14714-05-7Relevant academic research and scientific papers
A modified and practical synthetic route to indazoles and pyrazoles using tungstate sulfuric acid
Rahmatzadeh, S. Setareh,Karami, Bahador,Khodabakhshi, Saeed
, p. 17 - 20 (2015/02/19)
Tungstate sulfuric acid-catalyzed Knorr reaction have been used as a simple, rapid, atom economic and green method for the synthesis of indazole and pyrazole derivatives based on the condensation of hydrazine derivatives and ss-dicarbonyl compounds under solvent-free conditions. It was found that the catalyst could be recovered and reused without significant loss of its activity. The use of this method provides a novel and improved modification of Knorr synthesis in terms of clean reaction profile, use of a safe catalyst and solvent-free conditions. A green method for the synthesis of indazole and pyrazole derivatives from the condensation of hydrazine derivatives with dicarbonyl compounds has been described. Tungstate sulfuric acid (TSA) catalyzed efficiently the reactions to give good yields.
Layered zirconium sulfophenyl phosphonate as heterogeneous catalyst in the synthesis of pyrazoles and 4,5,6,7-tetrahydro-1(2)H-indazoles
Curini, Massimo,Rosati, Ornelio,Campagna, Valerio,Montanari, Francesca,Cravotto, Giancarlo,Boccalini, Mauro
, p. 2927 - 2930 (2007/10/03)
Pyrazoles and tetrahydroindazoles may be prepared by condensation of 1,3-diones and hydrazines under layered zirconium sulfophenyl phosphonate catalysis, in solvent-free conditions. Georg Thieme Verlag Stuttgart.
Reactions with Organophosphorus Compounds, XLVI. Reactivity Umpolung of 1,3-Dioxo Compounds through Introduction of a Triphenylphosphonio Group. - Regioselective Syntheses of Isoxazoles and Pyrazoles from (2,4-Dioxoalkyl)triphenylphosphonium Salts
Oehler, Elisabeth,Zbiral, Erich
, p. 2852 - 2867 (2007/10/02)
Phosphonium salts 2 and 6, upon deprotonation with BuLi and subsequent reaction with acyl halides, yield the γ-acyl derivatives 3 and 7, respectively, which on treatment with hydrochloric acid afford the corresponding (dioxoalkyl)phosphonium salts 4 and 8.Isoxazole derivatives 9 and 10 are formed regioselectivly from 4 and 8 with NH2OH*HCl, while with R-NH-NH2*HCl (R = H or C6H5) the pyrazole-containing phosphonium salts 14 and 15 are obtained in an analogous reaction.In each case the direction of cyclisation is different to the reactions of the corresponding non-phosphorus substituted 1,3-dioxo compounds.On treatment with aqueous NaOH 9 and 10 are cleaved to triphenylphosphane oxide and isoxazoles 11 and 12, while 14 and 15 yield the pyrazoles 16 and 17.Wittig reaction of 9a or 14a with aldehydes or ketones leads to the isoxazole olefins 13 or the pyrazole olefins 18, respectively.
