts. The role of Lewis acidity of the catalysts and plausible reaction mechanism is presented.

Graphical abstractAn efficient heterogeneous silica-supported tin exchanged silicotungstic acid catalyst is demonstrated for the synthesis of benzaxazoles by reaction of amonophenols with orthoesters under mild reaction conditions.Figure optionsDownload full-size imageDownload high-quality image (31 K)Download as PowerPoint slide