β-Cyclodextrin-propyl sulfonic acid: a new and eco-friendly catalyst for one-pot multi-component synthesis of 3,4-dihydropyrimidones via Biginelli reaction

β-Cyclodextrin-propyl sulfonic acid (β-CD-PSA) is reported as a new and eco-friendly catalyst for the synthesis of 3,4-dihydropyrimidinones from one-pot multi-component reaction of aromatic aldehydes, 1,3-dicarbonyl compounds and urea or thiourea under solvent-free conditions. The present methodology offers several advantages, such as shorter reaction time, high yields, mild reaction conditions and a simple work-up procedure. Furthermore, β-CD-PSA is inexpensive, biodegradable, and can be reusable. It could be reused six-times without a significant loss of catalytic activity.