Metin Zora

Synthesis of Pyrazoles via Electrophilic Cyclization

Electrophilic cyclizations of α,β-alkynic hydrazones by molecular iodine were investigated for the synthesis of 4-iodopyrazoles. α,β-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, α,β-alkynic hydrazones underwent electrophilic cyclization to afford 4-iodopyrazoles in good to high yields. Iodocyclization was general for a wide range of α,β-alkynic hydrazones and tolerated the presence of aliphatic, aromatic, heteroaromatic, and ferrocenyl moieties with electron-withdrawing and electron-donating substituents.

Synthesis of Pyrazoles via CuI-Mediated Electrophilic Cyclizations of α,β-Alkynic Hydrazones

Synthesis of pyrazoles via electrophilic cyclization of α,β-alkynic hydrazones by copper(I) iodide is described. When treated with copper(I) iodide in the presence of triethylamine in refluxing acetonitrile, α,β-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 α,β-alkynic hydrazones and tolerates the presence of aliphatic, aromatic, and ferrocenyl moieties with electron-withdrawing and electron-donating substituents.

Synthesis of ferrocenyl quinolines

A convenient one-pot synthesis of ferrocenyl-substituted quinolines via a molecular iodine-catalyzed reaction of ferrocenylimines with enolizable aldehydes is reported. First, nucleophilic addition of the in situ generated enol to ferrocenylimine produces β-anilinopropionaldehyde, which then undergoes intramolecular Friedel–Crafts reaction to give dihydroquinoline derivative. Finally, subsequent dehydration and aerobic oxidation affords ferrocenyl quinolines.

Reaction of ferrocenylcarbene complexes of Cr, Mo and W with alkynes: synthesis of ferrocenylcyclobutenones, ferrocenylfurans and ferrocenylketoesters

Abstract Ferrocenylcarbene complexes of Cr, Mo and W react with alkynes to produce cyclobutenones, furans and/or ketoesters. The reaction is quite sensitive to the substituents of the alkyne, regardless of the identity of the metal. Cyclobutenones are formed only in the reactions of diphenylacetylene, a rare occurrence for metal carbene complexes. Ketoesters are secondary reaction products and result from oxidation of furan derivatives during the course of the reaction and/or silica-gel chromatography.

Synthesis of ferrocenyl quinones

Abstract A squarate-based synthesis of ferrocenyl quinones is described. Thermolysis of ferrocenyl-substituted cyclobutenones, prepared from ferrocenyl cyclobutenediones and alkenyllithiums, affords hydroquinones, which furnish, upon oxidation, ferrocenyl quinones. Ferrocenyl cyclobutenediones have been prepared from known cyclobutenediones by nucleophilic addition of ferrocenyllithium followed by hydrolysis, Pd/Cu-cocatalyzed cross-coupling with (tri-n-butylstannyl)ferrocene or Friedel–Crafts alkylation with ferrocene.

Friedel–Crafts alkylation of ferrocene with Z-cyclooctene and cyclohexene

Abstract Cycloalkylated ferrocene derivatives, potentially useful as liquid burning rate modifiers for the HTPB/AP-based composite rocket propellants, were synthesized by the Friedel–Crafts alkylation of ferrocene with Z -cyclooctene or cyclohexene in the presence of AlCl 3 as a Lewis acid catalyst. The reaction with Z -cyclooctene yields a mixture of main products containing up to four C 8 H 15 substituents, each of which exists in several isomeric forms, as recognized by MS and GC–MS techniques. Two isomeric monosubstituted products, cyclooctylferrocene and (1-methylcycloheptyl)ferrocene, isolated by means of preparative GC, were identified by 13 C-NMR spectroscopy. In the case of cyclohexene, cyclohexylferrocene and a 2:1 mixture of 1,1′-dicyclohexylferrocene and 1,3-dicyclohexylferrocene were isolated and identified by MS and 13 C-NMR spectroscopy.

Coupling of ferrocenyl chromium carbene complex with cyclobutenediones

The coupling of ferrocenyl chromium carbene complex with cyclobutenediones leads to ferrocenyl-substituted 5-alkylidenefuranones and 4-cyclopentene-1,3-diones, methyl ferrocenoate and acetylferrocene in varying amounts. The scope and limitations of these processes are investigated. In comparison with the phenyl analog, ferrocenyl chromium carbene complex has been found to be less reactive. This is also supported by PM3 calculations.

Nucleus-independent chemical shift evaluation for benzo- and dibenzo-fused pyrrole, furan and thiophene derivatives

Abstract Aromaticity of pyrrole, indole, isoindole, indolizine, carbazole, furan, benzofuran, isobenzofuran, dibenzofuran, thiophene, benzothiophene, benzo[c]thiophene and dibenzothiophene has been examined via their nucleus-independent chemical shift values (NICS(0) and NICS(1)) calculated at GIAO-HF/6-31G*//B3LYP/6-31G* and GIAO-HF/6-31+G*//B3LYP/6-31G* levels.

Preparation of seven-membered rings by the reaction of cyclopropylcarbene-tungsten and molybdenum complexes with alkynes

Abstract The reaction between alkynes and cyclopropylcarbene-tungsten and molybdenum complexes has been examined. Depending upon the conditions of the reaction, either cycloheptadienones or furanones are obtained. The scope, limitation, and mechanistic rationale for observed selectivities are discussed.

Reaction of 4-methoxy-4-(1-methylethenyl)-2-cyclobutenone derivatives with 2-lithiopropene and α-lithiostyrene: synthesis of eight-membered ring carbocycles

Abstract 2-Alkyl- or phenyl-substituted 4-methoxy-4-(1-methylethenyl)-2-cyclobutenones react with 2-lithiopropene or α-lithiostyrene to produce 4-methoxy-2,4-cyclooctadienones in moderate yield, accompanied by varying amounts of 4-methoxy-4-(1-methylethenyl)-2-cyclohexenones. The reaction is general for 2-alkyl substituted 4-methoxy-4-(1-methylethenyl)-2-cyclobutenones.