Diphosphinite ligands, derived from inexpensive d-(+)-xylose, were tested in the rhodium- and iridium-catalyzed asymmetric hydrogenation of prochiral olefins. Our results show that the enantiomeric excesses are strongly dependent on the absolute configuration of the C-3 stereocenter of the carbohydrate backbone and on the metal source. Enantiomeric excesses of up to 78% with moderate to high activities were obtained under very mild reactions conditions with the catalytic systems [Rh(cod)( 2)]BF 4 and [Ir(cod)( 1)]BF 4.