Walphos versus Biferrocene-Based Walphos Analogues
in the Asymmetric Hydrogenation of Alkenes and Ketones
Afrooz Zirakzadeh
Manuela A. Groß
Yaping Wang
Kurt Mereiter
Walter Weissensteiner
10.1021/om401074a.s002
https://acs.figshare.com/articles/dataset/Walphos_versus_Biferrocene_Based_Walphos_Analogues_in_the_Asymmetric_Hydrogenation_of_Alkenes_and_Ketones/2032272
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 <i>C</i><sub>2</sub>-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 (<i>R</i>)-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 (<i>S</i>,<i>S</i>)-2,4-pentanediol with 98% ee.
2015-12-17 01:51:07
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KetonesTwo representative Walphos analogues
biferrocene ligands
acid
hydrogenation
Walphos ligands
Asymmetric Hydrogenation
biferrocenediyl
diphosphine ligands