title: B(C6F5)3 -catalyzed transfer of dihydrogen from one unsaturated hydrocarbon to another.
abstract: A transition-metal-free transfer hydrogenation of 1,1-disubstituted alkenes with cyclohexa-1,4-dienes as the formal source of dihydrogen is reported. The process is initiated by B(C6 F5 )3 -mediated hydride abstraction from the dihydrogen surrogate, forming a Brønsted acidic Wheland complex and [HB(C6 F5 )3 ](-) . A sequence of proton and hydride transfers onto the alkene substrate then yields the alkane. Although several carbenium ion intermediates are involved, competing reaction channels, such as dihydrogen release and cationic dimerization of reactants, are largely suppressed by the use of a cyclohexa-1,4-diene with methyl groups at the C1 and C5 as well as at the C3 position, the site of hydride abstraction. The alkene concentration is another crucial factor. The various reaction pathways were computationally analyzed, leading to a mechanistic picture that is in full agreement with the experimental observations.
authors.affiliation: Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin (Germany) http://www.organometallics.tu-berlin.de.
authors.forename: Indranil
authors.initials: I
authors.lastname: Chatterjee
authors.affiliation: Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstrasse 4, 53115 Bonn (Germany) http://www.thch.uni-bonn.de/tc.
authors.forename: Zheng-Wang
authors.initials: ZW
authors.lastname: Qu
authors.affiliation: Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstrasse 4, 53115 Bonn (Germany) http://www.thch.uni-bonn.de/tc. grimme@thch.uni-bonn.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Grimme
authors.affiliation: Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin (Germany) http://www.organometallics.tu-berlin.de. martin.oestreich@tu-berlin.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Oestreich
keywords: Lewis acids; alkenes; boron; density functional calculations; hydrogenation