title: 9-Ethynylfluoroenyl Radicals: Regioselective Dimerization and Post Ring-Cyclization Reactions.
abstract: 9-Ethynylfluorenyl radical derivatives were readily prepared in situ and underwent simultaneous intermolecular coupling reactions. Interestingly, the dimerization process took place in either a head-to-tail or a head-to-head mode between the acetylenic or the allenic resonance forms dependent on the terminal substituents, which could be well explained by their different spin distribution and steric hindrance effects. The structures of the products were confirmed by X-ray crystallographic and other spectroscopic analyses. It was also found that the newly generated dipropinyl dimers underwent a rearrangement and ring-cyclization reaction at room temperature, eventually giving unique difluorenylidene cyclobutene derivatives.
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, P. R. China.
authors.forename: Shuhai
authors.initials: S
authors.lastname: Qiu
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education), College of Chemistry and Chemical Engineering, Hunan Normal University , Changsha 410081, P. R. China.
authors.forename: Youyu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: College of Chemistry and Materials Engineering, Wenzhou University , Wenzhou 325035, P. R. China.
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST) , Wuhan 430074, P. R. China.
authors.forename: Lipiao
authors.initials: L
authors.lastname: Bao
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, P. R. China.
authors.forename: Youhua
authors.initials: Y
authors.lastname: Hong
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, P. R. China.
authors.forename: Zebing
authors.initials: Z
authors.lastname: Zeng
authors.affiliation: Department of Chemistry, National University of Singapore , 3 Science Drive 3, 117543 Singapore.
authors.forename: Jishan
authors.initials: J
authors.lastname: Wu