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Chiral Oxo‐ and Oxy‐Functionalized Diphosphane Ligands Derived from Camphor for Rhodium( I )‐Catalyzed Enantioselective Hydrogenation
Author(s) -
Komarov Igor V.,
Monsees Axel,
Spannenberg Anke,
Baumann Wolfgang,
Schmidt Ute,
Fischer Christine,
Börner Armin
Publication year - 2003
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200301)2003:1<138::aid-ejoc138>3.0.co;2-o
Subject(s) - enantioselective synthesis , chemistry , rhodium , camphor , diastereomer , substituent , catalysis , medicinal chemistry , organic chemistry , stereochemistry
The synthesis of two series of diastereomeric oxo‐ and oxy‐substituted diphosphanes 7a − 9a and 7b − 9b , as well as an analogous nonfunctionalized diphosphane 17 , was performed starting from ( R )‐camphor. The new diphosphanes were used as ligands in the enantioselective rhodium( I )‐catalyzed hydrogenation of functionalized olefins − α‐ and β‐dehydroamino acids and their esters − in order to elucidate the effect of the oxo‐ and oxy‐functional groups. The enantioselectivities, ranging from 2−90% ee , and the rates were strongly dependent on the type and relative position of the oxo or oxy substituent in the catalyst. Possible explanations for the effects are given. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)