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.
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...
Gold-Catalyzed Oxime-Oxime Rearrangement
Guven, Sinem; Ozer, Merve Sinem; Kaya, Serap; Menges, Nurettin; BALCI, METİN (2015-06-05)
The gold-catalyzed reaction of pyrrole and indole oximes having a propargyl group attached to the nitrogen atom was studied. The selective 6-endo-dig mode of cyclization was observed for the terminal alkynes giving rise to the formation of pyrazine N-oxides in the presence of a gold catalyst. However, the reaction with substituted alkyne transferred the oxime functionality intramolecularly from one carbon atom to another via the 7-endo-dig cyclization process. This transformation is unprecedented in the lit...
Butenolide annelation using a manganese(III) oxidation. A synthesis of 4-arylfuran-2(5H)-ones
Demir, Ayhan Sıtkı; Camkerten, N; Gercek, Z; Duygu, N; Reis, O; Arikan, E (1999-02-19)
A general procedure was developed for the annelation of a butenolide to an aromatic ketone that highlighted a manganese(III) oxidation of aromatic ketones. The oxidation of aromatic ketones with manganese(III) acetate in the presence of 2;bromoacetic acid or the Mn(II) salt of this carboxylic acid provided a regioselectively convenient synthesis of 2-(2-bromoacetoxy) ketones. An Arbuzov or Wittig reaction of 2-(2-bromoacetoxy) ketones followed by cyclisation furnished 4-arylfuran-2(5H)-ones in good yield. (...
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: