Efficient synthesis of 4-phosphinoyl-4,5,6,7-tetrahydro-2H-indazol-3-ylamines

Five-membered ring systems containing two nitrogen atoms adjacent to each other are called pyrazoles. This chapter serves to cover the extensive literature on pyrazoles during the 10 year period, 1996–2006. The previous two chapters of this series, on pyrazoles, dealt more with the theoretical, experimental structural, and thermodynamic methods and less with the reactivity, synthesis, and applications of pyrazoles. During the last 10 years, more literature has appeared on the synthesis and reactivity of pyrazole-fused ring systems. Furthermore, the medicinal chemistry applications of pyrazoles and fused ring systems have found numerous applications in drug discovery. Also, pyrazoles have been utilized as reagents in synthesis. This chapter focuses on these current developments.

4.01 – Pyrazoles

This review article provides critical analysis of literature data regarding the heterocyclization reactions of compounds containing alk-2-en-4-yn-1-one and alk-1-en-4-yn-3-one moieties. We discuss the reactions leading to the formation of furans, 2,3-dihydropyrans, 1,2,3-triazoles, 4,5-dihydro-1Н-pyrazoles, pyrazoles, isoxazoles, pyrimidines, aziridines, as well as a range of more complex fused ringsystems. The biological activity and photophysical properties of the obtained heterocyclic compounds are described. The attention ismainly focused on the studies published during the last 5 years. A total of 87 references are given.

Conjugated 2,4,1- and 1,4,3-enynones as polycentricelectrophiles in synthesis of heterocyclic compounds

Oxidative aminoaziridination: past, present, and future

The pyrazole nucleus and its reduced forms, pyrazolines and pyrazolidine, are privileged scaffolds in medicinal chemistry due to their remarkable biological activities. A huge number of pyrazole derivatives have been studied and reported over time. This review article gives an overview of pyrazole derivatives that contain a styryl (2-arylvinyl) group linked in different positions of the pyrazole backbone. Although there are studies on the synthesis of styrylpyrazoles dating back to the 1970s and even earlier, this type of compound has rarely been studied. This timely review intends to summarize the properties, biological activity, methods of synthesis and transformation of styrylpyrazoles; thus, highlighting the interest and huge potential for application of this kind of compound.

https://www.mdpi.com/1420-3049/25/24/5886/pdf

Styrylpyrazoles: Properties, Synthesis and Transformations.

Phenyl- and isopropylhydrazines react with 1,5-diphenyl-1,4-pentadien-3-one to give 4,5,6,7-tetrahydroindazole derivatives instead of the expected 4,5-dihydropyrazoles. The reaction of phenylhydrazine with 1,5-diphenyl-1-penten-4-yn-3-one leads to formation of 1,5-diphenyl-3-phenylethynyl-4,5-dihydropyrazole. 2,4-Dinitrophenylhydrazine reacts with 1,5-diphenyl-1-penten-4-yn-3-one, affording the corresponding unsaturated hydrazone rather than pyrazole derivative.

Reaction of 1,5-Diphenyl-1,4-pentadien-3-one and 1,5-Diphenyl- 1-penten-4-yn-3-one with Monosubstituted Hydrazines

Oxidation of N-aminophthalimide with lead tetraacetate in the presence of 1,5-diaryl-3-[(E)-2-arylethenyl]-1H-pyrazoles, as well as of 1,3-diphenyl-5-[(E)-2-phenylethenyl]-1H-pyrazole, gives adducts at the exocyclic C=C bond, the corresponding phthalimidoaziridinylpyrazoles. From 1,5-diphenyl-3-[(1E,3E)-4-phenyl-1,3-butadienyl]-1H-pyrazole, only product of addition at both exocyclic C=C bonds was obtained. In the reaction with 1-phenyl-3-[(1E, 3E)-4-phenyl-1,3-butadienyl]-5-[(E)-2-phenylethenyl]-1H-pyrazole, the adduct at the styryl C=C bond was isolated. Analogous 4,5-dihydropyrazoles, 1,5-diphenyl-3-[(1E, 3E)-4-phenyl-1,3-butadienyl]-4,5-dihydro-1H-pyrazole and 1-phenyl-3-[(1E, 3E)-4-phenyl-1,3-butadienyl]-5-[(E)-2-phenylethenyl]-4,5-dihydro-1H-pyrazole, turned out to be inert in oxidative addition of N-aminophthalimide.

A. N. Blandov

Papers

Reaction of 1,5-Diphenyl-1,4-pentadien-3-one and 1,5-Diphenyl- 1-penten-4-yn-3-one with Monosubstituted Hydrazines

Oxidative Addition of N-Aminophthalimide to Alkenyl-4,5-dihydropyrazoles and Alkenylpyrazoles. Synthesis of Aziridinylpyrazoles

Reaction of 1,5-Diphenyl-1,4-pentadien-3-one and 1,5-Diphenyl-1-penten-4-yn-3-one with Monosubstituted Hydrazines.