Distereoselective one-pot synthesis of pyrimidopyrimidines using sulfated tin oxide as a reusable catalyst: An extension of Biginelli-type reaction

The Biginelli-type compounds 4,5,8a-triarylhexahydropyrimido[4,5- d ]pyrimidine-2,7(1 H ,3 H )-diones were synthesized by a one-pot three-component reaction using sulfated tin oxide as a reusable catalyst. This method has the advantages of high yields, short reaction time, simple starting materials and reusability of catalyst for several times.