Sonogashira coupling using bulky palladium-phenanthryl imidazolium carbene catalysis.
[structure: see text] Bulky phenanthracenyl imidazolium-derived carbene ligands were investigated for copper-free Sonogashira coupling with terminal acetylenes. Aryl bromides and iodides gave coupled products in excellent yields from the Pd(PPh(3))(2)Cl(2) complex with potassium t-butoxide and 18-crown-6 in THF. A remarkable dependence on the size of the ligand was found. The highest yields were obtained with the bulky 2,9-dicyclohexyl-10-phenanthryl ligand 5.
Ma
Yudao
Y
Brigham Young University, Department of Chemistry and Biochemistry, C100 BNSN, Provo, Utah 84602-5700, USA.
Song
Chun
C
Jiang
Wei
W
Wu
Quansheng
Q
Wang
Yong
Y
Liu
Xueying
X
Andrus
Merritt B
MB
D000114:Acetylene / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry; D006838:Hydrocarbons; D007093:Imidazoles / Q000737:chemistry*; D008024:Ligands; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry*; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*; D010616:Phenanthrenes / Q000737:chemistry*
D006838:Hydrocarbons; D007093:Imidazoles; D008024:Ligands; D010616:Phenanthrenes; C030011:carbene; D010165:Palladium; D003300:Copper; D000114:Acetylene; D008697:Methane