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Chiral Complexes of Rh I Containing Binaphthalene‐Core P,S‐Heterobidentate Ligands − Synthesis, Characterization, and Catalytic Activity in Asymmetric Hydrogenation of α,β‐Unsaturated Acids and Esters
Author(s) -
Gladiali Serafino,
Grepioni Fabrizia,
Medici Serenella,
Zucca Antonio,
Berente Zoltán,
Kollár László
Publication year - 2003
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200390077
Subject(s) - chemistry , enantiopure drug , catalysis , ligand (biochemistry) , asymmetric hydrogenation , derivative (finance) , ring (chemistry) , chelation , stoichiometry , stereochemistry , medicinal chemistry , crystal structure , enantioselective synthesis , crystallography , organic chemistry , receptor , biochemistry , financial economics , economics
The enantiopure complexes 3a and 3b [Rh(NBD)(P,S)] + BF 4 − [P,S = ( S )‐2‐(diphenylphosphanyl)‐2′‐(methylthio)‐1,1′‐binaphthalene ( a ); ( S )‐2‐(diphenylphosphanyl)‐2′‐(isopropylthio)‐1,1′‐binaphthalene ( b )] have been prepared from [Rh(NBD)(THF) 2 ] + BF 4 − by reaction with a stoichiometric amount of the appropriate P,S‐heterobidentate ligand. Single‐crystal X‐ray analysis of the S ‐methyl derivative shows that the seven‐membered chelate ring is locked in a boat‐like conformation with the methyl group in the equatorial position. Variable‐temperature NMR measurements confirm that this conformation is maintained in solution and that the dynamic behaviour displayed by the complex is due to pseudo‐rotation of the diolefin. Complexes 3 have been tested in the asymmetric hydrogenation of α,β‐unsaturated acids and esters. Enantioselectivities of up to 60% ee have been recorded. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)