ASYMMETRIC HYDROGENATION OF DEHYDROAMINO ACIDS AND DEHYDRODIPEPTIDES WITH RHODIUM(I)-MODIFIED DIOP CATALYSTS.

Article abstract of DOI:10.1246/bcsj.57.1897

( minus )-DIOP was modified in two ways: i), introduction of a large aromatic substituent at the dioxolane ring of ( minus )-DIOP and ii), replacement of one diphenylphosphino group by diarylphosphino group to give unsymmetrical DIOPs. Modification at the dioxolane ring had a small effect on the asymmetric induction by DIOP in the hydrogenation. Modification at the phosphino group affected the stereocontrol by the ligand and the unsymmetrical DIOP with di-2-naphthylphosphino group gave higher optical yields than ( minus )-DIOP for the hydrogenation of alpha -acetamidocinnamic acid and dehydrodipeptides.