- Efficient asymmetric hydrogenation of (Z)-2-acetamidocinnamic acid catalyzed by the rhodium complex of modified n-Benzyl-(3R,4R)-3,4-bis(diphenylphosphino)pyrrolidine (degphos)
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Modified Degphoses (R,R)-MOD-, XYL-Degphos) have been prepared and catalytic asymmetric hydrogenetion of (Z)-2-acetamidocinnamic acid was carried out with their rhodium(]) cationic complexes. The catalytic activities of the modified Degphoses were enhanced.
- Inoguchi,Achiwa
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p. 818 - 820
(2007/10/02)
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- Enantioselective Catalysis, 4. Synthesis of N-Substituted (R,R)-3,4-Bis(diphenylphosphino)pyrrolidines. The Use of their Rhodium Complexes for the Asymmetric Hydrogenation of α-(Acylamino)acrylic Acid Derivatives
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A simple synthesis of (R,R)-3,4-bis(diphenylphosphino)pyrrolidine (6a) and some N-substituted derivatives 6b-m is described. 6l and 6m are optically active tetraphosphanes, composed of two (R,R)-3,4-bis(diphenylphosphino)pyrrolidine units and a dicarboxylic residue.The structure of the parent compound 6a was determined by X-ray diffraction.From the phosphanes 6a-m the cationic 1,5-cyclooctadiene-bisphosphane-rhodium complexes 7a-m were prepared.The complexes 7l and 7m are ligand bridged bis(rhodium) dications.The complexes 7a-m were used for the asymmetric catalytic hydrogenation of the α-(acylamino)acrylic acid derivatives 9a-l.Enantiomeric excesses up to 100percent were achieved.Between 1 and 70 at the optical yields do not depend on the hydrogen pressure.The substrate/catalyst ratio can be as high as 50000/1.
- Nagel, Ulrich,Kinzel, Elke,Andrade, Juan,Prescher, Guenter
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p. 3326 - 3343
(2007/10/02)
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