New approaches to high-activity transition-metal catalysts for carbon-carbon bond forming reactions. Rhenium-containing phosphorus donor ligands for palladium-catalyzed Suzuki cross-couplings.
The rhenium complexes (eta 5-C5H5)Re(NO)(PPh3)((CH2)nPR2:) (n/R = 0/Ph, 0/t-Bu, 0/Me, 1/Ph, 1/t-Bu), which contain electron-rich and sterically congested phosphido moieties, give active catalysts for the title reaction; typical conditions (toluene, 60-100 degrees C): aryl bromide (1.0 equiv.), PhB(OH)2 (1.5 equiv.), K3PO4 (2.0 equiv.), Pd(OAc)2 (1 mol%), and a Re(CH2)nPR2: species or a 1:2 [Re(CH2)nPR2H]+X-/t-BuOK mixture (4 mol% rhenium).
Institut für Organische Chemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestrasse 42, 91054 Erlangen, Germany.
Sandra
S
Eichenseher
Klemenz
K
Kromm
Olivier
O
Delacroix
J A
JA
Gladysz