Poly(4-vinylpyridinium)hydrogen sulfate: An efficient and recyclable Bronsted acid catalyst for the synthesis of fused 3,4-dihydropyrimidin-2(1 H )-ones and thiones

Aluminatesulfonic acid nanoparticles: synthesis, characterization and application as a new and recyclable nanocatalyst for the Biginelli and Biginelli-like condensations

A new, efficient and recyclable nanocatalyst, aluminatesulfonic acid, was prepared and used as a heterogeneous solid acid catalyst for the synthesis of a variety of Biginelli and Biginelli-like products under solvent-free conditions.