Premium
Synthesis and [2+2] Cycloaddition with Tetracyanoethylene of Ene–Diyne Scaffolds Bearing Ferrocenes at the Periphery
Author(s) -
Shoji Taku,
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.201100650
Subject(s) - tetracyanoethylene , chemistry , cycloaddition , ene reaction , sonogashira coupling , moiety , redox , ferrocene , cyclic voltammetry , cyclopentene , differential pulse voltammetry , photochemistry , derivative (finance) , fluorene , medicinal chemistry , electrochemistry , stereochemistry , organic chemistry , catalysis , palladium , polymer , financial economics , economics , electrode
Abstract The ene–diyne systems 1 and 2 , possessing ferrocenyl groups at the periphery, were prepared by a simple one‐pot Sonogashira–Hagihara coupling reaction of ethynylferrocene with 9‐dibromomethylene‐9 H ‐fluorene ( 4 ) and 9,10‐bis(dibromomethylene)‐9,10‐dihydroanthracene ( 5 ). Ene–diyne 1 reacted with tetracyanoethylene (TCNE) in a formal [2+2] cycloaddition reaction, followed by ring opening of the initially formed [2+2] cycloadduct, cyclobutene, to afford the corresponding 1,1,4,4‐tetracyanobutadiene (TCBD) derivative 6 in good yield. The redox behavior of the ene–diyne compounds 1 and 2 , and the TCBD derivative 6 was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which revealed their electrochemical oxidation properties with multi‐electron transfer depending on the number of ferrocene units in the molecule, in addition to the two‐electron reduction of the TCBD moiety in the case of TCBD derivative 6 . Moreover, a significant color change was observed by visible spectroscopy under electrochemical oxidation conditions and under reduction conditions in the case of TCBD derivative 6 .