10250-58-5Relevant articles and documents
Pyrrole and Pyrazole Ring Closure in Heterogeneous Media
Texier-Boullet, F.,Klein, B.,Hamelin, J.
, p. 409 - 411 (1986)
Pyrroles and pyrazoles may be conveniently prepared by dispersing primary amines or hydrazines and 1,4- or 1,3-diketones, respectively, on alumina or clay (montmorillonite K 10) without solvent, keeping the mixture at 20 deg C or higher temperatures for 1-26 h, and then eluting the product with dichloromethane.
Palladium-catalyzed coupling of pyrazole triflates with arylboronic acids
Dvorak, Curt A.,Rudolph, Dale A.,Ma, Sandy,Carruthers, Nicholas I.
, p. 4188 - 4190 (2005)
A general protocol for the palladium-mediated Suzuki coupling reaction of pyrazole inflates and aryl boronic acids has been developed. The use of additional dppf ligand was determined to increase product yields allowing for the use of a broad range of rea
Reactivity of p-phenyl substituted β-enamino compounds using K- 10/ultrasound. I. Synthesis of pyrazoles and pyrazolinones
Valduga,Braibante,Braibante
, p. 1453 - 1457 (1997)
The reactivity of the β-enamino ketones, 3-amino-1-(p-phenyl- substituted)-2-buten-1-ones 1a-d and β-enamino esters, ethyl 3-amino-3-(p- phenyl-substituted)-2-propenoates 5a-d was systematically studied when allowed to react with hydrazine and methylhydrazine under solid support K- 10/ultrasound conditions and in homogeneous media (reflux in ethanol or dichloromethane). The products were pyrazoles 2a-d, N-methylpyrazoles 3a-d, 4a-d and N-methylpyrazolinones 6a-c and 7a-c. The regiochemistry of the cyclization reactions showed dependence upon the reaction conditions employed as well as upon the substituent in the aromatic ring.
Small molecule library synthesis using segmented flow
Thompson, Christina M.,Poole, Jennifer L.,Cross, Jeffrey L.,Akritopoulou-Zanze, Irini,Djuric, Stevan W.
experimental part, p. 9161 - 9177 (2012/01/03)
Flow chemistry has gained considerable recognition as a simple, efficient, and safe technology for the synthesis of many types of organic and inorganic molecules ranging in scope from large complex natural products to silicon nanoparticles. In this paper
A novel synthesis of fluorinated pyrazoles via gold(I)-catalyzed tandem aminofluorination of alkynes in the presence of Selectfluor
Qian, Jianqiang,Liu, Yunkui,Zhu, Jie,Jiang, Bo,Xu, Zhenyuan
supporting information; experimental part, p. 4220 - 4223 (2011/10/04)
A mild and efficient protocol for the synthesis of fluorinated pyrazoles has been developed via gold(I)-catalyzed tandem aminofluorination of alkynes in the presence of Selectfluor. This method offers a broad substrate scope.
Regioselective synthesis of 1,3,5- and 1,3,4,5-substituted pyrazoles via acylation of N-Boc-N-substituted hydrazones
Tinarelli, Alessandro,Righi, Paolo,Rosini, Goffredo,Andreotti, Daniele,Profeta, Roberto,Spada, Simone
experimental part, p. 612 - 617 (2011/03/19)
Acylation of N-Boc-N-methylhydrazones followed by TFA treatment affords regioselective access to substituted pyrazoles. Both regioisomers of 1-methyl-3,5-disubstituted-1H-pyrazoles can be selectively obtained. This procedure can also be employed for the r
The preparation of substituted pyrazoles from β,β-dibromo-enones by a tandem condensation/Suzuki-Miyaura cross-coupling process
Beltrán-Rodil, Sandra,Edwards, Michael G.,Pugh, David S.,Reid, Mark,Taylor, Richard J.K.
scheme or table, p. 602 - 606 (2010/09/18)
Two consecutive tandem processes are described for the regioselective, two-step synthesis of 1,3,5-trisubstituted pyrazoles from α- hydroxyketones. The first, a tandem MnO2-mediated oxidation/Ramirez olefination reaction, provides a facile route to β,β-dibromo-enones. These valuable 1,3-dicarbonyl synthons can then be converted into 1,3,5-trisubstituted pyrazoles via a second tandem hydrazine condensation/Suzuki-Miyaura cross-coupling reaction. Using these procedures, a range of aryl and alkyl α-hydroxyketones have been transformed regioselectively into 1,3,5-trisubstituted pyrazoles. Georg Thieme Verlag Stuttgart.
Reactions of lithium silylcuprates with pyrazolium and indazolium salts
Gonzalez-Nogal, Ana M.,Calle, Mariola,Cuadrado, Purificacion
, p. 6089 - 6096 (2008/09/17)
Although pyrazolium salts have been shown to be unreactive toward lithium carbocuprates, these substrates were opened by lithium silylcuprate reagents to give versatile N-silylated β-enaminoimines stabilized by coordination of the silyl group with both ni
A new and a convenient route to enaminones and pyrazoles
Stefane, Bogdan,Polanc, Slovenko
, p. 28 - 32 (2007/10/03)
A new method has been developed for the regioselective preparation of enaminones and pyrazoles from 1,3-diketonatoboron difluorides. The reactions proceed smoothly under mild reaction conditions, producing enaminones and pyrazoles in high yields.
Scope and limitations in the regioselective synthesis of 1,3,5-trisubstituted pyrazoles from β-amino enones and hydrazine derivatives. 13C-chemical shift prediction rules for 1,3,5-trisubstituted pyrazoles
Alberola, Angel,Calvo Bleye, Luis,Gonza?lez-Ortega, Alfonso,Sa?daba, M.Luisa,San?udo, M.Carme
, p. 331 - 352 (2007/10/03)
β-amino enones react with hydrazine derivatives to give regioselectively 1,3,5-trisubstituted pyrazoles. The synthetic method only presents limitations when the β-substituent of the enone and the hydrazine substituent are bulky or possess an electron withdrawing character. Comparison of the 13C-NMR spectra of the seventy pyrazoles allowed us to estimate a 13C-chemical shift prediction rule for 1,3,5-trisubstituted pyrazoles, with deviations of less than ± 1 ppm.
