title: Iridium-Catalyzed Formal [4 + 1] Cycloaddition of Biphenylenes with Alkenes Initiated by C-C Bond Cleavage for the Synthesis of 9,9-Disubstituted Fluorenes.
abstract: An Ir-catalyzed intermolecular reaction of biphenylenes as a C4 unit with various alkenes as a C1 unit gave 9,9-disubstituted fluorenes in moderate to high yields. Preliminary mechanistic studies revealed that this formal [4 + 1] cycloaddition probably proceeds via C-C bond cleavage, alkene insertion, β-hydrogen elimination, intramolecular alkene insertion, and then reductive elimination. An example of enantioselective reaction was also disclosed.
authors.affiliation: Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University , 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Takano
authors.affiliation: International Center for Science and Engineering Programs (ICSEP), Waseda University , 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan.
authors.forename: Kyalo Stephen
authors.initials: KS
authors.lastname: Kanyiva
authors.affiliation: Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University , 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan.|JST, ACT-C, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Shibata