Diisobutylaluminum Hydride Promoted Cyclization of o‑(Trimethylsilylethynyl)styrenes to Indenes
datasetposted on 05.09.2014, 00:00 by Hidenori Kinoshita, Nobuyoshi Hirai, Katsukiyo Miura
The reaction of o-(trimethylsilylethynyl)styrenes with diisobutylaluminum hydride (DIBAL-H) provides 2-trimethylsilyl-1H-indenes efficiently. The cyclization mechanism involves regioselective hydroalumination of the alkynyl moiety, geometrical isomerization of the alkenylaluminums formed, and intramolecular carboalumination. With substrates bearing a 2-(trimethylsilyl)ethenyl group (R1 = Me3Si, R2 = R3 = H), bis-silylated benzofulvenes are obtained upon treatment of the reaction mixture with an excess amount of benzaldehyde.