Open AccessWalphos versus Biferrocene-Based Walphos Analogues in the Asymmetric Hydrogenation of Alkenes and Ketones
Author(s) -
Afrooz Zirakzadeh,
M. Gross,
Yaping Wang,
Kurt Mereiter,
Walter Weissensteiner
Publication year - 2014
Publication title -
organometallics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.231
H-Index - 172
eISSN - 1520-6041
pISSN - 0276-7333
DOI - 10.1021/om401074a
Subject(s) - chemistry , asymmetric hydrogenation , ligand (biochemistry) , rhodium , ruthenium , catalysis , noyori asymmetric hydrogenation , medicinal chemistry , stereochemistry , transfer hydrogenation , organic chemistry , enantioselective synthesis , receptor , biochemistry
Two representative Walphos analogues with an achiral 2,2″-biferrocenediyl backbone were synthesized. These diphosphine ligands were tested in the rhodium-catalyzed asymmetric hydrogenation of several alkenes and in the ruthenium-catalyzed hydrogenation of two ketones. The results were compared with those previously obtained on using biferrocene ligands with a C 2 -symmetric 2,2″-biferrocenediyl backbone as well as with those obtained with Walphos ligands. The application of one newly synthesized ligand in the hydrogenation of 2-methylcinnamic acid gave ( R )-2-methyl-3-phenylpropanoic acid with full conversion and with 92% ee. The same ligand was used to transform 2,4-pentanedione quantitatively and diastereoselectively into ( S , S )-2,4-pentanediol with 98% ee.