Covalently anchored sulfonic acid onto silica as an efficient and recoverable interphase catalyst for the synthesis of 3,4-dihydropyrimidinones/thiones

A novel covalently anchored sulfonic acid onto the surface of silica was prepared and investigated for the Biginelli reaction. The catalyst is highly stable, completely heterogeneous and recyclable for several times. The work-up procedure is very simple and Biginelli compounds were obtained in good to excellent yields.

Graphical abstractA covalently anchored sulfonic acid onto the surface of silica gel catalyzed one-pot synthesis of 3,4-dihydropyrimidinones/thiones has been reported under heterogeneous conditions. The catalyst 1 was found to be completely heterogeneous and is re-usable for several times without loss of significant activity.Figure optionsDownload full-size imageDownload as PowerPoint slide