Heterogeneous asymmetric reactions. Part 24. Heterogeneous catalytic enantioselective hydrogenation of the C=N group over cinchona alkaloid modified palladium catalyst

The enantioselective hydrogenation of C=N-C group containing compounds over modified metal catalysts is as yet an uninvestigated research area. This w ork contains results obtained on the hydrogenation of 1-pyrroline-2-carboxy late esters and sodium salt over cinchona alkaloid-modified alumina-support ed Pd catalyst. The effect of the reaction parameters and the structure of the alkaloid molecule on hydrogenation rate and enantioselectivity allowed us to assume that on the catalyst surface only a weak interaction exists be tween the modifier and the substrate, resulting in the low enantiomeric exc esses (up to 20%) obtainable in these reactions. (C) 2001 Wiley-Liss, Inc.