title: Ring Expansion to 1-Bromo-1-alumacyclonona-2,4,6,8-tetraene by Insertion of Two Alkyne Molecules into the Al-C Bonds.
abstract: Treatment of 1-bromo-2,3,4,5-tetraethylalumole (1) with 3-hexyne afforded the corresponding product 1-bromo-1-alumacyclonona-2,4,6,8-tetraene (2), accompanied by the formation of hexaethylbenzene. In the crystalline state, 2 forms a Br-bridged dimer with a pseudo C2-symmetric and twisted AlC8 nine-membered ring. Deuterium-labeling experiments and DFT calculations on the reaction of 1 with 3-hexyne suggested that 1-bromo-1-alumacyclohepta-2,4,6-triene, which is formed by the insertion of one molecule of 1-hexyne into the Al-C bond of alumole 1, is the key intermediate for the generation of 2 as well as hexaethylbenzene.
authors.affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan).
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Agou
authors.affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan).
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Wasano
authors.affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan).
authors.forename: Takahiro
authors.initials: T
authors.lastname: Sasamori
authors.affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan).|Fukui Institute for Fundamental Chemistry, Kyoto University, Kyoto, Kyoto 606-8103 (Japan).
authors.forename: Jing-Dong
authors.initials: JD
authors.lastname: Guo
authors.affiliation: Fukui Institute for Fundamental Chemistry, Kyoto University, Kyoto, Kyoto 606-8103 (Japan).
authors.forename: Shigeru
authors.initials: S
authors.lastname: Nagase
authors.affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan). tokitoh@boc.kuicr.kyoto-u.ac.jp.
authors.forename: Norihiro
authors.initials: N
authors.lastname: Tokitoh
keywords: DFT calculations; alkynes; aluminum; ring expansion; structure elucidation