title: C-C coupling reactions of superstrong CF3 groups with C(sp2)-H bonds: reactivity and synthetic utility of zero-valent niobium catalyst.
abstract: It was found that zero-valent niobium is an efficient catalyst for the intramolecular C-C coupling reactions of o-aryl and o-alkenyl alpha,alpha,alpha-trifluorotoluene derivatives. The superstrong C-F bonds of CF3 groups and neighboring C(sp2)-H bonds were doubly activated, and fluorenes and indenes were obtained in good yields. The niobium fluorocarbenoid species is proposed to be the key intermediate.
authors.affiliation: Faculty of Science, Department of Chemistry, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Fuchibe
authors.forename: Ken
authors.initials: K
authors.lastname: Mitomi
authors.forename: Ryo
authors.initials: R
authors.lastname: Suzuki
authors.forename: Takahiko
authors.initials: T
authors.lastname: Akiyama