title: Probing M-O Bond Cleavage in Silicon and Titanium Bisenolate Radical Cations.
abstract: In this study, several novel sterically congested silicon and titanium bisenolates of exceptional hydrolytic stability have been synthesized and characterized. The structure of the titanium bisenolate T2 could be determined by X-ray structure analysis. Preparative one-electron oxidation of the sterically shielded metal bisenolates S1-S4 and T1-T2 led to formation of the benzofurans B1 and B2. As the benzofuran formation is strong evidence for an initial M-O bond cleavage process at the stage of the initial radical cation we were able to measure the kinetics of this scission process using cyclic voltammetry techniques (first-order rate constants range at k(f) = 0.1-90 s(-)(1)). These data indicate that both silicon and titanium bisenolates are interesting candidates for oxidative intramolecular carbon-carbon bond formation processes.
authors.affiliation: Institut für Organische Chemie and Institut für Anorganische Chemie der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schmittel
authors.forename: Armin
authors.initials: A
authors.lastname: Burghart
authors.forename: Helmut
authors.initials: H
authors.lastname: Werner
authors.forename: Matthias
authors.initials: M
authors.lastname: Laubender
authors.forename: Rolf
authors.initials: R
authors.lastname: Söllner