N-Sulfonic acid poly(4-vinylpyridinium) chloride as a highly efficient and reusable catalyst for the Biginelli reaction

A mild, simple and efficient procedure for the preparation of 3,4-dihydropyrimidin-2(1H)-ones and -thiones is described using N-sulfonic acid poly(4-vinylpyridinium) chloride (NSPVPC) as a heterogeneous and efficient catalyst under solvent-free conditions.