33064-18-5Relevant articles and documents
Copper-Promoted Coupling of Propiophenones and Arylhydrazines for the Synthesis of 1,3-Diarylpyrazoles
Dang, Ha V.,Le, Ha V.,Nguyen, Tien M.,Nguyen, Tung T.,Pham, Thuyet L. D.,Phan, Nam T. S.,Tran, Khuong A.
, p. 801 - 804 (2020)
Synthesis of 1,3-diarylpyrazoles from commercial substrates and/or simple transformations is still underrated. In this report, we have developed a method for copper-promoted coupling of propiophenones and arylhydrazines. The reactions afforded substituted pyrazoles in the presence of TEMPO oxidant, acetic acid additive, and DMF solvent. A number of functionalities were compatible with reaction conditions, including halogens, methoxy, trifluoromethyl, and nitro groups. An indazole could be obtained if an electron-poor propiophenone was used.
[3+2]-cycloaddition of in situ generated nitrile imines and acetylene for assembling of 1,3-disubstituted pyrazoles with quantitative deuterium labeling
Voronin, Vladimir V.,Ledovskaya, Maria S.,Gordeev, Evgeniy G.,Rodygin, Konstantin S.,Ananikov, Valentine P.
, p. 3819 - 3828 (2018/04/14)
A novel synthetic methodology for the preparation of 1,3-disubstituted pyrazoles from in situ generated nitrile imines and acetylene is reported. The reactions are performed in a simple two-chamber reactor. One part of the reactor is loaded with hydrazonoyl chloride precursors of active nitrile imine species and a base. The other part is used to generate acetylene from CaC2 and water. Partitioning of the reactants improves the yields of desired pyrazoles up to 99% and simplifies their isolation to a simple procedure of solvent evaporation. The approach requires no complex equipment and utilizes inexpensive, safe, and easy to handle calcium carbide as a starting material. A model deuterium incorporation is carried out according to the developed methodology, producing a series of novel 4,5-dideuteropyrazoles with excellent deuterium enrichment. Theoretical calculations on reaction mechanism and characterization of possible intermediate structures were performed.
Single-step synthesis of pyrazoles using titanium catalysis
Dissanayake, Amila A.,Odom, Aaron L.
supporting information; experimental part, p. 440 - 442 (2012/01/05)
A simple titanium complex catalyzes the coupling of alkynes, isonitriles, and monosubstituted hydrazines to generate substituted pyrazoles in a single step.
