Silica-supported 1,3-dichloro-5,5-dimethylhydantoin (DCH) as a useful reagent for microwave-assisted aromatization of 1,3,5-trisubstituted pyrazolines under solvent-free conditions
作者:Davood Azarifar、Elahe Nadimi、Mohammd Mehdi Ghanbari
DOI:10.1016/j.cclet.2010.10.023
日期:2011.4
1,3,5-Trisubstituted pyrazolines are rapidly and conveniently oxidized to their corresponding pyrazoles by 1,3-dichloro-5,5-dimethylhydantoin (DCH) in solution and solvent-free conditions under microwave irradiation. The presence of silica gel as a supporting agent is shown to be effective in reducing the reaction times and increasing the yields.
An efficient oxidation of 2-pyrazolines and isoxazolines by bis-bromine-1,4-diazabicyclo[2.2.2]octane complex (DABCO-Br2)
作者:Davood Azarifar、Kaveh Khosravi、Rahman Ali Veisi
DOI:10.3998/ark.5550190.0011.917
日期:——
An efficient and simple procedure has been developed for the oxidation of 1,3,5-trisubstituted 4,5-dihydro-1H-pyrazoles and -isoxazoles to their corresponding aromatic derivatives promoted by bis-bromine-1,4-diazabicyclo[2.2.2]octane complex (DABCO-Br2) in acetic acid at room temperature. The products 2-pyrazoles and isoxazoles were produced in good to excellent 87-95 % and 78-95 % yields respectively
Regioselective synthesis of multisubstituted pyrazoles via cyclocondensation of β-thioalkyl-α,β-unsaturated ketones with hydrazines
作者:Weiwei Jin、Haifeng Yu、Zhengkun Yu
DOI:10.1016/j.tetlet.2011.08.168
日期:2011.11
Multisubstituted pyrazoles were efficiently synthesized by cyclocondensation of beta-thioalkyl-alpha,beta-unsaturated ketones with hydrazines under relatively mild conditions. A one-pot synthetic protocol through tandem Liebeskind-Srogl cross-coupling/cyclocondensation using alpha-oxo ketene dithioacetals as the starting materials was also realized for the same purpose. (C) 2011 Elsevier Ltd. All rights reserved.
Microwave-promoted Aromatization of 1,3,5-trisubstituted 4,5-Dihydro-1H-pyrazoles by Calcium Hypochlorite under Solvent-free Conditions
作者:Davood Azarifar、Azadeh Gharshasbi
DOI:10.3987/com-06-10701
日期:——
An efficient microwave-promoted aromatization of 1,3,5-trisubstituted 4,5-dihydro-1H-pyrazoles using calcium hypochlorite [Ca(OCl)(2)] has been reported. The reaction proceeds very fast to give pyrazoles in good yields on irradiation of a mixture of the dihydropyrazole and Ca(OCl)(2) on alumina without using solvent.
Azarifar, Davood; Khosravi, Kaveh, Journal of the Chinese Chemical Society, 2009, vol. 56, # 1, p. 43 - 46