A new modifier, 2-phenyl-9-deoxy-10,11-dihydrocinchonidine, has been synthesized for the enantioselective hydrogenation of ketopantolactone and α-ketoesters over chirally modified Pt/alumina. The results indicate flat adsorption of cinchonidine with the quinoline ring oriented parallel to the surface and, furthermore, give some insight into the conformation of the modifier within the transition state complex. Comparison of the structures and catalytic behaviors of 9-deoxycinchonidine and the new modifier allows to exclude the previously proposed perpendicular or tilted adsorption of the quinoline ring via the N atom.