CHIRAL RHODIUM CARBOXYLATES AS ASYMMETRIC HYDROGENATION CATALYSTS

The comparative catalytic activities of a few chiral rhodium carboxyla to complexes in combination with chiral and achiral phosphines are des cribed. III the,hydrogenation of alpha-acetamidocinnamic acid and its methyl ester, differences are observed in turnover numbers and enantio selectivities. Diastereomeric interactions between chiral carboxylato and chiral phosphine moieties resulting in different rates are clearly seen. Arrhenius plots of(+) and (-)DIOP [DIOP = 2,3 isopropylidene 2, 3 dihydroxy-1,4 bis (diphenylphosphino) butane] with rhodium (-) mand alato complex give markedly different activation energies.