title: The first halogen-substituted cyclotrigermenes: a unique halogen walk over the three-membered ring skeleton and facial stereoselectivity in the Diels-Alder reaction.
abstract: Dark red crystals of the halogen-substituted cyclotrigermenes [(tBu3Si)3Ge3X; X = Cl, Br, I] were obtained in good yields by the reaction of [(tBu3Si)3Ge3]+.TTFPB- (TTFPB- = tetrakis(2,3,5,6-tetrafluorophenyl)borate) with potassium halides (KCl, KBr, or KI) in diethyl ether. The crystal structures of the halogen-substituted cyclotrigermenes reveal a cis-bent Ge=Ge double bond, caused by the introduction of the electronegative halogen atom on the sp3 germanium atom of cyclotrigermene. In solution, an intramolecular halogen migration over the three-membered ring skeleton was observed. Facial stereoselectivity in the Diels-Alder reaction of new cyclotrigermenes with 2,3-dimethyl-1,3-butadiene is also reported.
authors.affiliation: Department of Chemistry, University of Tsukuba, Ibaraki, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Sekiguchi
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Ishida
authors.forename: Norihisa
authors.initials: N
authors.lastname: Fukaya
authors.forename: Masaaki
authors.initials: M
authors.lastname: Ichinohe
authors.forename: Nozomi
authors.initials: N
authors.lastname: Takagi
authors.forename: Shigeru
authors.initials: S
authors.lastname: Nagase