Boehmite Silylpropyl Amine Sulfamic Acid as an Efficient and Recyclable Catalyst for the Synthesis of some Pyrazole Derivatives

Background: The design of biologically-active compounds is a challenging viewpoint in medicinal chemistry, and pyrazoles play a crucial role as biologically-active molecules. Methods: Up to now, a few examples have been reported for the synthesis of pyrazoles catalyzed by heterogeneous catalysts. In this work, a new boehmite silylpropyl amine sulfamic (m-SABNPs) was applied as a catalyst for one-pot synthesis of pyrazole derivatives. Results: It was found that this heterogeneous sulfamic acid is a highly efficient catalyst for the syntheses of 5-amino-1,3-aryl-1H-pyrazole-4-carbonitriles and pyrazolopyranopyrimidines in good to excellent yields and can be recovered by a simple filtration of the reaction solution and reused for five consecutive runs without significant loss of catalytic activity. Moreover, its structure was characterized by FT-IR spectroscopy, TGA, XRD, TEM and SEM techniques. Conclusion: An efficient, and convenient method was proposed for the synthesis of pyrazole derivatives catalyzed by heterogeneous sulfamic acid in high-to-excellent yields. This method offers several advantages like milder reaction condition, shorter reaction time, cleaner reaction, and reusability of the catalyst.