Synthesis of 1-(pyridyl, quinolyl, and isoquinolyl)azulenes by Reissert-Henze type reaction

Azulene derivatives reacted with N-oxide of several heterocycles in the presence of trifluoromethanesultonic anhydride (Tf(2)O) to afford 1-(pyridyl, quinolyl, and isoquinolyl)azulenes in good yield, respectively. In the case of the reaction with the 1-azulenyl methyl sulfide (12), 1,1'-biazulene derivative 13 was obtained under the similar reaction conditions. The first synthesis of unsymmetrical 1,3-di(pyridyl)azulene derivative was also established via our new preparation method following the electrophilic pyriclinylation using the reaction with pyridine in the presence of Tf(2)O.ArticleTETRAHEDRON LETTERS. 51(39):5127-5130 (2010)journal articl

Synthesis of 1,3-Bis(tetracyano-2-azulenyl-3-butadienyl)azulenes by the [2+2] Cycloaddition-Retroelectrocyclization of 1,3-Bis(azulenylethynyl)azulenes with Tetracyanoethylene

1,3-Bis(azulenylethynyl)azulene derivatives 9-14 have been prepared by palladium-catalyzed alkynylation of 1-ethynylazulene 8 with 1,3-diiodoazulene 1 or 1,3-diethynylazulene 2 with the corresponding haloazulenes 3-7 under Sonogashira-Hagihara conditions. Bis(alkynes) 9-14 reacted with tetracyanoethylene (TCNE) in a formal [2+2] cycloaddition-retroelectrocyclization reaction to afford the corresponding new bis(tetracyanobutadiene)s (bis(TCBDs)) 15-20 in excellent yields. The redox behavior of bis(TCBD)s 15-20 was examined by using CV and differential pulse voltammetry (DPV), which revealed their reversible multistage reduction properties under the electrochemical conditions. Moreover, a significant color change of alkynes 9-14 and TCBDs 15-20 was observed by visible spectroscopy under the electrochemical reduction conditions.ArticleCHEMISTRY-A EUROPEAN JOURNAL. 15(18):11903-11912 (2014)journal articl

Synthesis, Properties, and Redox Behavior of 1,1,4,4-Tetracyano-2-ferrocenyl-1,3-butadienes Connected by Aryl, Biaryl, and Teraryl Spacers

Aryl-substituted 1,1,4,4-tetracyano-1,3-butadienes (FcTCBDs) and bis(1,1,4,4-tetracyanobutadiene)s (bisFcTCBDs), possessing a ferrocenyl group on each terminal, were prepared by the reaction of a variety of alkynes with tetracyanoethylene (TCNE) in a [2+2] cycloaddition reaction, followed by retro-electrocyclization of the initially formed [2+2] cycloadducts (i.e., cyclobutene derivatives). The characteristic intramolecular charge transfer (ICT) between the donor (ferrocene) and acceptor (TCBD) moieties were investigated by using UV/ Vis spectroscopy. The redox behaviors of FcTCBDs and bis-FcTCBDs were examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which revealed their properties of multi-electron transfer depending on the number of ferrocene and TCBD moieties. Moreover, significant color changes were observed by visible spectroscopy under the electrochemical reduction conditions.ArticleCHEMISTRY-A EUROPEAN JOURNAL. 23(21):402-409 (2015)journal articl

Synthesis and Properties of Azulene-Substituted Donor-Acceptor Chromophores Connected by Arylamine Cores

1-Ethynylazulenes connected by several arylamine cores reacted with tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) in a formal [2+2] cycloaddition-cycloreversion reaction to afford the corresponding tetracyanobutadiene (TCBD) and dicyanoquinodimethane (DCNQ) chromophores, respectively, in excellent yields. The intramolecular charge-transfer (ICT) characters between the donor (azulene and arylamine cores) and acceptor (TCBD and DCNQ units) moieties were investigated by UV/Vis spectroscopy and theoretical calculations. The redox behavior of the new TCBD and DCNQ derivatives was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which revealed their multistep electrochemical reduction properties. Moreover, significant color changes were observed by visible spectroscopy under the electrochemical reduction conditions.ArticleEUROPEAN JOURNAL OF ORGANIC CHEMISTRY. 2013(34):7785-7799 (2013)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