Cerium (IV) sulfate tetrahydrate as a reusable heterogeneous Lewis acid catalyst: solvent-free and green synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione scaffolds

An ecologically benign method for the synthesis of 1H-pyrazolo [1,2-b]phthalazine-5,10-dione scaffolds without the use of solvents is presented. It employs cerium (IV) sulfate tetrahydrate (Ce(SO₄)₂·4H₂O) as a reusable heterogeneous Lewis acid catalyst. The reactions conclude significantly more quickly and produce products with impressive yields. This environmentally friendly technique employs safe settings. It is inexpensive, efficient, and simple to use. Finally, a solvent is not required. Furthermore, after four cycles, the highly efficient and eco-friendly Ce(SO₄)₂·4H₂O remains rather stable and does not alter or lose its effectiveness. As a consequence, it is very advantageous for both cost-cutting and environmental protection during industrial operations. While the range of yields (79–92 %, with an average of 87.05 %) is fairly constant, the range of reaction times is fairly short (40–65 min, with an average of 48.52 min). It's also crucial that this method can provide yield excellent yields and a rapid rate of reaction even when used with a variety of functional groups that give or take electrons. The results suggest that, given relatively simple and effective reaction conditions, this technique is a productive one-pot procedure.