title: Brönsted acid-mediated intramolecular cyclization of biaryl triazenes for the synthesis of fluorenes and 9,10-dihydro-phenanthrenes.
abstract: The efficient synthesis of fluorenes from biaryl triazenes is successfully developed. Up to 27 examples of biaryl triazenes are converted into their corresponding fluorene derivatives in the presence of CF3COOH (4.0 equiv). Mechanism research indicates that the reaction undergoes concerted processes, and pentacoordinate carbocations may be involved in these reactions.
authors.affiliation: Department of Chemistry, Zhejiang Sci-Tech University , Hangzhou, Zhejiang 310018, PR China.
authors.forename: Lijun
authors.initials: L
authors.lastname: Xu
authors.forename: Weijun
authors.initials: W
authors.lastname: Yang
authors.forename: Lili
authors.initials: L
authors.lastname: Zhang
authors.forename: Maozhong
authors.initials: M
authors.lastname: Miao
authors.forename: Zhigen
authors.initials: Z
authors.lastname: Yang
authors.forename: Xin
authors.initials: X
authors.lastname: Xu
authors.forename: Hongjun
authors.initials: H
authors.lastname: Ren