title: Coupling of titanacyclopentadienes with a Cp ligand and elimination of one substituent.
abstract: Titanacyclopentadienes, prepared from [Cp2TiBu2] and either two equivalents of an alkyne or a diyne, were treated with PMe3 (3 equiv) at 50 °C for 3 h and then with azobenzene at room temperature for 12 h to give 4,5,6-trisubstituted indene derivatives with the loss of one substituent in good yields. This reaction contrasts sharply with our previously reported reaction for the formation of 4,5,6,7-tetrasubstituted indene derivatives without the loss of substituents by the treatment of titanacyclopentadienes with azobenzene without PMe3. (13)C NMR spectroscopy of the product derived from a (13)C-enriched complex revealed that the five carbon atoms originating from a Cp ligand were arranged linearly in the trisubstituted indene derivatives, in contrast to the 4,5,6,7-tetrasubsituted indene derivatives, in which the corresponding five carbon atoms are arranged in a ring.
authors.affiliation: Catalysis Research Center and Graduate School of Life Science, Hokkaido University, Kita-ku, Sapporo 001-0021 (Japan).
authors.forename: Yuki
authors.initials: Y
authors.lastname: Mizukami
authors.forename: Haijun
authors.initials: H
authors.lastname: Li
authors.forename: Kiyohiko
authors.initials: K
authors.lastname: Nakajima
authors.forename: Zhiyi
authors.initials: Z
authors.lastname: Song
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Takahashi
mesh_terms: D066241:Carbon-13 Magnetic Resonance Spectroscopy; D003517:Cyclopentanes / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D014025:Titanium / Q000737:chemistry*
chemical_list: D003517:Cyclopentanes; D008024:Ligands; D014025:Titanium
keywords: CC activation; CC coupling; cleavage reactions; cyclopentadienyl ligands; titanocenes