Catalysis of Organic..

296Chiral Ferrocene LigandsTable 1. Hydrogenation of methyl α-acetamido cinnamate (MAC) and dimethylitaconate (DMI) in MeOH.CHN C 6H 5NH HOO CHC 6H 5Ligand, [Rh(NBD) 2]BF 4b, 1 bar H 2, 25 °C3O 0.25 M MAC in MeOH, S/Rh = 200 a ,OOH OMACODMICH 3OO CH 3O0.25 M DMI in MeOH, S/Rh = 200 a ,Ligand, [Rh(NBD) 2]BF 4b, 1 bar H 2, 25 °COCH 3OH O CHLigand # P Substrate Rh / Lig reaction Conversio ee (%)time [h] (%)1 2 MAC 0.91 0.4 98 812 4 MAC 1.82 0.3 98 872 4 MAC 0.91 0.3 72 851 2 DMI 0.91 0.4 100 992 4 DMI 2 0.3 100 992 4 DMI 0.91 0.3 100 923 2 MAC 0.95 1 27 144 4 MAC 2 1 67 644 4 MAC 1 1 66 743 2 DMI 0.91 1 49 134 4 DMI 1.82 1 100 534 4 DMI 0.91 1 80 455 2 MAC 1 1 63 986 4 MAC 1.9 1 80 975 2 DMI 0.95 1 100 956 4 DMI 2 1 100 626 4 DMI 0.91 1 100 52S/Rh = substrate to rhodium ratio (200 corresponds to 0.5% Rh loading)NBD = norbornadiene# P = number of phosphines in the ligand.% ee = 100% x (moles major enantiomer – moles minor enantiomer) /(moles major enantiomer + moles minor enantiomer)The hydrogenation reactions were all performed at the same substrate-torhodiumratio and, since the tetraphosphine ligands 2, 4, and 6 can form bidentateO