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Chiral Bidentate (Phosphinophenyl)benzoxazine Ligands in Asymmetric Catalysis
Author(s) -
Bernardinelli Gérald H.,
Kündig E. Peter,
Meier Peter,
Pfaltz Andreas,
Radkowski Karin,
Zimmermann Nicole,
NeuburgerZehnder Margareta
Publication year - 2001
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(20011017)84:10<3233::aid-hlca3233>3.0.co;2-l
Subject(s) - chemistry , enantioselective synthesis , palladium , denticity , hydrosilylation , cyanation , catalysis , ligand (biochemistry) , acetophenone , enantiomer , allylic rearrangement , oxazole , chirality (physics) , stereochemistry , medicinal chemistry , combinatorial chemistry , organic chemistry , metal , quark , biochemistry , nambu–jona lasinio model , receptor , chiral symmetry breaking , physics , quantum mechanics
The new chiral bidentate (phosphinoaryl)benzoxazine ligands 2 were applied in asymmetric catalysis. Rhodium and copper complexes catalyzed the hydrosilylation of acetophenone and [4+2] cycloadditions with moderate enantioselectivity. Iridium complexes were used to hyrogenate di‐, tri‐, and tetrasubstituted alkenes, giving products with moderate to high enantiomer excesses. Enantioselective allylic substitution and Heck reactions catalyzed by [(phosphinoaryl)benzoxazine]palladium complexes occurred with high enantioselectivities. The results were similar to those obtained with the corresponding dihydro(phosphinoaryl)oxazole ligands. Comparison of the structures of (diphenylallyl)(benzoxazine)palladium and (diphenylallyl)(dihydrooxazole)palladium complexes showed that the coordination geometries and the chiral environments of the metal centers are very similar, which explains why the enantioselectivities induced by the two ligand classes are in the same range.