Chiral phosphine-phosphite ligands in the highly enantioselective rhodium-catalyzed asymmetric hydrogenation. |
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| Authors: | S Deerenberg O Pàmies M Diéguez C Claver P C Kamer P W van Leeuwen |
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| Affiliation: | Institute of Molecular Chemistry, Universiteit van Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands. |
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| Abstract: | We have investigated a series of enantiopure phosphine-phosphite ligands (P(1)-P(2) = ligands 1-4) in the rhodium-catalyzed asymmetric hydrogenation reaction. Intermediate [Rh(P(1)-P(2))(cod)]BF(4) and [Rh(P(1)-P(2))(5)]BF(4) complexes (cod = 1,5-cyclooctadiene; 5 = methyl acetamidoacrylate ester) were observed by (31)P[(1)H] NMR. The [Rh(P(1)-P(2))(cod)]BF(4) complexes were precursors to active catalysts of the asymmetric hydrogenation reaction of several prochiral dehydroamino acid derivatives under mild reaction conditions (1 bar of hydrogen and 20 degrees C). The enantiomeric excess reached up to 99%. |
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