title: Synthesis and application of arylmonophosphinoferrocene ligands: ultrafast asymmetric hydrosilylation of styrene.
abstract: 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.
authors.affiliation: Department of Chemistry, Building 201, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Henriette Lodberg
authors.initials: HL
authors.lastname: Pedersen
authors.forename: Mogens
authors.initials: M
authors.lastname: Johannsen
mesh_terms: 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
chemical_list: D005296:Ferrous Compounds; D008024:Ligands; D000075163:Metallocenes; D010720:Phosphines; D017655:Silicon Compounds; D020058:Styrene; C004998:ferrocene