Synthesis and application of arylmonophosphinoferrocene ligands: ultrafast asymmetric hydrosilylation of styrene.
A short and efficient synthetic route to a novel class of atropisomeric and planar chiral 2-aryl-1-diphenylphosphanylferrocene ligands is presented. The modular design of the ligands allows a synthetic approach in which both the aromatic moiety and the phosphino substituent can be varied easily. This permits fine-tuning of steric and electronic properties. The ligands have been tested in the asymmetric hydrosilylation of styrene where enantioselectivities up to 90% are obtained. Optimization of the palladium-to-ligand ratio resulted in hitherto unparalleled turnover frequencies (TOF) exceeding 180 000 h(-1). The absolute stereochemistry of the ligands was determined from an X-ray structure. 2D NMR experiments in combination with ab initio calculations were used to assign the conformation of the atropisomeric biarylic scaffold.
Pedersen
Henriette Lodberg
HL
Department of Chemistry, Building 201, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
Johannsen
Mogens
M
D002384:Catalysis; D005296:Ferrous Compounds / Q000138:chemical synthesis*; D008024:Ligands; D000075163:Metallocenes; D008968:Molecular Conformation; D015394:Molecular Structure; D010720:Phosphines / Q000737:chemistry; D017655:Silicon Compounds / Q000737:chemistry; D013237:Stereoisomerism; D020058:Styrene / Q000737:chemistry
D005296:Ferrous Compounds; D008024:Ligands; D000075163:Metallocenes; D010720:Phosphines; D017655:Silicon Compounds; D020058:Styrene; C004998:ferrocene