Synthesis of functionalized tetrasubstituted pyrazolyl heterocycles--a review.

Heterocyclic chemistry constitutes an essential branch of organic chemistry and heterocycles are widely known to display an array of biological properties. Pyrazoles represent key structural motifs in heterocyclic chemistry and are present in a large number of biologically active molecules relevant to the pharmaceutical and agrochemical industries. Compounds incorporating the pyrazolyl structural unit are being developed in a wide variety of therapeutic areas including CNS, metabolic diseases, and oncology. The current review summarizes recent advances in the synthesis of tetrasubstituted pyrazoles. The contents are discussed in five sections: (a) 1,3-dipolar cycloadditions, (b) related 1,3-dipolar cycloadditions, (c) condensations, (d) allenylphosphonates, and (e) synthesis of fused pyrazole containing heterocycles.