Synthetic Methodologies and Biological Importance of Phosphonylpyrazoles

Section: Reviews
Keywords: pyrazole, Phosphonylpyrazoles, Bestmann–Ohira Reagent, Phosphonates

Pyrazole derivatives are an important class of compounds with diverse applications in agrochemicals, coordination chemistry, supramolecular chemistry, and pharmaceuticals. This review focuses on the synthesis and applications of phosphonate-containing pyrazole derivatives. Phosphonates are known to mimic carboxylic acid groups and have been used in drug design to modulate biological activities. The review discusses the nomenclature and types of phosphonylpyrazoles based on the position of the phosphonyl group in the pyrazole ring. Synthetic methods for preparing phosphonylpyrazoles are categorized into three main routes: phosphorylation of the preformed pyrazole ring, ring closure of acyclic phosphorus-containing compounds, and cycloaddition-based strategies. Phosphorylation of the pyrazole ring can be achieved through C-phosphonylation and N-phosphonylation reactions, with palladium-catalyzed cross-coupling reactions being a useful strategy for introducing phosphorus substituents at various positions of the pyrazole ring. Ring closure of acyclic phosphorus-containing compounds can lead to the formation of N-phosphonylpyrazoles and C-phosphonylpyrazoles, with the use of Vilsmeier reagents and cycloaddition-based strategies being prominent approaches. The review also highlights the biological importance of phosphonylpyrazoles, with phosphorus substituents acting as biological activity modulators for antimicrobials and pesticides. The development of new methodologies for synthesizing phosphonylpyrazoles is crucial for both the chemical and pharmaceutical industries, and the review concludes by emphasizing the need for more general and efficient methods