Synthesis of donor-acceptor chromophores by the [2+2] cycloaddition of arylethynyl-2H-cyclohepta[b]furan-2-ones with 7,7,8,8-tetracyanoquinodimethane

Arylethynyl-2H-cyclohepta[b]furan-2-ones reacted with 7,7,8,8-tetracyanoquinodimethane (TCNQ) in a formal [2 + 2] cycloaddition reaction, followed by ring opening of the initially formed cyclobutene derivatives, to afford the corresponding dicyanoquinodimethane (DCNQ) chromophores in excellent yields. The intramolecular charge-transfer (ICT) interactions between the 2H-cyclohepta[b]furan-2-one ring and DCNQ acceptor moiety were investigated by UV/Vis spectroscopy and theoretical calculations. The redox behavior of the novel DCNQ derivatives was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which revealed their multistep electrochemical reduction properties depended on the number of DCNQ units in the molecule. Moreover, a significant color change was observed by visible spectroscopy under electrochemical reduction conditions.ArticleORGANIC & BIOMOLECULAR CHEMISTRY. 10(12):2431-2438 (2012)journal articl

Synthesis of 2-Aryl- and 6-Heteroaryl-1,3-di(4-pyridyl)azulenes by Katritzky’s Pyridylation of 2-Aryl- and 6-Heteroarylazulenes

Preparation of 2-aryl- and 6-heteroarylazulenes 2-6 and 8-10 was established by the palladium-catalyzed cross-coupling reaction of the corresponding haloazulenes with lithium aryl- and heteroarylmagnesium ate complexes, which were readily prepared from the corresponding aryl and heteroaryl halides. The reaction of 2-6 and 8-10, except for 3 and 8, with pyridine in the presence of Tf2O, followed by treatment with KOH in MeOH afforded the corresponding 2-aryl- and 6-heteroary1-1,3-di(4-pyridyl)azulenes 11-16 in good yields.ArticleHETEROCYCLES. 89(11):2588-2603 (2014)journal articl

Synthesis of 2-amino- and 2-arylazoazulenes via nucleophilic aromatic substitution of 2-chloroazulenes with amines and arylhydrazines

The SNAr reaction of 2-chloroazulene derivative 1 with ethoxycarbonyl groups at the 1,3-positions of the azulene ring with several amines afforded the corresponding 2-aminoazulenes 3-9 in excellent yields. 2-Chloroazulene (2) without the electron-withdrawing groups reacted with highly nucleophilic cyclic amines (i.e., morpholine, piperidine and pyrrolidine) under the high-temperature conditions in a sealed tube to produce the corresponding 2-aminoazulenes 10-12 in good yields. 2-Aminoazulenes 10-14 without the electron-withdrawing groups were also obtained in good yields by the treatment of compounds 3-7 with 100% H3PO4, but in the cases of the reaction of 8 and 9 with a secondary amine function, the decomposition of the products resulted. The synthesis of 2-arylazoazulenes 15-18 was also established via the SNAr reaction of 1 with arylhydrazines. The optical and electrochemical properties of the 2-arylazoazulene derivatives were examined by UV/Vis spectroscopy, theoretical calculations and voltammetric experiments.ArticleORGANIC & BIOMOLECULAR CHEMISTRY. 94(10):3917-3923 (2017)journal articl

Molecular Transformation of 2-Methylazulenes: An Efficient and Practical Synthesis of 2-Formyl- and 2-Ethynylazulenes

First published: 09 Jan 20182-Formylazulene derivatives have been obtained in good yields by the reactions of 2-methylazulenes with N,N-dimethylformamide dimethyl acetal, followed by oxidative cleavage of the intermediately formed enamines with NaIO4. Vilsmeier formylation of 1-phenyl-3-methylazulenes also afforded the corresponding 2-formylazulenes in moderate yields. The treatment of a 2-methylazulene derivative bearing a formyl group at the 1-position with sodium methoxide led, through a self-condensation reaction, to a trans-1-(azulen-1-yl)-2-(azulen-2-yl)ethylene derivative, the structure of which was verified by single-crystal X-ray diffraction analysis. The 2-formylazulenes obtained were transformed into 2-ethynylazulenes in good yields by a modified Seyferth-Gilbert reaction. The reactivity of a 1-iodoazulene bearing a 2-formyl function in palladium-catalyzed cross-coupling reactions has also been examined.ArticleEUROPEAN JOURNAL OF ORGANIC CHEMISTRY. 2018(9):1145-1157 (2018)journal articl

Synthesis of donor–acceptor chromophores by the [2 + 2] cycloaddition of arylethynyl-2H-cyclohepta[b]furan-2-ones with 7,7,8,8-tetracyanoquinodimethane

Arylethynyl-2H-cyclohepta[b]furan-2-ones reacted with 7,7,8,8-tetracyanoquinodimethane (TCNQ) in a formal [2 + 2] cycloaddition reaction, followed by ring opening of the initially formed cyclobutene derivatives, to afford the corresponding dicyanoquinodimethane (DCNQ) chromophores in excellent yields. The intramolecular charge-transfer (ICT) interactions between the 2H-cyclohepta[b]furan-2-one ring and DCNQ acceptor moiety were investigated by UV/Vis spectroscopy and theoretical calculations. The redox behavior of the novel DCNQ derivatives was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which revealed their multistep electrochemical reduction properties depended on the number of DCNQ units in the molecule. Moreover, a significant color change was observed by visible spectroscopy under electrochemical reduction conditions.ArticleORGANIC & BIOMOLECULAR CHEMISTRY. 10(12):2431-2438 (2012)journal articl

THE [2+2] CYCLOADDITION REACTION OF ETHYNYLATED 2H-CYCLOHEPTA[b]FURAN-2-ONES WITH 2,3-DICHLORO-5,6-DICYANO-1,4-BENZOQUINONE

Ethynylated 2H-cyclohepta[b]furan-2-ones reacted with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in a formal [2+2] cycloaddition reaction to afford the corresponding DDQ-adducts 10-15 in good yields.ArticleHETEROCYCLES. 83(10):2271-2274 (2011)journal articl

Synthesis and Redox Behavior of Cyanovinyl-Substituted 2H-Cyclohepta[b]furan-2-ones

Cyanovinyl-substituted 2H-cyclohepta[b]furan-2-ones 3, 4, 5 and 7 were prepared by the Wittig, Knoevenagel and electrophilic substitution reaction, respectively. The intramolecular charge-transfer (ICT) interactions between the 2H-cyclohepta[b]furan-2-one ring and cyanovinyl acceptor moiety were investigated by UV/Vis spectroscopy and theoretical calculations. The redox behavior of these novel compounds was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Significant color changes in these compounds were observed under electrochemical reduction conditions by visible spectroscopy.ArticleHETEROCYCLES. 86(1):305-315 (2012)journal articl

ChemInform Abstract: The [2 + 2] Cycloaddition Reaction of Ethynylated 2H-Cyclohepta[b]furan-2-ones with 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone.

Ethynylated 2H-cyclohepta[b]furan-2-ones reacted with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in a formal [2+2] cycloaddition reaction to afford the corresponding DDQ-adducts 10-15 in good yields.ArticleHETEROCYCLES. 83(10):2271-2274 (2011)journal articl

Synthesis of 2,6-Diaminoazulenes by the SNAr Reaction with Cyclic Amines

2-Amino-6-bromoazulene derivatives reacted with cyclic amines (pyrrolidine, piperidine and morpholine) under the sealed-tube conditions to afford the corresponding 2,6-diaminoazulenes in excellent yields.ArticleHETEROCYCLES. 90(1):85-88 (2015)journal articl

Synthesis, Properties, and Crystal Structure of DDQ-Adducts of Ethynylated 2H-Cyclohepta[b]furan-2-ones

Ethynylated 2H-cyclohepta[b]furan-2-ones reacted with 2,3-dichrolo-5,6-dicyano-1,4-benzoquinone (DDQ) in a formal [2+2] cycloaddition reaction to afford the corresponding DDQ-adducts in good yields. The electronic properties of the DDQ-adducts were investigated by UV/Vis spectroscopy. One of the DDQ-adducts was revealed the molecular structure by X-ray crystallographic analysis. The redox behavior of the new compounds was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV).ArticleHETEROCYCLES. 88(1):319-329 (2014)journal articl