Chiral 1,2-bis(phosphanes) 13, devoid of individual chiral centers, have be
en prepared in three steps from chiral sulfoxide 10. Their corresponding rh
odium complexes were used as catalysts for asymmetric hydrogenation, giving
high ee values (less than or equal to 95%) in the reduction of itaconic ac
id or its ester. A cationic rhodium complex involving coordination of two m
olecules of 13b and one molecule of oxygen has been isolated and its crysta
l structure established.