From 2000 to mid-2010: a fruitful decade for the synthesis of pyrazoles.

Pyrazole and its derivatives are considered a pharmacologically important active scaffold that possesses almost all types of pharmacological activities. The presence of this nucleus in pharmacological agents of diverse therapeutic categories such as celecoxib, a potent anti-inflammatory, the antipsychotic CDPPB, the anti-obesity drug rimonabant, difenamizole, an analgesic, betazole, a H2-receptor agonist and the antidepressant agent fezolamide have proved the pharmacological potential of the pyrazole moiety. Owing to this diversity in the biological field, this nucleus has attracted the attention of many researchers to study its skeleton chemically and biologically. This review highlights the different synthesis methods and the pharmacological properties of pyrazole derivatives. Studies on the synthesis and biological activity of pyrazole derivatives developed by many scientists around the globe are reported.

Synthesis and Pharmacological Activities of Pyrazole Derivatives: A Review

N-Tosylhydrazones have recently emerged as useful synthons in a variety of transition-metal-catalyzed and transition-metal-free reactions, which affords novel methodologies for the formation of carbon–carbon and carbon–heteroatom bonds. In this context, it has been found that N-tosylhydrazones can be used as versatile building blocks in the construction of a range of cyclic compounds. In this review, cyclization reactions based on N-tosylhydrazones as substrates are discussed. A series of cyclic compounds, including aromatic and non-aromatic ring systems, are demonstrated to be easily constructed by cyclizations with N-tosylhydrazones.

N-Tosylhydrazones: versatile synthons in the construction of cyclic compounds.

Nano-organocatalyst: magnetically retrievable ferrite-anchored glutathione for microwave-assisted Paal–Knorr reaction, aza-Michael addition, and pyrazole synthesis

Recent Advances in the Synthesis of Pyrazoles. A Review

Reaction of N-Monosubstituted Hydrazones with Nitroolefins: A Novel Regioselective Pyrazole Synthesis

Convergent Synthesis of a 5HT7/5HT2 Dual Antagonist

A novel regioselective synthesis of substituted pyrazoles from N-monosubstituted hydrazones and nitroolefins is described. The reaction is performed in a one-pot manner and the yields range from moderate to excellent. A key nitropyrazolidine intermediate is characterized and a plausible mechanism is proposed.

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Reaction of N‐Monosubstituted Hydrazones with Nitroolefins: A Novel Regioselective Pyrazole Synthesis.

4-Chlorobenzaldehyde




Methylhydrazine




Benzylhydrazine dihydrochloride




(E)-3,4-Methylendioxy-beta-nitrostyrene




Trans-p-Methyl-beta-nitrostyrene




5-Benzo[1,3]dioxol-5-yl-3-(4-chloro-phenyl)-1-methyl




1-Benzyl-3-(4-chloro-phenyl-5-p-tolyl-1H-pyrazole





Keywords:

substituted pyrazoles;
regioselective synthesis;
one-pot process;
monosubstituted hydrazones;
nitro-olefins;
cycloaddition;
michael addition;
waste disposal

Xiaohu Deng

Papers

Reaction of N-Monosubstituted Hydrazones with Nitroolefins: A Novel Regioselective Pyrazole Synthesis

Convergent Synthesis of a 5HT7/5HT2 Dual Antagonist

Reaction of N‐Monosubstituted Hydrazones with Nitroolefins: A Novel Regioselective Pyrazole Synthesis.

Regioselective Synthesis of 1,3,5‐Trisubstituted Pyrazoles by the Reaction of n‐Monosubstituted Hydrazones with Nitroolefins