Synthesis of Pyrazoles via Electrophilic Cyclization

Zora, Metin
Electrophilic cyclizations of alpha,beta-alkynic hydrazones by molecular iodine were investigated for the synthesis of 4-iodopyrazoles. alpha,beta-Alkynic hydrazones were readily prepared by the reactions of hydrazines with propargyl aldehydes and ketones. When treated with molecular iodine in the presence of sodium bicarbonate, alpha,beta-alkynic hydrazones underwent electrophilic cyclization to afford 4-iodopyrazoles in good to high yields. Iodocyclization was general for a wide range of alpha,beta-alkynic hydrazones and tolerated the presence of aliphatic, aromatic, heteroaromatic, and ferrocenyl moieties with electron-withdrawing and electron-donating substituents.


Synthesis of Pyrazoles via Cul-Mediated Electrophilic Cyclizations of alpha,beta-Alkynic Hydrazones
Zora, Metin (2011-11-18)
Synthesis of pyrazoles via electrophilic cyclization of alpha,beta-alkynic hydrazones by copper(I) iodide is described. When treated with copper(I) iodide in the presence of triethylamine in refluxing acetonitrile, alpha,beta-alkynic hydrazones, prepared readily from hydrazines and propargyl aldehydes and ketones, undergo electrophilic cyclization to afford pyrazole derivatives in good to excellent yields. The reaction appears to be general for a variety of alpha,beta-alkynic hydrazones and tolerates the pr...
PLE and HLE catalyzed reverse enantiomeric separation of (±)-methyl-2- methoxy-1-methyl-2,5-cyclohexadiene-1-carboxylate derivatives
Tanyeli, Cihangir; Demir, Ayhan Sıtkı; ALVES, Rosemeire Brondi; ARSENİYADİS, Simeon (1999-03-26)
We describe the diversities of hydrolase-type enzymes PLE and HLE on the hydrolysis of (+/-)-methyl-2-methoxy-1 -methyl-2,5-cyclohexadiene-1-carboxylate and (+/-)-methyl-2-methoxy-1 -methyl-2,5-cyclohexadiene-4-one-1-carboxylate to afford both enantiomers with 92-96% ee.
Dimethyl ether from syngas and effect of CO2 sorption on product distribution over a new bifunctional catalyst pair containing STA@SBA-15
Direct synthesis of dimethyl ether (DME) from syngas was investigated in the presence of a bifunctional catalyst pair containing silicotungstic acid (STA) incorporated SBA-15 (5, 10, 25% by wt. STA) for the in-situ dehydration of synthesized methanol. The methanol synthesis component of this catalyst mixture is a Cu/ZnO-based commercial (HF) catalytic material. The new STA@SBA-15 type solid acid catalysts synthesized in this study indicated ordered mesoporous structures with surface area values in the range...
The synthesis and sodium-silver ion exchange of sodalites
Acar, Aybar Can; Culfaz, A (2003-05-01)
Aluminosilicate sodalites of three different types-chlorosodalite, basic sodalite, and oxalate sodalite-have been synthesized in their sodium forms using hydrothermal synthesis. The syntheses were investigated in terms of their relative rates of crystallization and final crystallinities using powder X-ray diffraction. These sodalites were subsequently loaded with silver by aqueous ion exchange. The exchange was studied primarily by monitoring the solution phase. Rate of exchange and equilibrium behavior hav...
Synthesis and characterization of Ba/MCM-41
Kaya, Emine; Oktar, Nuray; Karakaş, Gürkan; Murtezaoglu, Kirali (2010-01-01)
Mesoporous Ba/MCM-41 type materials (Ba/MCM-41) with high Ba/Si molar ratios between 0.025 and 0.1 were synthesized by direct hydrothermal synthesis. The samples were characterized by XRD, nitrogen adsorption, TGA-DTA, FTIR, SEM-EDS, and TEM techniques. BET surface areas of samples with various Ba loadings were found between 722 and 931 m(2)/g with 28 A average pore size, which is consistent with the pore size of 30 A for pure MCM-41 samples synthesized by the same procedure. The crystal structures of synth...
Citation Formats
M. Zora and C. YAZICI, “Synthesis of Pyrazoles via Electrophilic Cyclization,” JOURNAL OF ORGANIC CHEMISTRY, pp. 6726–6742, 2011, Accessed: 00, 2020. [Online]. Available: