In conclusion, we have developed a mild, simple,
cost-effective and green procedure for the synthesis of
3,4-dihydropyrimidinones/thiones using re-usable covalently
anchored sulfonic acid onto the surface of silica gel solid acid
catalyst under heterogeneous catalysis conditions. Moreover,
the mild reaction conditions, high yield of products, ease of
work-up, compatibility with various functional groups, and the
ecologically clean procedure, will make the present method a
useful and important addition to the present methodologies for
the Biginelli synthesis.