Efficient Ag/La-ZnO core–shell catalyst for green synthesis of 4 <i>H</i> -pyrano[2,3- <i>c</i> ] pyrazoles

The advancement of green and efficient synthetic strategies is essential for the pursuit of environmentally sustainable organic transformations. Pyrazole derivatives, recognized for their broad pharmacological and synthetic utility, are key structural motifs in various bioactive molecules. This study reports a one-pot, four-component (aryl aldehyde, malononitrile, ethyl acetoacetate, and hydrazine hydrate) synthesis of pyrazole derivatives catalyzed by lanthanum-doped and silver-coated ZnO (Ag/La-ZnO) core-shell nanoparticles under solvent-free grinding conditions at ambient room temperature. The catalyst was synthesized <i>via</i> a chemical precipitation method and comprehensively characterized using XRD, FTIR, BET, EDAX, FESEM, HRTEM, SAED, and XPS techniques. The synthesized pyrazoles were characterized using FTIR, ¹HNMR, ¹³CNMR, and MS. Compared to conventional protocols, this nanocatalyst offers advantages such as high catalytic efficiency, superior yields, short reaction duration, inexpensive nature, operational simplicity, reusability, and environmental benignity. The findings underscore the potential of nanostructured catalysts in advancing green synthetic strategies.