Nitrogen heterocycles represent one of the most important units in modern organic chemistry besides their wide existence broadly in natural products, pharmaceuticals, and functional materials. Among these heterocycles, pyrazole, the molecule of the present work, received much attention in organic synthesis because it delivers significant therapeutic and biological values as it was found to be the core unit of many drugs, agrochemicals, and related candidates. Due to this fact, the development of practical methodologies for the preparation of pyrazoles has attracted the long-standing interest of synthetic chemists. Synthetic heterocyclic chemistry using green methods has captivated many researchers in the recent past due to its easy operation and environmentally friendliness. In this review, we summarized systematic approaches for the synthesis of pyrazole derivatives via heterogeneous catalysis, ionic liquid catalysis, and multicomponent reactions.

Different intermediates are key molecules to synthesize high-added value bioactive and pharmacology molecules such as propargylamines may be synthesized in several ways using catalysts in homogeneous and heterogeneous conditions. This review presents the catalysts which are used in the A3, AHA, and KA2 coupling reactions to afford propargylamines. It also provides a classification of all the propargylamines known up to date in the literature and their reported synthesis conditions.

Monometallic gold and bimetallic gold-iron catalysts supported on alumina were prepared in order to check their activity and selectivity in the reaction of cyclohexene oxidation. Au/Al₂O₃ was prepared by a deposition precipitation with urea (DPU) method, while the bimetallic catalyst Au-Fe/Al₂O₃ was prepared by under potential deposition (UPD). The characterization by ICP and EDS showed that very small amount of iron are deposited near gold nanoparticles. However, TEM images showed that the deposition method of iron induced gold nanoparticles sintering. All catalysts were tested in the reaction of cyclohexene oxidation in order to check the influence of both the size of gold particles and the presence of iron on the catalytic activity and selectivity. Small gold nanoparticles were shown be efficient in cyclohexene oxidation where the presence of iron influenced widely the selectivity towards the formation of cyclohexene oxide.