ASYMMETRISCHE KATALYSEN. XXX. ENANTIOSELEKTIVE HYDRIERUNG VON CROTONSAEUREDERIVATEN MIT RHODIUM-PHOSPHIN-KATALYSATOREN

Article abstract of DOI:10.1016/S0022-328X(00)99521-4

The Z- and E-isomers of the α-N-benzoylamino-2-butenoic acid methyl ester, the E/Z mixtures of α-N-benzoylamino-2-butenoic acid, and the Z-form of α-N-acetylamino-2-butenoic acid were hydrogenated enantioselectively.The hydrogenation products are derivatives of α-aminobutyric acid, which can be reduced to aminobutanol, the optically active component of the antituberculosis drug (+)-ethambutol.In situ catalysts consisting of 2 and the optically active phosphine ligands (+)- and (-)-Norphos, (+)-Prophos, (-)-Chiraphos, (-)-BPPFA, (-)-Diop, and (+)- and (-)-CpMn(CO)2diop were used.The best results were obtained with the substrate (Z)-α-acetylamino-2-butenoic acid and the catalyst 2/(-)-Norphos with 91.5percent e.e.