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Synthesis and Redox Behavior of Bis(3‐methylthio‐1‐azulenyl)methyl Cations and Dications Connected by 2‐Thienyl and 2,5‐Thiophenediyl Spacers
Author(s) -
Shoji Taku,
Higashi Junya,
Ito Shunji,
Okujima Tetsuo,
Morita Noboru
Publication year - 2011
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201001212
Subject(s) - chemistry , dication , carbocation , redox , cyclic voltammetry , hydride , electrochemistry , differential pulse voltammetry , aldehyde , medicinal chemistry , inorganic chemistry , photochemistry , catalysis , organic chemistry , ion , electrode , metal
Novel bis(3‐methylthio‐1‐azulenyl)methyl cations 3a + and 3b + and dications 4a 2+ and 4b 2+ were synthesized by thehydride abstraction reaction of the corresponding hydride derivatives 7a , 7b , 8a , and 8b , which were readily prepared by the acid‐catalyzed condensation reaction of 6a and 6b with the corresponding aldehyde and dialdehyde with DDQ. The p K R + values of novel cations 3a + and 3b + and dications 4a 2+ and 4b 2+ were determined spectrophotometrically to examine the thermodynamic stability of these carbocations. The redox behavior of the mono‐ and dications was also examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which revealed their reversible electrochemical reduction properties, except for the case of dication 4b 2+ . Moreover, a significant color change was observed by visible spectroscopy under electrochemical reduction conditions. Dications 4a 2+ and 4b 2+ were also chemically reduced by Zn powder to afford thienoquinoid compounds 9a and 9b , respectively.