400877-60-3Relevant academic research and scientific papers
Regioselective and guided C-H activation of 4-nitropyrazoles
Iaroshenko, Viktor O.,Gevorgyan, Ashot,Davydova, Olena,Villinger, Alexander,Langer, Peter
, p. 2906 - 2915 (2014/05/06)
A divergent and regioselective approach to 5-aryl-4-nitro-1H-pyrazoles was developed by guided transition-metal-catalyzed arylation of 4-nitro-1H- pyrazoles. This method provides a convenient tool for the functionalization of the pharmacologically relevan
Reactions of some arenes and pyrazoles in MeCN under conditions of undivided-cell electrolysis
Chauzov,Parchinsky,Sinelshchikova,Petrosyan
, p. 1274 - 1279 (2007/10/03)
As exemplified for the first time by pyrazole and its 4-nitro and 3,5-dimcthyl derivatives, N-arylation of pyrazoles can be performed under conditions of undivided-cell amperostatic electrolysis (Pt electrodes, McCN) of systems containing the pyrazolate anion and (or) pyrazole, arene (benzene, 1,4-dimethoxybenzene, or xylene), and a supporting electrolyte. In the case of electrolysis involving 1,4-dimethoxybenzene as arene, N-arylation followed simultaneously three routes to form an ortho-substitution product (1,4-dimethoxy-2-(pyrazol-1-yl)benzene), an ipso-substitution product (4-methoxy-1-(pyrazol-1-yl)benzene), and an ipso-bisaddition product (1,4-dimethoxy-1,4-di(pyrazol-1-yl)cyclohexa-2,5-diene) in a total current yield of up to 50%. The acid-base properties of the pyrazolcs under study affect the ratio of the N-arylation products and govern the required composition of the starting reaction mixture. In the case of a stronger base, such as 3,5-dimethylpyrazole, N-arylation with 1,4-dimethoxybenzene occurred even in the pyrazole-arene-tetraalkylammonium perchlorate system, whereas N-arylation of 4-nitropyrazole (a weaker base) proceeded only in the presence of the pyrazolate anion or another base, viz., sym-collidine. Oxidation of arene to the radical cation is the key anodic reaction. Not only the pyrazolate anion, but also highly basic pyrazole or a solvate complex of weakly basic pyrazole with collidine can serve as a nucleophilic partner in subsequent transformations of these radical cations.
