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Amino Alcohol Coordination in Ruthenium(II)‐Catalysed Asymmetric Transfer Hydrogenation of Ketones
Author(s) -
I. Petra Daniëlle G.,
Kamer Paul C. J.,
van Leeuwen Piet W. N. M.,
Goubitz Kees,
Van Loon Arjen M.,
de Vries Johannes G.,
Schoemaker Hans E.
Publication year - 1999
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/(sici)1099-0682(199912)1999:12<2335::aid-ejic2335>3.0.co;2-l
Subject(s) - chemistry , transfer hydrogenation , ruthenium , acetophenone , catalysis , ligand (biochemistry) , alcohol , medicinal chemistry , noyori asymmetric hydrogenation , stereochemistry , organic chemistry , combinatorial chemistry , biochemistry , receptor
The nature of ruthenium‐amino alcohol precursors in the catalytic cycle of asymmetric hydrogen transfer reactions was studied using two C 2 ‐symmetrical tetradentate ligands ( 1 and 2 ) that were synthesised from (nor)ephedrine. The structure of the catalyst precursor was examined through catalysis and NMR experiments. It was shown that the active catalyst contains one ligand per metal, which coordinates in a didentate N,O fashion ( 9 ). In addition, a Ru II Cl 2 complex, in which N , N′ ‐bis(2‐hydroxy‐1‐methyl‐2‐phenylethyl)‐1,2‐diaminoethane ( 1 ) coordinates through two nitrogen atoms, was structurally characterised by X‐ray diffraction ( 8 ). – Based on the results of this study a series of new amino alcohol ligands was synthesised from easily available starting materials. Optimisation of the amino alcohol ligand structure resulted in the most effective chiral amino alcohol ligand ( 5 ) so far that is capable of reducing acetophenone at 0 °C with up to 97% ee in the Ru II ‐catalysed transfer hydrogenation.