Peñafiel Andrés, Itziar, Pastor, Isidro M., Yus, Miguel
NHC-Ligand Effectiveness in the Fluorine-Free Hiyama Reaction of Aryl Halides
European Journal of Organic Chemistry. 2013, 2013(8): 1479-1484. doi:10.1002/ejoc.201201066
URI: http://hdl.handle.net/10045/40222
DOI: 10.1002/ejoc.201201066
ISSN: 1434-193X (Print)
Abstract: 
1-Benzyl-3-(2-hydroxy-2-phenylethyl)imidazolium chloride (5), which is a precursor of an N-heterocyclic carbene ligand, in combination with palladium acetate, has been employed as an effective catalyst for the fluorine-free Hiyama reaction. A systematic study of the catalytic mixture, by a 32 factorial design, has revealed that both the amount of palladium and the Pd/NHC precursor ratio are important factors for obtaining good yields of the coupling products, indicating an interaction between them. The best catalytic system involves mixing 0.1 mol-% palladium acetate in a 1:5 ratio (Pd/salt 5), which allows the effective coupling of a range of aryl bromides and chlorides with trimethoxy(phenyl)silane. The Hiyama reactions are carried out in NaOH solution (50 % H2O w/w), at 120 °C under microwave irradiation during 60 min.
Keywords:Synthetic methods, Homogeneous catalysis, Palladium, Nitrogen heterocycles, Cross-coupling, Carbene li­gands
Wiley-VCH Verlag GmbH & Co. KGaA
info:eu-repo/semantics/article